bearing damage

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af2
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Re: bearing damage

Post by af2 » Sun Feb 04, 2018 11:42 am

Was the car welded on at some point?
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Re: bearing damage

Post by AC sports » Sun Feb 04, 2018 2:30 pm

Definitely never welded.

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Re: bearing damage

Post by Barry_R » Sun Feb 04, 2018 2:44 pm

Cavitation happens when the oil film "collapses" or "implodes" - it is forced into something of a vacuum and when it "pops" away from the surfaces it takes a bit of the metal aways with it. If the clearance and eccentricity profile (or housing deformation) is such that the film got pinched off toward the parting lines it will get larger at the vertical areas and could cause this to happen. Just guessing' but good guesses are better than nothin'
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Re: bearing damage

Post by Tuner » Sun Feb 04, 2018 5:07 pm

af2 wrote:
Sun Feb 04, 2018 11:42 am
Was the car welded on at some point?
AC sports wrote:
Sun Feb 04, 2018 2:30 pm
Definitely never welded.
Battery charger or battery tender connected for a long time?

How long did this engine sit? Were the damaged areas on the crank and bearing in contact with each other when the engine was sitting for a long time?

What kind of fuel? Did the oil show any sign of water or other contamination?

It does look like it ran short of oil.

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Re: bearing damage

Post by af2 » Sun Feb 04, 2018 5:28 pm

Why does the crank NOT show the damage it should? With bearings like that? HMMM... Thinking that pit should go all the way around... It looks like a pit that was never run.
Last edited by af2 on Sun Feb 04, 2018 5:30 pm, edited 1 time in total.
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Re: bearing damage

Post by peejay » Sun Feb 04, 2018 5:29 pm

What are the oil temps?

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Re: bearing damage

Post by af2 » Sun Feb 04, 2018 5:31 pm

I edited above..
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Re: bearing damage

Post by AC sports » Sun Feb 04, 2018 11:56 pm

Cars battery was on occasion charged but disconnected from power. Car never sat more than a month but on one occasion 6 weeks. Crank journals all smooth except that first one. Definitely no water in oil. Oil Temps did hit 110*c when pushed hard. Crank is forged steel and I suspect tuftrided as a file won't take to it.
The car did have a pinking issue long ago but it was shut down and traced to faulty ignition pickup and was rectified.
It saw about 20,000 km on the street and maybe 2000 track miles without a very good sump I might add.
The pitting was a main journal remember. Steel caps, correctly torqued on build.
Question is....could I run it with a polish? Or is it toast?
If there is minor pitting after a polish I mean? I don't want to grind it since it's hardened.

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Re: bearing damage

Post by joe 90 » Mon Feb 05, 2018 1:19 am

You haven't said what engine it is?

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Re: bearing damage

Post by AC sports » Mon Feb 05, 2018 1:50 am

It's an 8v fiat twincam.

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Re: bearing damage

Post by joe 90 » Mon Feb 05, 2018 2:52 am

OK , looking at the rust marks on the no1 main journal I'd guess that it's sat around for some time unused, maybe had a bit of water in the oil to cause the rust.

It needs a regrind.

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Re: bearing damage

Post by n2xlr8n » Mon Feb 05, 2018 2:53 pm

Barry_R wrote:
Sun Feb 04, 2018 2:44 pm
Cavitation happens when the oil film "collapses" or "implodes" - it is forced into something of a vacuum and when it "pops" away from the surfaces it takes a bit of the metal aways with it. If the clearance and eccentricity profile (or housing deformation) is such that the film got pinched off toward the parting lines it will get larger at the vertical areas and could cause this to happen. Just guessing' but good guesses are better than nothin'
I trust your guesses, Barry.

Out of curiosity, would water in the oil give a similar appearance to what you describing (cavitation) ?
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Re: bearing damage

Post by tjus » Tue Feb 06, 2018 11:00 am

could there be ground issue in starter to block.

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Re: bearing damage

Post by Paul Kane » Tue Feb 06, 2018 12:31 pm

I doubt oil pump cavitation has anything to do with it--that would just impose a culprit of oil starvation and simply gouge the bearings.

What is the application and usage of this engine, specifically the peak oil temps that the engine experiences? Because it looks to me like exceedingly high oil temps are being imposed upon standard, common passenger car engine bearings which "flakes" the top layer off the bearing. Your picture in post #1 looks like the beginnings of the outer layer flaking off, and your picture in post #14 looks like the flaking off is much further along/advanced.

BEGINNING:
Image

ADVANCED:
Image


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Re: bearing damage

Post by Barry_R » Tue Feb 06, 2018 12:45 pm

Its not oil pump cavitation - its bearing cavitation - similar name but a different deal.

No signs of heat or smearing on the surface - it had lube, but something pulled the material away from the bearing.
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