Leaking from gearbox?

[muggwump]

I bought a Minor convertible last year. It's a fantastic car but unfortunatly it had a bad propshaft vibration and an oil leak when I bought it. I have had the prop sorted and now need to address the oil leak. I originally thought that the leak was coming from the engine but I've done 100's of miles with no noticable drop in engine oil level. The oild seems to be all over the bottom of the gearbox and I wondered if the leak could be from there as it has had a badly vibrating prop attached would this have damaged the seals? I have noticed the gearbox getting steadily noisier Also, how dificult is it to check/change the oil in the gearbox and what should I use.

[Stig]

If it's getting noisy then top it up! Have you got a manual? If not, then the filler is on the left - you can get to it from inside the car by prising out the rubber bung from the floor (well, gearbox cover really) and using a socket set to undo it. I'd suggest a suitable funnel to fill it with engine oil (20W/50 etc.), up to the filler hole.

The prop may well have damaged the rear seal which can apparently be replaced in situ - have a search of old posts as I'm sure it was discussed fairly recently. Best to clean off the old oil to work out where the leak is first though.

[MColes]

Yep it was discussed recently. I know this because...I needed to change mine and I started the thread

Here's the link:

http://mmoc.org.uk/index.php?name=PNphp ... ic&t=22865

[grumpygrandad]

I bought a Minor convertible last year. It's a fantastic car but unfortunatly it had a bad propshaft vibration and an oil leak when I bought it. I have had the prop sorted and now need to address the oil leak. I originally thought that the leak was coming from the engine but I've done 100's of miles with no noticable drop in engine oil level. The oild seems to be all over the bottom of the gearbox and I wondered if the leak could be from there as it has had a badly vibrating prop attached would this have damaged the seals? I have noticed the gearbox getting steadily noisier Also, how dificult is it to check/change the oil in the gearbox and what should I use.

hello is your gearbox standard morris as i know the engine isnt,, how are you grandad

[bmcecosse]

Clean the underside - then take it for a run, and park it over a clean sheet of cardboard - to see where the oil drips appear.

[muggwump]

Hi Grandad,
No the gearbox is midget I believe, the same as the engine.
I'll check the oil level in the box and the clean off the underside and take it for a spin.

[grumpygrandad]

hello ,graham thinks rear crank seal ,,,,grandad

[bmcecosse]

Which is caused by high internal pressure in the crankcase - so clean the breather pipes and make sure one is connected to the carb side inlet so the engine sucks and consumes it's own fumes!

[muggwump]

Hi Grandad,
Yes I know that Graham thinks it is coming from the rear crank seal but the engine is not losing any oil even over the 700 miles I've done in the car. The gearbox is getting noisier.
I'll investigate the oil level in the gearbox and go from there. I'll also check out the breather pipes again but I remember looking into that at about the time I had the prop sorted.

[muggwump]

Last round of trying to sort out the possibility of excessive pressure and correct breathing set up can be found here (as well as photos of my engine set up). OMG I hope I've not just opened the same can of worms!

http://mmoc.org.uk/index.php?name=PNphp ... sc&start=0

[muggwump]

On re reading one of the comments on that thread I thought I would just ask this. If the oil level in the engine does not drop but oil is leaking from the gearbox, how would I check for this " Check your geabox oil level to make sure there is no exessive wear on the front oil throw."
Not even sure what or where the front oil throw is. If after cleaning the whole underside down I find that the oil is coming out of the slit pin hole in the bell housing then could this be the cause rather than oil exiting the gearbox at the rear?

[muggwump]

Ok, looks like I've established that the leaking oil is deffinatly from the gearbox and not the engine as the gearbox needed quite a lot of oil in it to bring up to the filler hole. So it looks as though I didn't have an issue with pressure in the engine after all so I've put my breather arrangement back to what it was when I got the car and I must say it is running much smoother now. Also the gearbox is much quieter now that I have oil in it
So I just need to identify where abouts the oil is leaking out of the gearbox and the rectify.
Could the oil be leaking out of the front of the gearbox internals and into the bellhousing?

[bmcecosse]

Yes - it's a scroll type seal - and if there is /has been excessive play in the input shaft bearing, or if the input shaft is not being supported at it's outboard end in the little bush in the crankshaft tail, then the scroll may be damaged and have excessive clearance. Oil in the gearbox does tend to make it quieter!

[muggwump]

Thanks bmcecosse, is it a big job to put right? By the way, my clutch seems absolutly fine. I would have thought that it may have been effected by the oil, is that not the case?

[bmcecosse]

Not so bad when it's from the box - should run away without getting on the clutch. Yes - quite a job to fix it, depending on what is wrong. Would need engine out at least - maybe box too. Wait and see how bad the leak is!