??Heat Sheild Noise??

[BlackMagik]

Anybody notice a heat sheild noise coming from the bottom of the engine area but not actually have a loose heat shield? My '98 with 38K miles has this noise on start-up and sometimes at certain rpm's, usually when pulling out from a stop....pretty much the same conditions that you would experience spark-knock. Could it be spark knock? Any Ideas? My muffler guy is pretty sharp and he says it's not the heat sheilds but something else. My cams are quite and the noise seems to be low on the tranny end of the engine, not high on the cam end.

 

[stephen newberg]

It is not likely to be spark knock. The computer is very effective at retarding timing to prevent that. The cam problem is very obvious when it happens, so it is not likely that, and you are also at lower milage than is common for the cam sprokets to loosen. The fact that you are getting resonant vibration at particular RPMs strongly indicates loose metal somewhere. I woul get the car up on a lift and start tapping around with one of those small plastic mallets to see what moves.

pax, smn

 

[jasonty]

My heat shield rattles when I'm sitting, idling. It's just a little loose, but I've been too lazy lately to get under there and tighten it back up.

 

[MilTownSHO]

stephen newberg:
The cam problem is very obvious when it happens, so it is not likely that, and you are also at lower milage than is common for the cam sprokets to loosen.
pax, smn

It's happened with less miles than that on engines. Cams sometimes don't give any warning either. I've got low miles, but mine got welded, it's just not worth the chance.

 

[stephen newberg]

Yes, a few of the reports of cam sprocket failure have indicated the problem apparently can occur at low mileages, but in general they seem to be at the 60K+ level. I continue to think getting your cam sprokets welded or pinned is a good idea from a purely preventive viewpoint, but at very low mileages your chances of a problem are extremely small, from what we have in documented failures, so I would not think of it as being so urgent as it might be considered when the car is up to 60K or more.

pax, smn

 

[SHOZ123]

I had the cams welded on my motor with only 500 miles on it.

 

[stephen newberg]

Ya, but you had a new motor, right? If I was having a new motor put in, I would do the welding immediately also.

pax, smn