grinding noise from valve cover

So, as soon as i heard this odd noise, i dropped my bike off at home and got into my truck.
Anyway, i took it apart today and it looks like all my clearances are fine, nothing seemed to be grinding anywhere. But then i pulled my cams off, and those cam bearings seem to be whats wearing. They have odd paterns of wear and some metal-particles in them. This is very not good.

But what can i do about this?

What kind of metal particles are in the cam bearings?

That's rather strange as the only way that metal could get there is via the oil passage, and your oil filter should have prevented that, unless your oil filter is plugged and the oil is going through the bypass.

Pictures would help.

well, i think the particles are from either the bearings or the cams themselves.

The bearings are softer than the cams, so I don't think the cams are going to self destruct inside the bearings, and if it is bearing pieces, then I think they would just blend in with the relatively soft bearing material. Since you have the cams out, are there any pockmarks or any other evidence of cam damage on the cams?

Well, the bearing areas on the cams are extra shiny. Other than that they are great cams. I even took a caliper and made sure all the lobes and the bearing-spots were within tolerance.

I think i'm going to clean the bearings, bolt them all back on and make sure the caps are torqued on right and get riding agian. Cause i'm not sure what i can do at this point. I'm already saving up for some new cams, so i suppose i'll buy new bearings with the new cams.

The bearing area of the cams should be really shiny, almost mirror polished. The cam bearings are soft in order to allow any particles to embed themselves in the bearings instead of scratching the cam bearing surface.

I suggest removing the oil filter and cutting it open so you can see what metal particles may have been trapped.
You should also consider dropping the oil pan to see if you have any metal shavings laying in the bottom. It would be better to find out what is causing the grinding now, rather than risk destroying the motor.

By the way, it's common to find dirt particles imbedded in cam bearings (just the bearings doing their job).

Just my $0.0002

well i just finished taking it apart, cleaning it and putting it back together and i still get that noise. I guess i'll invest in some new cam bearings now. no sense in letting these go out and have my motor explode. Also, no metal shavings in the oil pan.

the first thing I would do is to put the bearings in the caps without the cams tighen them down to spec and check the size and see if they are round, then check the size of the cams, this will tell you the clearance, if it is in spec then you need to look someplace else for the noise, dont think I have run into cam bearings making a noise unless they are wore plum out

did the tensioner,chain or cam sprockets show any unusual wear?maybe someone got a little heavy handed with the cam chain adjuster in the past and the bearings were the weak link in the chain.when you change the bearings make sure to plasti-gauge the new bearings,to make sure its not a machining issue,clearance should be .020-.070mm pretty sure,but i havent done one in a while so might want to ask a couple others.good luck,happy wrenching!

Post edited by: wireguy, at: 2005/11/21 23:45