I have a '96 Cherokee. About a month ago (coinciding with colder temperatures here in Wisconsin), I noticed a rather loud "whirring" noise once I'd start the engine. The pitch of the noise varies with engine RPM. It sounds similar to a bad power steering pump (low fluid). I checked that first and even replaced all the fluid in the reservoir with new ATF. Noise was still there and there are no steering issues whatsoever. I noticed today that the noise briefly disappears (for less than a second) when shifting the auto transmission gear selector from park to reverse, reverse to neutral, neutral to drive, etc. This has me wondering if it is something in the transmission, even though the noise is there when the vehicle is in park and the vehicle shifts smooth as silk all day long. I deliver mail on a rural route with the Jeep (it's a RHD) so I'm really big on maintenance and change out about 4 to 5 qts. of ATF with fresh stuff every other oil change (since I have the tranny pan drain plug). Any ideas on what this might be? I'd hate to have it be something that is easily remedied that I'm making worse by continuing to drive it. The noise gets noticeably less and less as the vehicle warms up and is driven. Tranny fluid looks clean and is right at the full mark.

 

A transmission drain and refill should take about 3.8 quarts.

Running the transmission through the gears with you foot on the brake pedal changes the engine load and RPM.

Power Steering Fluid is probably better for your power steering. Thick ATF may make it noisy.

I am not sure what else to say.

 

I guess I'd check the simple stuff first on the chance it might be a serpentine tensioner, idler or bearing somewhere. Pull the belt and see if the whine stops.
How many miles are on your '96 with the mail route?

 

I've only got about 81,000 miles on this Cherokee. I'm guessing less than 30,000 of those were put on delivering mail, as I actually have two of these RHD Cherokees (both '96) that I use for the job. It's nice to have a backup. I wish this would have occurred a few months ago; belt removal with single digit temps will be fun.

 

Well, today was NOT a good day. Took it on the route and started with the usual whirring, which faded slightly after about 30 minutes. It remained all day, but not as loud as right after starting the vehicle. About 3 hours into the route, I thought I began to notice "mild" slipping. An hour later, the Jeep wouldn't move at all (forward or reverse). Towed it in and it's at the shop ready for diagnosis tomorrow. The transmission shop manager said it's possible that the screen is clogged with gunk; then again it could be something worse. Hoping for the best, as I never feel too comfortable having only one Jeep in running condition.

 

Hello Spudzy, I was just wondering what the problem ended up being with your jeep back then. I use mine on a rural route too and today it started being sluggish when pulling away and it also is making a whirring noise from the transmission. Thanks, Pat

 

I'm interested as well, since I am having the exact same symptoms.

 

My transmission ended up being toast shortly after my previous post. It had about 150,000 miles on it at the time. I use mine on a mile route too and I'm pushing 200,000 now with the new tranny. So far so good.