Should the copper show at all? Does the gray outside wear off with normal wear on the rear thrust bearing? IM thinking the copper is the bearing material and the gray is a breakin coating of some kind.

Thanks,
Mike

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Black 90 IROC, L98, A4, 323 gear. SuperRamed 406 in the works!

 

As far as I know if you see the copper then it's worn past its limits. The white stuff u seen on em is the "break-in" stuff. Then it's all shiny silvery stuff, then the copper.

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92 Z28 L98 350
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Ported and polished heads, ported stock TPI base, ported plenum, Comp Cams XR270HR-10 cam (lift .495/.502 duration 218/224 lobe separation 110), Edelbrock TES headers, LT4 valve springs, Crane AFPR, Flowmaster catback with LT1 style tips, MSD coil & wires...

"Take that auto, drop it in first, hold the brakes, stomp the gas and grin from ear to ear! :-)

 

They usually wear to the copper over a small portion of their surface, since the bearing bores are almost never perfectly round. Any significant amount showing, especially at the center of the cap half of the mains or the top half of the rods, indicates oil starvation or contamination.

The thrust bearing area comes from the factory with no tin coating for some reason.

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"So many Mustangs, so little time..."

 

Most widely used automotive bearings are a tri-metal bearing design, which means there are 3 materials sintered or cast over the steel shell. The order of material is, steel shell, copper,nickel,& finally a copper/lead matrix. Finally the bearing is flashed, ususally with tin. Obviously, when you see copper, you've got a worn bearing. The exception is the thrust surface, which ususally only has a copper overlay. The bearing manufacturers today are even elimnating the copper & are just using a plain steel surface. To judge the condition of the thrust surface, base it upon what crankshaft end play is & whether there is any cracks in the thrust flange, assuming it has a copper overlay.
Regards, FJK

 

I pulled the rear cap off my 400 and what I found was a penny sized showing of the copper in the middle of the cap Like RB said.

The block only has 10,000 miles on it. I turned and polished the crank Installed over size bearings. The clearances checked out fine when i assembled it.

Should I replace the bearings? Or are they okay? The crank still looks good?

Mike

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Black 90 IROC, L98, A4, 323 gear. SuperRamed 406 in the works!

[This message has been edited by MikeH (edited October 01, 2000).]

 

First off RB is the man! He hit the problem right on the head! He suggested that i look at the back of the bearing to see if the bolt that holds the oil pump on was making contact with the bearing.

It turns out that the bolt that holds the oil pump on was slightly to long and was pressing against the back of the bearing just enough to push the bearing into the crank. Im very lucky i tore it down now and didnt wait any longer or i would probably done some major damage to the crank.

The bolt I used for the oil pump may have been from a 5.7 motor.

Dont make the same mistake!

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Black 90 IROC, L98, A4, 323 gear. SuperRamed 406 in the works!

[This message has been edited by MikeH (edited October 02, 2000).]

 

after you gave the milage i was was definately gonna say look at the oiling system. the bearing should look like that after maybe 100,000 miles, not 10k. anyhow, glad you found the problem now, a spun crank bearing generally results in several broken rods, holes in the oil pan, and a ruined crank and block that is experiance from the racecar speaking there lol

Steve

 

Thanks Steve...Me too I spun the crank by hand After I torqued the mains and it turned freely. I never realized the bolt hole was tapped all they way thru the cap.

I wonder if i could just install a washer under the bolt? Or is this not a good idea?

Mike

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Black 90 IROC, L98, A4, 323 gear. SuperRamed 406 in the works!