Cam bearing surface slightly rough? [Archive]

Torchred96

11-25-2012, 02:42 PM

Hib Halverson

11-27-2012, 07:35 PM

After taking out the cams on the driver's side (left the sprockets on) I noticed about 4 of the lifters on the intake cam seem to have bled down and are soft. Recall I'm working on a ticking lifter noise.. This after sitting for about a month in my garage. None of the exhaust lifters exhibit this softness..or sponginess..

I ordered the complete set of lifters for that bank (16) and am awaiting their arrival. And since I have time on my hands, my mind was thinking...perhaps overthinking as I tend to do....but,Im thinking that perhaps an oiling issue to the intake cam may have caused the lifters to collapse? Then, I went to look at the head and noticed that the bearing surface where the oil galley that feeds the cam appears to be rougher than the rest. How rough is too rough and should I try to polish it somehow?

Also..How can I check to see if oil is indeed flowing through this galley?

I tend to think you don't need to worry about that.
Why?
Well...let's consider what would happen if there was no oil flow in that oil passage. There's be no oll to the cam bearing and the camshaft would have long ago seized up. Clearly, you don't have any camshafts which are seized so oil must be flowing to the cam bearing surfaces.

As pointed our earlier, the majority of the cam bearing wear occurs in the cam cover because load wants to push the cams outwards. If that cam bearing surface on the head seems more rough it may be because it's not worn.

Lastly, I would consider carefully using any abrasive to change that surface.

Torchred96

11-27-2012, 08:00 PM

Thanks Dynomite and Hib. Well, hope these pics don't change your mind. Keep in mind the car has been sitting so the oil u see is not the circulating oil, it's just old oil i dribbled on it keep moisture/rust at bay. Btw the 2 pics are of the same bearing surface.

http://i1096.photobucket.com/albums/g328/sirlancair1/IMG_4344.jpg
http://i1096.photobucket.com/albums/g328/sirlancair1/IMG_4342.jpg

Paul Workman

11-28-2012, 03:10 AM

I just happen to have a head sitting next to me (doesn't everybody?) and I see something on some of the bearing surfaces that looks like light scoring, similar to yours, but perhaps a little lighter.

There is some similar scoring on the cam cover bearing surfaces - perhaps slightly deeper (but still pretty superficial).

the head came off at approx 45000 miles to be ported. Up to then, it ran fine w/o any oil issues. Both heads had some of the same type of superficial scoring on some of the bearing surfaces, but deemed insignificant by me (and later by Pete).

For unrelated reasons, one head was damaged and I replaced it with a head off of a 92(?) LT5 that Marc was parting out. My motor now has 55k on it and there has been no problems with either head before or since.

All this to say you're probably OK. But, timing the cams is something best done with the motor out of the car anyway. So, sending the head off to one of the gurus for inspection and expert opinion and measuring is a consideration. (Can't really tell from the pictures...)

BTW...What kind of oil are you using?? I hope it isn't API rated "SN" or the like.

P.

Torchred96

11-28-2012, 12:41 PM

Thanks Paul, Hib and Dynomite.. It's not going back together anytime soon I don't think. I still want to look at a couple of the bearings in the bottom end. I wasn't comfortabe with the noise it was making with a stethescope on the plenum..sounded like metal to metal rubbing somewhere...along with the ticking. I've never heard that before on my lt motors. I've haven't put that many miles on the car since I've had it in a year..maybe 3k if that. I changed the oil shortly after buying the car, again after the porting process and added only one quart since, all mobil 1 10/30 synthetic. Of course that was before reading recommendations.

The Cam surface on cam cover opposite this oil bearing doesn't look bad at all. Scuffed but not gouged. The cam itself is shiny and does not appear to have any aluminum transferred to it, nor is it scored like the head. All the other bearing surfaces look fine, in head and cam cover.

One thing that still gets me is that several of the intake lifters can be depressed with finger pressure approx 1/8" or so. ON the exhaust side, none of them are soft at all. Just wondering if that may be an oiling issure which is really why I started this whole thread.

Hib Halverson

11-29-2012, 10:40 PM

Pete

11-30-2012, 01:50 AM

How many miles on the motor?
Has it been apart before?
Is it all factory assembly?
How do the cams look like?

From the looks of it they look like normal wear but without having it in front of me to feel how deep the grooves are can't really say for sure/100%.

Use some Scotch bright on one cam bearing surface and see if it polishes smooth then it's ok,you will not hurt anything.

It is very hard to find one ticking lifter if you know which bank it is i would change all the lifters on that bank.

