Annoying oil leak.

[paultv]

I've still got an annoying oil leak from the gearbox.

It's not the shifter seal - new and dry.... nor is it the output shaft seal - dry there too

but there is a small leak which I can see as the left hand rear rubber mount gets wet after a long drive, also oil gets blown onto the cross member and also some signs of oil burn on the exhaust sytem.

The right hand (drivers ) side is completely dry - so I'm thinking this is the rear cover to the the main bulk of the box - I know it has no gasket but should be fitted with sealant,
as they are prone to warp over time.

Anyone with any other thoughts -

Paul

[flybynite]

Oil can travel a long way down a car when driving, I've had a power steering leak that I swore was coming from the gearbox in the past, have you had it up on a ramp to be sure where it is coming from?

The back 'cover' on a G260 is what all the gears mount into. The actual cover is the main body of the gearbox which slides 'forward' to reveal the gears mounted in the back section.

If it is warped and you want to dress it flat you would need to disassemble the whole gearbox. I know because you need to do the same to replace the output bearing as I have done a couple of times.

[Brianmoooore]

I think the 'cover' being referred to is the strengthening piece that covers the hole between the bottom of the bell housing and the engine.
This part is completely external to anything with oil in it, but it does prevent access to the rear sump bolts, so they tend to remain untightened when someone decides to nip up the sump bolts a little.

[paultv]

Definitely gearbox oil...it has it's own smell....and yes its somewhere around that seam at the back of the box...so yes I guess a dismantle is in order if I can be bothered...

The car is dry forward of the rear section of the box and as I said it's only on the left side.

Maybe I'll have to add some UV dye to the transmission fluid so I can trace the leak.

Paul

[HJ1981]

Paul, when i replaced the clutch i resealed the transmission (front and back) as well as replacing the rear crankshaft seal and pilot bearing.

I kept getting a leak from the rear of the transmission, with regular driving the oil was blown back to the mounts as well as the CAT causing the oil smell.

After cleaning and checking the area, i determined it was the rear flange seal. I replaced it 3 times, including using Curil on the flange and bolt and i still experienced a leak.

One day, i cleaned the area, parked the car (moved it 20 meters), parked it and let it sit overnight, next day i pushed it onto the shop jack and checked again, it turned out to be the top selector seal. I replaced that twice since it also kept leaking, till i found out i was driving in that seal too deep.

My point was, despite cleaning and properly checking, one tiny leak drove me insane and made me replace one seal 3 times before finding the actual cause, take your time to check and be absolutely certain those seals are indeed bone dry.

Another area of leaks on the rear of the transmission is that cover plate, the one that holds in the springs on the top left side of the transmission. There is no gasket or o-ring there, just some good quality sealant/RTV/Silikon etc.





I guess the back up light switch could also be causing a leak? i do not recall if there is a crush washer there, maybe check for tightness?

[paultv]

I was leaning towards that cover plate...everything else forward is so dry...obviously it only leaks when running, so it's not easy to detect.

Thanks for your pointers..I too had an issue with the selector seal..but its clean and dry now after replacing it twice.

It's a bugger really as I had the box on the floor a few months ago!

Great help, I'll keep checking...did 100km yesterday after a clean down, so ill get under the beast this morning and have another look.

Paul

[HJ1981]

I was leaning towards that cover plate...everything else forward is so dry...obviously it only leaks when running, so it's not easy to detect.

Thanks for your pointers..I too had an issue with the selector seal..but its clean and dry now after replacing it twice.

It's a bugger really as I had the box on the floor a few months ago!

Great help, I'll keep checking...did 100km yesterday after a clean down, so ill get under the beast this morning and have another look.

Paul

Most likely it would be that cover plate, again if you are certain everything else is indeed dry. I know the feeling of getting leaks, and replacing seals since the box was removed for a clutch, then doing everything again in a tight work space later.

But could the reverse light switch also cause a leak? check there as well.

[paultv]

Reverse switch area is dry too, I nipped up the two bolts that hold the cover plate in place and cleaned it all with brake cleaner to get rid of any oil then added some high temp. RTV around the joint which should last long enough to prove this is the leak point or not.

I'm driving to italy in a couple of weeks...that should test it!!

Paul

[paultv]

I just wanted to give a shout to HJ1981 for flagging the detent cover as a possible oil leak culprit on my Getrag.

After tightening it up and sealing with RTV as a test to see if it was the problem area - I drove 2 hours of countryside and 60km on the autobahn at around 130kph.

Been under for a snoop today - totally dry! RESULT!!!

thanks mate,

Paul

[paultv]

and..... after my recent 1000 mile trip its still dry!

Brilliant!





Paul

[HJ1981]

I just wanted to give a shout to HJ1981 for flagging the detent cover as a possible oil leak culprit on my Getrag.

After tightening it up and sealing with RTV as a test to see if it was the problem area - I drove 2 hours of countryside and 60km on the autobahn at around 130kph.

Been under for a snoop today - totally dry! RESULT!!!

thanks mate,

Paul

Glad it was something minor, i do not recall the access/space reaching that cover with the transmission installed, i sealed my transmission (front, back and top) when replacing the clutch and the transmission was already out. Was access a hasel? especially when applying sealant?

[paultv]

Yes and no!

After your comments I decided to make a test - first without lowering the box I managed to tighten the two bolts - really difficult as the housings for the ball/spring make using a ring spanner impossible - anyhow I manged it in the end and then cleaned the area with brake cleaner and sealed around the cover plate with RTV. By the way, the bolts were NOT tight at all.

This was done to see if it reduced the leak - so now I know where it is - not sure how long the external RTV will last - I guess one day if I drop the box or have to do a clutch change then I'll di it properly with sealant under the plate.

anyhow its certainly a good one to remember, I kept thinking its the selector seal - but no.

thanks again

Paul

[HJ1981]

Yes and no!

After your comments I decided to make a test - first without lowering the box I managed to tighten the two bolts - really difficult as the housings for the ball/spring make using a ring spanner impossible - anyhow I manged it in the end and then cleaned the area with brake cleaner and sealed around the cover plate with RTV. By the way, the bolts were NOT tight at all.

This was done to see if it reduced the leak - so now I know where it is - not sure how long the external RTV will last - I guess one day if I drop the box or have to do a clutch change then I'll di it properly with sealant under the plate.

anyhow its certainly a good one to remember, I kept thinking its the selector seal - but no.

thanks again

Paul

The Bentley manual shows 10NM for those bolts "Dent ball and spring lock plate to transmission case - Bolt" incase you were wondering.