My old 355 I rebuilt is still a mystery. After 2200miles every rod , main,and cam bearing was wiped out, and it would knock when above 1000rpm. This was its life:

Bored/tanked, new cam bearings installed

Assembled by me and an ex-friend. Clevite 77 bearings, assembly lube. Didnt check any clearances (I was new at auto stuff) spun the crank freely by hand after it was torqued, so I was told "good enough"

Primed, Break in was 5 min at 2500rpm (re-used stock roller cam and lifters)

Ran it again to set the timing.

Put it in the car, ex-friend insisted he drive it first incase something felt wrong. First thing he did with the engine cold was punch it and spin the tires at 5500rpm

Changed the oil for the first time after that.(if Id a known better I woulda done it after the first time it was started)

Drove it around town, raced about 15-20passes.

It overheated quite a few times, 240*to 260* Turns out there was a pin hole puncture in the radiator causing the temp gauge to flucuate wildy.

Got home from a day at the track and it was a knockin'.

Tore it apart and all rod and main bearings were copper and black. They smelled like gas and burnt oil. None of them were blue from oil starvation, nor smelled like burnt metal.

Sold it all to another friend who took out the cam bearings and said they were all messed up to, but I didnt get to see what they looked like.

So, what would cause ALL bearings to get wiped out. After 17 months I need some closer,lol

 

I'd start with that, amonst a few other things.

 

And the other things are? Rod/Main clearances wouldnt effect cam bearings though,right?

 

Good, clear, detailed pictures of the damage, taken with a high quality camera in good light using the "macro" function, would help greatly.

Sounds to me like classic oil starvation.

I doubt punching it and taking it to 55000 RPM had anything to do with it. I've broken in PLENTY of them just exactly like that, except higher RPM.

I also rarely "check clearances", strictly speaking; however, I mic the OD of the parts, and the ID of the bearings, before I assemble it. I find that to be much more accurate.

You might want to turn the block upside down, and look down through the hole under the rear main cap, directly opposite the one for the oil pump drive rod. If you don't see a ½" freeze plug about an inch below the surface, i.e. if you can see all the way to the oil pressure sender, then your oil was never going to the filter. Dirty oil can be an issue sometimes too.

 

If it was starved for oil the bearings would have had blue hot spots and have smelled like burnt metal, at least thats what Ive read.

But the lifters and cam were still in good shape. My friend is actually using them in and engine right now.

I dug up a pic of a rod bearing:

 

That's oil starvation.

I don't know where this idea of the bearings being "blue" is coming from. I don't think I've ever seen a "blue" engine bearing.

Lack of oil makes them get very very hot, and the metal melts and sticks to the crank, and comes off in flakes; it leaves the underlying sunstrate black; all that molten-looking metal like you have there IS the "hot spots"; in a word, I could take your picture and put it in an engine autopsy textbook in the Oil Starvation chapter.

That freeze plug in there?

 

We would probably need to see afew more of the bearings to be sure, probably oil starved, but it might of had antifreeze in the oil as well.

 

yeah man that is definetely oil starvation. what caused it, i can't tell you without the motor here. not checking the clearances wasn't very smart though lol. a motor is one of the most precise components to a car, get something off a hundreth of an inch and you could be asking for serious trouble.

 

The engine had a Summit brand high volume oil pump. I didnt have an oil gauge in the car, but on the test stand when broken in, it was 30psi at idle, and 70psi when rev'd, it wasnt fully warmed though. The Summit "High Volume" pumps dont pump as fast as name brand pumps, so Ive heard, so I dont think the pan was being sucked dry. Im using the same kind of pump in my 350 right now with 6quarts of oil(Mobile 1 extra large filter) pressure is always good, never drops off at high rpm.

What I find wierd is that my friend bought the shortblock off me, rebearinged it, used all the same parts, rods, pistons, crank, cam, lifters, didnt have the crank polished or anything, and isnt knocking.

 

gas/coolant in oil

streached rod bolts

bad spring in oil pump

debris in the oil galley

bad bearing clearances

over heated and broke down oil

loose/bad fitting oil pump

many things can go wrong

 

I understand all of those can cause damage, but when every bearing in the motor is destroyed in the same manner, I wonder if there is one specific cause. I talked to my friend who checked the cam bearings. He said they were copper in the middles, but the edges were good.

My idea is:

excess fuel thinning the oil from running rich+ overheating thinning the oil+reving to max rpm when overheated cuz doing that got the coolant circulating again(like I mentioned, a pin hole size puncture in the radiator)

Does that make any sense?

 

I've seen oil starvation from improperly installed cam bearings.

 

now that makes sense to me. Oil goes from the pan through the pump into the filter up the block to the cam bearings down to the rod/main bearings, right?

If the cam bearings were installed incorrectly they would get some oil (explaining the edges being fine, but the center destroyed) but the flow to the bottom of the engine would be interupted.

 

i have seen bearings turned blue on the back side from a lack of oil, 99% of those times the bearings were stacked, which will also trash the rods & crank every time.

its hard for me to tell from the pic, but it looks like that bearing spin in the rod, did it?

pretty much everything has been mentioned except for, how thick was the oil you ran in it? a mistake alot of people make is putting too heavy of an oil in thinking the thicker oil will lube the motor better, but instead its run dry at every cold start up.

 

The bearings didnt actually spin, but I had to pick them off the crank. Always used 10-30 oil

 

You have the order backwards man. The mains recieve oil first. The cam bearings are really the last pressurized stop in the oiling system.

As far as the bearings, it looks like there was a fair amount of debris in what little oil was there. I would be interested in seeing the journals on the crank also, to see if there was any welding or transfering of metal going on.

 

This is the plug to which the Couch King referred:



One thing worse than having no plug installed and getting unfiltered oil is to have a plug installed too shallow, and getting no oil or very little oil, filtered or otherwise.

 

And technically (at least on a standard SBC) the mains and rod journals receive their oil supply from the cam bearings.

 

Yep, i had to go and look it up too.

 

Im pretty sure we installed that oil plug. Would that effect the oil pressure at all? The backsides of all the bearings were ok.

 

If the plug is missing, you'll get unfiltered oil. If the plug is too shallow, you'll get no oil or restricted oil flow - a.k.a. oil starvation.

 

Would that effect oil presure?

 

Help me understand why you're so unwilling to accept the patently obvious diagnosis of the cause of your bearing failure. I know building a motor and having it explode is a pretty ugly situation; and it's discouraging and all that; but, it can be a good thing (or at least not an all-bad thing) if you open your mind and let yourself learn from the experience, let it teach you whatever it has to teach you.



Imagine you're a detective, OK? You got a dead body in the morgue you're looking at. The victim was found in the woods, has 3 little holes in his skull, above his right ear; they're kind of little, and they're all exactly the same size, nice smooth round holes about a quarter inch in diameter; and the left side of his jaw is about half blown off, looks like from the insided. What did he die from?



Now, maybe he was wandering through the woods, and he saw a bear, and it freaked him out so bad that he lay down on the ground and accidentally ate a poison mushroom and when he got back up he was dizzy and he fell down and landed on 3 sticks.

Maybe. Those might not be gunshot wounds, and he might not have been murdered.

OK, maybe not.



So, maybe he was talking to his friend, and his friend told him that he had heard his wife was seeing some other guy on the side; so he whupped out his rifle and committed suicide by shooting himself in the back of the head downward above the left ear 3 times.

Well, maybe he did. You can't prove he didn't, now can you?

OK, maybe that's not how it was either.



We're in one of that same kind of situations here. Autopsy says, it died of oil starvation. Just like the guy with the 3 gunshot wounds to the head. You see that, you don't have to look any farther; you just found the cause of death. What you have is so classic and typical and looks just like every other oil-starved bearing everybody here has ever seen, right down to you having to pick the molten bearing metal off the crank, that the conclusion is inescapable. Why is it so hard to accept that they failed due to oil starvation, and instead of grasping at straws trying to invent some far-fetched thing about "well it was a waning gibbous moon and Venus is in the morning sky and Friday the 13th came on a Monday this month, so maybe it's {fill in the blank}". Just accept the obvious fact, and move on, and try to figure out why the bearings got oil-starved. That's the productive thing to do, instead of inventing creative convoluted explanations.

The way cam bearings cause oil starvation, is by being installed with their oil hole at 12:00. Or, by not being centered in their bore (driven in too far or not far enough), such that the edge of the bearing uncovers the oil passage behind it, and the motor has a massive internal oil leak. The rear one especially. Or, while we're on the subject of massive internal oil leaks, the plugs got left out of the front of the block, behind the cam gear.

The temp getting up to 240 didn't cause it, considering that the factory fan switch for electric fan cars, DOESN'T EVEN TURN ON until the temp gets to 234 degrees. Getting up to 240 once didn't hurt a thing.

