Moparts

toasted cam bearings on new build

Posted By: 70Sbird

toasted cam bearings on new build - 07/27/11 09:41 PM

Hoping someone here can shed some light on this problem.
I just completed the build on my stroker motor it’s a 440, 0.60 over bore, 4.15 stroke crank and new rotating assembly,cam, roller rocker valevetrain etc… no apparent assembly issues, engine was pre-lubed with Joe Gibbs break in oil and assembled with assembly lube on all bearings.
The engine fired right up and ran for 25 minutes at 2,000 – 2,5000 RPM to break in the cam before the valvetrain stared seizing.
Now it’s torn back down and we have a mystery.
The valve spring seat pressure was not out of line, the cam broke in well, but 4 out of the five cam bearings are toast. One spun and three are severely “wiped “ including the #4 cam bearing that feeds the heads. The mains and rods look great, so there was no lack of oil or pressure, the engine had 70 PSI from the get-go. Since the mains and cam bearings feed from the same source, there would not be any reason oil was not reaching the cam bearings. New cam bearings were installed as part of the block prep and the cam turned freely in the bearings prior to final assembly. You can still see the oil hole (although mostly wiped) on the 3 bearings still in the block from the feed hole under the mains, so the hole was lined up correctly.
Any ideas?
Posted By: Mopar-Al

Re: toasted cam bearings on new build - 07/27/11 09:47 PM

You didnt say what heads, but sometimes when running stock heads and they have not been cleaned out through the oil hole passage, it can have build up plugging the oil hole. This kinda happens when you took a head off the left bank and then installed it on the right side of the block. The oil passage sometimes is plugged up. I have seen it happen before, so I always check this area and clean everytime. Just something for you to check
Posted By: 70Sbird

Re: toasted cam bearings on new build - 07/27/11 09:51 PM

thanks for the response, yes the heads were cleaned, oil passages reamed, and even double checked after teardown, the lack of oiling appears to have begun as the cam bearings were wiping and closing off the oil feed hole. the engine ran for about 25 minutes before we shut it down
Posted By: Performance Only

Re: toasted cam bearings on new build - 07/27/11 11:06 PM

take a good close look to see if it there's debris embedded in the bearings. did any of the bearings have to be reamed or scraped to make the cam turn freely? that raises another question, if the cam didn't turn easily with 2 fingers during the assembly process, it was too tight.
can you take a picture of the cam bearings and the main bearings to post here? obviously, main bearings installed wrong could keep oil from the cam bearings too.
Posted By: rickraw

Re: toasted cam bearings on new build - 07/27/11 11:11 PM

get ur cam checked for straightness. a friend of mine had an engine built & there was babbit material on the edge of all his cam bearings. his cam was 1/4 thou out of being straight. something u should check. u must be getting oil to the top end cos u didn't mention about any burnt shafts.
Posted By: Performance Only

Re: toasted cam bearings on new build - 07/27/11 11:18 PM

Quote:

get ur cam checked for straightness. a friend of mine had an engine built & there was babbit material on the edge of all his cam bearings. his cam was 1/4 thou out of being straight. something u should check. u must be getting oil to the top end cos u didn't mention about any burnt shafts.



not sure why .00025 TIR would bother anything.
the OP did say;
Quote:

The engine fired right up and ran for 25 minutes at 2,000 – 2,5000 RPM to break in the cam before the valvetrain stared seizing.


Posted By: 9secondsatellite

Re: toasted cam bearings on new build - 07/27/11 11:45 PM

did you prime the engine after final assembly? debris in cam? cam walk to far? what does the intermediate shaft look like? also mentioned 1 brg spun. could it have spun on start up? cam brg installer too tight when installing brgs?
Posted By: quick77rt

Re: toasted cam bearings on new build - 07/27/11 11:54 PM

Any chance you have a cracked main webbing in the block? Block history? Ive seen this happen, all was good until motor got warm, broke in and things moved.

Turned out block was soon to be a two peice unit.
Posted By: 85_Ram_4speed

Re: toasted cam bearings on new build - 07/28/11 01:48 AM

Quote:

did any of the bearings have to be reamed or scraped to make the cam turn freely? that raises another question, if the cam didn't turn easily with 2 fingers during the assembly process, it was too tight.