Had this same issue with a friends low mileage Z (20k) we just changed all the lifters and no more ticking.

Melling JB-2236

Pete

Hog

11-30-2012, 12:28 PM

Any issue with putting a new lifter surface on a lobe surface that was broken in against a different lifter?
This a no-no on any other non-roller cam engine. The cam lobe and lifter burnish together as the lobe slides on the lifter which causes the lifter to rotate evidenced by the round burnished areas.

Be careful with Scotchbrite, its reminents are murder on bearings if it is circulated in oil. Be sure to wash all possibly exposed areas well.
I would say that you could do damage with a Scotchbrite cookie on a rotary, but a handheld pad would mitigate any risk. I'm sure that was what Pete was referring to.

GM wont pay engine warranty work to dealerships if there is evidence of Scotchbrite use.

peace
Hog

Torchred96

11-30-2012, 01:25 PM

Ok Guys. Thank for your input. I am, as Dynomite said having basically a dual post from the other forum, not for any particular reason other than I know that others might be interested in what I found and what you guys say. I'm trying to remain a-political and stick to the facts. I certainly appreciate all of your help.

Pete: The car and engine have approx 140k miles. I've had it a year and put on about 3k. Much of that was pre-new injector/porting etc, when it was running very poorly. After that, the car ran unbelieveably well, far exceeding my expectations..as well as my old hotcammed lt4 :) I assumed the heads have never been off. At least it did not appear to me to have been. However, inside the left cam cover appears to be painted the letters FU2. I don't know what that means, maybe someone had this head redone at one time. I can't tell. I bought the car without knowing any history except what carfax told me and the dealer who sold it to me.

Appears to be a factory assembly. All I did to this motor is port intake, IH and remove secondary port throttle plates and shafts, and coolant bypass etc..Also changed oil 2 times in 3k miles because of the above work that I did and not knowing the history when I bought it.

Basically The cams look excellent to me...no obvious wear either on the lobes or the bearing surfaces, and especially surprised that none (scratches) is where the scratched bearing surface are that I posted pics of. Honestly The pics are the only thing in the head that caught my attention OTHER than the 4 or 5 intake lifters that are soft. And again, NONE of the exhaust lifters on that bank are soft.

If you look closely at Dynomites photos, you can see little specs that look like pits in the aluminum. In mine, they are similar, pin hole small. That's basically what the rest of them look like.

I think I will carefully try the scotchbrite idea and report back my results.

Hog thanks for the tips. I won't be using anything so aggressive. I've heard that about lifters and cams too, but what is the alternative when you have bad lifters. Unless you're implying that it's time to upgrade my cam...while im in there?

Torchred96

11-30-2012, 01:40 PM

Is there more than one cam bearing surface in the heads that looks like that?

What did the cam journal that was running on that bearing look like?

By chance, had you been doing periodic oil analysis? If so, can you post the last print out from the lab?
__________________
Hib Halverson
Technical Writer
95 VIN140

Hib. No That's the only one that concerns me. The cam journal looks fine. No metal appears to have transferred to it from the head, and it is not scored..You can tell where it was riding, but it's only discolored as far as I can tell.
No oil analysis. Honestly I wouldn't even know where to get that done. Only changed the oil 2x so far in the circa 3k miles i've owed it.

Thanks for your responses.

WARP TEN

11-30-2012, 03:26 PM

.......... However, inside the left cam cover appears to be painted the letters FU2. I don't know what that means, maybe someone had this head redone at one time. I can't tell. I bought the car without knowing any history except what carfax told me and the dealer who sold it to me.

Maybe Frank Urb has been in there....:)

Torchred96

11-30-2012, 04:44 PM

Just received 8 (only) of the sealed power HT 2236 lifters in the mail. I emailed the seller that I was short 8 and he refunded half my $102. Oh well.

I thought I read somewhere that these lifters would suffice for the stock cams so being cheap ie 102 for 16 lifters, I jumped on them. Are the mellings that much better?

Hog

12-01-2012, 01:38 AM

Hog thanks for the tips. I won't be using anything so aggressive. I've heard that about lifters and cams too, but what is the alternative when you have bad lifters. Unless you're implying that it's time to upgrade my cam...while im in there?

Sure while you are in there lol, I just saw a set of brand new Stage 3 cams for sale for $3400. They are ground from the original GM blanks lift was 0.454" and duration was 242º. I cant find the link now, but it said there was 1 set left.

So long as there isnt any excessive wear and you are using teh appropriate oil, you should be fine.

