UNLUCKY?

[Bill]

Ok: I can’t be the only one this unlucky! :cry: My ’90 has 110k miles. Last week while driving into town the engine started ticking. :( To me it sounded like a collapsed lifter. I localized the noise the area of #7 cylinder. Further inspection reviled a missing screw on the secondary throttle plate for that cylinder. Has anyone had this problem? Were you able to recover the screw without pulling the head? Can the head be removed & replaced without taking the engine out of the car?

[WB9MCW]

so sorry to hear of your plight Bill...but I can say no lifters in the LT-5 to worry about...but I bet u knew that...lol...It will be interesting to see if any one else has had this problem and if indeed the missing screw has screwed up anything...I hope it turns out as an easy fix for you. i would see what jeffvette and the PNW boys have to say...here is a link for you to see abt tear downs...

http://www.pnwzr1.net/PNWZR1.htm

scroll down left index to tear down's section....very nice photos of it all put together by Jeff and the PNW gang...

[tomtom72]

Oh man Bill! Hey those screws are so small there is a chance it could have gone in & out and done nothing.....okay I should take my meds now. What about bringing 7 to TDC and go thru the plug hole with a magnet. Man if you could find/ or make a flex shaft to put a magnet at the end & fish around on top of the piston.

Okay wishful thinking. I'm fairly sure guys like John (phroggs) say you can do a head pull without r&r'ing the lump....maybe worth a call to Gordon to seek his opinion. Hey Brian, I thought LT5's had hyd lifters, no rocker arms, and the lifters are the same dimensions as the lifters in the Aurora V8....I remember that from a thread in this forum...I think I read that here? Maybe I read it over at CAC....oh, maybe worth a call to Mr. Haibeck also.

If you were closer I'd say I'd come over & help! Hey, I have a DVD of the training tapes for the LT5 tech training program...say the word & I'll mail it to ya...you could copy it...I would do it but my write drive don't work!:o

Shout at me if you want the DVD!:thumbsup:

Tom

[Corvette95]

Let us know what happens, also if its not too much trouble , could you post a picture of the missing screw area?

[Bill]

Thanks for the replies. Thanks also Brian for the link, I’ll look into that. As far as the lifter I was not sure what was there. Now I know it’s a silver mini hockey puck, at least that’s all I can see.

Tom Your right the screw is so small. But my luck it didn’t pass through. I have tried going through the plug hole with a magnet, no luck yet, still trying. I am just about to the point to start pulling the head, I am most worried about timing the cams when it goes back together. I have the video and will watch it again, also have the service manual and more reading is in order, Thanks for the offer of help, but we couldn’t be farther apart and still be in the same country. I’ll save a call to Mark until I really get in trouble!

Corvette 95 here are some pictures I’ve taken up to this point
1st is a look down #7 secondary bore at the throttle plate before removal.
http://home.comcast.net/~bsoomann/missing_screw.jpg

Next is the removed plate and the other screw from the plate.
http://home.comcast.net/~bsoomann/plate.jpg

Last is looking down the #1 primary bore at the open intake valve. That itty bitty screw didn’t even slow down getting into the cylinder
http://home.comcast.net/~bsoomann/valve.jpg

BTW the compression is good. Low cylinder is 180# high is 198#. Number 7 is 185#.

[Jeffvette]

so sorry to hear of your plight Bill...but I can say no lifters in the LT-5 to worry about...

Bryan you still have lifters to worry about. Although they look nothing like the regular SBC lifter.

Oh man Bill! Hey those screws are so small there is a chance it could have gone in & out and done nothing.....

Highly doubt it, as the quench area is relatively small. Those screws can cause a lot of damage to he head surface, and will gaul the side of the liner if wedged in between the piston.


Bill, the question is, how did the screw come undone? Also, trying to fish it out is a good idea, but I imagine it's already jammed into the head. I'll post pictures tonight of what the damage can look like.

