1999 Jeep Grand Cherokee won't come out of 4X4?

RW BRIAN

MEMBER
1999 JEEP GRAND CHEROKEE
6 CYL
4WD
AUTOMATIC
102,569 MILES

I think the problem is on going, I BOUGHT THIS JEEP WITH A FRONT DIFF. PINION BEARING OUT, I REPLACED IT WITH A LOW MILE 3.55 RATIO OUT OF A 03. Test drove all was fine until I shifted into 4x4 and out again. I seems to still be in 4x4. When stopped and t/case shifted it sometimes makes a loud pop. I then replaced the t-case. Same thing. This is a select trac system.

1 Reply

SERVICE WRITER

MECHANIC
9,123 POSTS

There is a hydraulic pump that is operated whenever there is slippage between the front and rear driveshafts. This hydraulic pump applies pressure to a clutch pack that is similar to a regular automatic trans clutch pack- with steel plates sandwiched between clutch discs. When the axles turn at the same speed, the hydraulic pump is not active and the pressure slowly bleeds off- releasing the clutch.

I understand that often times due to abuse or towing with one axle on the ground and one in the air, the clutch pack gets welded together and this causes the vehicle to do the old 4x4 hop since it is permanently locked in. This also causes rapid wear on the front axle since it is much lighter duty than the rear axle.