Welcome to our Site for MG, Triumph and Austin-Healey Car Information.


MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Access to front oil galley plugs

Hello All,

A couple of years back I did a complete engine rebuild
of my 69GT. At that time, I had the oil galleys tapped and used the NPT plugs.

Well no sooner than I put it all together, it developed an oil leak up front. I have lived with it until now.

Recently I had the car in the shop for several other things and had them look at the oil leak as well. They say it appears to be leaking from one of the oil galley plugs.

It's been so long since the rebuild I've forgotten whats involved in gaining access to these. Can anyone provide a synopsis? And once there, any recommendations for sealing them?


Bill Schoolfield

Bill. The plugs are located in the area of the block which is behind the front plate. So, the front plate would have to be removed if you were to obtain access to the oil galley plugs. If you used a tapered pipe tap, and the correct tapered plug to go with it, the system seals by tightening into the tapered bore. If the plugs are properly tightened, they should not leak unless they loosen in their bores. Sealant is not commonly used, but teflon tape or liquid teflon is frequently used as a lubricant to allow the plugs to be tightened more easily.

Other leak points, in that area, are the front plate, which needs to be properly tightened and gasketed against the front of the engine block and the timing chain cover which can leak at both the front seal and around the outside edges if the bolts holding it in place are not tight.

Les Bengtson


Thanks for the quick reply. I was pretty sure that plate had to come off :( The mechanic mentioned that the leaking plug was partially exposed (covered by the plate) and suggested that the plate could be machined a bit to gain access. The shop owner put an end to that idea ;) and I have to agree.

Can I do this while leaving the engine in place? I know, I'll need the gasket. Should I replace all the seals as well?

Bill Schoolfield

Bill. The front plate is part of the system holding the engine to the chassis. Whether it would be possible to unbolt the motor mounts, jack up the engine, remove the radiator, remove the brackets for the motor mounts (from their connections to the front plate), remove the fan, remove the harmonic balancer, remove the timing chain cover, remove the timing chain tensioner, remove the camshaft sprocket, remove the crankshaft sprocket and remove the timing chain, while working almost upside down, leaning over the front of the car, I do not know.

If I were doing this job, I would remove the engine and set it up on top a a bench, allowing me to get at the various parts easily. I would order a new front plate gasket, a new timing chain cover gasket and a new crankshaft pulley/harmonic balancer seal for the timing chain cover. Hard to say, until you have the front plate off, whether the cork seal between the block, the sump and the engine front plate, would need replacing.

To me, rate of loss is going to be a factor here. If you are in an area of Texas which is, like Arizona, hotter than the hinges of Hell in summer (with our driving season being winter), now might be a good time to do the work. If this is your driving season, and the oil loss is not excessive, I might be tempted to drive the car for a while. But, you know your needs better than I do.

Les Bengtson

Les, Gesh I feel sick! This sounds like a ton of work. This was my first engine rebuild and it seems it all went well but this! I've got a bevy of cars to choose from so I can afford to pull the engine. But its just about impossible to work on it in this heat (103 today).

I have the radiator out (being upgraded) right now in prep for a A/C install. That's what got me thinking about fixing the leak now.

Now I understand why the shop wanted so much money to do this.

Bill Schoolfield

When I assembled my engine I (stupidly) left out one of the front gallery plugs. After turning the engine over on the starter with the plugs out and not getting any oil pressure I found all my oil over the floor!

The missing plug was at the top left when looking at the engine from the front and it is only partially covered by the front plate. I was able to bung some old rag into the hole then using a Dremel carefully grind away the plate enough that I could hammer in a new plug. The rag stopped any dust getting into the block and was pulled out before fitting the plug of course.

Has been fine ever since. The mechanics suggestion might not be a bad one. In my case it meant grinding perhaps a quarter of an inch from the edge of the plate and that is not going to cause any problems as far as I can see.

Simon Jansen


Recently on a french MG Forum, we supported one colleague
that achivied this operation engine in situ. His oil leak came from a badly gasketed front plate. As Les says, You just need to take engine load to release the front engine plate to access the faulty plugg/gasket.

This thread was discussed between 13/07/2009 and 14/07/2009

MG MGB Technical index

This thread is from the archives. Join the live MG MGB Technical BBS now