Cam bearing surface slightly rough?

[Torchred96]

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]

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]

Originally Posted by Fully Vetted

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]

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]

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]

Originally Posted by Pete

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]

Originally Posted by Hog

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]

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]

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]

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.