1957 Gearbox oil leak

[Pucketsport]

I recently overhauled my 1957 Moggie and whilst still up on jack stands I filled the gearbox with oil to the filler hole as described in the manual. I now see that oil is dripping slowly from the bottom of the bell-housing past the split pin. Any idea what this could be? It is not from the Engine as I can feel the oil on the gearbox side and it only started leaking from here when I filled the gearbox.
Is it possible to fit the 1098 lipped seal type cover on my 57 Gearbox ? As pictured below. What type of seal does my 57 gearbox have in this area ?
Thanks

[philthehill]

The 803cc, 948cc & 1098cc Minor gearbox are not fitted with a lip seal for the first motion shaft.
The first motion shaft /gearbox front cover has a scroll return to screw the oil back into the gearbox.
It is possible that if the car is not level i.e. nose down and the front cover / scroll is worn - the oil can creep past the scroll and into the bell housing when the first motion shaft is stationary.
A lip seal can be fitted to front cover Pt No: 2A3087 which is fitted to the 803cc & 948cc gearboxes.
Both MOSS & ESM only appear to supply a 1098cc lip seal modified front cover though I have a 2A3087 front cover fitted with a lip seal - supplier unknown.
The standard (without lip seal) 1098cc gearbox front cover is Pt No: 22G118 and is not suitable for a 948cc gearbox.
The front cover has to be machined for the seal - so it is no good just buying a seal as it will not fit a standard front cover.
Phil

[Pucketsport]

Thanks Phil. So does that mean if I buy the seal supplied by Moss for cover shown ( 1098) I can machine my cover to accept this seal or do I need a different seal ?

[Pucketsport]

I found this part looks like its from the USA
https://www.spridgetmania.com/part/C-2A ... ris-Minors

[philthehill]

That is the one from Spridegetmania.com.

The front cover 2A3087 can be easily machined to fit the seal.
You will need to mount the front cover in a lathe independent 4 jaw chuck and use a large tail stock centre to centralise the front cover in the chuck.
I have a 2A3087 front cover with seal ready to be machined. When I do the job I will post some photos.
The letters/numbers on the seal is....TTO....G0185....4....VG....23....30....4.
Phil

[oliver90owner]

While PTH is right about doing it in a lathe, it would likely be easier if bolted to a mill table and using a boring head.

[philthehill]

There are two machining operations required when fitting the oil seal:-
1. The front of the scroll tube has to faced off at 22.5mm (gearbox flange face to front of scroll tube).
2. The scroll tube has to be bored out to 30mm or as required to suit the o/d of the seal.
The oil seal is then pressed square into the scroll tube with the outer face level with the front face of the scroll tube.
Whilst the machining can be done on a milling machine - the boring of the scroll tube I believe can be better controlled with an internal boring bar mounted in/on a lathe tool holder/cross slide/compound rest.
Phil

[Pucketsport]

Thanks for the replies. Sounds like I will need to buy our fitter and turner a few coffees in the near future. I'll leave it up to him how he wants to do the job. Phil I cant seem to find that seal on the internet. I'll keep looking. Will the seal that is supplied for the 1098 modified case work on the 948 ? In other words do they have the same diameter first motion shaft ?
Thanks

[philthehill]

I have just tried the 948cc front casing Pt No: 2A3087 fitted with the lip seal over a 1098cc Sprite/Midget first motion shaft Pt No: 22G172 and the fit is excellent in all aspects.
So to answer your question - the dia of the first motion shaft where a lip seal will rub is the same for both 948cc and 1098cc first motion shafts.
It should be noted that the first motion shaft for a 948cc Minor is Pt No: 22A141.
As the seal will fit the 1098cc first motion shaft I would suggest that in all probability the 1098cc seal (Pt No: 10G931) as sold by ESM is suitable for fitting to the 948cc front casing Pt No: 2A3087.
I personally would purchase the ESM seal and use it. You have nothing to loose other than the cost of the seal (£1.75 plus P&P plus VAT) if wrong but I very much doubt it will be wrong to the point of being unable to be used.
I am of the opinion that the ESM seal and 948cc front cover will fit together like a glove.
Looking closely at the ESM seal the letters / numbers on the seal appear to be TC....23....35....7.
Taking the 23 as 23mm as inside diameter.
Taking the 35 as 35mm as outside diameter.
Taking the 7 as 7mm as the depth.
Even though there are slight differences in the size of the two seals - putting those ESM seal measurements to the 948cc front cover the ESM seal will fit with careful machining.
Phil

[Pucketsport]

Thanks very much for going to all the trouble of checking the 1098 Phil, much appreciated. Will order the ESM seal as you suggested.

