Noticed something interesting on my LT5...

[bdw18_123]

I was in the garage tonight looking at the numbers on my '90 LT5 that I have on an engine stand and noticed something interesting.

The Mercury Marine numbers stamped on the oil-pan flange, driver's side look like the last part of the "10ZSH..." number was ground out and redone. Mercury Marine stamped the "10ZSH..." number, right?

Apparently, they didn't completely grind out the mistake, you can see very faintly that the end part of the previous number said "X0052299". They must have accidentally stamped the last 4 digits of the VIN instead of the "0001" that was supposed to be there. So Mercury Marine knew the VIN's of the cars that each engine was going in?

Here a picture of the driver's side oilpan flange showing the number:
http://i13.photobucket.com/albums/a292/bdw18_123/IMG_0837.jpg

Then I noticed that the VIN stamp that GM puts on was also re-done (what a coincidence, GM & Mercury Marine both screwed up their stamps on the same engine!). The passenger side transmission-mount flange of the LT5 where the VIN stamp usually is, is stamped out with "X"-type things.

Here is a picture of it:
http://i13.photobucket.com/albums/a292/bdw18_123/IMG_0844.jpg

Reading this from the ZR-1 Net Registry site explained that one:

"GM NEVER re-stamps an engine except for one reason which we will mention below. First, let's discuss the stamping process:

VIN numbers are put into a handle, then stamped on the right rear of the engine, where there is an upright portion. This stamping was done at the third station on the transmission line when the trans was attached to the LT5. Both the trans and the engine were stamped with the same stamp. As this was done manually, there is a chance that a mistake could be made. Sometimes the stamp wasn't changed after a previous stamp was made, maybe the L98 engine stamp was used mistakenly on a LT5. After all, they were both coming down the same line, a ZR-1 no closer than one every three units (there had to be 2 vehicles between each ZR-1 for assembly time purposes).

After the stamping process, the next station performed a quality control inspection, verifying the VIN stamped matched the build sheet. If a problem is discovered, there were alternate locations for a re-stamp. After the wrong VIN was XXXX'd out, the correct stamp was made on the opposite side of the engine, near the same place. Same with the trans."

The correct VIN was then re-stamped on the driver's side flange (the "9's" are hard to see, but they are there):
http://i13.photobucket.com/albums/a292/bdw18_123/IMG_0847.jpg

The transmission VIN stamp is the correct "1L5802299" though and is not "X'd" out so the LT5 must have gotten stamped before the transmission.

Just thought that that was interesting, so I thought I'd post it up. Anyone else find re-stamps on their LT5's?

[HAWAIIZR-1]

Thanks, I'll have to check mine out from curiosity now since my block is on the stand too. :cheers:

[ZR1Vette]

Interesting... where exactly is the stamp "driver's side oil pan flange" and is it visible without the engine removed?

When I was down at BG watching my C6 being assembled went over the the engine assembly area (meaning the engines sans accessories and drive train that come from the engine manufacturing facility are mated to accessories) the VINs are all computer/bar coded generated and then a device is placed in the correct location of the engine and 'engraves' the number...no stamping or human involvement (other than placing the 'engraver' on the engine)... at the same time elsewhere in the assembly plant a device is 'engraving' the chassis with the same VIN.

[1989ZR1#74]

Another possibility is the engine was a MM remanufacture swap. Do you know the entire history of the car? Like you said, what are the odds?

How does 3/07/1990 engine cast match with your build date?

[Ccmano]

Another possibility is the engine was a MM remanufacture swap. Do you know the entire history of the car? Like you said, what are the odds?

How does 3/07/1990 engine cast match with your build date?

Sounds about right time frame wise. My 90' is sn#1723 with a casting date of 2/15/90. No cross outs and engine is original to the chassis.
H
:cheers:

[rhipsher]

Must of been a Friday car.:sign10:

[bdw18_123]

Interesting... where exactly is the stamp "driver's side oil pan flange" and is it visible without the engine removed? ...

It's on the flange of the block on the driver's side just above the oilpan. It's a number stamp that Mercury Marine stamps on at the time of engine manufacture. It would probably be very hard to see it with the engine installed, the exhaust manifold would be in the way.

Here is a pic of the driver's side of my LT5 with the driver's head removed to give you an idea where the MM stamp is at (ignore the red dots at the top, was a mistake :mrgreen:):
http://i13.photobucket.com/albums/a292/bdw18_123/IMG_0853.jpg

Another possibility is the engine was a MM remanufacture swap. Do you know the entire history of the car? Like you said, what are the odds?

How does 3/07/1990 engine cast match with your build date?

What exactly is involved with a "MM remanufacture swap"? I don't know what the build date of my car is, is it on the build sheet or do you have to calculate it somehow?. There was no build sheet on my gas tank, however I did pull the one out of the front crossmember. Lots of it is unreadable though, I need to get a copy from the NCM.

Here is a pic of the buildsheet from the crossmember:
http://i13.photobucket.com/albums/a292/bdw18_123/IMG_0854.jpg

As for the history of my car, I do have a carfax printout (I know that doesn't tell you a whole lot) and also a bunch of service records from the early ninties. The guy I bought the car from, bought it new, so I am only the 2nd owner.

