MGB: gas in the oil pan

We've benn having problems our mgb lately. We thought we had fixed the problem when we found gas in the oil pan. We put new oil in the car, ran it through the car a little. We checked the dip stick and could smell gas. We checked the compression so no holes there, what is our problem.
Thank Carl

You'll smell gas for a good little while after you've gotten it out. About the only thing that can put gas in the oil of our cars is the carb(s). If you have anything other than a Weber downdraft I can't be of further help. With gas getting in the oil I'd bet you don't have a Weber.

what could be happening, is the floats for the carbs are sticking, and then the excess raw fuel is being draw in to the manifold.. kinda like when your toilet does not shut after you flush it, and it continues to run...

pull your spark plugs out and see if they are gas soaked also.. the excess fuel may have fouled them out..

I think John is probably right. You didn't say what year your car is. Depending on the emission controls, the overflow might end up in the crankcase. Looking at my Moss catalog I see that on 1970-1974 cars, for example, the hose from the oil separator connects to the carburetors.

If this theory is correct, you should see other signs of this problem - rough idle, gas dripping from the carburetors.

- Terry

It is a '71 B. Plugs are soaked, rough idle, seems to foul out. I also wander about the floats sticking. Just didn't know if there might be something else. Very strange circumstances. It all started with a tune up. Changed plugs, points, condensor, cap & rotor. Went to retime it and it would not start. Tried a number of things - finally got to start but extremely rough. Adjusted distributor by ear only to find out that the time (check with a timing light) was way off - about 10 degrees in the wrong direction. When I adjust, while running, to the right setting, it dies and will not restart. In all this stuff, I check the oil only to find out that the oil pan was full of gas - what the heck. Changed the filter and oil - the next day found gas in the oil again. It all started with a simple tune up. Will check the floats. Appreciate any and all suggetions and as always, many thanks!

what might have happened, if you do not drive the car much, is there may be some sort of varnish on the needles and seats.. what i have done sometimes in the past, on some, is sprayed the carb fuel inlet with a good quality sort of carb cleaner. i did this with the carbs removed on the engines i did this with.. , and then afterwords i ran a good quality type of fuel / carb cleaner.

one thing you may want to do, if you do not drive the car often, is to put some sort of fuel stabilizer in it, and then fill the tank all the way up, and then let the car run for about 15 minutes.. that way the stabilizer will have a chance to work its way thru to the carbs, and the float bowls.. this will prevent the varnish from forming later on.

the most common brand is called STA-BIL.. but STP and some of the other major companies make the same sort of thing. just follow the instructions on the conatainer.


good luck, and keep us informed.

I would check my fuel pressure before I did too much (I think it is supposed to be 3 pounds) and then a sticky float or a bad needle and seat.

Checking the fuel pressure is an excellent idea if someone has substituted a non-SU fuel pump. I can't see how the standard pump could really generate too much pressure.

- Terry

Sea Foam will stabilize gas for up to two years, desolving gum, varnish, carbon deposits is it's real forte. Use this stuff and you could forstall several several problems at once.

Maybe we are all overlooking the obvious. If this problem started with an ignition tune-up isn't possible that the dizzy or the new ignition wires are 180* out of time.
Wouldn't this explain why the car runs "well" when it is so far out of time and runs poorly at the correct timing point?
Also, wouldn't the mixture go rich under these conditions flooding the engine and dumping raw gas into the cyls which drains into the pan ?

just my.02
Jim

I also have a '71 B, and I had a problem with the SU's flooding the engine. Turned out to be that the carbon canister was clogged or the line to the reclaim tank was blocked. I removed the line and installed an over flow line as described in older manuals(A drain right to the ground). The plugged line allowed the floats to remain open.

I continue to appreciate everyones help! I am please to tell you all that I am up and running again, however embarassed to tell you why. Jim was right. I setting the timing and moving the distributor I some how turned it 180 degrees. What Jim described is what happened to a "T". The car ran, but rough, would not respond correctly to adjusting the timing and later realized that it caused the carbs to flood and drain into the oil pan. Again, missed the obvious. Thanks for everyones help!

RIGHT ON!! I'm surprised.