Thread: R380 Gear Box Oil leak

My Dad’s Disco was given to a Landrover mechanic to rectify oil leaks around the Gear Box – including oil coming from the drain hole at the bottom of the bell housing.

From the invoice the following oil seals were replaced: front & rear output seals on transfer case; t-case input seal; gearbox output seal; front intermediate shaft “O” ring (transfer case). (Also replaced the speedo transducer and front & rear output flanges).
And on the engine replaced were the rear crankshaft seal and 5th main bearing “T” seals.

The Disco came back but there was still oil coming from the bell housing drain hole. So back it went & the gearbox came out again. This time the gear box front plate seal was replaced; and sealant used on the plate (apparently there is no gasket here).

Again the car came back – and still oil coming from the bell housing drain hole.

He’s not sure what to do now. Apparently there is “slight pitting” on the input shaft. Mechanic is not keen on speedie-sleeves and says if this is the problem the gearbox input shaft needs to be replaced. But the leak is quite bad and maybe too much to be caused by “slight pitting” which is apparently quite difficult to even see.

He’s fairly sure the engine rear main seal is OK (can’t really tell from colour of oil as both engine & gearbox are new and clean).

The oil leak is evident by slow drips coming from the bell housing drain hole – but when he raises the rear of the vehicle the drip rate increases to about 1 drip every 8 seconds. This seems to confirm the oil leak is from the front of the gearbox.

In the early years of the Disco he used mineral oil (MTF94 and Castrol VMX80) in the gearbox. In more recent years he has been using a semi-synthetic oil (Penrite Trans Gear 75W-80); the mechanic has been using a full synthetic oil (Penrite Pro Gear 75W-90).

So now for the 3rd time the gearbox is coming out again. The mechanic has agreed to leave the oil in the gearbox so it can be tipped up and hopefully see exactly where the oil is coming from.

Any advice would be appreciated. Maybe it’s time to get a reconditioned gearbox – though apart from the oil leak the gearbox is all good.

Thanks in advance for your advice!!!

When the gear box was pulled out again it was clear the oil leak was from the rear main engine seal (crankshaft) – even though it had just been replaced. Plenty of other threads on here about how difficult it is to get the rear main seal right.
So this time when the new seal was fitted, the flywheel went on too, and the engine was run for ½ hour. No leaks so the gear box was fitted and all good now.