Anyone have the p/n for NOS GM lifters?

peace
Hog

Pete

12-01-2012, 02:43 AM

XfireZ51

12-01-2012, 08:44 AM

Paul Workman

12-01-2012, 10:23 AM

Just so you have something to compare, here's a pic of my cam bearing surface when I removed covers earlier this year. Took off cam cover to replace breather vent material to relieve crankcase pressure.

http://i187.photobucket.com/albums/x198/Z51Xfire/CamCover002-1.jpg

http://i187.photobucket.com/albums/x198/Z51Xfire/CamCover001-1.jpg

http://i187.photobucket.com/albums/x198/Z51Xfire/CamCover004.jpg

As Pete said I used the Scotchbrite to clean surfaces before reassembly. BTW, cams had already been run several thousand miles at this point.

For what it is worth, mine looked about the same as well. I shrugged and haven't had any problems in 10k miles since. Light duty Scotch Bright sounds like the way to go - if only to take the microscopic edges off. Maybe some light oil to go with the SB would be worth considering?

P.

Fully Vetted

12-01-2012, 10:50 AM

Is that normal wear for 10k miles? What's it going to look like at 40k miles?

XfireZ51

12-01-2012, 11:08 AM

Is that normal wear for 10k miles? What's it going to look like at 40k miles?

I can't honestly tell you that what you see in the pic is wear from having run cams. For all I know this is what it looked liked originally. The motor these covers are from has about 30k miles on it. As you can see from the corresponding cam journal, there does not appear to be any damaging effect.

Fully Vetted

12-01-2012, 12:05 PM

True, true...

Torchred96

12-01-2012, 08:48 PM

Here's a couple pics after the scotch brite. The only stuff I had on hand was green. Also used wd40 which seemed to help a little. I don't think I want to go any further. You can't feel the scratches that are left. Thanks for the pics of the cam cover journals. Mine are similar.

http://i1096.photobucket.com/albums/g328/sirlancair1/IMG_4356.jpg
http://i1096.photobucket.com/albums/g328/sirlancair1/IMG_4357.jpg

Torchred96

12-01-2012, 10:32 PM

With the cam bearing surfaces issue out of the way for now (still want to check the passenger side. I decided to go ahead and use this opportunity to fix the oil pan leak. There is some kind of putty on the bottom of it, along with a longitudinal scrape ie, evidence of a strike.

More than the oil leak though is inspection of the bottom end. Recall that with a stethescope on the plenum, I could hear a low frequency noise. Might have been the water pump bearing but I'd like to be sure before I go through all the trouble to do this. The water pump is going to be replaced as well.

I guess I will be checking the mains and the rod bearings. Any caveats besides DONT DO IT :) and what I should look for. I plan on keeping the car so I'd like to know for sure the bottom is sound after what happened. I already have the crossmembers off and am pretty much ready to drop the pan but will have to wait a couple days.. Back to work.

Thanks

A26B

12-01-2012, 11:39 PM

Sam, if you are adament about checking the mains, you will have to pull the engine. Remember the LT5 has a lower crankcase "girdle" that houses all of the main caps together. All the main caps come off at one time.

Rod bearings, not a problem.

phrogs

12-02-2012, 07:44 AM

Is that normal wear for 10k miles? What's it going to look like at 40k miles?

The above photo that you are refering to is normal wear, I have seen it on Multiple LT5s from 19K to 80K and I think my hands have been on 5 different engines that I have torn apart, done top end work and rebuilt and parted out.

So that wear is nothing to worry about.

Torchred96

12-03-2012, 09:54 AM

I wasn't sure about the mains or being able to get to the rods. I do know for sure that I need to fix the oil pan so it's coming off and I'm curious to see what else I may find in the bottom..screws, broken parts, gold etc.

Initially I just noticed the ticking/lack of power and assumed I broke it bad. I'm still operating under the assumption that something bad has happened down below. But, I don't have a lot of experience with the motor and confidence that you guys have. I guess it's one of things I need to see with my own eyes, given the mileage and unknown history.

So, Jerry, Can I can still grab hold of the rods and see if there is any noticeable play by just pulling down the pan? I kind of want to see the condition of at least the rod bearings too since it should be pretty easy to do at that point no? If the bearings on the rods do look fine should I change them as a matter of course just because it has 140k miles? Also, if I find a bad rod bearing would that necessarily or at least likely include having taken out a main or two?

The head news is encouraging. Thanks for all of your help guys. I'm determined to get her back on the road, even if it means replacing the engine to get there.

