Hi all,

I was wondering if there is any rule of thumbs or taboos about pulling the girdle and rod caps to inspect bearings on an unknown engine.

Is it a no no to just re-assemble the bottom if the bearings all look good? Or if you pull caps, expect to put new bearings in for every one you pull regardless of how the original bearings look?
.
.

 

I always did that with imported sr20det engines though i put assembly lube on them before reassembly.

 

If there was a claim of being rebuilt, would you verify the tolerances with plastigauge first before, cleanup, assembly lube and re-assemble?

 

I think as long as the bearings were perfect AND you kept each half in it's original position then you'd probably be okay.

I think it's one of those things that since the bearings are so cheap that you are better off replacing them since you already have them apart but I have replaced a v8 main bearing (thrust bearing no less) with the motor in the car on a lift, oil pan off, and the crank still held in place by the other main caps.

Guy didn't seat the torque converter in all the way and pushed the crank forward and ended up with .050-.060" clearance after noticing oil pressure problems. Even with a new bearing it didn't take up all the clearance as the crank counterweight had some material removed as well . . . it was basically a band-aid fix that he made work for a couple of months.

 

So if you move the shells expect to put brand new shells in? So in reality if you want to be sure the bearing cap or the outer bearing resting surface is in good order, plan on pulling the shells out and replacing them regardless of their condition?

Another question. If a main bearing spun, or a rod bearing spun, either or, and the original owner did not replace the rod or block, only had either of them honed and used oversized bearings, would the chances of that same bearing spinning be higher?

 

Bearing Wear Analysis - Bob is the Oil Guy - Bob is the Oil Guy

Heres some good info regarding bearing wear and inspection.
Good info on that entire site actually.

Depending on the situation and reason for rebuild, if theres no reason to replace the bearings, I think its ok to re-use them.
Ive taken apart a 200k mile engine before and the bearings were literally just about perfect. I had no concerns with re-using them (crank still measured perfectly as well) and the vehicle is still running today.

If good oil was always used and no dirt or crap got into the engine (nothing embedded in the bearing), and no wear observed (should never wear in a perfect world), I see no problem with re-using bearings.

 

I meant more along the lines of keeping pairs together . . . bearing crush essentially makes pairs when you torque them down. It may not be enough of a difference but keeping the pairs together is going to minimize any chance of change in clearance however small (.0001 or less?)

 

for a race/total performance mind,i always change them when i inspect the engine.For a swap/more normal application i dont mind to keep the old bearings in.

 

Awesome, thanks for all the feedback guys.

Also in addition to the Bearing Analysis link posted above from BITOG, I had stumbled across this site a while back that also goes into a lot of the bearing failures and the looks of them:

http://www.nb-cofrisa.com/docs/web_fallos_ing.pdf

I'll have to pull out my stethoscope as I'm not to sure my giant snap-on was accurate, but based off of what I heard with the massive flat tip screw driver, the knocking wasn't heard in the head above 1 and 2, nor at the bottom of the block between 1 and 2 nor at the top of the block by 4.

The knock did come through at the top of the block between 1 and 2. Not a loud knock yet but definitely audible.

I was curious to know the consensus of pulling caps to inspect bearings and reusing them. Good to know for a DD spirited driver, it's okay if they check out as long as you keep the halves together and mated to their respected journal too.

Seller claimed everything but the block was replaced but receipts seemed to only indicate rings and possibly bearings. They claim rod #3 spun a bearing and caused them to replace everything.

I want to verify the bearings are good without pulling the head and full dismantle as the compression is near perfect at 180 PSI on 4 cranks at sea level on warmed engine.

All of your help and information is greatly appreciated.

 

In the cases I did it was just a visual inspection and making sure that there was no chance of dry bearings on startup, which at the time I was told was fairly common. If I had seen any sings of wear that seemed out of step with the age of the engine, or if i felt that it just looked bad for whatever reason they were replaced. The last engine I did it to was a FWD SR20DET out of a bluebird that went into a 1992 sentra se-r, we just opened it, took a look and lubed it up putting everything back where we found it. the guy drive it for a few years, raced it til he blew his diff at the track, replaced the trans and sold it. Was it per manufacturer spec? Who knows but in that case it worked...

if the word rebuilt was used I would expect all new bearings, new rings, new pumps and gaskets...

 

In my experience with honda engines, it is not uncommon for rod and/or main bearings to have collapsed even if there is near zero wear. which generally means they can last quite a long time if you never take it apart, but as soon as you take it apart the bearings just fall out and you're forced to replace them. this is most common with the lower main bearings and upper rod bearings. keep this in mind as well as you disassemble it. Generally speaking, if I'm going to pull things apart, I just replace the bearings either way.

 

When bearings lose their crush it is also a sign of detonation so your tune might be off. When the bearings stick to the crank when engine is pulled apart this is also a sign of this.

 

After all the feedback here, I felt the best course of action is to just let the motor be. The compression is very solid at 180 across all 4 and I heard no knocking on the bottom of the block or in the head.

What sounded like a knock (not severe) was actually at the top of the block. I believe the kid was running it pretty hard thus his crash and the total of the shell. So I figure I should be able to get use out of it, if it blows up, I can always drop my old b7 back in with just a swap back to my old ecu.

It was a crap shoot purchase, I might as well see where the dice land.

 

I did not read all the responses but giving that when you pull them apart and the bearings look to be in good condition you can absolutely put them back in with no problem.

 

I think this counters your opinion with solid experience and convinced me it's an unwise idea. It may work out fine but I definitely think it increases the odds of it not being fine after re-assemble:

 

In your specific case you are asking if you could reassemble the motor if the bearings look good on a unknown engine. Assuming you are on a shoe string budget because instead of you paying $60 for bearings, you asked the forum. If the bearing has had no damage and look healthy, why would they fail?

 

Essentially yeah, that was what I was asking. I wanted to know if doing so would be asking for trouble.

Based on all the feedback what I got is, you can peek at them and it can be fine, but also you are increasing chances of things going very wrong.

So the final answer is, yes you can look and it might be okay but then again, it could be so very costly if it doesn't go okay and there is a chance it might not go okay.

The motor runs and I didn't hear anything on the bottom of the block so I figure, why take the chance, just run it.

Hope that clarifies the understanding I got from all the feedback,

 

I understand, when you do take it apart post some picks of the bearings!

 

Are you interested in these bearings in particular?

I have already taken apart the crank of two other blocks, one known running condition with a light knock, still ran good, and another of unknown condition.

If I rip this Z6 motor apart it will be for a rebuild/build of some sort assuming I don't throw a rod. And that will be a loooong ways off.

Is it these bearings in particular you want to eventually see?