[Bill]

Bill, the question is, how did the screw come undone? Also, trying to fish it out is a good idea, but I imagine it's already jammed into the head. I'll post pictures tonight of what the damage can look like.

Thanks Jeff, I think?
I don't know how it came loose. I have had the car for about 2 1/2 years and put about 25k miles on including a trip to Daytona. I have not touched any of those screws. My guess is vibration. You are probably right about it being jammed into the head. I hope the damage is minimal and leaves the head useable. I am planning to use lots of red locktite when putting it back together. My biggest fear is the cams. Is it possible to re timed the cams with the engine in the car?:confused:

[Jeffvette]

You "can" retime the cams with the motor in the car, but you are better off pulling the motor. Getting the motor out is only about 3 hours.

[Bill]

OK Jeff Maybe 3hrs for you more like 3 days for me. Thankfully I'm retired and time isn't that important. We are off for a weekend cruise near Yosemite in the wife's 90 vert. ;) Any more thoughts or pointers will be appreciated. I’ll check back in Sunday evening.
Thanks all for the comments and keep them comming

[Aurora40]

Oh man... I hope everything turns out ok and the damage is minimal! :(

[4DSZR1]

This will be an interesting thread to follow. Hope its not serious!!!!!!!!

[WB9MCW]

Well I stand corrected on the lifters. I know there are no stinkin pushrods so I figured no reason for lifters plus I dont really see em in this pic....Where are they at Jeff? do they really call em lifters? Can you point em out in the pic's for me. Thnx....inquiring minds wanna know...lol are they hydraulic and can they collapse and make the ticking sound?

http://memimage.cardomain.net/member_images/6/web/390000-390999/390224_236_full.jpg

http://memimage.cardomain.net/member_images/6/web/390000-390999/390224_224_full.jpg

[tomtom72]

I'm :o at what I said about the "in & out" thing Jeff! I should have realized that with our comp ratio & flattop/dished pistons the chamber volume has to be waaay small! Thank you Sensi Master!:worship:

The lifters are the 'hat' lookin' things over the valve springs in the line drawing Bryan. The rockers act directly on the lifter bottom.

Hey, yea, how does one of those little buggers come loose? I would have thought that they would have been "loc-tighted' in upon assembly??? This chit makes me wanna take my stuff apart again and check all those little screws....my luck I'd loose one of them & they would punch a hole thru the chamber to a water jacket.

Okay another dumb Q from the weed eater:mrgreen: .....Is it possible to fix, by welding, any damage to the chamber and then clean up the weld so the chamber configuration is close to original condition or is the head "junk"? I mean is ain't like we can call Dart or anyone else and get a new head? We can still buy new sleeves, right???

Bill, if I was filthy rich...... I'd come out there but not to work on the car. I'd do one of those pranks like on overhauling....steal it & have the car sent to be "overhauled" by a dream team of ZR-1 specialists.....unfortunately, I'm just filthy. I just finished boiler maintenance, #6 fuel fired! My collar isn't even blue, it's black!

Good luck with this, Bill.
:cheers:
Tom

[WB9MCW]

Well they need to change the name on em to "pushers" cause they ain't liftin a damm thing...LOL

[Jeffvette]

I'm :o at what I said about the "in & out" thing Jeff! I should have realized that with our comp ratio & flattop/dished pistons the chamber volume has to be waaay small! Thank you Sensi Master!:worship:

Kind of hard for the screw to overcome gravity and magically flow out the exhaust valve as well :D

Okay another dumb Q from the weed eater:mrgreen: .....Is it possible to fix, by welding, any damage to the chamber and then clean up the weld so the chamber configuration is close to original condition or is the head "junk"? I mean is ain't like we can call Dart or anyone else and get a new head? We can still buy new sleeves, right???


Yes, it can be repaired. Head would need to be welded and machined back to specs. Cheap heads are available.

Here is the damage a screw can cause

http://www.pnwzr1.net/Jeff/Damage_head.JPG

http://www.pnwzr1.net/Jeff/damage_piston.JPG

[WB9MCW]

IT AIN'T PURDY

[RedZR]

WOW !!
Was that caused by a secondary screw that came loose also? Any idea how often that happens?