A26B

12-03-2012, 10:42 AM

The rod bearings would have to be worn pretty bad to "feel." You should be able to get to a couple of rod caps with the crank in any position, but with the top end apart (cam covers off) I would not recommend turning the crank. You could get a sampling of rod bearings that way.

I would expect to see normal wear on the rod bearings with 140,000 miles. You could probably drive it another 60,000+ miles, but the problem is, once you start, where do you stop, short of a major overhaul? That's always a difficult decision on an engine with that many miles.

To answer you specific question "should I change them as a matter of course just because it has 140k miles?" $40.00 for a new set of rod bearings? You betcha I would put new in. Are there other factors to consider? Yes, time & labor as well as condition inspection of the rest of the engine.

Your question: "Do rod bearings necessarily indicate similar condition of main bearings?"

Maybe, but not necessarily. The LT5 has a tendancy for the #4 main bearing to fail first. After noticing this in several engines, I mentioned it to Brain White, who was an engineering intern with Lotus in England on the "new" LT5 project during development and then an Engineer on the LT5 project with Mercury Marine at Stillwater. Brian said that the problem was initially with the #5 bearing, due to the load imposed by the heavy dual mass flywheel. The #5 bearing width was increased and appeared to solve the problem. Considering the propensity of #4 bearing failure, he believes the #4 bearing should have also been resized.

What does all this mean? To me it means you may be able to get a sampling of bearing wear by looking at a couple of rod bearings, BUT it is not necessarily indicative of main bearing condition, #4 in particular.

The LT5 can be expensive to overhaul, but is still preferrable to buying "another" used engine of questionable condition. Horsepower by increased displacement can be had with little additional cost with new sleeves, pistons & rings for the same or less cost as stock replacements. The stock rods are heavy but hell for stout. The crank is most likely in great condition. Your heads may need new lifters, guides, seals and a valve job but very likely rebuildable.

About new or used lifters on new or used cams. Here's my take on that;

New cam, New lifters only

Used cam, reinstall used lifter (if servicable) on the same lobe only
or
Used cam, new lifter OK

No easy answer or shortcuts, just a decision by you on how much time & money you want to invest.

Hog

12-04-2012, 01:44 AM

The Scotchbrite i'm talking about is the green scrub pads you buy in the sponge section at your local grocery store made to wash dishes and used by hand,some sponges have this stuff on one side.
I use this stuff to clean head & cam cover surfaces from old aneroabic sealent w/parts cleaner it does not take off any aluminum to do so you'll work your fingers down to the bone.

Of course anytime you take things apart you wanna clean eveything thoroughly before putting it back togather,i thought this was common practice when assembling a motor,i didn't think i needed to explain this.

Sorry for the confusion.
Pete

Gotcha Pete, I more understand what you are using now.

About repairing engines, you'd be surprised how many techs. will pull an intake or head and clean away old gasket or RTV with a 3M Scotchbrite cookie on a air powered rotary tool, then wipe down the exposed areas, call it good and then reinstall the intake. Its hack work like this which forced GM to not pay warranty work to dealerships where evidence of Scotchbrite is apparent. To get it all out, you'd have to pull the engine and wash it all out. If not the bearings will be affected.

Obviously you and others here do good work and yes, washing thoroughly is a common practice, but its not a bad idea to point out the importance of such washing when very abrasive 3M Scotchbrite is involved. And when many folks here are in the learning phase of doing their own work on LT5 engines so that they can avoid much of the hack work that is practiced by SOME auto repair shops/dealerships. If you cant do the work yourself, a good mechanic is worth their weight in gold.

How much do you weigh Pete? lol

Anyone have the p/n for stock GM LT5 lifters?

peace
Hog

Pete

12-04-2012, 02:11 AM

Gotcha Pete, I more understand what you are using now.

About repairing engines, you'd be surprised how many techs. will pull an intake or head and clean away old gasket or RTV with a 3M Scotchbrite cookie on a air powered rotary tool, then wipe down the exposed areas, call it good and then reinstall the intake. Its hack work like this which forced GM to not pay warranty work to dealerships where evidence of Scotchbrite is apparent. To get it all out, you'd have to pull the engine and wash it all out. If not the bearings will be affected.

Obviously you and others here do good work and yes, washing thoroughly is a common practice, but its not a bad idea to point out the importance of such washing when very abrasive 3M Scotchbrite is involved. And when many folks here are in the learning phase of doing their own work on LT5 engines so that they can avoid much of the hack work that is practiced by SOME auto repair shops/dealerships. If you cant do the work yourself, a good mechanic is worth their weight in gold.