There's bound to be a super-simple, one-step, uncomplicated explanation. And as the ancient wisdom says that somebody who is obviously far smarter than me has posted on these boards before, "The simplest explanation that fits all the facts is usually the right one". Put the emphasis on SIMPLEST, and look at your block for SIMPLE things that could go wrong, that could cause either an oil passage blockage or a large leak. Follow the path of the oil, BE the oil, and it will lead you to the truth.

Look real carefully at your block, and take the mental attitude as you look at it, that you're looking for something that would explain oil starvation to the crank. With that approach, you'll find the cause for sure, and you won't build it all over again, and have the same thing happen all over again; which might be the case if you don't FIND the malfunction and fix it. Youll have the peace of mind of knowing you found it and fixed it and no longer have to worry about it.

 

Time to bring in CSI with all their internal shots from the oils perspective and such, lol.

I understand "oil stavation" looks to be the cause, buts its simple for some people to just look at the pic, hit Post Reply, and say "oil starvation" without reading all the facts.

Ive just tried to carefully go through each of the possible causes of oil starvation.

First a lot of people went straight to "sucked the pan dry" cuz it was a high volume pump. Did they read where I said oil pressure never dropped off. And if a high volume pump sucks a pan dry all the oil is in the top of the engine(lifters/cam) so why would the cam bearings be worn??

The cam bearings being installed incorrectly. A possibility, makes sense to me.

Then the plug people mentioned, a possibility. If that would not effect the oil pressure the gauge is showing, Id say thats a real possibility.

I do not accept an answer so easily because there are so many choices, and I know only the more experienced guys here will stick around this thread reading every post, resulting in the most logical explanation. Cant inspect the block, its being used and runs fine with all the same parts, which makes me wonder even more...

If everyone puts together all the stated facts and conditions, we can say:

"Oil starvation caused by [?????]"

 

On CSI they do an autopsy. It's a little late for that now since it's been reassembled and you don't even own it anymore anyway. All you can do now is guess why the bearings didn't get oil.

 

Ill get ahold of my friend who has it now,and ask him if the oil plug was in it. Does this plug come out easily, like could have fallen out during dissasembly?

 

No, it has to be driven in and out.

 

you said it never lost pressure, so i would have to go with the gasoline in the oil, gas in oil = little to no film strength = metal to metal.
with gas in the oil you would still have good pressure. i have seen motors that had as much gas in the crankcase as they did oil & still have pretty good pressure.

i couldn't see it lasting very long any other way, by very long i mean knocking within 50 miles if it made it that far & probably putting a rod through the block.

 

Id a noticed if gas were in the oil when I changed it

 

If the same parts went back together and work correctly this time, then it probably was something in the assembly of the block.

The cam bearing thing is widely overlooked. The cam is constantly being pushed down, toward the crank, by all of the forces applied to it; so, if you put the oil holes upward, then whatever clearance there is in the cam bearings, all appears right at the holes, and oil will flow out liberally. Ideally, you want the cam bearings installed such that the holes are at about 5:00 to 5:30, viewed from the front of the block; that being, where the cam journals will be pressed the most against the bearing, and also the point at which the journals need the lube anyway.

It's also possible that there was a blob of something stuck in the center oil gallery. A piece of Teflon tape, or a chunk of silicone, something like that; remember, a "vat" is just that, a "vat", and whatever came out of however many other parts that have been cleaned in it, is all still in there, and that could include all sorts of unexpected goodies. All of those passages are downstream of the pressure gauge, so the gauge will show normal pressure; maybe even higher than normal, which will give you that false sense of security, since the total oil flow in the system will be reduced. For that reason, I ALWAYS ALWAYS ALWAYS specify that the machine shop return a block to me WITH ALL PLUGS OUT, and NO CAM BEARINGS; that way I can run a rifle brush through every single passage, and a toothbrush-shaped wire brush around the groove behind the cam brgs (which is part of the passages that carry oil to the crank), and get any leftover metal chips from the last blow-up, casting sand, or just plain trash, out of everywhere. I've seen some stuff come out of freshly "cleaned" blocks, that would make your eyes pop out, would have caused a blow-up for sure; you'd NEVER EVER put a motor back together again without cleaning it YOURSELF, if you'd seen it. Remember, anything in those passages, only has ONE WAY it can go go, to get out: right straight into your bearings. I have a cam bearing tool of course, and I put them in myself, just exactly how I like them put in; but those who don't, can take their block back to the machine shop AFTER THOROUGH CLEANING, and have the cam brgs put in. It doesn't cost much, and IMO is money well spent, to make sure there's no metal shavings in the groove behind the bearings.