Dan

Kind of hard for the screw to overcome gravity and magically flow out the exhaust valve as well :D



Yes, it can be repaired. Head would need to be welded and machined back to specs. Cheap heads are available.

Here is the damage a screw can cause

http://www.pnwzr1.net/Jeff/Damage_head.JPG

http://www.pnwzr1.net/Jeff/damage_piston.JPG

[Bill]

OK We are back from our weekend run. So now it’s back to the problem at hand. As I dig deeper into my LT5 I get more questions. I have brought #1 to TDC on the compression stroke, but can’t find any marks on the crank pulley. Is there some kind of mark there?
For those of you following along in my attempt to gain knowledge I will be posting pictures to my yahoo photo album. Here is a link

http://new.photos.yahoo.com/bsoomann/album/576460762325655518#page1

Tom said
Bill, if I was filthy rich...... I'd come out there but not to work on the car. I'd do one of those pranks like on overhauling....steal it & have the car sent to be "overhauled" by a dream team of ZR-1 specialists.....unfortunately, I'm just filthy. I just finished boiler maintenance, #6 fuel fired! My collar isn't even blue, it's black!
Tom At one time my job was to make steam, but my Uncle Sam wouldn’t let me clean in there, Thanks for the offer, we could learn together.

Jeff that head looks terrible. I hope mine doesn’t look that bad.

More to come as I proceed

[Bill]

Here is an up date. I have been treading water for the last couple of days. I keep looking at the cams and worry that I won’t be able to get them back in right. I finally found my copy of the LT5 training tapes and now feel a lot better about proceeding. From the tapes I learned that the cam chain tensioner is not re usable. Is this true and is it still available? Found that my crank pulley does not have a timing mark on it. This made life a little difficult but was able to overcome. I painted a mark on the pulley for future reference; I hope I never need it.
More updates as I proceed.

Brian I'll post a picture of a "cam follower" when I get them out :thumbsup:

[Bill]

A little more progress. The cams are out, I hope I can get them pack in correctly. Here is a picture of the head with out the cams.
http://home.comcast.net/~bsoomann/no_cam.jpg

and just for you Brian, I pulled the 2 “lifters” out. The top one is an intake the lower one is an exhaust. They look the same to me, but that is where they came from.

http://home.comcast.net/~bsoomann/folower.jpg

[RedZR]

Did you encounter any trouble getting the cam cover bolts out?

Dan


A little more progress. The cams are out, I hope I can get them pack in correctly. Here is a picture of the head with out the cams.
http://home.comcast.net/~bsoomann/no_cam.jpg

and just for you Brian, I pulled the 2 “lifters” out. The top one is an intake the lower one is an exhaust. They look the same to me, but that is where they came from.

http://home.comcast.net/~bsoomann/folower.jpg

[Bill]

I stripped the head one camcover bolt and one injector housing bolt. Had to drill the head off of both then use vice grips to remove the stud. I have not tried to replace them yet.

[WB9MCW]

Thnx Bill for the pic's of the pushers er ah I mean lifters!! funny lookin critters they are...

[blackjack]

just came back from moose hunting(no luck),and i feel i had to add my 2 cents here,as this happens quite frequently in my line of work(motorcycles)
there are three possibilities here...
1-the screw will go out through the exhaust(it happens)
2-the screw will inbed in the soft aluminum of the head(most likely)
3-the screw will jam in a valve,causing the engine to run very funny.although the owner will NOT find that funny at all...
problems 2 and 3 require removal of the head(sorry)
if the screw gets stuck in the head,it will not (ever) come out with a magnet...i know...i tried...(sorry)
the ticking sound is (usually) the piston touching the inbedded screw at tdc
best of luck
blackjack
91/1735

[Bill]

I suspect the screw has found a home imbedded in the head. The last time it was running the engine ran smoothly just made that ticking sound. I haven’t made much progress this last couple of days. I can’t believe how tight the head bolts are (maybe I’m just getting old). So far I’ve used 4 different air impact guns and broken one brand new 18 mm 6 pt Craftsman socket and only gotten 2 bolts out. The impact guns have not worked at all, a ½ inch breaker bar with a 36 inch hander is what broke the 2 bolts loose and broke the socket. Another surprise for me was the size of the head bolts they are the longest I’ve ever seen.

