Puzzling leak from Hiace Gearbox FILLER Plug…

[Red_V_Roger]

After changing the gearbox oil on my 1992 2.4L 2RZ 2WD petrol manual carb Hiace Camper…its leaking oil out of the filler/level plug..!

Yes first time I did it, I re-used the crush washer, but now I’ve replaced both the plug and the washer with genuine Toyota and tightened it as mush as I dare and yet I’m still getting a leak.

If its on a level surface then surely the oil will be below the filler so it can’t leak – but it is! only a few drips, but a definite leak.

Is there some kind of gearbox breather that could be blocked and causing an over pressure?

Other interesting thing is that I also bought a new filler plug and washer for the differential at the same time. Whilst the plug is the same, the differential uses a different type of washer. The gearbox is a plain flat washer, but the diff. is a more formed half round affair.

Any suggestions on using PTFE tape on the threads, different type of washer, liquid gasket paste, etc?

[elmoticus]

The flat alloy washers are used for the gearbox because it's mating surface is the machined cast body of the gearbox, whereas the crush washer for the diff is used because the mating surface is not machined flat.

When you tighten the crush washer it will flatten slightly. You MUST replace this type of washer with a new one every time it is removed.

I always replace the alloy ones as well, but if they are in good condition you should get away with using them again.

If the gearbox filler plug, washer and mating surface are in good condition there is no way it can leak so the oil must be coming from somewhere else.

I wouldn't recommend using any tape or sealant at all, the proper washers will give you an oil tight seal.

[Red_V_Roger]

The flat alloy washers are used for the gearbox because it's mating surface is the machined cast body of the gearbox, whereas the crush washer for the diff is used because the mating surface is not machined flat.

When you tighten the crush washer it will flatten slightly. You MUST replace this type of washer with a new one every time it is removed.

I always replace the alloy ones as well, but if they are in good condition you should get away with using them again.

If the gearbox filler plug, washer and mating surface are in good condition there is no way it can leak so the oil must be coming from somewhere else.

I wouldn't recommend using any tape or sealant at all, the proper washers will give you an oil tight seal.

STILL having problems, I tried replacing the Toyota flat washer with a sort of fiber/gasket washer and as soon as it got warm, it just flowed out. So now I've used the differential crush washer and its back to how it was before - a few drips coming out when it gets warm.

I can't think of anything else now but to get a new flat washer and try some type of gasket paste.

[vassam]

If you are still getting a leak then possibly as you have tried tightening the filler plug as tight as you could, then you may have cracked the housing. As its only aluminium these housings are quite easy to crack.

Edited April 24, 2008 by vassam