Not so nice Easter drive.

Had not driven my car for about a week. Decided to take her out for a spin. Everything was running fine until I got back near home. At a stop sign, I noticed the car was smoking pretty bad. Got to a red light and a guy pulled up next to me and said I was really leaking oil. Couple hundred yards I was home. Left lower rear side of engine and the whole exhaust system was dripping oil. Oil pressure never went below 50 psi. Dipstick shows oil just at the tip.

I AM BUMMED! Where do I start looking to find the leak? Right side and oil cooler and lines look good. :-(

Mike

Have you checked at the back where the flexible oil cooler line goes into the block? Wiggle it around and see if any oil appears.....

Tappet covers if it's not the valve cover..

Left side.. Look at the tappet covers first. Did the oil pressure bypass nut back off?

I think the tappet cover is secure. Oil bypass nut? I'll have to check the book for the location of that one. Thanks.

I think he means pressure relief valve.

Back left side of the engine, a little more than halfway down. Dont remember the nut size but its a fairly large one, you can miss it.

The cover might be secure, but the gasket/seal might be defective. But it might be something else.

marcamus8 Wrote:

Wish I could help you, and I will be interested to see the posts. I'm in the same boat, but can't get shit on my topic.
:http://www.mgexperience.net/phorum/read.php?1,756611

I would replace the valve cover gasket to start with, it is probably about time to check valve lash again anyway...atleast that is what I did on mine. You can see if oil was leaking past a gasket, it will have a clear wet, dark spot on the gasket where it was passing through. Tappet cover would be the 2nd thing I would check since it requires removing the manifolds, and while you're back there, the relief plug I believe is back there. Also, if you have a moss catelog, look on page 6. There is parts 30 and 31, the fuel pump blanking plate, which could leak oil right onto the exhaust. #20 and 22 could be suspect too. If you don't have the catelog, it is on the diagram with external engine parts. Part number for the fuel plate is 460-095, if you type that into the search on Moss, it should bring up this diagram

Hurst

Looking at the pressure relief valve, found it ok, it is tight. But, just under it is a hole in the block where a plug is supposed to be. I put the car on jack stands and found a LOT of oil on the Peco header and pipes. I started the engine, and put a light on that relief valve area. When I rev'd it a little, oil spewed out of this hole. So, it appears this plug blew out.

My engine builder is going to get an earful on this one. Let me see, 3 core plugs, engine has oil leaks front and rear and now a blown block plug....

Mike

Hurst, thanks for your thoughtful reply. The plug that blew out is not shown on that page in Moss. In the Haynes repair manual on page 33 it is #5 in the illustration just below the relief valve hole.

Mike

Is it this plug? See photo.

Clifton

That's the one!

VB has the plug, but I cannot see a way to get it in without removing my headers, and even then there may not be enough room. I assume the plug just is tapped in with a taper fit.? Anyone ever done this before?

Mike

I did one several years ago, as I recall it's round, no taper and has a interference fit.

Clifton

Interference fit? Does that mean the plug is just a little larger diameter than the hole? That would make it harder to get started into the hole. I have devised a way, don't laugh, using a long crow bar in which I could push the plug in using the bar as a lever. Do I sound desperate??

Mike

It is a little bigger than the hole. I drove them in with a soft drift. If the hole was enlarged when the OE plug was removed a new plug may not fit tightly enough. In that case you need a slightly bigger plug. It could be tapped and fit a threaded plug but it's difficult/impossible to keep the chips out of the engine, lots of grease on the tap helps.

Clifton

What is the plug for?

The manual calls it the pressure relief vent plug. Mine got vented big time!

Mike

Paul, Barney Gaylord explains the reasons and has some drawings showing the MGB block drilling's and plugs. It's five pages with some labeled photos, interesting reading.
http://mgaguru.com/mgtech/engine/of101a.htm
As I understand his explanation it keeps the area behind the oil pressure relief valve from hydraulic locking so the relief valve can function as intended.

Clifton