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| Cam bearing failure analysis https://slantsix.org/forum/viewtopic.php?t=54467 |
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| Author: | RustyDusty [ Wed Jan 29, 2014 10:43 pm ] |
| Post subject: | Cam bearing failure analysis |
Just purchased this motor (69 225 supposedly 95k on it). It was supposed to be turn key that just drove from fl to ohio... Not so much! She's all sludged up, so I went to pull the pan during sludge removal and saw a chunk of bearing hanging off the 2nd cam bearing from the rear. Pulled the cam and bearing to investigate... Below is what I found. The bearing is burned on the back and chunks missing from the inside. Can anyone pinpoint the cause of failure? My guess is oil starvation causing localized overheating? Some google searches also suggested misalignment or overloading? Surprisingly the cam journal looks fine!! Sorry I can only give a Facebook link as I can not copy the image URL on my iPhone. You should not need Facebook to be able to see the image though. Is an alignment hone required at this point? Or will new bearings be enough so long as it wasn't originally an alignment issue? https://fbcdn-photos-f-a.akamaihd.net/h ... n.jpg?dl=1 |
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| Author: | Joshie225 [ Thu Jan 30, 2014 8:10 am ] |
| Post subject: | |
I have seen quite a few Chrysler small blocks with cam bearings failed in this manner and know that big blocks do the same thing. From what I can tell Chrysler used crummy cam bearings. If that bearing didn't spin then the discoloration on the back side is probably staining and not heat damage. I would put in new cam bearings and if you can get the cam in the block by hand you're almost certainly in good shape. |
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| Author: | Doc [ Thu Jan 30, 2014 9:10 am ] |
| Post subject: | |
Agreed... Replace the cam bearings and 'run-it'. Pay close attention to the amount of 'press fit' on the over-heated cam bearing bore. (#2) You should be fine if all the bearings go in with the same amount of "press" but rethink the plan if the #2 bearing seems tighter or looser when being installed. DD |
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| Author: | RustyDusty [ Thu Jan 30, 2014 12:37 pm ] |
| Post subject: | |
Great, thank you. I appreciate the help! So was the overheating an oil starvation problem? |
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| Author: | Doc [ Thu Jan 30, 2014 1:34 pm ] |
| Post subject: | |
It's hard to say what happened but look to see if the bearing's oil feed hole is clear & still aligned with the passageway in the block. If the bearing was installed wrong or "spun" in it's bore, that can block the oil supply and caused overheating. Also see if some bearing material seperated and "fell-off" in a way that created a "short-circuit" pathway from the oil feedhole out to the side of the bearing... that would bleed-off a lot of the oil pressure / flow needed to keep the rest of the bearing cool. DD |
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