The first record that the Carfax shows is an emissions inspection report with a date of 12/30/1993. There are no records before that. The PO did mention that the car had been sitting at the dealership for awhile, so maybe that's why there's no records before '93?

[1989ZR1#74]

It's on the flange of the block on the driver's side just above the oilpan. It's a number stamp that Mercury Marine stamps on at the time of engine manufacture. It would probably be very hard to see it with the engine installed, the exhaust manifold would be in the way.

Here is a pic of the driver's side of my LT5 with the driver's head removed to give you an idea where the MM stamp is at at (ignore the red dots at the top, was a mistake :mrgreen:):



Well it is a Friday Mistakes happen.

[1989ZR1#74]

The LT5 was not serviceable at the local Chevy dealer. If there was a problem with the engine they would pull it and send it back to Oklahoma and have MM rebuild it, or the customer could opt for a replacement MM LT5. I was thinking outloud that perhaps this ZR-1 had it's engine replaced by MM under warantee. And the factory numbers reapplied. The bad LT5 would then be rebuilt and placed in inventory for a future replacement. I have never seen a replacement LT5, but I would imagine the markings would deviate from standard production practice. Since, as you point out, the likelyhood of both MM and BG making a mistake is rather low, it should be considered. It would be the equivalent of a CE block in C2/C3 corvette world.

[1989ZR1#74]

The build date would be close to the date found at the top middle of your build sheet. If it is still visable it will be in Year/day format. The day will be listed in solar calendar/Ordinal date format, (often mistaken for Julian) meaning 00/60 would be the 60th day of 2000 or February 29th, 2000.

http://www.fourmilab.ch/documents/calendar/

http://www.fs.fed.us/raws/book/julian.shtml

[LGAFF]

The LT5 was not serviceable at the local Chevy dealer. If there was a problem with the engine they would pull it and send it back to Oklahoma and have MM rebuild it, or the customer could opt for a replacement MM LT5. I was thinking outloud that perhaps this ZR-1 had it's engine replaced by MM under warantee. And the factory numbers reapplied. The bad LT5 would then be rebuilt and placed in inventory for a future replacement. I have never seen a replacement LT5, but I would imagine the markings would deviate from standard production practice. Since, as you point out, the likelyhood of both MM and BG making a mistake is rather low, it should be considered. It would be the equivalent of a CE block in C2/C3 corvette world.

My 90 engine was rebuilt in 1993, numbers match.

[1989ZR1#74]

My 90 engine was rebuilt in 1993, numbers match. So the LT5 was shipped back to MM, they rebuilt it and sent it back for install. The customer had the option of a replacement LT5 to expidite the repair. So the rebuilds look the same, now we need to find a swap LT5..

[bdw18_123]

I searched through the service records that I have on the car, but I didn't find anything mentioning the LT5 getting removed and sent off for repair.

I did find the temp ID tag for the car when it was first delivered from the lot. Delivery date to the original owner from the dealer was 11/22/1990. Then on 12/13/1990, it went in to a GM dealer for service. 8 issues are listed (a heck of a lot for a brand new, couple week old car). One of them states "Engine RPM's surge badly - when coming off fwy wants to stall, nec. to throttle" and just below a tech wrote "Check & set min idle to specs", which I guess is all they did to fix the problem. I don't think re-setting the min idle to specs would fix bad rpm surging.

The next service record was on 8/14/92, so who knows what happened between those dates. One clue is a receipt from the DMV stating "Acknowledgement of Nonoperational Status" valid from 11/24/91-11/24/92, with an issue date of 11/27/91. License plate number listed on this matches my ZR-1. Weird for it to be put into Non-Op with it only being 1 year old, maybe it was during that time that the swap was done (if there was one)?

[LGAFF]

I just have a service invoice from the dealer that says "Engine Rebuild" no cost listed. I spoke to prior owner, Former CEO of Illinois Tool, and he did not remember why they redid the motor, all he recalled was that it took forever to get it back. I would be surprised if it went back to Merc Marine......car had 69K miles on it. Prior owner said it was done at no charge however.

[A26B]

I have friends at Mercury who were core personnel in the LT5 program. I'll ask them about rebuilds @ MM. Frankly, I would be very surprised if any engines were rebuilt at MM.

[1989ZR1#74]

I have friends at Mercury who were core personnel in the LT5 program. I'll ask them about rebuilds @ MM. Frankly, I would be very surprised if any engines were rebuilt at MM.

Let me ask then if not MM where would it go to?

as LGAFF said " took forever to get it back" back from where?

I have read in several sources (not available to me right now) that it was what they did. The LT5 was way too complex to rebuild at a dealer.