[Pucketsport]

I chatted with Darren Goff from Minor Magic here in Australia and he made the comment that generally if the gear box scroll seal is leaking it is as a result of a worn bearing on the first motion shaft so ideally I should replace that bearing and possibly all the bearings whilst the box is open. Is there a quick and dirty way of assessing that particular bearing without opening the entire gearbox ?
My take on this is that even if the bearing is at fault and I need to replace that bearing, a lipped seal is a better option as a scroll seal in perfect order probably wont be able to hold back the oil when parked on a steep decline.

[Pucketsport]

So close to the first Engine test and now its gearbox out again !!! ....Its all a learning experience I guess. Not sure if its quicker to take engine and gearbox out together or drop the gearbox. really fiddly getting at the gearbox to engine bolts and the steering rack is very close to the bell housing .....
Note my revised routing of the fuel hose. This is what happens when you work for Toyota PD and then Ford PD for the last 30 years.

[philthehill]

I would say that Darren is probably right about the condition of first motion shaft bearing but personally I would not rush into replacing the bearing - when you have the front cover off the gearbox to machine and fit the lip seal check the condition of the bearing and then take it from there.
There is no easy way to get to the front of the gearbox so do what ever is easiest for you.
The scroll will not hold back the oil if the gearbox oil level is correct and the car is parked nose down on a reasonable slope only the lip seal will do that.
Phil

[Pucketsport]

Thanks Phil

[Pucketsport]

Now I am really confused and need some advice please. I removed the gearbox and found that oil wasn't leaking from the input shaft but there is some weeping around the casing that surrounds the input shaft. So it could be that it is just in need of a new gasket. However, I have also noticed that there is oil on the mating surface between the gearbox and the engine. The strange thing is I dont know how the oil could have got there or where it came from. Its almost as if it has wicked its way between these two surfaces. The engine has never been started since the overhaul, all I have done is spun the engine to confirm oil pressure.
I was thinking of attaching the starter motor without the gearbox attached and spinning the motor to see if any oil comes from the scroll seal. Is this a good idea ?

[Pucketsport]

I have spent thousands of dollars on this engine and is virtually new but I never line bored the bearing housings/ scroll seal housing to ensure the clearance of the scroll seal so this may be a problem. I also unknowingly removed the scroll cover which I have since found out is wire-locked in the factory for a good reason. But I'm not even sure that this is where the oil is coming from.

[philthehill]

The oil can only come from these places.
1. The gearbox.
2. The scroll on the rear of the crankshaft.
3. The oil pump cover.
4. The rear sump seal.

1. You have looked at the gearbox return scroll and determined that the scroll is ok and the gearbox front cover needs a new gasket.

2. It is not the end of the world if the top half of the rear main cap is removed. What is important is that it is centralised when refitted
with new gasket.
See BMC Wksp Manual Section AA34 for details. Check also the radial clearance of the scroll (0.0015" - 0.004") (details in same
section)

3. The oil pump covers on 948cc 'A' Series engines are notorious for leaking between the cover flange and the rear engine plate.
BMC recommended that the cover is soldered to the rear engine plate and latterly soldered the cover to the rear engine plate at the
factory.

4. The rear sump seal cork gaskets need to be fitted as per BMC Wksp Manual section AA34, Fig AA26.
The cork seals need to be soaked in engine oil overnight and then trimmed (if required) to suit. There is no need for sealant if fitted
correctly.

Did you remove and replace any of the oil gallery plugs?

Phil

[Pucketsport]

Yes the workshop that did the rebore removed all the plugs and I replaced them Phil. I will check the items you mentioned above thanks for your advice.

[philthehill]

Thanks for the reply.

Whilst I am not a great lover of sealant - the standard oil gallery plugs would benefit from a smear of Loctite Lock & Seal when being fitted.

I have got the 948cc front gearbox cover Pt No: 2A3087 set up in the lathe but I am reluctant to start machining until my camera is back working - I can then have some photos to accompany the commentary.
I will start a separate thread to cover the machining and seal fitment.

Phil

[Pucketsport]

That video or photos will be most welcome Phil , looking forward to it
Thanks