Morris Minor Owners Club

I've noticed a small oil leak from the gearbox bellhousing - not a huge amount but enough to cause droplets to hang from the dangling split pin and drip on to the floor.

I'm guessing it's the fault rear crank seal on the ex-Marina 1275cc engine fitted, and I understand there are kits available providing a better seal than the old cork ones. The engine has done around 50,000 miles since being rebuilt in 1990.

However, the question is, how urgently do I need to replace the seal? Is it an engine-out job or could it be done in situ? And is it an easy job or something best left to an expert?

Also having a little weep is the tailshaft seal on the 1275 Sprite gearbox. Again, is replacing it an easy or another job for a pro?

Thanks all!

There is no lip seal on the rear of a Marina block/crankshaft only a return scroll. To change to the lip seal type you will have to either take out the engine or gearbox. You have to remove the flywheel to fit the adapter/seal holder, oil seal and the thin spacer between the flywheel and crankshaft. If the oil leak from the jiggle pin hole is as little as you describe I would leave well alone.
I did fit one of the lip seal kits to my engine but removed it because the hardness of thin spacer was not up to my requirements.
If you do decide to rectify the oil leak I would suggest that you replace the main bearings as part of the cure as any wear allows the crankshaft to go off centre/oscillate and increase the probability of leak past the scroll.
The oil leak from the rear of the Sprite gearbox is reasonably easy to do just take care when removing the old seal and fitting the new seal.

Check that the engine crankcase breathing system is correctly plumbed in. The 1275 works on a negative crankcase system with the pressure being drawn out through the carb. Any excess pressure will cause the engine to leak through the rear main bearing. If the gearbox is removed check for sideways movement on the first motion shaft.
Meanwhile avoid parking on newly laid block paved driveways

As above -also any wear on the rear main allows extra oil to flood over the return scroll - and it can't cope. The real answerr is to improve the crankcase breathing - so it creates a negative (or at least non-positive) pressure inside the crankcase. Any positive pressure easily forces oil past the scroll. Gearbox tail - the felt seal is easy enough - but the real problem is likely some wear on the tailshaft bronze bush - which is a bigger job to change, and then it needs to be reamed to size....... A few drops of oil...I doubt there are many completely 'oil tight' Minors around..... As long as you maintain the oil level in the gearbox - don't worry about it too much!

Just had this seal fitted to my midget 1275 engine.Car went to Tomroy as the engine had to come out for machining to fit it correctly.

Tysonn
Would be interested to know what Tomroy did as the rear seal conversion kit normally does not need any engineering/machining work.
The seal lip sits on the flange/register that supports the flywheel and to allow that a thin spacer is fitted between the flywheel and crankshaft. What fitting the spacer does do is distance the flywheel from the flywheel register on the crankshaft flange. Under normal use it is all o.k. but it can lead to problems as I found out and it is no good relying on the two flywheel locating dowels to hold it all together.
Phil

Hi Phil I'll give him a ring and ask.When it was here in Scarborough he came over one night with his engineer mate to measure it up(he did mention something about because it was a midget 1275 it wasnt exactly the same as another 1275 but I never listen).Car ended up going to his works for a myriad of other problems and it was done whilst it was there.
Mick

The surface of the tail register is often 'not smooth' and this may have been why 'machining' was required. Overall most reports of this rear seal conversion are poor - and there is no need for it if the crankcase ventilation is correct - and the engine not worn of course.

Tysonn
My Marina block is fitted with a MG 1275cc crankshaft which is much better than the 1275cc Marina crankshaft. I thought I was doing good by fitting a rear seal conversion. How wrong I was. The finish on the outside of the register does vary but a quick clean up with a bit of fine wet/dry will do the job. Make sure that all surfaces are well cleaned to remove any wet/dry/grinding material before fitting the crank.
With the seal kit now removed and only the breather on the rocker cover and the timing cover it does not leak oil from either the scroll or rear sump seal. I have to say though that my bores/rings are good and there is negligible blow past.
Look forward to hearing what Tomroy has to say.
Phil