[1989ZR1#74]

From the registries archives:

"However, the question still remains: once an LT5 problem is diagnosed as being other than with engine management, what framework is in place to acquaint dealer service departments with the revolutionary technology of the LT5? At the press introduction of the LT5 at Riverside, California last June, that question was raised. Chevrolet said that training would commence a few months before the introduction of the ZR1 and until servicing ability is up to speed, any LT5 problem requiring the opening-up of the motor will be handled with an engine exchange. The dealer will remove the offending LT5, replace it with a known-good unit then ship the bad motor to Mercury for repairs. "

http://www.zr1netregistry.com/LT5tech.htm

[1989ZR1#74]

So #2299 has an LT5 with a deviation in the MM stamp/markings, and with the BG stamp/markings. Both correcting a previous mark/stamping. It was clearly done at two seperate points of manufature 100s of miles apart. It was delivered to customer on 11/22/1990. It has a block casting date of 03/07/90. It has a documented history of being off the road for a year early in it's life. Engines, at least in the early days of the ZR-1 were shipped back to MM for repair. The only point I can not foot note right now is my belief that the customer was given the option of repair their LT5 or replacing it with an available "core" from MM.

There is nothing in what I just typed that will ensure that that did happen, but there is also nothing as of yet to prove it did not happen.

Another thought/theory, "Mary" the inmfamous BG lot driver who in 1990 was cold starting ZR-1s at WOT and grenading the LT-5s must have taken out several LT5s. What process did Chevrolet go through to replace these engines? What did they do with the damaged blocks? when did Mary stop killing LT5s? Could #2299 have started it's life with a new block because Mary killed it? That would make #2299 an interesting footnote in the lexicon of ZR-1 history. Time to order your build sheet and invoice to find out when it was built and when it was shipped. If there was a large gap maybe it was waiting to get a new LT5.

[A26B]

I just spoke with Chris Allen who was the man in charge of design & supervision of the LT5 assembly line at Mercury.

Chris said "to the best of my recollection, for the first year, dealers were not allowed to open an LT5 engine. He went on to say "I only recall one engine that was ever returned to Mercury. We opened it up and the only thing wrong with it was carbon buildup. We cleaned it up & sent it back to the dealer with no other work."

Chris also said that Mercury did not have any procedure for rebuilding LT5 engines and that he would have known about it if they did.

Apart from engineering development & test units, there appeared to be a couple of warranty replacement engines in the group of 30 engines I had that were remaining from the lot of engines GM sold off 2 or 3 years before I got them. As I understand it, what actually happened was that dealers did not rebuild LT5's. The dealer received authorization and was shipped a new crate engine from GM stock (not Mercury). The dealership returned the original engine to GM, in the same crate the new one was shipped in, where upon receipt, it was simply placed in a storage warehouse with all of these other test & development engines. The warrany replacement engines were never rebuilt as the cost to GM would have been greater than the cost of a new crate engine.

I probably have some photos of the engines I think were returned & recall some instructions to the dealer about what all to remove & return to GM. Those crates were different than the crates I've seen for crate engines offered for sale.

It seems probable to me that procedures & policies perceived to be feasible when written may have turned out in actual practice to not be practical.

[1989ZR1#74]

Good stuff Jerry, you have moved the ball forward and I learn more and more. Ok so if the block was replaced it would not have been restamped.

2 seperate issues:

So why was MM mark on #2299 restamped? The fonts on the MM restamp appear to be the same. They appear to have been done to document not to deceive (ie like a 63 Corvette Restamp) Perhaps you could send your friend the link for the picture and ask him what he thinks.

VIN stamp. This LT5 perhaps was destined for another 90 Corvette at BG but was diverted to #2299 that would explain the VIN restamp again to document not to deceive. At what point was the LT5 assigned to a ZR-1? how much time is there between assignemnt and installation?

It does not seem plausible that an outside repair shop would go through the effort to restamp the block. Nor would they have access to the correct stamps/fonts etc. So I would think this had to have originated at MM and BG.

[A26B]

....... So why was MM mark on #2299 restamped? The fonts on the MM restamp appear to be the same. They appear to have been done to document not to deceive (ie like a 63 Corvette Restamp) Perhaps you could send your friend the link for the picture and ask him what he thinks.

Can do. He's on an extended weekend vacation, but will be home tomorrow. I'll work on an answer.


VIN stamp. This LT5 perhaps was destined for another 90 Corvette at BG but was diverted to #2299 that would explain the VIN restamp again to document not to deceive. At what point was the LT5 assigned to a ZR-1? how much time is there between assignemnt and installation?


Someone else can answer that better than me. I will recount a story that Ryan B. & I worked on a bit. He acquired a 405 new, crate engine with a build VIN stamped on the engine. We "acquired" the current owners contact info & found out the ZR-1 has a numbers matching engine, WITH THE SAME VIN AS THE CRATE ENGINE. Through a few phone calls we surmised that the first engine was VIN stamped @ BG (like all engines), placed in the car, but on final inspection may have had finish blemishes & was removed & replaced with another engine that was VIN stamped with the same VIN. The removed engine was sent back to MM, then back to GM crate engine inventory, still with the original VIN intact.

So, things do happen that are not in accordance with the standard procedure.


It does not seem plausible that an outside repair shop would go through the effort to restamp the block. Nor would they have access to the correct stamps/fonts etc. So I would think this had to have originated at MM and BG.

Agreed..

[1989ZR1#74]

Can do. He's on an extended weekend vacation, but will be home tomorrow. I'll work on an answer.



