oil leak from bellhousing

[Rob K]

Hi. I've just finished rebuilding my 1500 engine, and refitted, mating back up to a reconditioned gearbox (off Ebay). I have noticed an oil leak  (more of a weep really), with the odd drip coming from the bottom of the bellhousing. The engine has been run and sounds fine, with good oil pressure, but the car has not yet been driven on the road. it is on axle stands. I decided to loosen the bellhousing bolts, and lever a gap between engine and housing, to see inside the housing and check for major leaks. It looked pretty dry, and when I looked up towards the rear crank seal (which was replaced) that looked pretty dry too, although my view was extremely restricted. I also removed the clutch slave cylinder, and starter motor to have a look inside, and again everything looked fairly dry.

I am worried that oil will find its way onto the clutch and cause slip, but I can't for the life of me work out where this oil is coming from, and I really don't want to take out the engine and/or box having only just got the things in! I have two questions: 1 any ideas as to where this leak might be coming from and 2 should I be worried?

Note: The car is a 1974 Mark 4. It was sold to me as a 1300, and so I bought a 1300 gearbox, but when i started stripping the engine, i discovered that the engine was a 1500, so I had to buy a modified flywheel to allow the 1300 gearbox to fit.  

[Velocita Rosso]

Two things
Mainly , have you fitted the gearbox onto bell housing properly?
The five bolts affix but the bottom one should have a copper sealing washer. If not correctly fitted  oil will come out of that one bolt hole
The other is ,there are two bell housings. I think one has a seal ....I cant remeber which way round and what bell housing fits to waht gear box
Other than that the only other thing is ,as youve mentioned the crankcase oil seal

[alan pettit]

early gearboxes have a system on the oil front seal which means you cant park the car facing downhill or the oil will leak out the front of the gearbox

[Rob K]

Thanks for the speedy replies! I didn't fit the bellhousing to the gearbox, so i don't know whether its been fitted properly or not. The car is parked flat, which is a bit of a pity, because turning the car round is the kind if quick fix that I'm looking for!

[sparky_spit]

My 2Ps worth.... When you say oil is coming out of the bellhousing I'm assuming you mean from the small (1/4" ish) hole in the bottom very near the engine end?

All early gearboxes (and I'm not sure where "early" ends and "late" starts/finishes) do not have an oil seal as such on the gearbox input shaft; they rely on a scroll-type seal which works using the rotation of the shaft under normal use to keep oil in by some magical viscosity of oil friction against the inwardly turning screw thread in the scroll type of effect. There is no conventional rubber lipped seal. Therefore, if the oil level is right up to the max in the gearbox when cold, or was filled to the max when cold and the car was up on a jack/ramps and therefore not level, the actual hot level will be quite close to level of the bottom of the scroll seal and will leak out if it needs to. The drip hole in the bottom of the bellhousing is to allow this oil to escape.

As regards contaminating the clutch; a previous owner of a 1500 Spit I once owned had sealed that hole up (presumably as he was selling the car and didn't want any prospective buyer to see any oil drips from the gearbox). After about 6 months I noticed this, poked a screwdriver in there to unblock it, and got covered in what must have been at least 100ml of gear oil. This had been sitting in the bottom of the bell housing, but amazingly had not contaminated the clutch at all, even though the inside of the bell housing and engine backplate were an oily mess.

So, in my opinion, I would not worry for the moment. I'd get the car on the road and monitor the situation. If it drips a bit, then make sure you check the level and top it up every now and again. If it is gets bad, than you might want to think about checking it out further.

If you can 100% be certain that your box is a late one and has got a proper rubber lip type oil seal on the input shaft, then you probably need to worry a bit more. I'd still leave it and see what happens though before ripping it all out.

Lastly, Triumph are supposed to leak oil. It's a design feature.

[Rob K]

Thanks Mike. This is just the reassuring answer I was looking for! I've spent the afternoon separating the gearbox from the engine to try and put my mind at rest, but you've done it for me. I did manage a sneaky peak inside the bellhousing and could see no sign of any oil in there at all... weird. Anyway, I am now going to bolt it all back together and stop worrying! Thanks again. Rob   :)

[greenbonnie]

hi rob i have an oil leak on my 73 spitfire. its comming from the left rear of the head gasket. and runs down the bellhousing. worth a look. im taking my head of in the winter.pete

[Rob K]

Thanks Pete. Good idea. I'll check that. Good luck with your head work in the winter. Nice easy job! Rob

[lancepar]

The smell of engine oil and gearbox oils are different. this will tell which unit the leak is comming from that's all.

8)

[greenbonnie]

hi rob thanks. im looking to put a lead free head on. with new rocker shaft. yes easy job. have done loads of heads. mostly minis. pete

[Rob K]

Hi Pete. Nice to be able to sit on a nice comfy wheel while you work! Rob

[Rob K]

Great idea Lancepar. I'll go and have a sniff! Rob :)