Moparts

What happened to this bearing

Posted By: mopster

What happened to this bearing - 01/01/09 10:39 AM

This is main bearing from my friends engine. Something is wrong, but what? It has some brown colour and little spots in it, and in some areas the tin surface has been flaking off. Clearances are fine, .0025" rods and .003" mains.

Could too hot oil, or some kind of oil pump cavitation problem cause this? My friend doesnīt run oil temp gauge, but oil pressure has been dropping in some cases, like in highway with engine running 5000 rpms, indicating that oil is getting too hot. He does run B&M 5 x 11" oil cooler. Itīs a sbc engine with hv oilpump in it, and he has been told that the hv pump is causing a cavitation problem, and that he needs smaller volume pump with some kind of anti-cavitation grooves. Does this sound right to you?

Attached picture 4914506-bearing.jpg
Posted By: Tig

Re: What happened to this bearing - 01/01/09 02:46 PM

I saw something similar on a mains bearing in my old 528. Looked like the surface was de-laminating, had a sort of crazing effect to it. Happened on only one half of the bearing as well. Never figured out why, just put it down to a manufacturing fault. Didn't mark the crank either. Cant remember any disclouration though
Are all the bearings like this? in our case it was just one shell.
Posted By: torkrules

Re: What happened to this bearing - 01/01/09 02:48 PM

Quote:

This is main bearing from my friends engine. Something is wrong, but what? It has some brown colour and little spots in it, and in some areas the tin surface has been flaking off. Clearances are fine, .0025" rods and .003" mains.

Could too hot oil, or some kind of oil pump cavitation problem cause this? My friend doesnīt run oil temp gauge, but oil pressure has been dropping in some cases, like in highway with engine running 5000 rpms, indicating that oil is getting too hot. He does run B&M 5 x 11" oil cooler. Itīs a sbc engine with hv oilpump in it, and he has been told that the hv pump is causing a cavitation problem, and that he needs smaller volume pump with some kind of anti-cavitation grooves. Does this sound right to you?



Pump cavitation (if I can remember my fluid dynamics classes from college) usually occurs from problems on the suction side of the pump (suction tube too small, restricted, etc.) You would usually see this on the pump rotors.

What you have here might be from detonation/cap walk, although oiling could be an issue as well (brown could indicate overheating).

Oil pressure should not be dropping at 5000. If you follow the rule of thumb you need at least 50lbs at that speed. What is the pressure dropping to? A high volume pump will also provide high pressure if all of the clearances are correct.

Check and make sure there is no air leaks around the pick up hole in the pump. The pump body has been known to crack if the pick up is over tightened.
Posted By: boatracer572

Re: What happened to this bearing - 01/01/09 03:37 PM

with the pics you posted I would say It looks like there is/was some detnation going on!

Attached picture 4914790-_WI_0326.jpg
Posted By: SKR8PN

Re: What happened to this bearing - 01/01/09 04:08 PM

Look at how much of the oil groove in that bearing is either filled with bearing material or worn away. Oil starvation would be my first guess. What do the rest of the bearing upper and lower shells look like??? How about the rod bearings??
Posted By: CompWedgeEngines

Re: What happened to this bearing - 01/01/09 04:41 PM

From THAT picture ( its VERY hard to read a bearing from a picture) but I would say you have bearing fatigue or whats called surface fatigue. Ity doesnt appear to be 100% cavitation or lack of oil to me. That is what most people want to say is lack of oil, but there are many factors that go into reading bearings, and they are like spark plugs, most read them wrong.


Fatigue can be ( as mentioned) detonation, overloading, ( which can be lugging the motor, detonation and overfueling, rich condition thinning oil). It could also simply be a bad bearing choice for the application.

You would want to really take a good look at the distributor and timing, make sure the oil pick up is in good shape and sealed well, there is proper clearance pan/pickup and make sure its not overly rich.

With all that being said, it does appear that there could be some surface wiping, which would indicate some starvation, but it usually doesnt show the signs of the distressed plating ( the wrought peppering look) that your bearing is showing. Without knowing all the exact details of the bearings, clearances, how it was assembled, primed properly etc, as well as the visual first hand observation of the bearings, its educated analysis from our chairs.

Again, I still believe bearing fatigue from what I see.

