Internal shift shaft seal leak in 308?

Open the filler plug and use something like a turkey baster and a piece of tubing to suck out a sample of the gear oil. If it's black there is motor oil in it.

 

Can it leak the other way, from the gearbox side into the engine side?

 

The oil level on the dipstick will be lower, and if you take off the fill level plug on the transmission case, if much/any oil comes out, then it is higher than it should be.

One indirect indicator is if the seal is leaking oil outside the engine around where the shaft goes into the casing, making for some drips and weeping of oil that might appear to be coming from elsewhere. If it is leaking there, it is probable the inside seals are nearing their service life too.

They are just square profile o rings, I am surprised they seal pretty well as along as they do.

Not too bad to replace them both, it can be done by taking off only the tranmission pan, there are some threads on how to do that.

 

Mine’s a 2V; the oil level on the dipstick is ALWAYS lower

 

When my 328 leaked several years ago, routine checking of the engine oil level suddenly revealed a lower reading on dipstick. It is doubtful that the tranny oil can get into the engine because, as I recall, the oil level in the engine has a higher free surface.

 

This is mostly true. The seals on the early cars were just a round O ring. The later cars were not really square, they were shaped with a square face on one side a hollowed out rear side with an inner and outer lip seal very much like a drum brake brake piston seal. A brake piston seal works because it is pressure activated and increased sealing with an increase in pressure. There is not much pressure or none in the engine/trans but the seal had little lip pressure to start with. They work pretty OK until heat and constant oil exposure conspire to make the rubber hard. If the outer leaks the inner is almost certainly leaking too.

 

When things are running, it's probably possible for a small amount of either oil to move in either direction past a leaking seal, but, when the engine is not running, the engine oil level in the wet sump is well above the oil level in the gearbox = the pressure difference is always from the engine to the gearbox so it's mostly during car disuse that the engine oil is moving into the gearbox past a leaking seal.

 

The most obvious way to tell engine oil is leaking into the gearbox, or already has, is when the engine is fully warm it is very difficult to shift any gear

 

It can overflow from the trans vent. I added dye. Also when I opened the level plug it over flowed