This is what I am going with. I don't build as many motors as some on here, but I have done a handfull of big blocks that had cam/cam bearing interference issues. My understanding is it is a fairly common issue on big blocks.

Regaurdless of what engine though, I always check how the cam spins before the chain goes on.

I now use an old cam I grooved the journals on (after I saw the idea here on Moparts ) so it fixes any interference issues. It works great.
Posted By: 70Sbird

Re: toasted cam bearings on new build - 07/28/11 10:10 PM

Thanks for the replies everyone, I couldn't get back to my computer yesterday night so here are answers to some of your questions. The cam fit well and turned freely with 2 fingers, the block was prepped by a knowledgeable Mopar only engine builder and was checked for cracks and machined before the cam bearings were installed. The main and rod bearings are still in great shape, no excessive wear and no evidence of debris. The engine block was cleaned and prepped by the engine machinist, then I cleaned it again "just to be sure",including all the oil pasages from the lifter galley to the mains and cam bearings. The mains were installed correctly, with the groovs in the top, and the cam would still get oil regardless of the mains orientation and since the mains are good, I know this to be true. The engine was primed for about 10 minutes before ignition and I was turning the crank over by hand for about 5 minutes of that to be sure everything got oil.
It looks like the bearings began "wiping" and closing off the oil holes that feed the rockers and heads at some point of the 25 minutes it was running. The part that makes no sense is how can the cam bearings be destroyed if they had oil going to them, there was 70 psi of oil at startup and during the break-in.
Here is a pic of the cam bearings smearing themselves out of the bottom of their bores


Attached picture 6751435-IMG_0295.JPG
Posted By: 70Sbird

Re: toasted cam bearings on new build - 07/28/11 10:18 PM

Rod bearings and pistons:

Attached picture 6751447-IMG_0287.JPG
Posted By: 70Sbird

Re: toasted cam bearings on new build - 07/28/11 10:19 PM

cam bearing closer up:

Attached picture 6751450-IMG_0297.JPG
Posted By: dennismopar73

Re: toasted cam bearings on new build - 07/28/11 10:21 PM

did you verify oiling at both rocker arms before firng?
Posted By: 70Sbird

Re: toasted cam bearings on new build - 07/28/11 10:27 PM

yes, before and after. Even after the engine was shut down and we discovered the issues, I ran the oil pump with a drill and when the cam was indexed properly still got some oil appearing at the rocker roller tips
Posted By: MR_P_BODY

Re: toasted cam bearings on new build - 07/28/11 10:30 PM

Quote:

cam bearing closer up:



It looks like the cam bearing is tipped partly sideways
in there... are you sure its smeared as in turned to
a putty state... it would have to get very hot to do that
Posted By: Performance Only

Re: toasted cam bearings on new build - 07/29/11 12:55 AM

you know, perhaps the best way to approach this is by using just a smidgen of logic. there's really only two basic things that will cause what happened to your cam bearings. it's either lack of oil, or it's lack of clearance. of course lack of clearance can be for a large variety of reasons, but it's still a lack therof.
not to be too critical, but based on your pictures and the fact that you only have 25 minutes of run time on the engine. i think i'd go back and check the clearance on those mains as well. you really shouldn't have shiny edges and shiny wear spots like what the pictures show. basically they should look like brand new still if the clearances are correct.
so anyway, are you sure all the holes in the cam bearings were lined up with the oiling holes? one can't really see much of the cam bearings from the pictures you posted. best of luck with it. i'm sure you'll get it figured out.
Posted By: Thumperdart

Re: toasted cam bearings on new build - 07/29/11 02:36 AM

Quote:

you know, perhaps the best way to approach this is by using just a smidgen of logic. there's really only two basic things that will cause what happened to your cam bearings. it's either lack of oil, or it's lack of clearance. of course lack of clearance can be for a large variety of reasons, but it's still a lack therof.
not to be too critical, but based on your pictures and the fact that you only have 25 minutes of run time on the engine. i think i'd go back and check the clearance on those mains as well. you really shouldn't have shiny edges and shiny wear spots like what the pictures show. basically they should look like brand new still if the clearances are correct.
so anyway, are you sure all the holes in the cam bearings were lined up with the oiling holes? one can't really see much of the cam bearings from the pictures you posted. best of luck with it. i'm sure you'll get it figured out.

