Gearbox over filling

[Gavin Waddell 19]

Quick question, what happens if you over fill a be3 gearbox.

 

Thanks Gavin

[petert 641]

It will build up pressure, pushing out the seals, if the vent can't manage it. How much are you talking about? 100mL? 500mL? 1L? It's easy enough to drain out and start again.

Edited June 2, 2025 by petert

[Gavin Waddell 19]

Basically I took the gearbox out to do the crank seal, and also paint it, so I drained it dry over winter, when I refitted it I added  2l excatly and I had a small leak from the passenger driveshaft seal. So I today I changed the seal and but back 1.8l knowing  that there would still be some oil in the gearbox. Took it for a drive and no more leak. Maybe it was a faulty seal? 

Maybe when I refilled it the first time I put to much oil in and it was pushing it out of the seal?

[petert 641]

Sounds fine to me.

[Leslie green 166]

If you were putting it in the side filler bung  it would just run out again if on level ground but a little extra won't make any difference .if you are worried just remove the side bung with a tray underneath to catch any spill.

[Gavin Waddell 19]

Drove it to work this morning and no more leak. Happy days

[Gavin Waddell 19]

Been driving the car on a daily basis and first few weeks were fine but noticed the seal is leaking again. Going to check the oil level if that is good what could it be.

[welshpug 1,737]

main bearing cap hockey stick seals

[SRDT 255]

Did you install the driveshaft seal correctly? It should not be all the way in nor flush.

[Gavin Waddell 19]

It's not the mains as I tasted the oil and it's gearbox oil, plus I can see it leaking down the drivshaft.

 

The seal.is brand new and is seated about 2-3mm proud.

 

Going to see if the gearbox has to much oil in it tomorrow.

[welshpug 1,737]

what diff/gearbox is fitted?

[Gavin Waddell 19]

Standard be3from a 1.6 gti

[Leslie green 166]

The not going all the way in with the seal refers to earlier be1 gearboxes I believe ,1.5mm right hand side and 1mm left hand side as shown above by SRDT  I put my be3 seals flush from what I remember and they seem ok , 3 mm out seems too far out as the seals are not very wide to start with.

Edited June 29, 2025 by Leslie green

[Gavin Waddell 19]

Forgot to mention only seems to leak when I'm driving, when the car is parked up it doesn't leak. Kind of maybe points to an overfilled box.?

[Gavin Waddell 19]

This morning l I did a oil level check and about 150 ml of oil came out, so maybe it was overfilled, and pushing out the seal, maybe why it only leaks under load ?

 

Gavin

[Leslie green 166]

Its won't be because its overfilled as it will come out the top breather at worst , 150ml won't make much difference to the actual level.It leaks while driving as thats when the oilis thrown about and most likely is the seal isn't in square as its difficult to do in situ as you are not pushing it in till it seats .If you had a piece of metal the seal could fit though 1mm thick that would sit against the gearbox  flange to  guarantee its in square once to get it started in the bore or just use a 1mm washer at the side of the seal to limit how far it goes in each tap when you are near seated.

Edited June 30, 2025 by Leslie green