The oil level is too high.

Adjust the oil level.

The lubricant in the transmission is incorrect.

Replace the transmission oil.

Bolts are loose or missing.

Tighten the loose bolts to the proper torque value. Refer to Fastener Tightening Specifications .

Bearing cap seals are worn.

Overhaul the transmission.

The transmission breather is plugged internally.

Overhaul the transmission.

Seal plugs are loose or missing.

Replace the seal plugs.

There are worn gaskets.

Overhaul the transmission.

There are cracks in the transmission case.

Overhaul the transmission.

Drain or filter plugs are loose.

Tighten the drain or filter plugs to the proper torque.

Bearing caps are worn or plugged.

Clean or replace the bearing caps.