What a Hot Mess!

[E36M3]

My wife and I drove 140 miles and picked up a 2001 QX4 4WD with 206K miles. The car drove so nice that we decided to drive it back home, and we did, 100 miles later we felt a loud bang and suddenly it started to slow down. From what I saw from the rear view mirror is a smoke. We got off the freeway onto a Subway parking lot. I noticed the reservoir was boiling and some coolant came out of the front grill. There's enough coolant in the reservoir so I have no idea where the coolant came from.

I started the car so I can drive it to the gas station across the street but there is no reverse. The rear wheels won't roll backwards but it rolls forward.

Is it my transmission or transfer case or rear differential?

Please help.

[Towncivilian]

Can you check the transmission fluid level?

1. Park on a level surface and apply the parking brake.
2. With P selected, shift through every gear and return to P.
3. Pull the transmission dipstick with the engine idling, wipe it clean, reinsert it completely, and read the level. It must be within the notched area labeled "COLD". Check for fluid contamination after wiping on a paper towel.



The fluid should be red, and not smell burnt.

What color is the engine coolant?

It's possible that the transmission was on the brink of failure, then grenaded and spewed debris through the transmission cooler lines and filled the fluid with contaminants. The cooler lines clogged and fluid stopped moving, and the fluid pickup screen also became clogged. However, that's just speculation.

[E36M3]

Thanks Town!

The po replaced the transmission about a month ago. There is plenty of transmission oil. I didn't see any coolant right now but it was green.

What puzzles me is that while in neutral the rear wheels will not roll backwards, seemed like it's locked but it will roll forward.

[Towncivilian]

Why was the transmission replaced? If it wasn't done properly (i.e. cooler not flushed, maybe improper fluid used), the new trans is set up for failure too.

Please check the color of the transmission fluid, and see if there is a significant amount of material deposited on a paper towel after wiping the dipstick.

I also suggest removing the differential fill plug to check the fluid level, color, and contamination amount? You should do the same for the transfer case.

I'm not sure why the vehicle will not roll in reverse. Perhaps the driveshaft was damaged when you heard the bang?

[E36M3]

The car has 206k miles that's probably why the transmission was replaced.

The transmission fluid is fresh red. The rear diff fluid is full but not red. There is a clunking noise to the half shaft upon turning it by hand. I don't know. I'm out of theory.

Spoke with the shop's owner where the car had the transmission replaced, he will replace it no charge. My only option is to have it towed there --138 miles.

What a hot mess!

I can't wait to get her going.

[Chuck Tribolet]

The differential fluid won't be red. Usually a light tan color.

Chuck

[E36M3]

I just want to let you guys know that I have my '01 QX4 back.

The cause to the problem were the cooler lines being blocked and so poor lubrication to the transmission definitely damaged the drums inside. I now have a rebuilt transmission with new radiator. I'm hoping to see another 100k miles before she decides to take a dump again.

Thank you to all inputs.

[Towncivilian]

The transmission cooler clogging is a more common occurrence with WD21 and D21 models (1987 - 1995 Pathfinders and Hardbodies) and is a result of not maintaining the fluid properly. Keep up with fluid services and install an inline Magnefine filter and you'll never have the issue again.

[E36M3]

install an inline Magnefine filter and you'll never have the issue again.

I'll look into it. Thanks.