Grinding Noise When Fully Warm Up

[pearlm30]

MY 98 forester with auto trans. I got this loud grinding noise only when engine reaches its operating temp(after driving 40 mins with 80F outside temp, AC off). The noise is present when I rev the engine rpm up in P and N, also present in D when drive around town.

When I got home and ready to pop the hood(with the engine running ) to see where the grinding noise came from, the car no longer making noise:confused::confused:

All the fluids are full and clean except power steering ATF( its dirty but no leaks).

So what are the possibilities? Oil pump? Pulleys? Front diff? Trans?

The car drives good without any warning lights on

Please help

Edited March 31, 2009 by pearlm30

[nipper]

HOw many miles are on the car?

 

Normally i would say wait till the noise gets worse, but since it is a grinding noise that comes and goes:

 

When was the last time the timing belt was changed?

What was replaced along with the timing belt?

Is it more of a rattle (Heat shields)?

 

Next time you hear it, spray water (water bottle) on the accessory drive belt tension pulley and see if it goes away.

 

nipper

[crockettbrat]

Is it something that you feel as well as hear? My first thought was the heat shield on your y pipe, or a rattley cat.

 

If you feel it too then maybe a bushing, or other rubber isolator like an engine mount or tranny mount has broken and is causing some problem.

 

Hope this helps.

 

Daniel

[Suzam]

Also look at your crank pulley and make sure it's not not loose and contacting the front timing belt cover. The rubber insert in between the pulley and harmonic balancer may be staring to come apart causing the pulley to rub when the rpm's go up. I had one do that on our MY01.

 

-Sam

[Gloyale]

Moszt common source of mystery grinding I have run into is timing belt pulleys. they often start making noise before failing.

[88whitecat]

Moszt common source of mystery grinding I have run into is timing belt pulleys. they often start making noise before failing.

 

+1

 

when my lower TB idler went a couple months ago it made the same kind of noises.

 

In the course of a 45 minute trip I went from a quiet engine, to a faint noise when accerating, to a faint constant noise, then finally to a clear loud noise

 

My noise was definitely from the front of the motor when I pulled over to check so i figured bearings in one of the accessories. Took both belts off (on the side of the highway, I ALWAYS carry tools w/ me!) and the noise was still there. Drove very gently home and when I got the TB cover of the idler just fell out in pieces. The ball bearings had been flung everywhere inside the cover and there where metal shards all over. There was almost no tension on the belt and a lot of cuts in the belt too. It's a 98 so I got really lucky it didn't jump time.

[pearlm30]

The engine got about 125,xxx miles on it. Its time for the timing belt change but the reason I didnt do it yet is because it has minor blow headgasket and I would like just to put a 95 EJ22 in it.

 

The grinding noise is more like when you drive in reverse in a manual 5 speed transmission. I couldnt really think of anything to describe this noise. But its for sure temp related.

 

I can let the engine idle and rev many times about an hour without the grinding noise. So far only way to produce the noise is to drive the car more than 30 mins. Maybe its transmission related????

I checked all the heatshields and found one thats a little loose, I bent it back a little to stop the rattle.

 

I also checked acc.belts/pulleys/alternator, they seems OK. The crank pulley didnt grind/loss on the center piece of timing belt cover.

Could the timing belt pulleys making noise only when warm up?

 

What about the oil pump and flex plate of the transmission? The trans shift ok and the ATF has been drain and fill last week.

 

Thanks again for all the suggestions

Edited March 31, 2009 by pearlm30

[nipper]

You are living on seriously borrowed time on that timing belt. I bet its a tensioner/idler going bad.

 

 

A flexplate is a rythmic clicking that amy be temp related, but will get worse over time. It will match the engine RPM.

 

 

Oil pump isnt really a problem on these cars.

 

 

nipper

[pearlm30]

I finally fig out whats making the grinding noise. Its the front diff!!!! :eek:

Dont understand why it will making noise only when the car/engine/trans been driving for a few miles. I did replaced the gear lube and it still making grinding noise when warmed up.

Any advice?

Thanks

[Gloyale]

I finally fig out whats making the grinding noise. Its the front diff!!!! :eek:

Dont understand why it will making noise only when the car/engine/trans been driving for a few miles. I did replaced the gear lube and it still making grinding noise when warmed up.

Any advice?

Thanks

 

You said earlier, it will do it in P and N range sitting still. can't be the front diff. it doesn't spin in when the car isn't moving.

 

Is it perhaps the pump in the trans? it is just behind the diff.

 

It could also be the Torque converter, which rides directly over it.

 

Might be worth pulling the access cap on the engine bell and checking to make sure all 4 bolts holding the TC to the flexplate are tight, not backing out.