Oil leak at rear of gearbox

[dasadrew]

Hi Guys,

I'm trying to trace the source of an annoying oil leak which on my MOD seems to be at the rear of the gearbox. It's very minimal, but the oil accumulates - especially in that cross member - and gets on to the exhaust during a run and on the driveway when stationary.

At the moment, it looks like it could be the overdrive sump pan and/or the speedo drive - any thoughts on known sources of leaks in that area? There is also a very slight moistness on that drain hole (?) in the bottom of the bell housing but that oil doesn't travel back along the box so it doesn't seem to be the source.

Cheers

Drew

[Markvh]

Same for me, see my post

https://socforum.com/forum/forum/stag-owners-club/soc-forum/764611-gearbox-oil-leak-from-bolt-in-adaptor-plate

I haven't done anything about it yet. I'm going to try and fit a replacement bolt with copper crush washer with the oil still in the gearbox. Hopefully it will stop the leak or slow it down enough until I have the time to look at it properly.

[brian0443]

I had a very obvious leak from the speedo drive some years ago. A cheap fix with a seal and 'o' ring.

[dasadrew]

Thanks guys, that other thread has given me some good pointers. In actual fact, one of the O/D sump bolts had a teardrop of oil on it and so did one of the O/D adapter bolts. I was actually able to pinch up two of the adpater bolts which seemed to have relaxed a bit since the restoration. Overnight no new oil has appeared, but I've now ordered up some copper washers and am getting myself mentally prepared to drain and refill gearbox oil!

Brian, which bits do you mean with seal and 'o' ring?

Drew

[sujitroy]

I think he is referring to the bit in the box where the right angle speedo cable drive thingy screws into. I just did this.
Sujit.

[brian0443]

Hi Drew
Both on the speedo pinion: NKC105A Oilseal speedo Pinion. NKC 106 'O' ring/seal in Rimmers.

https://rimmerbros.com/Item--i-GRID005241

I had the leak for quite a while so it was well established and evident when I dealt with it. Might even have been because I had to replace a speedo cable!
Brian

[dasadrew]

I think he is referring to the bit in the box where the right angle speedo cable drive thingy screws into. I just did this.
Sujit.

Yes, I know; it was the actual seals I wasn't sure about as some vehicles which use that angled drive list a copper washer, others a fibre seal, others a sort of 'O' ring.

[dasadrew]

Hi Drew
Both on the speedo pinion: NKC105A Oilseal speedo Pinion. NKC 106 'O' ring/seal in Rimmers.

https://rimmerbros.com/Item--i-GRID005241

I had the leak for quite a while so it was well established and evident when I dealt with it. Might even have been because I had to replace a speedo cable!
Brian

Thanks Brian!

[Marco Polo]

Thanks guys, that other thread has given me some good pointers. In actual fact, one of the O/D sump bolts had a teardrop of oil on it and so did one of the O/D adapter bolts. I was actually able to pinch up two of the adpater bolts which seemed to have relaxed a bit since the restoration. Overnight no new oil has appeared, but I've now ordered up some copper washers and am getting myself mentally prepared to drain and refill gearbox oil!

Brian, which bits do you mean with seal and 'o' ring?

Drew

Hi Drew,
Filling the gearbox isn't such a chore if you do it like this;
You need a funnel, about 1.5 meters of garden hose and a 90 degree copper pipe joiner, assemble them together, open the bonnet and run the hose with the 90 degree bit of copper pipe down the side of the gearbox, get under the car, remove the filler plug, the copper pipe is a tight squeeze into the filler hole. Then fill the gearbox from the funnel in the engine bay.
hope that helps, regards,
Raoul

[barkerwilliams]

Filling the gearbox / diff.

I just use a 200ml (large) syringe (£5 ebay) with three or four inches of flexible tube (1/4"'ish) pushed on the end.
Clean, drip free and you can measure the volume of oil you need.

Alan

[garyf]

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F122535901475

[dasadrew]

Thanks again for the tips - and thanks Gary for that very cheap way of giving yourself an enema!

When I did the initial refill I used the funnel and hose - but there were no carpets etc. in at that time and I'm already having nightmares of the tube popping off the end of a full funnel!

And now, just 'cos I'm being lazy at the moment, can someone tell me what the gearbox fill plug wrench is? hex? square? size?

Cheers

Drew

[Sarge66]

I use a 7/16 AF open ended spanner spanner and a hand pump I bought from my local car pares store. Pumps about a litre at a time. No mesh and simple to use on both the gearbox and differential. ope this is helpful. By the way I really enjoyed your post of the restoration you completed. Excellent work by you and taught me a lot.

Noel

[dasadrew]

I suddenly remembered that I took some photos of the gearbox when it was removed and I see that I have an internal hex bolt. Can't remember whether I installed that as a mod, as the 7/16" spanner refreshed my memory and was probably original fit.

Also found a photo which confirms that those bolt holes in the overdrive extension/adapter do indeed go into the gearbox and are not blind holes.

DSC00999 - plug extract.jpg

DSC00955 (Custom).JPG

[dasadrew]

Just removed the first couple of bolts from the overdrive adapter plate but the threads were completely oil free. I'd fitted them with thread sealant and that seemed to have done the job.

Now removed the overdrive sump and the gasket came away from the overdrive very easily and a film of oil on the mating flange was visible. I'd assembled it with my earlier favourite sealant - Blue Hylomar - but have had a couple of bad experiences on the Stag with it. I'm not sure, but it always seemed to seal well on the other cars but they didn't have alloy engines and gearboxes. I have the feeling that a lot of mating surfaces on the Stag relax with time and I'm continually finding correctly torqued up bolts which have definitely relaxed. It seems that Blue Hylomar is not so reticent when the opportunity to let a monolayer of oil or water through when the torque relaxes and opportunity presents itself, as it stays quite soft.

My favourite sealant now is, of course, STAG Wellseal, so I'm hoping that the overdrive sump will benefit from it.

Waiting on a Rimmers delivery for the speedo drive seals.

Drew