Thursday, January 02, 2014

2001 Jeep Grand Cherokee rear differential fluid change

The real differential fluid wasn't completely changed ever since I bought the Jeep in 2007 -- I knew it would be a messy job if I take down the differential cover and refill the pumpkin after cleaning. In 2010 or so I used a pump to suck the fluid and to refill the pumpkin a few times without taking down the cover.

Last year I was informed by an engineer at a Jeep dealership that the rear differential was making a sound when the car started to move. They would charge me about $300 for overhauling it. I decided to change the fluid myself.

Tools and materials i used:

0. 75W-140 gear oil; two bottles (2 qts)

1. 3/8'' flexhead rachet; (the room above the pumpkin is very tight, big sockets would be inconvenient to apply)

2. Permatex┬« High-Temp Red RTV Silicone Gasket;

3. Gasket Scrapper


1. Put an oil pan below the differential and go underneath the car to take down the differential cover -- no need to raise the Jeep otherwise is dangerous working under a car and it would not help with more room for taking down the cover; 

2. After unbolting all the bolts, the cover did not come down automatically since old RTV sealant was still adhesive. Take a hammer to knock the cover horizontally to the joint surface. 

3. When the cover comes off, old fluid will drain down into the oil pan. It smells weird, though.

4. Clean the housing cover with brake cleaner or WD-40. 

5. Use the scrapper to remove the old sealant on the edge of the cover.

6. Remove the rubber refilling insert on the cover. It was damn tight because it lost plasticity after sitting there for so many years.

7. Clean the differential house and the use the scrapper to remove old sealant on the edge of the housing.

8. Apply the RTV on the edge of the differential cover.

9. Install the cover back; do not over tighten  (Torque: 25 lbs.ft). I don't think it is realistic to use torque wrench tighten the bolts in such a small room. Just evenly tighten each of the bolts until you cannot rotate the wrench by hand.

10. Since the room is very small behind the gas tank, I use turkey flavor injector to refill. It took a million years to refill with two bottles of the gear oil. So far I did not figure out a better approach, keeping in mind that the room is small and the usual pumps will make a big mess using vinyl tubes.

11. When the service port starts to overflow fluid. Stop refilling and put the rubber insert back to the service port. Use a long-handle chisel to push it in if necessary. 

12. That is it.

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