Gearbox Still Leaking!

keynsham1

keynsham1

Active Member
My BW35 has been leaking for ages. I have changed the inhibitor switch, the speedo cable seal and the sump gasket (twice) now with an uprated rubber one). It isn't leaking from the oil cooler pipes and doesn't leak when driven. In fact it takes the best part of a week to start leaking after a drive. As I use it very occasionally, this means it is often leaking.

There doesn't seem to be any other place on the gearbox where oil can leak so I am now thinking back to the advice I was given many years ago when i was told that these gearboxes get oil draining back from the torque converter if not regularly used which causes them to leak. As my leak only starts after a week, this seems a very likely cause. What I don't understand is if the oil leaks back into the gearbox from the torque converter, how does it then get out?

My NADA has the filler/level sight on the side of the sump and where the oil filler normally goes, I have a breather. But this breather pipe goes right up into the engine bay and then downwards again and as its highest point is way above the top of the torque converter, the oil shouldn't get out of it regardless.

Any ideas??

Picture showing breather before gearbox rebuild!.
1698065932626.jpeg
 
Just had a look and no fluid is leaking from the breather (I didn't believe it could!0 or from what I can see, the oil cooler attachments. The only seal I haven't changed is the one on the operating linkage shaft on the left side. It could be leaking from there and around the sump gasket to the rear of the box. More investigation is needed!!
 
The oil seal in question is ROVER PART NUMBER 601009. Can this seal be replaced easily? (When I say easily, I mean lying upside down in poor lighting conditions on the cold garage floor with gearbox fluid running up your arm, all the wrong tools and not enough coffee!)
 
It's quite difficult to replace that seal in situ but it can be done. The problem is that the shaft has a step on it which roles the lip outwards. Buy more than one seal. It takes a week to leak because the fluid runs back from the converter, artificially raising the fluid level in the box
 
So it isn't the oil seal on the operating arm that is leaking. After a lot of cleaning and watching, there is nothing leaking there but I am still getting oil gathering at the rear offside corner of the sump gasket. On further inspection, and after stuffing a piece of tissue paper next to it, it seems I am getting oil leaking from where my breather pipe is screwed in (Where the dipstick tube is on the UK version). So, I have two issues. Firstly, I cannot see how it can leak from here and pool at the rear of the gearbox unless it is working its way along the top edge of the sump gasket by capillary action? This would explain why it is pooling where it is though as the front of the car is on ramps and so anything leaking will go backwards. Secondly, it is totally impossible to tighten this nut with the gearbox in place as there is absolutely no access! I am thinking possibly about taking the exhaust, change linkage and prop shaft off and dropping the back of the gearbox to get access. On that note, does anyone know what size the fitting is? I know it is bigger than 24mm as I tried getting to it with a crowfoot but no luck!!
 
Dropping the rear of the box is the easiest way to get to it. there may be a rubber plug in the side of the transmission tunnel under the carpet but turning the spanner might still be an issue.
Do check where the nut is leaking as it may be dribbling from the nut or from the protuding pipe joint. From the above picture I'd suspect the band adjusting screw as it is quite wet but it's a long way up the body...

If lowering the tail be careful you don't foul the fan at the front and the throttle linkage etc at the rear of the engine...
 
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Brother, I have been chasing leaking ATF for nigh on 30 years now. I've tried all the obvious and usual things at least twice... Running the motor every few days does seem to help... I read here years ago that there may have been a bad batch of casings that were inadvertently used in our nada cars... Mine was converted from a 'sight glass' to regular dipstick early in it's life... I imagine it's a bit of a hassle to check it?
 
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Well it isn't 27mm. I have a 27mm spanner and it is way too big. My guess is a 1" as it is bigger than 25mm, (I have one of those), and smaller than 27mm. I cannot get to it to measure so I have ordered a 1" spanner for my collection!
 
Then there are differences in the nut. Last week I opened the nut on my gearbox with a 27mm spanner.
Greetings Bernd
 
Now I know that they are different sizes. On my spare gearbox the 27mm spanner fits and when I removed my gearbox I realised that the 27mm spanner is too small and it has to be 33mm.
Greetings
Bernd
 
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