Rattle coming from passenger side engine bay at idle

[Colby]

Hey guys.. I pulled the ol' 911 out today and ran it for the first time in many months (it was hibernating). Started up just fine, however I hear a rattling coming from the passenger side engine bay. It's most noticeable at idle, and seems to go away once I rev the motor up. There is no smoke, oil leaks, or anything else that would cause concern, but I want to isolate the problem before I take it out on the road. I did a valve clearance last winter, so I don't think it's out of spec, but is it possible a nut came loose and backed out causing a the rattle (or am I just being paranoid)? What else in that vicinity could be causing a metallic rattle? If the sound is coming from the valvetrain, would it run different? I popped the engine lid and tried to locate the problem, but between the whistle of the K&N and the rumble of the exhaust, I can't even hear it back there (I should note my car has all the engine padding and sound deadener, along with the rear seats, removed so I can hear a lot from inside).

The car is an '84 Cab with the A/C removed, filter box removed, backdated heaters, so a lot of factory "unnecessaries" are gone. Isn't there some method of listening through a screwdriver or something to act as a stethoscope to help pinpoint the noise? I am also not convinced its not coming from underneath the car, since I can hear it from inside, but not outside listening from above.

Colby

[Colby]

bump

[carmad]

You need to get a stethoscope and check various locations on the engine to try to isolate the sound. I would not drive the car until you know what you are dealing with.
I don't want to be alarmist but I had the "chain in the metal garbage can "sound, it turned out to be a rod bearing.

[Por_sha911]

Have you got upgraded tensioners?

[Colby]

Yes, it's a Carrera, so it has the upgraded tensioners. I bought a stethoscope today and will start prying around. Sometimes I can hear it, then it goes away. It's not consistent with it being warm/cold, idling, etc. I stuck my head under the front of the passenger wheel with it idling and couldn't hear it. Couldn't hear it from listening above either. Mainly, I can hear it from inside. Very odd, has me worried...

Colby

[Wayne 962]

Check the sheet metal that surrounds the heat exchangers - these little spot welds often break loose and then rattle...

-Wayne

[Colby]

Brand new SSI's and new backdated sheet metal shrouds (from last winter when the motor was out). You know what it really sounds like is the starter motor gear coming in contact with the ring gear, like it didn't fully disengage and is just barely coming in contact with it... would be in the proper vicinity as the sound I hear. It's not a high pitch rattle like sheet metal, it's more like two solid pieces tapping against each other...if you know what I mean.

Colby

[n8marx]

Colby, Did you ever resolve this? My car has been doing the same thing for the past year and I can't find the noise. Can only hear it from inside, sounds like it's coming from high up in the engine bay, passenger side. What was it?

[raceman]

sounds like tensioner,l had to replace one of mine and l`ve got the newer style on my 84,it does happen sometimes

[n8marx]

MIne is definitely not a tensioner. I've been all over those with my stethoscope and they sound normal. The rattling I'm getting is actually more of a buzz. Sounds like something vibrating against metal. I'm gonna give the engine tin spot welds a check tonight.

[targa911man]

How about the charcoal can or hose going to it in the passenger rear wheel well?