Originally Posted by BigAl.NZ
How did you find out it was the injection pump leaking?
We usually need to add oil regularly to our 4108 (but have not had to recently) and now find that the oil pressure is very low with the alarm on at low revs. This is not normal for our engine.
The oil dipstick shows full but have not added any oil for ages.
Well, it does sound like you are getting diesel in the crankcase. The 4-108 runs low oil pressure when idling normally, if you have thin oil from diesel in it, it probably makes the alarm go off.
There are a few things that get diesel in the crankcase: (and probably more than I have noted)
-leaking lift pump diaphragm
-leaking injection pump
-a bad injector streaming fuel
-bent pushrod. (I had a perkins that the push rod popped off the rocker. It ran great on 3 cylinders! but smoked and gained fuel in the oil. (pushing raw fuel past the rings as the valve wouldn't open.) When we removed the rocker cover it was obvious the push rod was just sitting there along side the rocker.)