Morris Minor Owners Club

Where could I expect oil to drip from if there was an issue with the scroll seal, would it collect inside the gearbox bell housing, or appear from between the rear of the sump and the rear engine plate ?

It will leak from the jiggle pin hole in the bottom of the gearbox bell housing. A gearbox input shaft scroll leak will also drip from the same hole so it's important to determine whether the oil is coming from gearbox or engine. Usually that is not difficult due to the blacker colour of oil coming from the engine even though of course both engine and gearbox use the same type of oil. If oil is coming from between back plate and sump that would be a back plate gasket I think?

I remember ages ago you were trying to improve the engine breathing. Has that not helped?

Stephen

The theory is that any oil getting past the return scroll is caught by the grooves in the three bolt top cap and rear main bearing cap and then returned to the sump via the holes drilled in the rear main bearing cap.
If you have oil coming down the front of the rear engine plate and the rear of the sump then that indicates you have faulty sump gaskets and the sump gaskets should be replaced firstly before doing anything else.
The jiggle pin hole is there in the main to allow any oil that gets past the gearbox first motion shaft return scroll to drain out of the bell housing. The jiggle pin is there to jiggle about and keep the hole clear of crud. Oil leaking past the first motion shaft return scroll can be caused by parking nose down hill. If the first motion shaft is not turning oil is not returned to the gearbox. For oil leaking past the first motion shaft fitting a gearbox front housing with lip seal is of benefit. Having the lip seal fitted gets rid of any wear to the first motion shaft return scroll.

Thanks to you both for the detailed replies. Stephen, yes I did improve the breathing issue which has greatly helped things, however I still have a leak, although small, I wish to eliminate it completely. A while ago I did remove and replace the sump gaskets so wondered if I could blame another area ! From this response I seems the sump may still be the issue, so will deal with it as soon as I can.

les wrote: ↑Sun Oct 05, 2025 9:44 pm Thanks to you both for the detailed replies. Stephen, yes I did improve the breathing issue which has greatly helped things, however I still have a leak, although small, I wish to eliminate it completely. A while ago I did remove and replace the sump gaskets so wondered if I could blame another area ! From this response I seems the sump may still be the issue, so will deal with it as soon as I can.

That's good that the improved engine breathing did significantly improve things. Good luck with the sump gasket and cork seals. At least you can clean any sludge out of the sump at the same time. It too strove for a drip free engine and although it took ages and failed attempts I have (fingers crossed, touch wood) achieved it for now at least!

Stephen

We had this problem on our Morris. This is what I found when I took the engine out! A piece of old towel that had been jammed in between the sump and backplate.
I had to use a screwdriver and a mallet to remove it as it was so tightly packed.