Someone else can answer that better than me. I will recount a story that Ryan B. & I worked on a bit. He acquired a 405 new, crate engine with a build VIN stamped on the engine. We "acquired" the current owners contact info & found out the ZR-1 has a numbers matching engine, WITH THE SAME VIN AS THE CRATE ENGINE. Through a few phone calls we surmised that the first engine was VIN stamped @ BG (like all engines), placed in the car, but on final inspection may have had finish blemishes & was removed & replaced with another engine that was VIN stamped with the same VIN. The removed engine was sent back to MM, then back to GM crate engine inventory, still with the original VIN intact.

So, things do happen that are not in accordance with the standard procedure.

Agreed..

Wow that is again more neat info. So there was a history of LT5s being pulled after the VIN deravation is stamped and placed back in inventory. So that could be an option.

[A26B]

Well, I would hesitate going plural and counting this as a definite occurance, but after analyzing all the tags on the engine & crate and talking to GM personnel, it is the most likely circumstance. Fact remains, there are 2 engines with the same VIN, one is in the ZR-1, the other is a crate engine.

[1989ZR1#74]

Well, I would hesitate going plural and counting this as a definite occurance, but after analyzing all the tags on the engine & crate and talking to GM personnel, it is the most likely circumstance. Fact remains, there are 2 engines with the same VIN, one is in the ZR-1, the other is a crate engine.

You are correct. Only theories, but it "appears" that an LT5 could have been stamped with a VIN deravation and then not installed in that same sequence numbered ZR-1.

I guess I would ask what if that crate motor was sent back to BG what would the VIN stamp look like?

What was the reason that the 405 LT5 was not installed in the correct ZR-1?

[A26B]

You are correct. Only theories, but it "appears" that an LT5 could have been stamped with a VIN deravation and then not installed in that same sequence numbered ZR-1.

I don't think so and don't mean to imply that possibility. The 1st engine had the VIN stamped on it at BG & put in the car. When the 1st engine was removed at BG, another, un-stamped engine was taken from inventory at BG & then stamped with the same VIN at BG, making it the 2nd engine & put into the car. In essence, both engines would be, for all practical purposes the correct engine for the car.


I guess I would ask what if that crate motor was sent back to BG what would the VIN stamp look like?

By "that crate motor" you are referring to the 1st engine that became a crate motor after the 2nd engine was installed. I think the engine went to GM warehousing stock and not to BG after leaving MM.


What was the reason that the 405 LT5 was not installed in the correct ZR-1?

I believe there are 2 correct engines for the subject ZR-1. The 2nd engine which is in the car now & correctly matches the car VIN, and the 1st engine which ended up being a crate engine with a VIN. I'm guessing the 1st engine VIN should have been stamped out at some point after it was replaced.

[1989ZR1#74]

I don't think so and don't mean to imply that possibility. The 1st engine had the VIN stamped on it at BG & put in the car. When the 1st engine was removed at BG, another, un-stamped engine was taken from inventory at BG & then stamped with the same VIN at BG, making it the 2nd engine & put into the car. In essence, both engines would be, for all practical purposes the correct engine for the car.

By "that crate motor" you are referring to the 1st engine that became a crate motor after the 2nd engine was installed. I think the engine went to GM warehousing stock and not to BG after leaving MM.

I believe there are 2 correct engines for the subject ZR-1. The 2nd engine which is in the car now & correctly matches the car VIN, and the 1st engine which ended up being a crate engine with a VIN. I'm guessing the 1st engine VIN should have been stamped out at some point after it was replaced.

Jerry, You responses are terrific. I appreciate the time you have taken to reply.

Earlier you stated "The dealer received authorization and was shipped a new crate engine from GM stock (not Mercury)." So was the Same VIN derivation 405 LT5 (double vin) placed in this same stock source? What if a dealer was sent the 405 LT5 (double vin) as a warrantee replacement would they have XXXX out the Vin?

Eric

[A26B]

.......Earlier you stated "The dealer received authorization and was shipped a new crate engine from GM stock (not Mercury)." So was the Same VIN derivation 405 LT5 (double vin) placed in this same stock source? What if a dealer was sent the 405 LT5 (double vin) as a warrantee replacement would they have XXXX out the Vin?
Eric

When I worked as a mechanic in a GM dealership, long,long ago, warranty work involving engine replacement required authorization from the district warranty inspector. That's the authorization I'm referring to.

I see where you are going with the next question regarding the GM engine stock source. All I can say is I don't know the answer. Same is true regarding whether the dealer would xxxx out the VIN. My guess is probably not.

From what I understand, engine replacement was not a common ocurrence and this double VIN engine deal is probably a one-of-a-kind happening and that's how the VIN escaped intact on the 1st engine.

[1989ZR1#74]

When I worked as a mechanic in a GM dealership, long,long ago, warranty work involving engine replacement required authorization from the district warranty inspector. That's the authorization I'm referring to.

I see where you are going with the next question regarding the GM engine stock source. All I can say is I don't know the answer. Same is true regarding whether the dealer would xxxx out the VIN. My guess is probably not.