My
Posted By: MR_P_BODY

Re: What happened to this bearing - 01/01/09 05:14 PM

If you can take a couple more pics, 1 to get the
glare off of it and take a pic of the thickness of
the bearing(side view) to see how much wear it has.
It looks like the oil groove is full of material
or it could be worn away. But looking at the end
of the bearing it would show a different material
if it was worn that thin
Posted By: CompWedgeEngines

Re: What happened to this bearing - 01/01/09 05:19 PM

Yes its just hard to tell. The bearing filling up could be after the initial damage was done which may or may not be the reral problem, only a result of. Just so hard to tell from pics.
Posted By: JAKE68

Re: What happened to this bearing - 01/01/09 05:30 PM

The way the groove seems to taper I would have to belive that is not a full groove bearing.
Posted By: mopster

Re: What happened to this bearing - 01/01/09 06:41 PM

The groove isnīt filled, itīs a 3/4 groove bearing, and theres really nothing wrong with the groove. No surface wiping either, only the thin tin layer has been flaking. So I donīt think itīs oil starvation. Detonation shoudnīt be a problem either, itīs a quench motor with 8.1 dynamic CR.

We thought the problem is oil temp related because this engine has been ruining the oil very fast. After about 600 street miles the oil looks really bad and it has lost most of its viscosity. Oil used is valvoline VR1 20W/50. Oil pressure drops to 55 psi from normal 65 psi when driving in highway at 5000 rpms for about 10-20 miles, so the oil is probably running very hot.

Theory about the HV oil pump is, if I have unerstood it right, that itīs producing more oil at higher rpms that the engine can take and basicly cooking up the oil. Cavitation probably isnīt the right term. Pressure relief valve is circulating the oil back to suction side, so it most likely just creates more heat as the oil is circulating very fast around the pump.
Posted By: mopster

Re: What happened to this bearing - 01/01/09 06:49 PM

Another pic.

Attached picture 4915383-bearing2.JPG
Posted By: mopster

Re: What happened to this bearing - 01/01/09 06:50 PM

One more.

Attached picture 4915385-bearing3.JPG
Posted By: Cab_Burge

Re: What happened to this bearing - 01/01/09 07:03 PM

Quote:

One more.

That bearing looks like it has been real hot I'm suprised that it didn't spin or fold up and sieze on the crankshaft. 20 minutes at 5000 rpm on the hiway
Posted By: Anonymous

Re: What happened to this bearing - 01/01/09 07:33 PM

can you post a picture of the mating shell. my guess is it doesn't look as bad as the one you already posted. if that's the case, detonation, overloading would be the likely culprits.
Posted By: 1_WILD_RT

Re: What happened to this bearing - 01/01/09 07:44 PM

Quote:



Theory about the HV oil pump is, if I have unerstood it right, that itīs producing more oil at higher rpms that the engine can take and basicly cooking up the oil. Cavitation probably isnīt the right term. Pressure relief valve is circulating the oil back to suction side, so it most likely just creates more heat as the oil is circulating very fast around the pump.



THe person with the cooking oil theory probably has worked with hydraulics, any time your pushing oil over a relief valve it creates some heat, but a 60 PSI relief likely wouldn't create much...At 3000 psi you don't want to push allot of oil past the relief so you need to be able to size the pump to the flow...60 PSI not so much...

BTW This is what cavitation at 3000+ psi does...Air bubbles actually explode & that energy erodes metal...
Posted By: torkrules

Re: What happened to this bearing - 01/01/09 08:04 PM

Detonation shoudnīt be a problem either, itīs a quench motor with 8.1 dynamic CR.

Pressure relief valve is circulating the oil back to suction side, so it most likely just creates more heat as the oil is circulating very fast around the pump.



With the detonation, you are right 8.1 should not cause detonation, but other factors could cause even and 8.1 motor to detonate (something glowing hot in the combustion chamber, bad fuel, timing, lack of mixture swirl, a combination of the above, etc.) I guess you would need to look at all the evidence to rule this out (pistons, plugs, rod bearing, etc)

As far as the pump, others can correct me if I am wrong, but my understanding is that Mopars have a very efficient pressure relief system where the oil does not get dumped directly to the sump (I believe Chebby does this). On Mopars, as you said, the oil swirls around the rotors which taxes the suction side less which in turn results in cooler oil (like I said, I could be wrong on this as I'm going by memory).
Posted By: Anonymous

Re: What happened to this bearing - 01/01/09 08:53 PM

while your at it, how about a picture of the back of the bearing shells? (both)
Posted By: mopster

Re: What happened to this bearing - 01/01/09 09:02 PM

This is a sb chebby engine we are talking about. Sorry for posting here, but I donīt hang out in chebby forums, and I also didnīt thought that we need a chevy guy to read a bearing

Back to the issue. Rod bearings were looking better, only a little brown colour and spots, but no flaking. Mains were all looking like the one in the pic. If it was a detonation issue, shoudnīt the rod bearings be worse.

