bearing damage

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AC sports
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bearing damage

Post by AC sports » Sat Feb 03, 2018 1:09 am

Finally pulled the bottom end out .
All bearings are conventional type steel/ alum.
All mains and rod bearings have same wear patterns.
Cratering/ dimpling. What do people make of it?
Looks like fatigue to me with bearings beginning to break down.
Would it be a side effect of oil starvation? Excessive load as the car has done quite a few circuit miles, or something I'm missing.
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202ci EH
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Re: bearing damage

Post by 202ci EH » Sat Feb 03, 2018 3:58 am

That's debris embedded in the bearing, what do the journals look like?

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Re: bearing damage

Post by Newold1 » Sat Feb 03, 2018 8:46 am

I have always been told cratering in an engine bearing is fatigue failure of the bearing caused by using the wrong bearing type (makeup) for the application. I've never seen it in any engines I have opened though.

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Re: bearing damage

Post by AC sports » Sat Feb 03, 2018 10:16 am

Definitely doesn't look like there is anything embedded in the metal.

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Re: bearing damage

Post by AC sports » Sat Feb 03, 2018 10:16 am

Journals look perfect.

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Re: bearing damage

Post by Newold1 » Sat Feb 03, 2018 10:26 am

What exact bearing brand and style/part number?

Engine application and use?

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Re: bearing damage

Post by CharlieB53 » Sat Feb 03, 2018 11:26 am

I could easily be wrong, but to me that looks suspiciously a lot like the cavitation pitting I see on a boat prop from the air bubbles created, pulling molecules from the metal.

I would be checking the oil pump pick-up[ position in the pan, making double sure that it cannot suck any air at RPM.

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Re: bearing damage

Post by AC sports » Sat Feb 03, 2018 12:17 pm

Bearings are FM std bi metal types. I suspect cavitation also. Maybe time for an accusump. The original sump wasn't baffled as well as I'd liked.

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Re: bearing damage

Post by jed » Sat Feb 03, 2018 1:45 pm

CharlieB53 wrote:
Sat Feb 03, 2018 11:26 am
I could easily be wrong, but to me that looks suspiciously a lot like the cavitation pitting I see on a boat prop from the air bubbles created, pulling molecules from the metal.

I would be checking the oil pump pick-up[ position in the pan, making double sure that it cannot suck any air at RPM.
X2-I agree on the could be cavitation??? That is very unusual pitting.

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Re: bearing damage

Post by Barry_R » Sat Feb 03, 2018 4:46 pm

Looks like cavitation to me as well. What is the application, clearance, etc.?
Looks like the crank is in contact for almost the full diameter.
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Re: bearing damage

Post by Tuner » Sat Feb 03, 2018 6:53 pm

Any sign of detonation on the piston, edge of the head land or perhaps teeny black freckles on spark plugs? Is there any past history of the engine to think it may have been subject to detonation, such as low octane fuel or too much timing, too hot a plug, etc?

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Re: bearing damage

Post by ProPower engines » Sat Feb 03, 2018 9:37 pm

CharlieB53 wrote:
Sat Feb 03, 2018 11:26 am
I could easily be wrong, but to me that looks suspiciously a lot like the cavitation pitting I see on a boat prop from the air bubbles created, pulling molecules from the metal.

I would be checking the oil pump pick-up[ position in the pan, making double sure that it cannot suck any air at RPM.
That was just what I was thinking. Bi metal bearing the surface may not be as hard or strong as a A series or a tri metal bearing surface is has caused it to pit.
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Re: bearing damage

Post by MadBill » Sat Feb 03, 2018 9:41 pm

Barry_R wrote:
Sat Feb 03, 2018 4:46 pm
...Looks like the crank is in contact for almost the full diameter.
2X.
In fact it looks to be in contact right up to the chamfer at the parting joint. Pinching off the oil wedge that way might well cause/contribute to the blistering and would certainly invite failure. Either the bearing has insufficient eccentricity and/or the rod is oval at rest or dynamically.
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Re: bearing damage

Post by AC sports » Sun Feb 04, 2018 11:26 am

Finally got round to a proper inspection.
Found this in the bottom of rod bearing no. 3, and pits in number 1 main which is closest to the oil pump.
Can we conclude this is oil starvation & or cavitation?
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Re: bearing damage

Post by AC sports » Sun Feb 04, 2018 11:29 am

Crank pits.
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