From what I understand, engine replacement was not a common ocurrence and this double VIN engine deal is probably a one-of-a-kind happening and that's how the VIN escaped intact on the 1st engine.

And the strange 'OP's block restamp is probably a one of a kind as well. As a longtime NCRS member we have attempted to deal with these issues on the judging field, like a 87 Calloway at a Denver Regional with only 1000 miles that was not judged because the "B2K" was missing on the SPI. We went around and around to try and figure out why it appeared to be a factory B2K but was delivered to Calloway without the B2K. Or why my 84 with 3000 miles has tires that are 1 month newer then the car but no evidence has ever been shown that they were changed. Or why #004 has non ZR-1 seats and radio.

Not that #2299 will ever be judged or need to justify the stamp, I am very curious how two stamps in two places were wrong.

I alway like to try and wrap my brain around these even though I have no skin in the #2299 game.

[bdw18_123]

... Time to order your build sheet and invoice to find out when it was built and when it was shipped. If there was a large gap maybe it was waiting to get a new LT5.

I do need to order the build sheet since the build date area is unreadable on the one I pulled out of the crossmember. However, I do have an original invoice which appears to document the transfer of the vehicle from GM to the dealership from which the car was sold from and lists all the options, pricing & other things. I can take a picture of it and post it if that will help, maybe you guys can help me decode it. :mrgreen:

There are several dates on this invoice, listed as follows (I'm not sure what the last two mean):

INVOICE 5/24/90
PRICED 5/22/90
SHIPPED 5/24/90
EXP I/T 5/29/90
INT COM 5/29/90

So that means my car sat at the dealer for about 6 months before it was sold to the P.O. on 11/22/90. Since my block has a cast-in date of 3/7/90, that means the build date of my car should fall somewhere around March of '90 I would think. Are there any dates anywhere on the car itself that would give a clue as to what the build date was?

...
Not that #2299 will ever be judged or need to justify the stamp, I am very curious how two stamps in two places were wrong.

I always like to try and wrap my brain around these even though I have no skin in the #2299 game.

Agreed, my ZR-1 is definitely not an NCRS candidate, but I like learning about stuff like this and I'm also very curious as to why both stamps from both manufacturers were redone. My Z might have an interesting history and I want to learn about it.

... Another thought/theory, "Mary" the inmfamous BG lot driver who in 1990 was cold starting ZR-1s at WOT and grenading the LT-5s must have taken out several LT5s. What process did Chevrolet go through to replace these engines? What did they do with the damaged blocks? when did Mary stop killing LT5s? Could #2299 have started it's life with a new block because Mary killed it? That would make #2299 an interesting footnote in the lexicon of ZR-1 history. ...


Who was this "Mary" person and what kind of moron starts a car at WOT?? :icon_scra

[bdw18_123]

Any thoughts on the dates in my above post?

[1989ZR1#74]

Any thoughts on the dates in my above post?

Sorry missed, the previous post.

I am a little curious about the gap between the "priced date" and the block date. The price date is typically the date the car is completely assembled. There is a 76 day lag between the two. That to me would seem quite a bit longer then what I would expect. I would imagine that Mercury Marine was working at about their maximum output to keep up with the 1st year supply demands. It seems unusual that an LT5 would be out there for more than a week or so. MM was struggling to keep up with demand

From "Heart of The Beast":

"As the ZR-I was launched and demand for the car soared, MerCruiser struggled with both demand for the engine and its supplier problems. Production was falling behind demand for a number of reasons. Steve Campbell, who joined MerCruiser in the mid-Seventies, was directed by MerCruiser president David Jones to take over LT5 project management from Jim Cunningham in June 1990."

"Chevrolet could not build a car that was the class act of the world unless the LT5 was the class engine of the world. Certainly, meeting production demand was part of all this. By October 1990, MerCruiser had made up all the backlog and was producing 22 engines a day. Two months early"

So I would think a 76 day lag was almost impossible without some intervening story. The evidence is there. A double stamped block in two places 76 days after it was made. In an environment that could not keep up demand. So I revert to my original idea hypothesis. For whatever reason the block was sourced for a different ZR-1 was not used, and due to the lack of LT5 supply was repurposed for #2299.

Although I think the "Mary" failures did not start until December of 1990 so that more then likely has nothing to do with your 5/22/90 ZR-1.

FWIW here is the quote about Mary from "Heart of The Beast":

"They both heard the familiar whine of the Nippondenso starter motor of the LT5 as a ZR-I was being started up but then heard the LT5 immediate go to maximum rpm-something no ZR-I owner in his or her right mind would ever do. Behan turned to Barton and said, "I think I' ve found our problem." He walked over to the young woman starting the cars, introduced himself and asked her if she started all the cars that way. She said yes. Behan tried to maintain his composure. In all of Lotus' development and durability testing, they had never started a car in such a manner in such cold weather. Still, simply starting the engine in such a way could not explain why an LT5 had failed while still in Bowling Green. But Behan felt sure this abusive starting technique definitely had something to do with it."


I can't wait to find out why this happened, it will be an interesting footnote to the legacy of the ZR-1

[bdw18_123]

I can't wait to find out why this happened, it will be an interesting footnote to the legacy of the ZR-1

Thanks for that info!

