Diesel fuel leaking into engine oil revisited

Hi Folks,

Back in January I had posted a message about diesel fuel leaking into the crankcase and had received responses that it could be the lift pump or the seal on the injector pump. I had replaced the lift pump the previous summer, so I changed oil frequently to get me through the winter season.

Over the summer I have been checking the oil carefully and there has been NO sign of diesel leaking into the crankcase, sn now I am beginning to worry that it will happen again this winter when I change to lighter winter fuel.

A local fellow mentioned that because the engine works harder blowing snow that it is most likely the seal on the injector pump shaft. Is this a possibility and if so how difficult is it to change the seal? He also mentioned that the tractor would need to be retimed which sounds like a much bigger job.

Thanks,
Richard

Hi Richard,
Yes the front seal on the main pump is a strong possibility. The seal is likely to have gone hard or be split. I don't recall which tractor you have but assume its a MF 3 cyl 35 onwards.
Retiming is valid to a small degree. Removal of the pump is straight forward. With the inspection cover in front of the pump removed and sprocket bolts removed you can remove the pump nuts and remove it. You will see a slot in the sprocket which aligns with a peg on the pump shaft. For your peace of mind you could always mark the pump sprocket and its mate with a spot of paint. The pump sprocket will not drop. Note the position of the line on the pump body relative to the one on the timing casing before removal. Assuming that this is correct aim to replace the pump to this noted position. That should be OK. However if there is any excess smoke or reluctance to start you may need to give it a tweak either way until you achieve the best results. It can be timed by the marks but this way normally is satisfactory.
It is advisable to have the seal replaced by a diesel shop. While the pump is off the tractor they would be able to test it and tell you if there are any other problems brewing.

DavidP