To me it looks like the bearings have just been running too hot, and the tin surface has been baked. And if so, we should figure out why. The guy who was thinking that HV oil pump is cooking the oil is actually a race parts dealer, and he claims that a pump with anti-cavitation grooves and only 10% more volume (instead od of 25%) will cure the problem.
Posted By: mopster

Re: What happened to this bearing - 01/01/09 09:14 PM

Quote:

while your at it, how about a picture of the back of the bearing shells? (both)


Sorry, no picture of the other halve, but I think it looked the same. Iīll ask my friend.
Posted By: Anonymous

Re: What happened to this bearing - 01/01/09 09:15 PM

please post good clear pictures of the front and back of a pair of rod bearings and main bearings.
it's hard to tell what the problem is when it's only being described by someone. pictures ar worth 1000 words.
Posted By: dodgefarmer

Re: What happened to this bearing - 01/01/09 09:15 PM

Quote:

After about 600 street miles the oil looks really bad and it has lost most of its viscosity. Oil used is valvoline VR1 20W/50. Oil pressure drops to 55 psi from normal 65 psi



I hav'nt used Valvoline 20W/50 since 1977 for that very reason. That being said I would suggest that you get an oil sample analyzed (like I should have done) . Looking back I believe that I probably had severe fuel contamination but I'll never know for sure.

Randy
Posted By: mopster

Re: What happened to this bearing - 01/02/09 02:12 PM

Quote:

please post good clear pictures of the front and back of a pair of rod bearings and main bearings.
it's hard to tell what the problem is when it's only being described by someone. pictures ar worth 1000 words.


Here we go.

Attached picture 4917442-mains.JPG
Posted By: mopster

Re: What happened to this bearing - 01/02/09 02:14 PM

2.

Attached picture 4917447-mains2.JPG
Posted By: mopster

Re: What happened to this bearing - 01/02/09 02:15 PM

Rod bearings

Attached picture 4917450-rods.JPG
Posted By: mopster

Re: What happened to this bearing - 01/02/09 02:29 PM

4.

Attached picture 4917468-rods2.JPG
Posted By: torkrules

Re: What happened to this bearing - 01/02/09 02:47 PM

Quote:

4.



Is there any spring left in the bearing (so they fall right into the saddles or do you have to push them in). If the spring is gone it would indicate an overload/detonation. Look at the cap mating surface. Does it look like there has been metal transfer? Another indicator of overload/detonation.

How does the crank look (scratches, etc). Could some particles have gotten in the oil?

I would suppose with a chevy oil pump that it could be possible that the pump is cavitating/overheating the oil on bypass. You could try using a thinner oil (10/40 or 10/30) If the clearances are tight the above 2 oils should be fine.
Posted By: mopster

Re: What happened to this bearing - 01/02/09 05:28 PM

Spring is still there. They may look very bad in the picture, but they are not hammered or wiped out of shape, even the clearances are still like they were new. Only the topmost flash tin layer seems to be boiled or baked or whatever. There are some minor scratches in some of the journals, but polishing is all that needs to be done there.
Posted By: Anonymous

Re: What happened to this bearing - 01/02/09 06:04 PM

Are those std. size bearings or are the bigger?Next what does the crank look like? any ridges burrs around the oiling holes. Have you mic-ed the crank? Check for taper and roundness...
Something is definitly heating up the bearings...

Attached picture 4917909-00popprofile.jpg
Posted By: Lee446

Re: What happened to this bearing - 01/02/09 06:10 PM

This may sound very basic, but, what is the capacity of the oil pan? I was rebuilding my Chevy truck 350, and as a matter of course, I told the machine shop to get me a high volume pump. My machine shop builds lots of Chevy's for dirt track and drags, and the engine builder advised me not to use one with the stock 5 qt. pan as it would suck it dry at higher rpm. I have never had that problem with my Mopars, but they are all BB with at least a 6 qt. pan.
Posted By: mopster

Re: What happened to this bearing - 01/02/09 07:11 PM

Std. bearings. 8qt. oilpan, completely new engine with all the parts new including the block, rounded oil holes in crank. 1200 street miles and a few races behind this far.

