Syn

Yes, another one of these threads. Since the weather turned cold (which may or may not be the cause) I have noticed a few times when I come home that I can hear a rattle or tapping sound before I shut the car off. I can't say I've noticed it at any other point in time such as start-up. It sounds like it might be valvetrain noise but it also sounds like something that's just rattling.

If I give it some gas I cannot hear it increasing in frequency with RPM. When I let off the gas the sound disappears and doesn't come back again until it settles into idle (about two seconds after it returns to idle RPM it comes back).

The car runs fine. No loss in power or anything. I know how these issues can be, so I really don't want to waste a bunch of time trying to track something benign down. I'm thinking about taking it to a mechanic to at least check if the valves are in spec. Is there anything else I should check aside from a visual inspection for anything that could be loose?

flyingtoaster

I adjusted my valves and the problem went away. Do you notice a difference between revving in neutral, and revving in neutral with the clutch pressed?

Carbon Blue

my guess is timing chain tensioner, and if it is take the worm screw out and have it sand blasted, or you can save yourself some time and buy the sand blasted worm screw from billman250 (i think thats his sn).
does it sound like this?[media]http://www.youtube.com/watch?v=EVS-JLfmTnc [/media]

Syn

I have not tried with clutch pressed in--I'll do that next time I drive the car. When I tested it I just tried it in neutral.


As for the YouTube video--it does not sound like that. I can only hear it faintly from inside the cabin. If I'm outside the car or I pop the hood I can't distinguish it from regular valvetrain noise honestly. Also the noise is not quite that frequent--there is slightly more gap between each tap. Sort of reminds me of the piston slap I had in my LS1 on cold starts as far as frequency of the tap but not quite the same sound.


Thanks for the replies!

oldskooleskimo

I have the same issue! It only seems to appear when the weather is very cold (below 35 F) and the car is idling. I also cannot seem to pinpoint the source of the sound. Looking forward to the responses!

Sixth.Gear

I was thinking the same thing that I was the only one with this issue. I've narrowed the sound down to somewhere in the driver's side footwell/firewall area. I can't hear the sound outside, so I'm beginning to think its something on the inside.

I've also noticed that if I blip the throttle up to about 1.5-2kRPM, the rattle will go away for about a second, and the tapping will fade back in. If you increase the throttle slightly, the tapping sounds like it stays constant.

Any others on this?

Syn

I can tell you that from inside, my sound also seems like it's coming from the area you're describing. I didn't try putting my head in the footwell but when sitting down it sounded like it was definitely coming from the firewall area. I'm going to listen for it again and see what happens. I'll also try slowly increasing throttle to see if the sound remains or not. As noted in my earlier post, the sound goes away when I blip the throttle and then comes back once the car settles into idle again.