Annoying oil leak

[Malcolm Parker]

For the past couple of years the engine in the Pytchley has had an annoying oil leak.   The engine is the first I built when I was in my mid 20's (a while ago!) and has a 1934 crankcase.   Even after a short run of a few miles, there would be a pool of oil on the crankcase 'shelf' under the fuel pump.  I have lost count of the number of times I have refitted the valve chest cover, an aluminium plate fitting off a Reliant SV engine.  While doing the above, I always checked the block retaining nuts for tightness, all to no avail.   The mechanical fuel pump has been off several times, rebuilt, swapped etc.   Still no joy.   The oil leak extended down the nearside of the bell housing so I was latterly thinking that the rear main bearing could be at fault.
I took the car out for a run a few days ago and it went very well but on return there was a serious amount of oil on the crankcase and elsewhere in the engine bay.   After dealing with the nearside I checked the other side which was largely free of oil except for around the oil gauge pipe union at the rear of the crankcase.  I checked the union for tightness, all okay.   Thinking that the leak could be the soldered olive at the engine end of the oil pipe, I took the whole pipe off which is a five minute job on the Pytchley.  The pipe , olives and retaining nuts were all perfect.   Next I looked at the brass union in the crankcase.   Running my finger up the thread I could feel that the thread was shot.   The tread had become a thin coil of brass.
I will select a good replacement union from my spares and report back!    

[Steve Jones]

Had this on the Ulster engine, Malc. Trouble is, we use new pipe nipples and nuts and 90 yearold crankcase unions and expect it all to work. In the Ulster's case, new crankcase union solved the problem.

Steve

[Malcolm Parker]

I've found an original crankcase union in very good order and fitted it.  Tomorrow I'll take it out for a run and see if the oil leak has been cured.