BMW N62 Vacuum Pump Oil Leak Repair - 650i 645i 750i 745i

Timms BMW Repairs and Information. As a general rule I’m not too worried by a small oil-leak, after owning seven M62 V8’s you get used to the slight weeps around the valve covers. The problem with the leak from the vacuum pump on my 650i is that the oil blows back onto the exhaust manifold - and that stinks. These pumps are a problem on many models of BMW - the leak comes mainly from the front o-ring which is under the machined front cover. The cover is thin and only has five fixings, a tiny loss of elasticity of the o-ring and the small bow of the cover between fixings is enough to let the oil out.As there is very little manifold vacuum, when the throttle is given a good poke the crankcase pressure cannot be relieved by the feeble vacuum pump. The positive pressure is too much for the thin face plate on the pump and out comes the oil - it gets blown backwards and onto the exhaust. It is easy to think that you have fixed this oil-leak as during normal driving it doesn’t leak, but after a good thrashing it can start spewing oil out again. There are a few routines around on various BMW models for replacement of the o-rings and I looked at quite a few before I started this job, but using the standard method there is a possibility of breaking the lugs on the pump and other ghastly hassles that you don’t need. I decided to do the job in an unusual order so that there is no possibility of damaging the pump - but I’ll explain this as we go along. The on-line routine can be...