How much do you weigh Pete? lol

Anyone have the p/n for stock GM LT5 lifters?

peace
Hog

Your very right about the learning curve for some.
I'm not that heavy so i'm not worth much in weight lol,but you do have to do things right with the LT5 or it can bite you in the butt real fast.

I have seen heck jobs a few times in my life.

Lifter Numbers
AC Delco Part # HL110C
GM Part # 17120991

Pete

Torchred96

12-04-2012, 09:25 AM

Dynomite, thanks for reminding me. I took this apart so long ago, I almost forgot why. My initial observation was the lack of power and the clacking noise. Then, shut engine down, started it back up, there was an even louder knocking noise which subsided seconds after startup and settled into or rather back to the clacking. So, then with first on the cam covers, then on the plenum I heard the rumbling noise, like a heavy round bar rolling on concrete. At that point, I just assumed the worst and walked away for a couple weeks.
Then with all the support here, I thought maybe I was over reacting. So, went out with a long handle screwdriver and was able to hear the clacking over number one very clearly, but still bothering me was the low frequency rumbling. Water pump bearing is bad so I eliminated most of the noise by taking tension off the belt and eliminating all accessories as the culprit....But, I still heard a low frequency rumbling, albeit at higher freqency than the waterpump bearing.....think of a lighter metal rod rolling on concrete. This is why I am STILL concerned about something I have not found to my satisfaction....and why I was more suspicious of that cam bearing surface. That now eliminated as a concern, I'm back to just the lifters and the wp. ..and a prayer

Torchred96

12-04-2012, 09:40 AM

Ok, last night I pulled the oil pan and was pleasantly surprised to find no spare parts on the tray or in the pan. Good news! There is only one rod cap that I felt I could get to without rotating the engine, which I can't do because of the cams out on the driver's bank.

First, what a beautiful sight looking up into the wonder of the HEART of the BEAST! That was worth the price of admission alone and I suspect you gear heads know the feeling of first seeing this legend's internals first hand. As I digress, in the real world, I have only seen ONE other ZR1 in the flesh. That was around 1998 and the car was an obvious daily driver and already been rode hard and put away wet. So, even though my high mileage knocking ZR1 is presently down for the count, she is still very special and I think, more than deserving of some love, and as such, I feel privileged to be able to learn all that makes her tick....and tick and...

I held back from removing the one cap I could get to and only reached up and shook each rod and looked for any excessive up and down, left right or front to back. There was NO play that I can discern except in the front to back motion, which I assume is normal clearance since all of them did this. So, I guess i will have my oil pan repaired and see what happens.

Torchred96

12-04-2012, 09:54 AM

Jerry, with all that information, I would love to just take it out and pull it down the rest of the way. Mainly because of the block I see on Ebay with spun bearings and the want to prevent such a catastrophe.

At this point however, I've decided to just go ahead and change all the lifters, both banks and put it back together and pray that the bearings have not failed. But like you said, you have to make a decision somewhere along the line. I suspect this trial will end up costing me around 1000(incl water pump) by the time I'm ready to start it and see if the issue is gone or not.

THEN, if still present, more decisions. That engine that Marc has advertised looks enticing to say the least! But I'm not ready to give up on her yet.

Torchred96

12-04-2012, 06:45 PM

I went ahead and got 16 melling jb236. I would have tried the sealed power ones if the seller had sent me 16, but he says he only had 8. If I get what I ordered this time, I will order another 16 for the other side. Money is tight..isnt it always :(

tomtom72

12-05-2012, 05:20 AM

as one of those that are staring up at the LT5 learning curve...man that curve looks steep too! I admire your fortitude in taking on this work. I hope it is just a case of lifters doing the trick for your motor and then smooth sailing after.

I also want to say that actually seeing the internals of an LT5 when viewed from the oil pan looking up into the case must be like seeing the Sistine Chaple's ceiling in person versus seeing a picture!

Good luck with this job, and I hope all is well with the rest of Her heart!
:cheers:
Tom

Torchred96

12-12-2012, 06:43 PM

Tom, Thanks for the words of encouragement. Someone said here and I can't remember who, if the car is right for you, it will speak to you. I guess it helps if you think that part of the fun of owning a corvette is that after you drive it, you can park it and take out your tools and/or rags and let the fun begin.

I spent all day yesterday flat on my back cleaning (and admiring) the undercarriage while I wait for parts. The whole time, I'm thinking..this is not just any old corvette, it THE ZR-1!!!! How lucky am I!!! Never ending fun :) And when I do get to drive it again, it will be that much nicer than when I parked it.