I guess the cam bearings are shot...
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*NEW PICS*I guess the cam bearings are shot
I bought a '98 motor a while back to replace the one in my car (spun rod bearing) and decided to install a new cam before I put it into the car...here are what the cam bearings look like...
and the corresponding journal...
The grooves are around .005 - .010" deep and only on the lower half of the bearings. I'm assuming this was due to oil starvation?
and the corresponding journal...
The grooves are around .005 - .010" deep and only on the lower half of the bearings. I'm assuming this was due to oil starvation?
Last edited by braap; 06-25-2006 at 10:55 PM.
#7
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I agree. It's common for cam bearings to be coated with a copper alloy, the copper we are seeing is not the issue IMO, it's the grooves that are a concern.
I think the cam and bearings should be replaced.
Maybe the grooves can be removed from the bearing but then there may be too much clearance.
Disclaimer: I'm not an engine builder. I could be wrong on this!
I think the cam and bearings should be replaced.
Maybe the grooves can be removed from the bearing but then there may be too much clearance.
Disclaimer: I'm not an engine builder. I could be wrong on this!
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#8
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I faced this same situation, copper colored bearings(which i guess are normal on 98's) and grooves on the lower halves of the bearings. The grooves were not that severe but i decided to change the cam bearings because i did not want to have to tear into it again or destroy my new cam. I bought a universal cam installation tool and popped the bearings in myself. By the way, you might want to check your rod and main bearings as well, mine had a spun rod bearing... engine runs great now.
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I already picked up a new set of cam bearings...looks like I'll be replacing the main/rod bearings as well for peace of mind. Oh well, I guess it's a good thing I decided to slap a new cam in before I put it in the car. No telling when that sucker would have let loose
#13
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Originally Posted by braap
I already picked up a new set of cam bearings...looks like I'll be replacing the main/rod bearings as well for peace of mind. Oh well, I guess it's a good thing I decided to slap a new cam in before I put it in the car. No telling when that sucker would have let loose
i would go the extra step and measure everything... i have a feeling your crank may look similar to how your cam does... and if thats the case, you need to get it turned and the matching bearings.....
#14
Launching!
I had a 98 also, and the color is normal, the second cam bearing looks scrached too.
I agree with changing bearings, polishing crank, grind the bearing caps to 0.0015" clearance in a competent machine shop; they are too cheap (little expensive!) to trade for a blow up, while youre at it do yourself a BIG RELIEVE! buy ARP R*O*D*** B*O*L*T*S!!!!!!! the oem are made of chocolate, asparragus or some other simmilar material!!!!!!
also install NEW! oil pump, ported radiused, polished & shimmed, also install new chain, (cadillac variety) they are beefier than `98stuff, and a fraction of aftermarket price!
I suppose youre smart enough to assembly everything w/ ARP`s (at least new OEM crap!)
greetings from Guatemala!!!! (its raining cats&dogs :-/ )
I agree with changing bearings, polishing crank, grind the bearing caps to 0.0015" clearance in a competent machine shop; they are too cheap (little expensive!) to trade for a blow up, while youre at it do yourself a BIG RELIEVE! buy ARP R*O*D*** B*O*L*T*S!!!!!!! the oem are made of chocolate, asparragus or some other simmilar material!!!!!!
also install NEW! oil pump, ported radiused, polished & shimmed, also install new chain, (cadillac variety) they are beefier than `98stuff, and a fraction of aftermarket price!
I suppose youre smart enough to assembly everything w/ ARP`s (at least new OEM crap!)
greetings from Guatemala!!!! (its raining cats&dogs :-/ )
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Well, I finally got around to checking out the bottom end...looks like it's in similar shape as the cam, just not as severe.
Here are one of the rod bearings...
and the journal...
...main bearing (looks worse in person...couldn't get the camera to focus too well)
Looks like I'll be taking the crank to the local machine shop to get it polished.
Here are one of the rod bearings...
and the journal...
...main bearing (looks worse in person...couldn't get the camera to focus too well)
Looks like I'll be taking the crank to the local machine shop to get it polished.
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Here's something I found rather peculiar...it appears that this engine has two completely different pistons.
Three are like the one on the left...the other five are like the one on the right, even down to the burnt oil coating. It looks as though someone replaced them...surely it wouldn't have come from GM like this, no?
Three are like the one on the left...the other five are like the one on the right, even down to the burnt oil coating. It looks as though someone replaced them...surely it wouldn't have come from GM like this, no?
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Nope, didn't clean it at all. I bought the longblock a couple of months ago to replace the motor in my car which has a spun rod bearing. After I get this one back together I would've been better off pulling the stocker and repairing it ...oh well, at least I'll have a good spare.