MG Car Repair: Oil Leak, cylinder head gasket, engine oil pressure

Question
QUESTION: First THANK You for all the answers you have given everyone !! My experience , so far, and my question on a 79 Midget. I had clutch failure and had to pull the engine and transmission. Replaced the top Transmission gasket and oil pan gasket at that time as I knew I had oil leaks and these areas showed probable issues. Have reassembled and car runs great.  However still have a leak and now with cleaning visibility is better for leakage. I THINK that there is oil coming from the rear of the engine at the cylinder head gasket. There is no blowby of gases just a oil leak. Is that even possible ? I think that maybe the reason for the clutch failure as the oil leaked down into the clutch assembly and caused problems. The leak only occurs when the engine has been run and then parked. It drips and then stops which further leads me to believe it is the cylinder gasket. Would other seals leak regardless of running or being parked as fluid levels would be at the bottom end of the sealing fixture ?  Any thoughts or suggestions ?  It appears that , according to the manual,  cylinder gasket replacement is pretty straight forward. Any words of wisdom if this is the course of action taken ?  Thanks, again

ANSWER: Hi Mark,
I would suspect the valve cover gasket first as that would closer match your leak. No external oil leak can gain access to the clutch. The 1500 Spitfire engine (used in the late Midgets) had a single internal oil galley that feeds the rocker shaft but that would most likely only leak when you have engine oil pressure not afterwards.
Howard

---------- FOLLOW-UP ----------

QUESTION: Morning and Thanks! I did check the value cover gasket and its dry. ( replaced and sealed a couple of years ago ). I put diapers on areas that I thought would have a possible leak, including the one I mentioned. They were all dry . So obviously I was wrong. Further investigation , lying under the car , I find what I feel pretty sure is the issue. When I pulled the drive components I remember making a comment to my assistant about the oil on top of the transmission cover as the unit came out.  Seems that the top of the cover acted as a tray and held onto the leaked oil and when the car moved , in whatever direction ,the oil gave the impression that it was coming from somewhere it wasn't. Sloped over the side ?  I replaced the top gasket when I did the other work thinking that was the issue- again , I think I was wrong. On top of the transmission cover was a very small breather plug. This I now think may be the issue as thats the only way oil could get on top of the unit ( ? ). The plug was at a angle and must have had exposure to some kind of force over the past. I did briefly check it and it seemed solid so I left well enough alone , especially when I examined the underside of the cover and a provision had been designed into the part to keep the thrown oil directly off the breather plug. If the leak is there it would support the idea that the car only leaks when driven and right afterward- i.e. not sitting. As the transmission gears spin the oil in driving and to the leak. I know there is another plug directly behind and below the cover and I do remember it had the usual accumulation of dirt etc. Not a obvious leak.  Does this sound more feasible ? As for the repair ---- The catalogs I have seen do not have the breather plug. Infact the top cover for the Tranny is no longer a stocked part in same. Does the Transmission need to be vented ?  What if I poped the breather off and apply a appropriate sealer and reapplied the plug. Plug probably divide in two and fall into the tranny in any case ? It seems crazy to have to pull the engine etc. again to try and fix a 50. cent part so I am looking at options. If I manage to use monkey fingers will that top cover even come off and have the room to exit the cavity in the car for repair ? So , again questions on my behalf.  

Answer
It is possible that that breather vent is in line with a gear and is receiving a stream of oil off of a gear. I don't remember looking close at a breather vent to see if it is open enough to leak splashed oil or not. I do know that you can't seal up a gearbox because of the pressure built up when heated up from driving. Oil would be forced out the seals at the front and back.

If it were mine and was a problem rather than removing the engine and trans to gain access to it I would raise the tunnel carpet and cut a hole over that area and make a short metal draft tube in place of the vent (as I remember it was a piece of plastic) Then just make a plate to cover the hole in the tunnel and screw it in place.

Howard