It's cool that my Z has an interesting history & I too want to know all the details about exactly how and why this happened. I just spent probably around 7 hours typing up all the service history, milage & dates info that I have. :jawdrop: I would never have done that with any other car. I didn't even do that with the '93 Corvette I had. I guess the ZR-1 bug has definitely bitten me. :sign10:

But unless other documentation can be found or someone remembers my car or another car that a similar thing happened to, we might not ever find out the reason. Hopefully though, we do figure it out.

[LGAFF]

Anyone ever think that maybe someone at the plant was just hungover and stamped the same # twice and had to fix it? Bound to happen in 6K stampings.

[1989ZR1#74]

Anyone ever think that maybe someone at the plant was just hungover and stamped the same # twice and had to fix it? Bound to happen in 6K stampings. Yeah I did, but that would have to be two hungover people in two plants. Hundreds of miles apart on an LT5 that just happened to be lying around for 76 days in an environment where they were behind the schedule on delivery so every LT5 build was close to immediately installed. In the NCRS world we call this NTP (Not Typical Production).

Anyone else have a #2000 range 90 ZR-1 that can findo out their block date/price date??

[tomtom72]

My Z is a 90 number 2233, my door sticker says May 1990......tell me what I'm looking for and where to find it and I'll see if I can get it done in the near future. Oh, forgot I do have a copy of my build sheet from the NCM.

We have a bit of snow that's causing some issues and it may be hard to find parking at my garage site. Besides, I will have to wait till the wee hours as I'm not allowed to do mechanical work in my rented space....:neutral:

:cheers:
Tom

[1989ZR1#74]

Here is my summary of ideas:

1. Original block damaged sent back to MM for repair. MM sent replacement and restamped. FALSE, Jerry's MM source says he only remembers 1 LT5 coming back from a dealer and it just had carbon build up.

2. Car had original BG LT5 damaged as it was driven out of the plant by "Mary" Replacement was installed that had been planned for another ZR-1. False. "Mary" did not start killing LT5s until the Cold December of 1990. #2299 was build in sunny warm May of 1990.

3. Somehow a rebuilt LT5 was installed at the factory due to limited LT5 supplies. FALSE, LT5s were not rebuilt they were destroyed. To expensive to a repair a terminal LT5.

4. An LT5 that was planned/stamped for another LT5 failed to get installed. This LT5 was later restamped and installed in #2299. Similarly to how Jerry found an LT5 in Chevrolets crate motor stock with a vin stamped in it. They confirmed that the car that had that VIN also had a correct VIN stamped motor. OPEN. If it happened once it cannot be said it never happened.

5. Bock gets cast and set aside for 70 days. MM assembles the LT5, then stamped the wrong assembly seq number. MM employe grinds off wrong number to correct it then sent it to BG. BG employee stamped wrong number on pass side, realized it XXX'd it out the stampred correct number on driver's side. Installs LT5 and #2299 leaves BG to resurface later with everyone scratching heads... OPEN. Not to plausible in my mind but it could have happened.

More thoughts on the restamp. Since this LT5 has two apparent restamps, both with apparently correct fonts. This block was restamped at both locations. Here is a question for MM. What were the reasons MM would restamp a block? Did they only do this if there was a "hungover" guy who messed it up? Were there other reasons?

[1989ZR1#74]

My Z is a 90 number 2233, my door sticker says May 1990......tell me what I'm looking for and where to find it and I'll see if I can get it done in the near future. Oh, forgot I do have a copy of my build sheet from the NCM.

We have a bit of snow that's causing some issues and it may be hard to find parking at my garage site. Besides, I will have to wait till the wee hours as I'm not allowed to do mechanical work in my rented space....:neutral:

:cheers:
Tom

Thanks Tom, It is a bit of a PITA to see the date on the block. You can start by jaccking up the drivers side and looking at this number:

http://i13.photobucket.com/albums/a292/bdw18_123/IMG_0853.jpg

Your car is very close to #2299 ao it should be interesting to know.

Then the block date is on the driverside. In the area where it mounts to the bellhousing. It is very hard to see it when the LT5 is in the car. It can be done, but you probably wont be able to take a picture of it:

http://i13.photobucket.com/albums/a292/bdw18_123/IMG_0844.jpg

I have heard you can see this from the firewall side of the car looking down. Not sure though.

[LGAFF]

Here is a thread on VIN stamps

http://www.zr1.net/forum/showthread.php?t=8196&highlight=stamp

[bdw18_123]

Actually, Eric, the last picture you posted showing the cast-in date of my LT5 is on the passenger side. The re-stamped VIN is on the driver's side.

Here is another interesting piece of this puzzle. The piece that is between the block and the oilpan has a cast-in date of 3/8/90. This would seem to indicate that this LT5 was started one day and finished the next day. I don't know if that was something that would happen a lot or not.