One thing we thought that might cause problems with the HV pump is that sbc engine has bypass also for the oil filter, and some oil may have been passing the filter and the cooler. I believe the oil filter bypass is there for winter usage mainly, and we thought it should be blocked.
Posted By: Anonymous

Re: What happened to this bearing - 01/02/09 08:01 PM

I still think something else is going on.SBC motors have a pretty good oiling system. The returns to the pan are good..How did the filter look? Have you cut it open? I have seen problems leading to galling of bearings due to a clog in : a filter or filter mounting pickup..just a thought..
Posted By: sixpackbee

Re: What happened to this bearing - 01/02/09 08:27 PM

Excessive acids in the oil can cause the pocking evident in some of the photos. When the oil was drained what was its condition?
Posted By: B G Racing

Re: What happened to this bearing - 01/02/09 08:39 PM

Quote:

Excessive acids in the oil can cause the pocking evident in some of the photos. When the oil was drained what was its condition?

mostly in part that contamination,acids,fuel,antifreeze can and will cause the pocking and unraveling but the rods don't show much evidence.How tight was the main bearing clearence?Was there excessive end play?What about the line bore or crank run out?It's hard to tell from the pictures.Just my thoughts as to some of the maybe causes.
Posted By: mopster

Re: What happened to this bearing - 01/02/09 10:13 PM

Quote:

I still think something else is going on.SBC motors have a pretty good oiling system. The returns to the pan are good..How did the filter look? Have you cut it open? I have seen problems leading to galling of bearings due to a clog in : a filter or filter mounting pickup..just a thought..


You may be right, a lot of sbc engines are built with HV oil pumps and this isnīt a usual outcome. Filter is cut open and there was some minor particles in it, probably from the bearings, but it wasnīt clogged or anything.
Posted By: mopster

Re: What happened to this bearing - 01/02/09 10:41 PM

Quote:

Quote:

Excessive acids in the oil can cause the pocking evident in some of the photos. When the oil was drained what was its condition?

mostly in part that contamination,acids,fuel,antifreeze can and will cause the pocking and unraveling but the rods don't show much evidence.How tight was the main bearing clearence?Was there excessive end play?
What about the line bore or crank run out?It's hard to tell from the pictures.Just my thoughts as to some of the maybe causes.


Main bearing clearance .003" and rods .0025". This possibility of contamination is interresting, but should it show in rods as well as in mains? How about the brown colour, could contamination cause it, I thought that it must be heat causing it?
Posted By: sixpackbee

Re: What happened to this bearing - 01/03/09 02:37 AM

Certain contaminants can cause lubricity problems. If the friction modifiers get compromised then excessive heat usually results. The pock marks can be caused by acids ect. which in turn lead to greater friction coefficients which lead over heated parts. It could be a situation of one thing causing two different appearances on the bearings for two different reasons. Was an oil change, brand change, performed recently? There are some oils that do not play well with others and can cause problems.
Posted By: mopster

Re: What happened to this bearing - 01/03/09 08:49 AM

The car was driven a few hundred miles with faulty powervalve. It was stuck open and consumed about 1/3 more fuel than usually. Could this contaminate oil badly enough to cause bearing failure?
Posted By: B G Racing

Re: What happened to this bearing - 01/03/09 09:07 AM

Quote:

The car was driven a few hundred miles with faulty powervalve. It was stuck open and consumed about 1/3 more fuel than usually. Could this contaminate oil badly enough to cause bearing failure?

Posted By: B G Racing

Re: What happened to this bearing - 01/03/09 09:08 AM

Quote:

The car was driven a few hundred miles with faulty powervalve. It was stuck open and consumed about 1/3 more fuel than usually. Could this contaminate oil badly enough to cause bearing failure?

That info helps,and as Sixpakbee stated,something effected the lubricity of the oil.In this case more likely gas.The reason it is more prevalent on the mains is that the crank takes more constant loading and unloading as well as thrusting where as the rods more or less float on the crank journal and only recieve a load during compression strokes which is minimized and helped by the opposing piston and rod.
Posted By: torkrules

Re: What happened to this bearing - 01/03/09 03:46 PM

Quote:

The car was driven a few hundred miles with faulty powervalve. It was stuck open and consumed about 1/3 more fuel than usually. Could this contaminate oil badly enough to cause bearing failure?



That could cause some bog problems. How do the cylinders/rings look? This usually gas washes the cylinders.
© 2024 Moparts Forums