My 96 Acura Integra with 100k and a manual trans runs like a dream, but it makes a strange sound every once in a while. I don’t know if it is a bad sound or just normal. It sounds like a loud groan for about a second. It is definitely coming from the engine compartment and I cannot find a rhyme or reason to the timing of the groan. It does it while idling or while I’m driving. if the car is on, it will make this noise every once in a while without provocation. Also, when the noise happens the rpm’s dip ever so slightly and the lights dim ever so slightly, but everything goes back to normal afterward. I have no idea, but it sounds like something is adjusting itself, like a belt or something. Any ideas?
Since it’s causing the RPMs to drop slightly, which I suspect means that it’s loading down the engine likely thr crankshaft, I’m guessing that you have a peripheral component like perhaps the alternator or AC compressor that’s going bad. The sound is probably the bearings of that component. Try removing the serpentine belt and checking the various pulleys by hand for looseness and binding.
Post back with the results.
My first thoughts were exactly the same as Mountainbike’s, namely that the bearings in your AC compressor or your alternator are going bad. Just in case we are correct, I would suggest that you have this checked out before one of those components seizes up. A relative of mine had the compressor bearings seize up on a late '60s vintage Barracuda with only ~14k on the odometer, so with your vehicle at 100k, this is certainly a possibility for your car.
Of course, there are undoubtedly other possibilities, which other board members will likely list, but I think that the AC compressor and the alternator are two good places to start looking for the problem.
Would the fact that my A/C doesn’t work be pertinent information? It actually works, but it is very weak.
So I finally got around to getting it looked at because I couldn’t find anything, and it turns out that something is wrong with the abs system. The pump, apparently is trying to pump the brakes and is draining the current on the battery, making the engine loose power. I’ll post again when I get more information, if anyone is still interested.