Since the last 4 digits of the re-stamped MM number indicates that this LT5 was the very 1st build of the day the stamp was done, I would think that day would have to be the 8th of March, 1990. Here is a picture of my LT5 with arrows pointing to both cast-in dates:
http://i13.photobucket.com/albums/a292/bdw18_123/IMG_0845.jpg

The other strange piece of this puzzle is the fact that you can just make out what the number was that MM tried to grind out. It looks like it might be X0052299 (I added the underline here). I can tell for certain that the 1st two digits of the last 4 ground out numbers are both "2's". The last two could be "0's" I suppose, but the lower part of those numbers are more flattened out like the "9" stamp would be, so that is probably unlikely. If you look at the first picture in my first post, you can kind of see the ground out number.

If in fact it is true that the last 4 numbers originally said "2299", that would mean that this engine probably was always originally intended for #2299. Maybe MM had a new employee that accidentally stamped the last 4 of the VIN instead of the number that was supposed to be there. That would also mean that MM knew what engine was going in what car (the first year anyway).

The fact that there was a backlog in the middle of '90 makes that more likely since there would be more orders for ZR-1's than the number of built LT5's. In '93, this would have been the opposite. They were making way more engines than the amount of orders for ZR-1's that GM was sending, since they were making the rest of the engines ahead of time for the Z's all the way to '95.

[1989ZR1#74]

You are right , and I knew that.. it is the pass side.

I'm I seeing thigns or are the two dates:

03/07/1990 on the block

and

05/08/1990 on the other part?

so there is a 2 month gap right?

The 05/08 part fits much better with the 5/22 build date. I wonder what range the MM stamp would have been in March of 1990? Any one have an early March 1990 ZR-1 engine stamp they can share?

[A26B]

I may be missing something here, but I don't see the significance of different casting dates for the upper & lower crankcases. They weren't "mated" parts until the machine work was done.

[1989ZR1#74]

I may be missing something here, but I don't see the significance of different casting dates for the upper & lower crankcases. They weren't "mated" parts until the machine work was done.

Until the last post the only date I saw was 3/07/90. Now that we have a 5/08/90 it makes the gap from LT5 to ZR-1 install much shorte and typical. I am just curious why the upper took so long to get mated? any idea why?

[bdw18_123]

Until the last post the only date I saw was 3/07/90. Now that we have a 5/08/90 it makes the gap from LT5 to ZR-1 install much shorte and typical. I am just curious why the upper took so long to get mated? any idea why?

It's actually not 5/08/90, it's 3/08/90. I guess in the picture it kind of looks like a "5", but it's actually a "3".

The oil pump also has a number printed on it (with ink) that reads: 03 0815 88. That may just be the part number, but could the first 4 numbers (03 08) refer to the date?

[1989ZR1#74]

It's actually not 5/08/90, it's 3/08/90. I guess in the picture it kind of looks like a "5", but it's actually a "3".

The oil pump also has a number printed on it (with ink) that reads: 03 0815 88. That may just be the part number, but could the first 4 numbers (03 08) refer to the date?

So the whole LT5 appears to be assembled around 3/7/90. 2 things I now need to know. What were the stampings for ZR-1s from March? what do other May 90 ZR-1s have for casting dates??

[1989ZR1#74]

I may be missing something here, but I don't see the significance of different casting dates for the upper & lower crankcases. They weren't "mated" parts until the machine work was done.


Jerry, In you stock of LT5s are the two dates real close? Whats typical?

[bdw18_123]

So the whole LT5 appears to be assembled around 3/7/90. 2 things I now need to know. What were the stampings for ZR-1s from March? what do other May 90 ZR-1s have for casting dates??

Jerry, In you stock of LT5s are the two dates real close? Whats typical?

This thread seems to keep dying, so I have to bring it to life. :hello:

Discussion on this has been very interesting, still waiting on thoughts on Eric's questions above & any one with a '90 ZR-1 numbering in the 2000's (or any '90 Z really) somewhere to compare the casting date on their LT5 with their build date. 70-something day lag seems like a long time.

I want to figure this mystery out!

[phrogs]

I have my 90 LT5 from #1908 Ill check that and post photos for you.

My ZR-1 is #845 or 854 I cant recall ill have to get that one on the lift and check it.

I also have a 91 LT5 that Ill post the pics of as well so we can see what I have.

Will have to wait until later

johnny

[1989ZR1#74]

Ok let me summarize my questions that will help decipher this mystery:

For now I am focusing on the Mercury Marine oil pan stamping and casting info. Any of these questions will move the ball forward:

What is a typical casting date for a May 1990 ZR-1 LT5?

What is a typical date separation on the upper and lower castings on any 1990 LT5?

What is a typical oil pan MM stamp number for a May 1990 casting date LT5?

What is a typical oil pan MM stamp number for a March 1990 Casting date LT5?

What is a typical oil pan MM stamp number for a #2000 to #2400 1990 ZR-1?

Anyone with this information on any 1990 ZR-1 may help so don't be shy post.

[bdw18_123]

I notice BOB HDZ has 1990 ZR-1 #2293, his also would be a good one to check (in addition to phrogs' cars he said he would check and anyone else that has a '90 Z that can check) the LT5 cast date/car build date since that is the closest one to mine so far, tom tom's being the 2nd closest.

