Buzzing Noise

Shot in the dark here as I know it's hard to diagnose problems from someone explaining a noise but I just wanted to see if anyone has experienced this or might know what it is before I haphazardly start trying to pinpoint.

My daughter's '98 2wd 4.0 auto is making a buzzing noise that's coming from either the transmission or lower/back engine. It happens in all gears (PNDR) and increases pitch as rpm increases. It's intermittent but happens more often then not.

Oil pressure is ok. Fluid levels are ok. Drivability/shifting is ok.

My first thought was either the oil pump (but pressure is fine) or transmission fluid pump.

Make sure the bolts on the bell housing cover are tight, as well as the starter bolts.

So I used the stethoscope underneath the Jeep and determined the noise was coming from the bottom of the transmission. Checked the fluid (operating temp/running in park) and noticed it was over the max.

Drained the fluid and added 3qts new. Drove it around for about 20 minutes. The noise was still there, just not as frequent and loud.

Checked the level again and still over max!

I'm guessing the 4qts referenced in the manual assumes you dropped the pan.

I'll drive it a bit and drain the fluid again tomorrow but only add 2 qts and see what happens.

This is my 1st auto Cherokee BTW.

Dropping the pan on the AW4 I was never able to get more than about 2.7 quarts out of a properly filled AW4.

Also make the sure the rig is level side to side and front to back, and check the level in park with the fluid hot!!!!

What spec fluid are you using?

Ecomike said:

Dropping the pan on the AW4 I was never able to get more than about 2.7 quarts out of a properly filled AW4.

Also make the sure the rig is level side to side and front to back, and check the level in park with the fluid hot!!!!

What spec fluid are you using?

Click to expand...

Ended up just around 2 quarts. I'd guess there are more then a few people with AW4's with 2 quarts over.

I used Valvoline MaxLife Dex/Merc. I also added Lucas ATF conditioner which I've never tried before. May be snakeoil but I figured I'd give it a shot. Didn't hear the buzz/whine afterwards.

I have a '99 4wd AW4 from the salvage yard on standby for a 4wd conversion. Just don't want a catastrophic failure to strand my daughter before I get to it.