cam bearing...should it be replaced?
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On The Tree
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cam bearing...should it be replaced? a buddy from cali sent me this picture and asked if he should replace his cam bearings in his lq9. i didn't know the answer so i figured id ask those that could provide a better answer to me.
i was told that it still feels smooth to the touch and his fingernail does not get caught on anything.
i was told that it still feels smooth to the touch and his fingernail does not get caught on anything.
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Insane I know but thats how it usually goes.....choose machine shops carefully. I have a rule with machine shops, If they don't have a 2-3 week back log of work I look else where. Now you guess how I came to that bit of wisdom?
Personally I wooooodn't touch that used bearing, how long do you think it will be before a new one looks like that? That frt bearing ALWAYS looks that way.
I'd move on to more important things like valve guide clearances(no one ever checks) or main shaft thrust sufaces etc.
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If you find one that knows how to properly, I seen many machine shops botch cam bearing installs badly and later on refuse to repair the ruined engines. I had some one call me up after a rebuild claiming their rebuilt engine had a squeak. I pulled the valve covers...dry as a bone....cam bearing turned blocking the holes and you realize that means the engine needs major repairs AGAIN. They called the machine shop that did the complete rebuild and told them what they found. Machine says we can't stand behind that because how do we know you guys didn't mess with it.
Insane I know but thats how it usually goes.....choose machine shops carefully. I have a rule with machine shops, If they don't have a 2-3 week back log of work I look else where. Now you guess how I came to that bit of wisdom?
Personally I wooooodn't touch that used bearing, how long do you think it will be before a new one looks like that? That frt bearing ALWAYS looks that way.
I'd move on to more important things like valve guide clearances(no one ever checks) or main shaft thrust sufaces etc.
Insane I know but thats how it usually goes.....choose machine shops carefully. I have a rule with machine shops, If they don't have a 2-3 week back log of work I look else where. Now you guess how I came to that bit of wisdom?
Personally I wooooodn't touch that used bearing, how long do you think it will be before a new one looks like that? That frt bearing ALWAYS looks that way.
I'd move on to more important things like valve guide clearances(no one ever checks) or main shaft thrust sufaces etc.
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The LS engines just seem to do that to the front bearing. Used oil analysis always shows high copper, from the bearing. If you search, you aren't the first to ask this as many have found similar bearing conditions when they open the motor. Also, it has been stated that GM line bores the bearings after installation, not sure if that is true or not but many who have replaced later spun a bearing.
Do some searching then decide.
Do some searching then decide.
I had to have cam bearings replaced in my lq9 engine and the local shop I went to charged me $50 to install new ones plus the cost of the bearing. Cheap insurance if you ask me.
FWIW....looks the same as my 70k mile LQ9...as well as a buddy of mines LQ4...
I have seen a pic of a brand new G8 with less than 10k and the bearing looked like that....
I have seen a pic of a brand new G8 with less than 10k and the bearing looked like that....
Did I see something wrong? It looks like there's a chunk missing on the inside edge.
My question is, is it necessary to replace the cam bearing when doing a rebuild? Or it just depends on the condition of the bearing? After reading what you guys posted, it scared me.
My question is, is it necessary to replace the cam bearing when doing a rebuild? Or it just depends on the condition of the bearing? After reading what you guys posted, it scared me.
Look closer you can see the edge of the bearing doesn't go back to the "chipped" area, that would be a roughness in the block casting. The area of interest is the copper colored area where the lead has been worn away exposing the copper layer beneath. The valvetrain is always pushing down, and the timing chain pulling down, on the cam causing the bottom of the bearings to wear more than the top (picture is looking toward the bottom). A rod bearing showing copper like that would be giving you a knock but a worn cam bearing just causes a loss in oil pressure, mostly noticable at idle.
Years ago when I had a cam swap done by a shop at 10k miles, they saw a small amount of copper at the bottom of the front bearing and insisted on replacing that, and 1 or 2 others. In hindsight it was highly unnecessary. I share the opinion of the others on here, if there aren't major surface imperfections, I'd leave it.
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On The Tree
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well the block is getting hot tanked,mic'd and cleaned up.... so the bearings are gonna have to come out.
plus the shop warranties there work. ie if they install improperly or a part is defective they will repair at no cost to me..
plus the shop warranties there work. ie if they install improperly or a part is defective they will repair at no cost to me..
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