My 1996 1500 RAM with 110K miles started making low frequency rumbling noises about 30 minutes after parked with the engine off. Loud enough to be heard ten meters away. Very difficult to isolate the noise but it seems to be in the front half of the truck. Removing the negative lead from the battery stops the noise but leaving it on for a couple of days does not seem to drain the battery below the point where the truck will not start. The truck drives normally and everything seems to function as usual. I removed the gas cap to see if there was a pressure venting problem, but there was no change. BTW, I searched the forum for "noises" and looked at all ten pages with no results. Any ideas?

 

Hmm, unplugin the battery makin it stop means its electrical. they basics of electricity say that if componts work when there not supposed to , you have a short. So id start lookin over all the electrical components on your motor
edit: and belive me ive seen shorted components do some funky things

 

I thought about a short in the electrical system someplace - and that almost has to be connected to the noise - but the drain is very small because when I reconnect the negative terminal there is no spark or a very small spark.

 

Just thinking out loud here but it would seem to me to be a good idea to check the wiring around the fan for the heater and then the wiring around the fuel pump. From what I have read around here it might be an idea to smack the bottom of the gas tank to see if it stops the noise, ( fuel pump running ), crazy as it sounds.

All I can think of that is electrical and would make that much noise with that small of an amp draw. Need more coffee I guess.

Larry

 

like i said, shorts can do funny things. the low power draw means that whatever is shorted out is just barely shorted. so much that if you had a meter you probably wont even be able to see a significant change in resistance

 

just my two cents... when its making that noise start pulling the relays out from underneath the hood, one at a time and see if it stops the noise. It may help ya narrow down where to start looking..

 

The pulling relays is a good idea; I hadn't even thought of that. Might at least get me in the right part of the truck. Got a busy week so I'll try it next weekend and report back. If there are any more ideas plz post them as I'll have a laptop at the track and can make notes.