MG-Cars.info

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

Parts

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 - Bernie's Special Oil Leak

I've always had a good coating of oil on the bottom of my 66 B with 5 main bearing engine. It was covered from the engine back. I didn't really worry about it because it's an MG and a oil leaking is sorta the norm. This past summer my clutch started slipping so now I've taken the engine and transmission out to replace the clutch, clean up the engine compartment and tackle the oil leak. To my surprise, the rear main seal, the tranny front seal, timing chain cover, valve cover and tappet covers were all intact and not leaking oil. I cleaned the engine and on the next day there was oil leaking out of a hole in the block. This hole is located below the rear tappet cover about 3 inches above the oil pan flange at the top of a bump-out in the block. The hole appears to be filled with lead and it is leaking oil.

I can't find any information on this hole but I'm assuming this is how they drill out internal oil passageways in the engine and then fill the access hole with lead. Does anyone have clue on how to repair this?
bhall1

Unless you're willing to drill out and re-plug the passage, your best bet would be to epoxy over it. Not elegant, but functional. RAY
rjm RAY

yeah
I'd drill it out , tap a thread and screw a bung in it
cheers willy
William Revit

It would be hard to tap threads due to the uneven surface. I was thinking of pounding it with some sort of punch in with the hope of expanding it. But I wonder if it might go in too far and block something or having it fall in. I just don't know what's behind it.

I've attached a photo.

bhall1

The drilling in the block will guide the tap, I'm sure it would thread ok
William Revit

Hmm this one is going to be a challenge....
I would second Ray's approach initially. You can always revert to Plan B if it isn't successful which, to be honest, is quite likely. I recently tried to use "chemical metal" to fill a hole in an alloy head without success. In that case it was in a low pressure area e.g not in a pressurised gallery. You'll need to make sure the surface is very clean before applying your chosen product.
I wouldn't risk tampering with the plug for the very reason you highlight i.e. pushing it in further and blocking something. Plan B should be to remove the plug, check what's behind it and how far you can safely insert a tap and plug.

Best of....
MGmike
M McAndrew

As you say that is going to be a drilling across the block i.e. joining a couple of other passages together. Probably an oil passage - that horizontal rib immediately to the left of it is said to be one, so even drilling out with a view to replacing needs care, or full dismantling and flushing the passages, if you are not to leave debris behind.

I'd be inclined to drill a little way into the plug exactly where it is leaking from, hopefully not all the way through, then fill the resulting depression with some kind of filler.
Paul Hunt

After much advise, I wound up taking the engine to an engine rebuilder with MG experience. He removed the old non-standard lead plug and replaced it with a proper new plug. Thanks for all your suggestions.

As a side, he said that my engine is running too rich due to the smell of gas in the oil and very black, dampish soot in the exhaust ports. Time for hotter plugs and/or leaner jet adjustment/needles.
bhall1

Out of interest, what is the proper plug?
Paul Hunt

I understand that the factory installed a brass plug. The rebuilder I went to put in a steel plug with sealer.
bhall1

This thread was discussed between 18/10/2014 and 03/11/2014

MG MGB Technical index

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