Q: I own two ’02 Grand Cherokee Overlands with 4.7-liter, eight-cylinder engines, and both make a groaning noise. One car is in Florida and the other here in Massachusetts. The Jeep in Florida we had diagnosed by a rear-end specialist. He concluded it was the clutches in the differential. They are made of paper and the bridle assembly can’t be taken apart to replace clutches. Even though the gear assembly was in great shape, the only remedy was to change the whole bridle assembly. He assumes this is why Jeep adds the gear additive to differential fluid. The fix cost me $1,100. That was the cheapest estimate I could find. Chalk it up to planned obsolescence from the auto industry.
A: It’s unfortunate for sure. This is a common problem with this particular vehicle, but the problem can be avoided. Proper maintenance calls for servicing the rear and front differentials at particular intervals. For an all-wheel drive vehicle, I recommend a differential service at 30,000-mile intervals. And the manufacturer’s recommended gear oil and additive of course needs to be used as well. Because the clutches are so thin on your vehicle, once the fluid gets gritty it does not take long to wipe them out.
Larry Rubenstein is a master technician who owns a North Shore service station. His column appears every Saturday. Write to Larry at The Salem News, c/o Auto Scanner, 32 Dunham Road, Beverly, MA 01915, or send an email to email@example.com.