Phil spoke to Chris.He says he machines the face of the back bearing cap and you're welcome to ring him for a chat about it if you wish.I don't mind servicing but thats as far as my interest in the oily stuff goes,It bores me rigid.Give me bodywork anytime.Suffice to say the engine has been (supposedly but thats another story)rebuilt before I bought the car.It leaked like a stuck pig from that area before Chris got it and now doesnt.
Mick

Tysonn
Many thanks for taking the time to find out what work Tomroy did regarding the crankshaft seal.
Yes by machining the rear bearing cap and the spacer supplied with the kit you should be able to get rid of the dreaded spacer/shim between the flywheel and crankshaft.
Again thanks.
Phil

They must have machined off the labyrinth on the main cap......no going back now...

Well I could have just left it dripping I suppose.

If the engine is good condition and the crankcase ventilation connected correctly........they DO NOT drip....

My understanding of what has been done is that the scroll has not been removed. You do not have to remove the scroll to fit the oil seal conversion without the packing shim which fits between the flywheel and crankshaft. All you have to do is machine slightly more off the back end of the main bearing cap and the spacer (part of the conversion kit) than the thickness of the packing shim (max 3mm). Carrying out the machining allows the lip seal to fit closer to the block so doing away with the packing shim. So all is not lost and the lip seal can be removed and the rear of the engine returned to factory spec.
Having been down the road of fitting and rejecting the lip seal I have a good understanding of what is in the conversion kit and how it could be improved as demonstrated by Tomroy.
The packing shim is supplied so as to allow the home mechanic to fit the conversion kit without having to resort to a machine shop.

If that's all that is to be removed - a good sharp file would do the job in a few minutes!

A file is no good as the seal has to fit square to the crank and it would be very difficult to get a good square file cut with the engine still in place as the kit in original form can be fitted with just the gearbox and flywheel assembly removed
I have attached a picture of the kit for a 1275cc engine.
The alloy half moon spacer (above the seal) is the one to have the machining on it as well as the rear main cap. The multi hole packing shim fits between the flywheel and crankshaft. [frame][/frame]

Surely all that is needed is to get 'clearance' for the seal holder to be fitted such that the seal can be held squarely on the rotating crank tail flange? What was your problem with the kit, Phil? Reports I have read are that the seal doesn't last long - mainly because the surface of the tail flange is not good enough, and partly because of crank movement. Unfortunately it's not like a Mini where the seal can be reasonably easily renewed....

The packing shim is required to allow clearance for the seal holder to be fitted without modification.
Removing metal from the back of the rear main and the spacer to which the seal holder is bolted through to the block allows the seal holder to fit closer to the block and should remove the need for the spacer. I am afraid it is all of a compromise to get it to work well and a bit of 'Suck It & See' attitude is required.
My problem was that the original packing shim supplied with the conversion kit was not hard enough. The packing shim squashed and ultimately allowed the flywheel to come slack (everything was torqued up correctly, with the lock washer fitted and ARP bolts used). Fortunately I realised what had happened and stopped the engine before major damage occurred. The crankshaft flywheel mounting flange was very slightly damaged as well as the flywheel mounting face. I did after much searching (nearly 6 months and £400 lighter) manage to source a very good S/H crankshaft and had Oselli do the upgrades on it. The damaged crankshaft kept me away from the 2001 Brighton Speed Trials (and I had paid my entry fee ) and several speed hill climbs. The damaged crankshaft and flywheel are salvageable and will be reworked if and when required. I now have a Oselli fully reworked Midget 1275cc crankshaft on the shelf as a spare. The engine now runs with the standard oil return system and it does not leak from the rear main or sump seal.
To sum up: In my case with heavy standing starts and sticky slicks I would not recommend having a conversion kit with a packing shim fitted between the flywheel and crank. For normal use I would say it would be okay.
I managed to obtain a new packing shim to go with the conversion kit and it did seem to be of harder material though I did not do a Brill hardness test to compare harness. The Tomroy way of doing the rear seal conversion may be the solution!!!
Tysonn
Any chance of PM ing me Tomroys 'e' mail address as I would like to follow through on this one.
Phil

Thanks Phil - my point is that there is NO NEED for this rear seal conversion - folks should fix the problem, not waste money trying to dam up the symptoms.