345 engine cam/main bearings question

R

Richard

Member
maybe this is a simple question, with a really simple answer, but I need to ask anyway:

What actually makes bearing go bad? what actually causes them to "delaminate"? I get the "running dry" part, but what other causes would there be? I didn't think that small particles would be able to make their way into the bearing surface, given the tight tolerances.

Anyway, just curious.
 
Funny, I have started typing up an answer to your question 2 times, and both times some one has walked into my office at work and I lose it. I finally decided to post the best information on bearing failure analysis available. The FAA has great write ups but nothing on line.
Good reading.
http://www.mahle-aftermarket.com/media/local-media-north-america/mahle.swf


The often seen cam bearing failure seen in old IH's if not listed. It is related to the bearings having bond failures between the layers that make up the bearing. My theory on the root cause for this has focused on either inter layer corrosion, or thermal cycling. the lead and steel have much different CTE's which means the grow and shrink at greatly different rates when heated and cooled. This causes stress on the bond layer and ultimately fails the bond.
On each factory built IH that I have rebuilt, all showed the same problem. The babbitt/lead alloy layer had begun to peel like tape stuck on a dirty surface . Many times it was on the upper bearing surface that sees high loading, like my Scout 80 engine. The bearings were perfect other than the peeling lead layer.

A well bonded bearing will not peel like this. The chronic bearing kibble in the pan can not be attributed solely to non preoiling. Even an properly preoiled engine that is 40 years old will most likely suffer from bearing failure if the bond between layers fail.

Please continue to preoil your engines before tying to bring them out of hibernation.
 
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thank you for the reply. Very informative. When putting the engine back together after sitting for 30+ years, I wanted to "verify" bearing surface. The engine had never been run, I bought it from the local IH dealer. I was surprised to find zero rust or wear (very happy). When I did the "pre-oil" recently, I can see where the oiling of the bearing comes into play, very important.

I appreciate the quick response.
 
Thanks for the informative link and your own analysis Robert. On the mark as usual! I believe there was much development in bearing technology in the 1960's through the 70's judging from all the SAE articles on the subject.

I have seen such "kibble" and long shards of it in the oil pan from the 71 1210. I worried a lot about failure or an overhaul needing done. Then I thought to run it 'til it makes noise or oil pressure starts dropping. It's been 10 years and many many miles and still no signs of impending doom.
 
I have a thought/question:

technology being what it is, the design of a bearing (cam/crank) from the 60's/70's is what it is. Have there been improvements in bearing design for the IH engine since then? or are the bearings on the market now (IH Parts America) the same as from the 60's/70's? If there is a newer/better design, are those available? (Must be my nervous tick.)
 
Richard said:
I have a thought/question:

technology being what it is, the design of a bearing (cam/crank) from the 60's/70's is what it is. Have there been improvements in bearing design for the IH engine since then? or are the bearings on the market now (IH Parts America) the same as from the 60's/70's? If there is a newer/better design, are those available? (Must be my nervous tick.)
Click to expand...

We only sell USA made Dura-Bond brand cam bearing sets which are "freshly made". So yes they would be considered of the newest/best design currently available.

Engine Camshaft Bearing Set for IH 152, 196 4cyl & 266, 304, 345, 392 V8

084pp.jpg
 
Those are what I'm running in my rebuilt 345. About 12k now and no issues. Probably won't have definitive results for the next 35 years though.
 
Richard said:
I have a thought/question:

technology being what it is, the design of a bearing (cam/crank) from the 60's/70's is what it is. Have there been improvements in bearing design for the IH engine since then? or are the bearings on the market now (IH Parts America) the same as from the 60's/70's? If there is a newer/better design, are those available? (Must be my nervous tick.)
Click to expand...

I have never seen the delamination failure on rod or main bearings, only the IH original cam bearings

So here is my feeling on the old production cam bearings in IH engines. I have a brand new 152 block on a stand, it is was earmarked to be my stroker engine build. It has brand new IH installed cam bearings in it..............they are getting replaced with DuraBonds from Jeff.

Will the old bearings be OK or will they fail??? I can't say 100% either way. They have not been exposed the acidic effects of 40 years of running, nor have they seen any heat cycles.
Chances are they will be OK.

If your engine is assembled and ready to go for the most part, don't tear into it just to satisfy your nervous tick.

Preoil and run it like you stole it.. :icon_xd: Well just drive it. Open up a few of the first oil filters and check for abnormal metal. You will see some iron as the rings and bores bed in but it should calm down after 500 miles of firm driving.
 
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