98 GST Engine Grinding Noise

I need help pin-pointing this noise. Its coming from the right side of the engine bay where all the belts are. Sounds like a bearing going bad, I took the belts off so the alternator or water pump would not spin, the sound was still there. It happens as soon as you start the car and doesn't go away until you shut it off except for if the car goes under 900rpm then it magicly goes completly away. Under load the noise isent too bad, like I said just sounds like a bad bearing but sitting at idle if you rev the engine it gets very loud and raspy. I work at a shop, we all checked it out and have come up with nothing other than maybe a cam shaft bearing going bad (probeing with a stethoscope leads me to believe its not though), although I have tested the alternator and water pump I'm still not going to rule them out. The idler pully and tensioner pully don't seem to be what's making the noise when we probed it. I just dont want some pully to freeze up and heat my timing belt or anything like that. any advise would be great as well as questions. The car has about 140,000 miles on it, 5 speed trans, front wheel turbo, all the belts look fine.

P.S. The list of stuff below is from my old gs-t, this one I just bought about a month back, has no modifications at all and only one previous owner

although I have tested the alternator and water pump:screwy:

how do you test a water pump? isn't it good or bad, nothing in between?



:licka:

Dude post in the right forum, dont give admis here a hard time, moving topic around.

the water pump it self is working fine, but that doesnt mean it doesnt have a worn bearing causing that anoying grinding hum i'm hearing

Dude post in the right forum, dont give admis here a hard time, moving topic around.

how is this not the right forum?
Automotive Forums > Mitsubishi > Eclipse/Talon/Laser >

he was refering to the sub-forums at the top of the page, this thread belongs in the diagnosis sub-forum...:smokin:

well had I have seen that I would have most certainly put the post under the right forum, other than that do you have any suggestions for the problem I'm having with my car

Does the sound go away , after you drive around a bit ?. Is the sound only heard when you revert the engine, is the sound gone after thirst gear ? if you can record a clip, what the sound like, that will be great, or call me tomorrow ( message me for phone #). I will tell you what the noise is.

The sound stays from start to finish. its a low huming sound when the car is idle, when you rev the engine it gets louder and very raspy although when your in gear and the rpm's are just as high it just sounds like it does while the car is idling and not so loud or raspy. It makes this noise in any gear although harder to hear because of the road noise. I'm going to try and get a video clip tomorrow

Have you had the timing cover off recently? I bet its something rubbing on it.

I had the upper timing cover off, I actually already looked to see if anything might be rubbing against the cover but didnt see anything, none of the belts look like they've been wearing against anything either. I'll look again though tomorrow just to be sure.

Low on the power steering fluid?

i think it's the altenator, when i first got my gst i was freaking out because it started making a grinding noise, at first i thought it was something in the engine, but my dad kept telling me it was the alternator, it was was still charging the battery and everything but i guess the bearing went bad, end of the story we replaced the alt. and noise was gone.

What all have you checked with a stethoscope? Is it a grinding noise like a bearing, or more like a low growl? I'm guessing alternator bearing or something with the PS pump (low fluid, bad bearing, etc)

Edit: After re-reading your post and realizing that those could not be the problem (I'm an idiot), the only other bearing that could cause a noise like that would be the water pump or idler pully for the timing belt. And if you think that it could be the cams making that noise, you'd better pull them off and check it out asap before you ruin a head (if you didn't already).

well...... i was positive it was the water pump because when i recently took off its belt the noise was completely gone. pulled everything off, replaced the water pump, timing belt, auto tensioner, tensioner pulley, idler pulley and ps pump also. everything's back together and runs fine but the noise is still there! i was pissed since i knew it was the water pump. the only thing i can think is that maybe its the actual crank and that it only makes the noise when the alt, ps, wp, and ac are hooked to it because of the strain they put on it. other than that my buddy brandon who has a first gen said he had heard of a problem where the crank pulley some how comes apart and starts making a weird grinding noise? while i had the wheel off i could really notice that the noise is extremely loud near the crank pulley.

good news is i have all brand new belts! im going to check it out again tomorrow when im a little less.. mad as hell

for anyone interested or having a similar problem. the second pulley on the water pump which comes from the crank pulley and runs the alternater was on backwards. you check all the little things first but.. i really didn't even notice that. :banghead: