Engine Noise 95 Eclipse

GOOD MORNING EVERYONE

i bought 95 eclipse for my son's 18th birthday in march. it's a-ok car, though obviously was damaged on the front end (bumper is fiberglassed from the inside and oil pan is dented in about 1/4 inch; drain plug seat is welded around and plug drops about 2 drops of oil a night).

it's 4 cyl engine. i got rid of most of the noises so far, there's one left. it's a dull tum-tum-tum noise coming from passenger side front engine end, down there, around a/c compressor. i used stetoscope to pinpoint it, yet still am not sure. a/c is low on freon and he does not use it at all, but clutch can be engaged, just with fair vibration to the engine.

anyhow, that noise does not appear to be rpm relevant. it is quite faint, rythmic, and, like i said, dull. not a clunk, just really sounds like tum-tum-tum-tum. i'd guess about 160 beats per minute. any ideas what it might be? besides slight oil loss, which we had 3 mitsu-s before, and ALL of them do so, car appears to be doing fair for what we paid for it. mileage is around 60K.
will appreciate suggestions. i am bit worried it's oil pump, as caved in oil pan might have damaged oil pickup thing and led to internal damage? definitely down there, from around a/c compressor area.

thank you

Hi. I'm going to assume you're talking about a non-turbo model since you said the front of the engine is on the passenger side, correct?

For the oil pan being dented, I don't think you would have done damage to the oil pickup. If damage was done, you'd be experiencing more bigger problems. The pickup itself is actually pretty high inside the oil pan. I just replaced my pan 2 weeks ago as it was dented serverly and rusted, however, the pickup was untouched. You might want to replace the pan (about $60 off ebay) with a new one to stop that drip. Very easy also. Also be able to see any damage if there is any to the pickup.

So if you raise the rpms, the same rhythm is kept correct? It doesn't raise with the rpms? Is the timing belt cover on there good?

Does the power steering work? And is there fluid in there?

Has the car been overheating at all? Could be the water pump starting to go out if it's coming from that area too.

Would it be possible to take a video so we can hear it?

1. yes, it's non-turbo
2. yes, i do have oil pan sitting in garage since april. i dragged on repalcement as i'll have to remove part of exhaust manifold to pull it out, plus it was too cold to mess with this on concrete floor. unless there's magic that permits bypassing that L-shaped exhaust pipe to remove the pan
3. last i remember it is not relevant to rpms, but my memory ain't worse a flip, so i'll double check.
4. i used mechanics stetoscope to point the noise down. it's the loudest when touching a/c compressor. but with it not being engaged, i don't see how it could make any noise, unless it's clutch/bearing, but they make different kind of noise, i've been through that before on our LR-V.
5. no overheating; power steering works fine; i had suspiscion on power steering pump myself. when i test drove the car, and noticed the noise, seller told me "it's that pump pulling in......" and then i got sidetracked and did not really persue the issue of noise anymore. so i am not sure if he was referring to PS pump.
6. noise can be there from the start, or can manifest itself when engine warms up.
i'll let my son know to make a vid of this and youtube it or something so that you can hear the noise. good idea.

For the pan you have to pull the downpipe on the exhaust, the cross member, and then a little transmission shield (2 bolts) to get to it. Kind of a pain but will save you oil and lets you inspect internals to some extent.

The AC wheel on the compressor still spins even when off so it could be something attached to it or on the inside. I would say, pull off the belt on the AC and PS pump and run the engine like that and see if the noise still occurs, if not, it's one of those and probably the AC since you heard it. If the noise still persists, it's something else.

If you're not sure on the belt removal, right between the AC pump and the PS pump there is the tensioner belt. I believe it's a 14mm bolt that you loosen, move the little pulley outward, and remove the belt. You have to wedge the belt out between the chassis and the underdrive pulley but it's doable.

why i did not think of removing the belt myself? makes things better, we had all of them removed anyways about 2 mths ago. getting old, getting old. will do this weekend, i have long one. great suggestion, thank you. yes, clutch does spin, but it does not engage anything inside the compressor. spinning will produce squeeky noise, rubbing, not thumping.
i guess i'll do oil pan same weekend, it's well over due.
it's 2nd eclipse we own, and in the 1st one, at some point, all i had left inside the engine bay was engine block. so i am familiar with my ways around that car, but appreciate friendly help always. not that i am much worried about that tum-tum-tum, i just can't stand noises coming from under the hood.. not on my book, naah-aahh.

Haha... just wanted to save time than having to type a new post with a How-To. Plus was pretty bored at work at the time.

For the oil pan you should be able to reuse the gasket inside, just clean off and apply some gasket sealer before reinstalling.

Let us know how it all works out.

that's all good and cool.
that car plays games on me. i just listned to it when son was leaving - no noise at all. tum-tum's gone.
well, we'll change oil pan this weekend, bumper and headlights. he goes for 97 bumper and projectors. will get that belt off same time and see what happens.