But meanwhile, if the motor is working OK now, then whatever killed those bearings, got corrected either by deliberate attention or by accident, in the afterwards build-up; so it's all water under the bridge now.

Gasoline in the oil wouldn't have killed ALL the bearings THAT BAD and THAT FAST, unless the oil was half gasoline or more. I think we can give that whole idea a rest.

The plug in question, goes in from the crank side, and needs a punch or something to drive it in; it's exactly the same (just a ½" welch plug) as the ones behind the cam gear; then to get it out, you use a long rod or something, stuck in where the oil pressure sending unit goes, behind the distributor. The oil flow from the pump is, up through the rear cap, into that hole; then there's a horizontal passage that leads over to the filter; then there's another horizontal passage that leads back from the filter, to THE SAME VERTICAL PASSAGE, which then carries the oil up to the top rear of the motor, to the rear cam bearing where it gets distributed to the crank and to the lifters. The plug goes at a point in between the 2 horizontal passages to and from the filter, separating them. If it's missing, then the oil isn't forced to go to the filter, but rather can go straight up from the rear main cap to the rear cam brg, bypassing the filter. Effectively taking the filter out of the system and just turning it into a little 1-qt tank off to the side there, with no flow through it.

 

I think that it was oil starvation with out the antifreeze or gas to do with it now. I had an engine once that had the bearings ruined because of an internal coolant leak, they were not black like that. If it were gas or antifreeze in the oil the bearings would look more uniform.

And can we please stop talking about CSI. Sofakingdom, your the worst!

 

Thanks!!! I resemble that remark.

I just really like the idea of deciding that a guy with 3 gunshot wounds to the brain, is a suicide. That's a true moron at his finest. And yes, it's been done before, in the real world, by people who are paid to know better.

On the AF/gas thing, anohter quickie to consider: if the oil was sufficiently diluted to wipe stuff all the bearings like that, in as short a time as it did, the crankcase would also have had to be WAY WAY overfull at tear-down time, due to the extra contaminant. Taking more fluid out of a motor than you originally put in, is a sure sign of something suspicious going on. Taking the same or less out, if it doesn't leak or smoke, pretty much rules that sort of thing out.

 

Unless the machine shop took the plug out, it would still have been in there from the factory, cuz I never took it out.

I had the hot tank/bore done at a reputable shop, owned by Bill Walls, a former pro drag race champ, but anything is possible.

My friend who has the engine now is gonna let me run it hard on the test stand. The only things different are the new bearings installed by him and crappier heads.

 

you said the bearings "smelled like gas", so i took that to mean it did infact have gas in the oil, my bad.

another thing i have heard about but as far as i know i have never seen is excessive oil pressure washing out the bearings, seems like i was told it takes around 120+ PSI to do that, but you said it had 70 PSI on the test stand.
without a good gage in the car, it very well could have lost pressure at some time. did you do some hard cornering with the RPM up high? taking a 180 degree interchange on the freeway at
speed is more than enough to do it.

 

The car never had any hard cornering, not with a V6 suspension and open read end. The bearings smelled like gas, but did not reak of gas. It was always running kinda rich, so the unburned fuel could get past the rings into the oil.

 

Machine shops will often take all the plugs out, including that one, at some point in the process. But not necessarily. And, not always before vatting, even when they do. There are no guarantees. So who knows. And, if they take it out, there's equally no guarantees, that they will put it back.

That's why I always specify that I get blocks back WITH ALL PLUGS OUT; that way, I know they're out (duh). And after I put them all back in myself, I know they're all back in (duh again). Back when I built motors for people alot, I noticed ALOT fewer warranty claims after I started doing it that way, which was after a bad experience. It helped eliminate any more unpleasant surprises.

"Good judgement is the result of experience. Unfortunately, experience is usually the result of bad judgement."

 

Just to shed light on the oil passage soft plug issue as quoted from gm performance shop manual:

"A VERY IMPORTANT soft plug needs to be installed in the oil passage at the rear of the block at 1" from the top of the plug lip to the base of the bearing register. If it is missing or incorrectly installed the engine will have no oil pressure at start up and will be destroyed almost immediately."

So to answer the question would this soft plug missing effect oil pressure? Yes and in a devastating way.

I highly doubt the engine would have run as long as it did with this soft plug being the issue, just my thoughts.

 

Gee, wonder if that had anything to do with it.

One has to wonder, also, why it's an "ex" friend. . .