[leonardpower]

The only way to do a job good it to pull the motor. if it goes well should only take about a day with the right equipment. With the motor out the cam timing can be done far easier than in the vehicle, also the cam covers can be fitted alot easier and less chance of the leaking particuly from the rear sealing plugs. I have seen these screws come out before and unfortunately they tend to get inbeded in the squish area of the head and piston.

[Bill]

Here is the latest update. Today was a good day after fighting with head bolts for a week I got them all out. Tried 4 different ½” drive air impact wrenches and one ¾” impact wrench, none of them worked. The head bolts are 9” long all the impact wrenches did was to flex the bolt. The only thing that worked was a good 6pt impact socket and a long breaker bar (36”), lots of sweat and one smashed thumb.

http://home.comcast.net/~bsoomann/bolts.jpg

When the head came off I had to look very close to find the screw. The next picture is the piston down in the cylinder, I see some nicks I don’t think there serious.

http://home.comcast.net/~bsoomann/piston.jpg

The next picture is the #7 combustion chamber. It’s a little fuzzy but if you look close you can see the screw near the bottom of the page close to the right exhaust valve

http://home.comcast.net/~bsoomann/chamber7.jpg
http://home.comcast.net/~bsoomann/stuck.jpg

Last one is the culprit removed from the head. As you can see it does not take much to make bad noises and cause bad things to happen to our engine

http://home.comcast.net/~bsoomann/removed.jpg


So now to clean up and put it back together :)

[Jeffvette]

Good job on the extraction.

Now might be the time to refinish the exterior while you have it apart.

[RedZR]

Wow !! That's amazing. It looks as if there was no real damage to the liner, piston or head. What's the plan- to simply put it back together?

Also, how does the head gasket look and what type of coolant were you using (sorry- I had to ask)?

Dan

[Bill]

I think I’ll pass on the PC job at this time, Jeff, I have not pulled the engine so the right side cam cover would be a PIA to get off with out further disassembly of the car. The wife’s ’90 vert helps a little with the vette addiction but I want my car back on the road.

Dan I was very pleased to find the minimal damage. My plan is to clean things up a bit, smooth down any rough edges, new gaskets and belts and reassemble. I bought the car 2 1/2 years ago with 85K miles, it had the green stuff in it then and I’m still using about 10% green stuff with water wetter. The head gasket is a little rough around the coolant passages near the bottom of the head. Don’t know what caused it. :)

[RICHARD TILL]

i had the same exact thing happen on a 496 chevy drag boat motor about 4 years ago. luckily there was no damage on the outer edge of the piston. i thanked the lord, bought a new head, intake, header gaskets and reassembled. its still running today.

[Jeffvette]

I think I’ll pass on the PC job at this time, Jeff, I have not pulled the engine so the right side cam cover would be a PIA to get off with out further disassembly of the car. The wife’s ’90 vert helps a little with the vette addiction but I want my car back on the road.


The passenger side is easier than the drivers side :D

I understand about having it on the road. It's an addiction.

[RedZR]

Thanks for the great pictures! Please keep them coming as you assemble the car.

This brings a question to mind...what bolts must be reinstalled as new and which ones can be reused? Does anyone know?

