Engine Oil Blow By

Dear Friends,
I have read this forum many a times, but I have never logged in before, so I am a new member. I have a problem with my 1972 MGB. The motor was rebuilt back in 1994, but was not started until 2 years later. Even though the car was complete, do to different circumstances, the car was never really driven until the last couple of years, and even then it was only driven about 200 miles a year. Now, that I have the time I am driving the car again, but now the engine is blowing oil out of the breather tube that comes from the side of the block.
I am running an aluminum valve cover that is not vented and the vent that is on the side of the block is vented to the atmosphere. This is where the oil is coming from. It will only do it above 4500 RPM and if I let off the throttle and let the engine idle down, it will stop and I can go on. I am not burning any oil, but I do have low compression (only about 75 PSI average). I am guessing the the rings have never properly seated and that is causing the low compression and the high pressure in the crankcase is causing the oil to blow out. The engine does not blow oil all the time. It only does it when the engine is hot and sometimes it will be fine and I can drive it for hours with no problem all the way up to redline. It seams real speradic. Has anyone ever had this problem before? I think that I am going to pull the pistones and put new rings on and rehone the block, but I would like some input from others before I dive into this project. Thank you for your help. And if any other information is needed I would be glad to answere questions. Thanks.

Ross

Ross, Doesn't your oil fill cap have a small vent hole? Most caps for alloy valve covers are vented. If you still have SU carbs it may be best to install the OE type venting, with a vented oil fill cap. That doesn't solve the low compression problem. For that I would try some additives that are supposed to free gummed up rings and other parts. Pour it in the oil or where recommended and pour about a table spoon of the additive in each cylinder and let sit overnight. If you have gummed rings the additive may help. I wouldn't want to hone the cylinders without having a bare block, it's too hard to keep the honing grit out of the engine. Some old mechanics told me many years ago that you can seat rings quickly with some borax added to the cylinders. I have never tried it but it may help, on the other hand it may be snake oil. I don't think it would hurt to try.

Clifton

Ross, try Flash75 suggestion if you still have the SU carburetors, that is probably the best solution for your problem. For the compression problem try a product called "restore", you can find it at most auto stores.