Makes good sense plus,in the one photo of the cyl., that seems like a lot of verticle scratches for such a short run time suggesting maybe it wasn`t perfectly clean or, as stated it passed some crud.
Posted By: crsnles

Re: toasted cam bearings on new build - 08/24/11 05:54 PM

Any one heard if he figured out his problem?
Posted By: Bob_Coomer

Re: toasted cam bearings on new build - 08/24/11 06:21 PM

Never had a issue with cam bearings. I always check to make sure that the oil holes are lined up.. Even this if they are off a little bit will NOT hurt anything. Are the oil holes still lined up?
The engine looks trashy to me... whats all the pieces of blue and orange paint.
Cylinder walls look scored too. I have run engines for thousands of miles that look better. Bearings also dont look good IMO. They shouldnt even look like the crank has rolled over on them.
Pull the filter cut it apart, and the oil pump see what you find!
Good luck
Posted By: moparniac

Re: toasted cam bearings on new build - 08/24/11 07:01 PM

Several years ago had the same thing happen to me! not sure what happened but the machine shop that installed the cam bearings bought me a brand new set of gold cranes cause the first set welded to the shaft....
Posted By: crsnles

Re: toasted cam bearings on new build - 08/24/11 07:55 PM

I want to be straight up with every one here. I have an engine that is having a similar problem but it is after break in and ran for approximately 30-35 miles. The bearings look very similar to the pictures posted here, I still carry good oil pressure even after the bearings look like they do.
The engine I have is not a MOPAR but an inline 6 200cid ford built pretty good, and being car guys and girls it shouldn't matter but wanted all to know I could use the help. All tolerances are within manufacture specs. Just totally clueless at this point. It has happened twice now. Thanks in advance
Posted By: fishy340

Re: toasted cam bearings on new build - 08/24/11 08:07 PM

Quote:

you know, perhaps the best way to approach this is by using just a smidgen of logic. there's really only two basic things that will cause what happened to your cam bearings. it's either lack of oil, or it's lack of clearance. of course lack of clearance can be for a large variety of reasons, but it's still a lack therof.
not to be too critical, but based on your pictures and the fact that you only have 25 minutes of run time on the engine. i think i'd go back and check the clearance on those mains as well. you really shouldn't have shiny edges and shiny wear spots like what the pictures show. basically they should look like brand new still if the clearances are correct.
so anyway, are you sure all the holes in the cam bearings were lined up with the oiling holes? one can't really see much of the cam bearings from the pictures you posted. best of luck with it. i'm sure you'll get it figured out.

best quote par none.
Posted By: Sport440

Re: toasted cam bearings on new build - 08/25/11 03:17 AM

Quote:

Any one heard if he figured out his problem?



He hasnt had a post since July 28th.

IMO, no doubt that motor has some dirt and clearence issues. The Mains look terrible as well.
Posted By: 70Sbird

Re: toasted cam bearings on new build - 09/05/11 05:11 AM

Well I thought I'd provide an update - of sorts. No root cause was ever determined. The bearing manufactures looked at the pics, the engine machine shop and I also went over all the parts with a fine tooth comb, and nothing stands out as installed incorrectly. So far the best "guess" was that the cam bearing that #4 cam bearing with the oil holes that feed the rockers began to "wipe" and closed off part of the hole that allows the oil through. From there the rockers did not get enough oil and began to sieze, increasing he load on the valvetrain and ultimately pushed even harder on the cam bearings. The cam bearings were installed correctly and the cam turned easily in the bearings prior to assembly. The bearing "expert" contaced by my engine machine shop said that the cam must have been installed "dry" and taht caused the failure. This did not happen and I even have pictures of the installed cam with assembly lube seen clearly on the edges of the cam/bearing. So no root cause, the mains and roda are not as bad as they look and the marks in the cylinders came out with cleaning.
So the block has been prepped again with new bearings and will be assembled within the next few weeks. Does anyone have any better theories or experience?
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