Dan



Dan I was very pleased to find the minimal damage. My plan is to clean things up a bit, smooth down any rough edges, new gaskets and belts and reassemble. I bought the car 2 1/2 years ago with 85K miles, it had the green stuff in it then and I’m still using about 10% green stuff with water wetter. The head gasket is a little rough around the coolant passages near the bottom of the head. Don’t know what caused it. :)[/quote]

[Bill]

A few more pictures
The first one “The Screw” stuck in the head between the exhaust valves

http://home.comcast.net/~bsoomann/imbed.jpg

This is the piston top after light buffing with a wire wheel, notice the reflection of the piston top in the cylinder wall. I can not see any scoring in the wall.

http://home.comcast.net/~bsoomann/piston_damage.jpg

And this is the head after buffing

http://home.comcast.net/~bsoomann/damage.jpg


Oh yea Jeff you’ve got me thinking about a PC job! Do you have pictures of black w/red letters? :D

[tccrab]

Bill:

Jeff does a Black Chrome that is to die for.
:drool

There's pics around here somewhere..
I'll go looking.
Wasn't that Phrogs (Johnny) car?

TomC
'90ZR1 #792

[tccrab]

Ah yes, here it is:
http://temp.corvetteforum.net/bss/phrogs//DRM_500/engine_outside.jpg

And here:
http://forums.corvetteforum.com/showthread.php?t=1464958

TomC
'90ZR1 #792

[RedZR]

[Did the screw beat on the two valves also? It looks that way. Did you check the screws in the other secondary butterflies to see if ant others were loose?
http://home.comcast.net/~bsoomann/imbed.jpg

This is the piston top after light buffing with a wire wheel, notice the reflection of the piston top in the cylinder wall. I can not see any scoring in the wall.

http://home.comcast.net/~bsoomann/piston_damage.jpg

And this is the head after buffing

http://home.comcast.net/~bsoomann/damage.jpg


Oh yea Jeff you’ve got me thinking about a PC job! Do you have pictures of black w/red letters? :D[/quote]

[Bill]

I don't think there is any damage to the valves. The valves are recessed up into the head so that unless the screw is standing on end it would not contact both the head and piston at the same time. The roughness on the valves is real hard carbon that did not brush off easily.

[Tyler Townsley]

This is a little late but I thought I would post it for future reference. Find a borescope borrow it, use it to look before you take it apart. Get a good vacuum cleaner neck it down to a flex hose that fits into spark plug hole and rotate piston to bottom and suck until it comes out, also can sometimes use a flex magnet. I also have used air pressure through a flexable hose when the motor was rotated with the exhaust valves open, used the air until it bounced the dropped screw(yeah I dropped it down the IH when the intake exhaust valve was open) around and out.

Tyler

[Bill]

Good advise Tyler. Glad you were able to get your nasty little screw out without opening it up. I did try all of you recommendations except the bore scope. I was not able to find one small enough to fit through the spark plug hole and then flexible enough to bend around inside the cylinder. Also tried both vacuum and air pressure to no avail. Just my luck! So it was time to learn what was under the covers of the LT5. This thread is my effort to share the knowledge as I gained it. The big thing that comes to mind now is how hard the head blots were to remove. Because of their length (9”) an impact wrench is useless. As you know an impact wrench works by a series of rotational blows, all this did was to twist the length of the bolt then relax, then repeat. What worked was a ½” breaker bar with a 36” handle and all the muscle I had. Now it time to start cleaning parts and pieces to put things back together, and hopefully running.
Wish me luck
ßill

[Jeffvette]

Jeff you’ve got me thinking about a PC job! Do you have pictures of black w/red letters? :D

Yup

http://www.pnwzr1.net/Jeff/Powdercoating/Ken_Koester/PDR_0493a.JPG

http://www.pnwzr1.net/Jeff/Powdercoating/Ken_Koester/PDR_0492a.JPG

[RedZR]

Tyler,

You sound as if you have experience with this. Just how common of a problem is this- do these bolts often come out?

Dan

This is a little late but I thought I would post it for future reference. Find a borescope borrow it, use it to look before you take it apart. Get a good vacuum cleaner neck it down to a flex hose that fits into spark plug hole and rotate piston to bottom and suck until it comes out, also can sometimes use a flex magnet. I also have used air pressure through a flexable hose when the motor was rotated with the exhaust valves open, used the air until it bounced the dropped screw(yeah I dropped it down the IH when the intake exhaust valve was open) around and out.

