chattering from valvetrain area

[niller]

hey guys, i am trying to help a friend out with her alero. she is neither car or internet savvy, so here i am.

its a 1999 Alero w/ 2.4L Twin Cam, i have listened to the car for a few minutes and there is a chattering noise coming from the valve cover area. she says there is no power loss and notheing else out of ordinary with the car (but she may just not have noticed). i have suggested she run some seafoam through it, but she hasn't tried yet.

any ideas on what it could be? even if you could give me a few ideas of where to start it would be appreciated. I live about an hour away and can only go on the weekends, so i would like to get a list of things to look for and try before i go out again. on top of all that, she has no internet so its difficult to look up info while i'm there.

anyways, thanks in advance for any help you guys can give.


nic

[clutch1]

Could be a few things.. depends if only one is doing it, or if they all are. I'm not as good with OHC engines.

I'd assume that oil pressure is required to keep the cams lubed on the part they press on.. so low oil pressure could cause noise in them all.

If just one's doing it I'd say it probably needs further investigation, I'd get to the valves and make sure all the springs are tight, valve guides are tight, etc.

[alero_bmxer]

if its more of a ticking that your hearing its normal. the ticking is just the injector pulses.

[clutch1]

Hehe, better put in some silenced injectors! I kid I kid.

To help, get stethoscope from harbor freight and use it to listen. Poke the injectors.. are they making your noise?

Then I'd listen all along the head and see if the ticking is the same on all the valves, or if some are louder than others.

[niller]

thanks for the quick replys.

its definitely more of a chattering sound, almost, but not quite, like a marble being kicked around in there. it seems to be louder on the driver side.

some pics i have seen of this motor make it seem like there are two valve covers, one over each cam, is this correct?

in any case, if it is the valves, in this engine, the cam lobes push directly on the valves right? so would it be a valve not closing all the way? it would have to be 2 parts that normally stay in contact that are getting some space between them i would think.

[clutch1]

Could be a weak spring, perhaps..

Another test is hooking up a vacuum gauge onto the manifold... Should have about 18"HG reading on the gauge at idle... rev it up and it'll normally drop a bit.. but the point is, the needle should be steady.

A weak spring/s will have steady needle and idle, and start to bounce as your rev it up. One more thing to check for.

[niller]

thanks for the info, i would only get the crazy needle if it were an intake valve sticking right?