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MG MGA - SAME OLD S**T OIL LEAK

I was just under the car and noticed what looks like oil leaking from the distributer where it mounts to the block. I know there is a gasket but any other things to look for as to my problem. I was planning on checking my timing before I removed it . The car runs great and does not over heat. The distributer does not move.
JEFF BECKER

There is no gasket. The distributor mounts in a long cylindrical slip fit into the base casting, which in turn is a long cylindrical slip fit into the engine block. See here: http://mgaguru.com/mgtech/ignition/ig107.htm

A leak here is very unusual, and implies that there must be positive pressure in the crankcase. That could be from a sealed valve cover, elimination of the draft tube on the front tappet cover, or connecting the tappet cover vent directly to the valve cover vent.

Other possibilities: Check for an oil leak at the oil filter mount, or a leaky valve cover gasket.
Barney Gaylord

Oddly enough, the Moss catalog does not show a gasket in this location (at least, that I can find).
Del Rawlins

I agree with Barney that a properly ventilated engine does not have positive crankcase pressure, and therefore you should not have an oil leak from the Distributor housing.
However, why do Lucas Distributors on the MGA not have an O ring seal?
The lucas Distributors on Triumph cars have an O ring fitted to a groove in the Distributor where it fits into the engine block.

See item 81 in the Moss Motors catalogue, also the groove is visible:

http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=32907

I have half a dozen Lucas Distributors on a shelf in my garage. They all have O rings.

Mick
Mick Anderson

Here are pictures of Lucas distributors that do not have o-rings:
http://mgaguru.com/mgtech/ignition/pics/dist.jpg
http://mgaguru.com/mgtech/ignition/pics/dizzy10.jpg
Barney Gaylord

On one occasion I did not have the dipstick fully pushed down and oil splattered out of the hole onto the distributor and surrounding area. Could this be the cause of your apparent distributor oil leak?

Steve
Steve Gyles

So why is it that MGA's do not have an "O" ring to fit in the bottom. There is a groove in the DM2. Would it help improve that problem. I do have an vent pipe on the valve cover and my oil filler cover is also vented as I am using a Judson Supercharger. I like the idea about using a oil dye to find the source of the leak in case it is not from the distributer. Tomorrow a hunting I will go and it won't be foxes!!!
JEFF BECKER

Barney once mention that a missing dipstick rubber cover will spray oil all over the engine block. Seeing as the dizzy and dipstick are so close togeather, is it possible that the leak is the DS and not the dizzy? Gordon
Gordon Harrison

Without pressure in the crankcase oil would never flow out of this area. If you find oil is actually coming out past the distributor find the cause don't mess with the symptom.
R J Brown

The dipstick is in the hole tight. This is a 18v engine and does not have the cover as it is not needed.
JEFF BECKER

Jeff

Mine is an 18V also. I transferred my dipstick and cover from my 1500 and recalibrated it. It leaked, as described above, when I did not seat it fully. I have just looked at the MGB parts book and, as you say, the 18V does not have the cover. Why did mine leak then? Are the dipsticks a different diameter?

Steve
Steve Gyles

Instead of an oil dye, you might try heavily dusting the area with talcum powder. This simple method shows up localized leaks quite well.

Steve
Steve Brandt

Today I put dye in the engine and used a black light to see the leaks. The good news is it is not the rear main. I do see an excess amout of oil driping and with the black lite I can see it is coming from the distributer area. There are no signs of oil from the valve cover or the oil line behind the distributer. I can not see any oil leaking above the distributer. The first thing I will try is a o ring to the bottom of the distributer. Is there any oil plugs..ect that I can not see and am missing near the dist. that may be leaking and not coming from the dist?. This was the best $6.00 I spent to see all the leaks. I see some others, but they are very minor and not leaking like this one

The oil dipstick on the 18v has a rubber seal at the top the stick which prevents leaks. The 1500 does not have this seal at the top of the stick.
JEFF BECKER

Jeff. Yes, there is an oil galley plug just below and to the left of the distributor. You can see it if you remove the dizzy and clamp. I have heard about oil leaking from the distributor, but never seen it myself either with, or without an O ring in place. The distributor is not serviced by an oil galley, or other form of pressurized oil. The distributor drive is lubricated by oil running down from rocker arms and draining over the tappets and cam. The distributor drive is angled upwards, from the cam engagement, and has a large head on it which tends to block oil splash. The distributor housing, which fits into the block, hold the distributor drive in place, and receives the distributor, has an inside diameter smaller than the outside diameter of the distributor drive. Were oil to be commonly found there, we would see traces of it collected on top of the distributor drive, on the bottom of the distributor and inside the housing when we remove the distributor for annual points change and cleaning/lubrication and inspection. I never have.

Les
Les Bengtson

I will check for that oil galley plug. I have already had one blow out and used and allen screw to close it up.
JEFF BECKER

Jeff. What you really want to use is a pipe plug which, because of its taper, is self sealing. An allen screw is non-tapered and can work its way either out of, or into, the engine from vibration.

Les
Les Bengtson

Les,
I can see two plugs just under the distributer. they are brass. Can I hammer them to try to spread them out or am I stuck with trying to get a long drill bit and drill them out and then tap the holes and use a pipe plug which looks to be a 1/4 inch. If I have to drill them out, which size drill bit do I need?
JEFF BECKER

My main oil leak was from under the distributer. As Les stated there are two oil galley plugs there.
They are put in place with a hammer and a punch as they are made of brass. The fun part is trying to use a hammer and a punch on them when they are in the car. I used a 3/8 ratchet extension and a socket to hold the punch and very carefully lined up the punch on the brass plug. I used the hammer to hit the end of the extension which held the punch and re- smached the plugs. (The extension is a Craftsman with a lifetime warrantee) I just took the car out for a drive and when I parked it back in the garage and waited for 5 minutes to see if the car spotted the ground from the distributer area. It is DRY. I did spot a few other areas that showed some leakage but the car is ready for me to take it to the car show this week-end and not worry about it dumping a lot of oil. When I get back I will try to fix the other leaks. My problem was fixed because of the answer I received from Les about the two oil galley plugs that I could not see with the distributer in.
JEFF BECKER

Okay, I plead ignorant, and curious. An MGA engine has no oil plugs below the distributor, and no oil galley in that location. What is the function of these parts on the 18V engine?
Barney Gaylord

Barney,
I only work on them!!! Again and again and again!!!!
Talk to someone from BMC who might still be around. Opps that should be BL
JEFF BECKER

This thread was discussed between 13/05/2007 and 21/05/2007

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