Hi all i have a 1990 fc 5spd man and occasionally after high revs the gear box area starts smoking any ideas?

 

apart from the front and rear seals, the shifter likes to make a mess

 

Thanks, looks like tue box will be coming out then.

 

i would lean toward oil off the bottom of the engine drafting to the catalytic converter/exhaust that is burning. the transmission itself pretty much can never get hot enough to burn oil. not to say transmission leaks aren't a problem too. after 35 years, im sure there is lots of leaks under there.

 

There is a "Breather, Air-Transmission" (https://www.mazda-parts.com/oem-part...r-air-88417530) on top right of your gearbox. It might be restricted causing pressure buildup resulting in oil being forced out of the front or back seals.

 

there is, but personally after working on about 3000 FCs, i have never seen it be an issue, it would virtually have to be intentionally sealed up somehow.

 

You're probably right about that, but never say never. I would first suspect the rear e-shaft seal and o-ring are causing the leak.

 

NA RX-7 (M type) transmissions are notorious for leaking out the rear seal during racing.

To keep the rear seal from wearing out so fast at high rpms racers would commonly weld material onto the tailshaft so they could bore it and fit a bearing just behind the seal to support the shaft so it wouldnt wallow out the rear seal so fast.

If you look inside the trandmission bellhousing and its not super oily inside there its probably that common rear seal...

 

Believe it or not but as the 2nd owner from new and only 88000kms on the clock and driven maby 4times a year shes pretty dry underneath. And its using next to nothing oil. Do you think maby its passing through the internals? only thing is that it aint blowing smoke out the back just thru the center where the box is.