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MG Midget and Sprite Technical - 1275 head oil gallery

I have a significant oil leak, front top of engine. It's either the head gasket or it's leaking from the end of the oil gallery. I need to clean the area and investigate more closely. I would rather not disturb the head and head gasket if its not necessary.

The oil gallery is a horizontal drilling from the front corner, intersected by 2 vertical drillings, up from the block (front cam shaft supply) and then on up to the front rocker pedestal. The horizontal is sealed off at the outer end.

The question is how is the drilling sealed? Can the seal be re-made with the head in situ?
The head is an MG Metro big valve head.
GuyW

Minispares parts list shows an oil plug, tapered brass/bronze, 2K1345.

https://www.minispares.com/catalogues/catalogue/cat001/chapter/chap0102/page/27/

Photo here may also be useful:

https://www.morrisminorforum.com/forum/morris-minor-forum.2/oil-to-the-valve-train.56263/

Not something I've ever had trouble with. I have had small oil leaks from that area of the head gasket.
AdrianR

Not sure of any difference in 1275 heads but is it this drilling ?
If so it’s a brass plug - interference fit.
If it’s protruding you could try tapping it in a bit and slightly dress around the edges to spread it.

In the past I have replaced one on a b’s block insitu.
Drilled in a bit and filled hole with grease and slowly drilled by hand, withdrawing and changing grease to trap swarf.
Then did same with a hand tap. Bolt threaded in with a tube to form a puller and withdrew the plug.
I then machined another soft brass plug but added the slightest taper (the engine was a gold seal and may have had bad treatment at the factory !) tapped it in for a good seal and worked very well.


richard b

Thanks Richard and Adrian I knew it was sealed but wasn't sure if it would be a plug or tapped for a threaded screw. I suppose I could have looked it up.

Car has been on SORN since before Christmas and although I would normally start it up every 4 or 5 weeks I confess to neglecting it this winter. Age (mine) lazyness, wet weather, family stuff - take your pick of excuses.
When started yesterday 2 things. It fired up on the first turn of the key, second compression stroke! This engine has always been a good starter. And oil pressure went straight up to 85 so I wonder if the pressure relief valve had stuck and the system has found the next weak point and dislodged the brass plug. Maybe!
GuyW

I’ve posted it many times the later 1275 from the factory were always at 80 or even a bit more (cold) from new in the garage a mate worked in - we both had Spridgets at the time so we’re always looking at the new ones coming in.

Shouldn’t think a few extra psi would make any difference to an interference fit like that unless it was poorly fitted.
richard b

Busy fitting new windows today (house, not car) so no chance yet to check it out.
GuyW

This thread was discussed on 24/04/2026

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