[1989ZR1#74]

I found a note in the 9/1990 Corvette Fever that supports the non warrantee exchange that we discussed early in the thread. This supports the conclusion that the LT5 in #2299 was not a repaired LT5.

http://www.syreal.com/nolt5problemssm.jpg

[LGAFF]

Work order for rebuild:

http://i134.photobucket.com/albums/q115/lgaff/ZR-1005.jpg

http://i134.photobucket.com/albums/q115/lgaff/ZR-1006.jpg

[bdw18_123]

Ok let me summarize my questions that will help decipher this mystery:

For now I am focusing on the Mercury Marine oil pan stamping and casting info. Any of these questions will move the ball forward:

What is a typical casting date for a May 1990 ZR-1 LT5?

What is a typical date separation on the upper and lower castings on any 1990 LT5?

What is a typical oil pan MM stamp number for a May 1990 casting date LT5?

What is a typical oil pan MM stamp number for a March 1990 Casting date LT5?

What is a typical oil pan MM stamp number for a #2000 to #2400 1990 ZR-1?

Anyone with this information on any 1990 ZR-1 may help so don't be shy post.



Apparently, the "ball" fell into a deep hole and got stuck... :mrgreen: :mrgreen:

Anymore thoughts on this, or is it going to stay a mystery forever? :icon_scra

[1989ZR1#74]

Apparently, the "ball" fell into a deep hole and got stuck... :mrgreen: :mrgreen:

Anymore thoughts on this, or is it going to stay a mystery forever? :icon_scra
Have not had anyone offer up any examples yet so its still 2 down and 7 yards to go. Someone did ask the Engineers at the Gathering about restamps during a session. They said they did restamp, and they did not "throw" any LT5s away. They were fixed and reused. In fact the LT5 in the 24 hour record car was a rejected and repaired production motor. It was originally destined for a production car but was pulled back. So FWIW it may reset the idea that this block was repaired. So now that the weather is nicer perhaps you May 1990 ZR-1 owners can check out your numbers and offer up a little info (pictures would be even better) Eric

[BlackWidow#2]

Years ago I heard that the replacement engine in the record car was rejected at MM for having the delicate silver finish tarnished, not internal damage, cosmetic damage only.
George C.

[bdw18_123]

I'm gonna resurrect this year-old thread and add to the mystery even more. During the process of reassembling my LT5, I have come across even more stamped dates. It seems that pretty much every major component has a date stamped on it.

I don't know what the typical date range for all the parts on the engine is. Should they all be within a month? 3 months? More? On mine, the earliest dated part I found is 9/20/89 all the way to the date on the girdle which is 3/8/90. That is an almost 6-month span which seems excessive to me. And the car wasn't even assembled until 5/22/90 which is the "PRICED" date on the original invoice that I have.


I've posted a list & pictures below of all the stamped dates I've found and what part they are on. Some of the dates have a letter after them.

Crankshaft main
bearing cap girdle ------------ 3/8/90

Engine block ----------------- 3/7/90 B

Oil pan ---------------------- 1/8/90 C

Secondary actuators --------- 1/8/90

Plenum ---------------------- 1/5/90 A

Crankcase
breather cover --------------- 12/22/89

Oil pan
suction tube ----------------- 9/20/89 B

Both cylinder heads also have a cast-in number "89" which could indicate the year, but I'm not sure.


Pictures:

Engine block & girdle dates.

http://i13.photobucket.com/albums/a292/bdw18_123/IMG_0845-1.jpg


There is also some free-hand engraving in the "V" area of the block under the starter with a date (matches the stamped date). I colored in the engraving with a sharpe to make it more visible.

http://i13.photobucket.com/albums/a292/bdw18_123/IMG_0251-1.jpg


Oil pan date, it's on the front, passenger side edge of the lower surface of the oil pan.

http://i13.photobucket.com/albums/a292/bdw18_123/IMG_0321.jpg


Secondary actuators date, which is the same date as on the oil pan.

http://i13.photobucket.com/albums/a292/bdw18_123/IMG_0323.jpg


Plenum date, this is on the bottom just behind the DIS module.

http://i13.photobucket.com/albums/a292/bdw18_123/IMG_0369.jpg


Crankcase breather cover date.

http://i13.photobucket.com/albums/a292/bdw18_123/IMG_0256-1.jpg

[bdw18_123]

There is also some free-hand engraving on the top of the crankcase breather cover with a date of "12-21-89" (the year isn't very legible, but that is most likely what it says judging from the "12-21" part that is legible), one day earlier than the stamped date.

http://i13.photobucket.com/albums/a292/bdw18_123/IMG_0258-1.jpg


Oil pan suction tube date, it's on the surface just under the metal netting. This picture was hard to take because the camera kept wanting to focus on the netting, not on the surface below it.

http://i13.photobucket.com/albums/a292/bdw18_123/IMG_0307.jpg


Possible cast-in dates on the cylinder heads. Maybe that symbol thing with the numbers in the middle in front of the "89" is part of the date code?

Driver's side head, there is a "V6" stamped on this head.

http://i13.photobucket.com/albums/a292/bdw18_123/IMG_0343.jpg


Passenger side head.

http://i13.photobucket.com/albums/a292/bdw18_123/IMG_0344.jpg