Tyler

[8upZR1]

I just wanted to chime in and say that I too found those marks that the screw threads left on your head/piston when I took my motor apart, although my issue was a head gasket. Aparently the screw(s) bounced around for a while and then went out of the exhaust. All of my cylinders looked this way. I dunno where my screws came from though as my secondary throttles ahd all of their fasteners.

My daily driver/family transport is a 05 Toyota Scion Xb. A month after I got the car I sucked a dime through the motor. Yes 10 cents. It bent the ground strap on the plug and then made an exit. I found the dime in the cat. I was very lucky but it is very possible that relatively large objects can pass through a motor without major damage.

[Tyler Townsley]

Tyler,

You sound as if you have experience with this. Just how common of a problem is this- do these bolts often come out?

Dan

Just make sure you tape off the IH openings after you pull the plenum, it keeps one from droping things into the motor.

Tyler

[blackjack]

i hate to tell you this,but sometimes the screw will beat the piston just enough to make it collapse a bit and squeeze the top ring ,preventing it from mooving freely,resulting in a bit less compression in that cylinder...the engine will still run very good,though....just a tought....ive seen it happen
bj

[Bill]

I talked to several knowledgeable people last weekend at the ZR1 gathering west. Like 8up said,comments were made about having found screw marks in combustion chambers, but no screws. I guess that the screw can go out the exhaust.

bj I did check a compression check on all cylinders when I started low was 180 high was 198 and the affected cylinder was 185 so I don't think I had that kind of damage.

The more imput we have here the more it might help me and others in the future
Bill:)

[WB9MCW]

IM GONNA LOCKTITE MY LOOSE SCREWS....LOL...I HAD TO SAY IT!!!

[Tyler Townsley]

IM GONNA LOCKTITE MY LOOSE SCREWS....LOL...I HAD TO SAY IT!!!

I hope you made sure to avoid your eardrums.

Tyler

[blackjack]

=D>
bj

[Jim Jones]

WOW!! Great educational thread!! Bill, I am thrilled for you that everything worked out as well as it did! As I was reading it, I was getting that sinking feeling at the beginning, you know, the one that says, 'what else can go wrong with my baby' feeling. As everyone began to chip in with suggestions, I started feeling better. Congrats on solving the problem!

I hope:pray that I never have this problem, but if I do, I'm glad that there is information like this to help me out. Thanks!

Jim

[Hammer]

Hey Bill,
Haven't seen any postings from you in awhile so guessing things are going good. You gonna port the Plenum and IH's. Post a pic when you are done. Red with black letters looked great on Ted's Z an the black chrome with red letters was pretty nice also.
John

[Bill]

Hi John

Thanks for thinking about me and the project. Things have basically been on hold since returning from Vegas. I sent the cam covers, injector housings, plenum and the claw of to Jeff for powder coating. When they arrived Jeff & Bob felt that I would benefit greatly from some P & P work on the plenum and injector housings. Lots of time required to do it right. Jeff seems to have quite a horde of parts that GM can’t find so a good resource to keep in mind. GM could not find me a head gasket, Jeff had them. Unfortunately Fedex bent the box and ruined the gasket. I’m waiting for another. Then I will be able to put the head back on then re-install and time the cams. Jeff is going to get the cam covers done and shipped so that I will be able start putting the engine compartment back together. By the time Bob works his magic on the injector housings and plenum and they coated it will be around the first of the year.
Well that’s it for the update stay tuned, more to come on this ”same bat channel” :mrgreen:

[Hammer]

No problem. I was just curious (as I mentioned) and especially after we talked outside and at the table at Calico Jack's. I read all these articles with great interest because I know someday I will be there too. Maybe not to the extent as you but I WILL be there. I think it is great that you are doing this yourself though, as there is always a mystery on these cars until you get your feet wet (hopefully).