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tbhudson 12-15-2008 01:20 AM

Diesel injector pump
The previous owner of my sailboat never changed the oil in the diesel injector pump on my Ford Lehman 80hp engine. Normal recommendation is to change it every 50 hours. He put about 2000 hours on her over the past 12 years. I've put about 120 hours on her with no problems.
When I drained the "oil", it came out mostly the consistancy of diesel fuel and not oil. Smelled of it too. Ran just fine after the change.
Anyone have any idea of what damage may have occurred to my pump due to being neglected? What should I expect in the future? Should I get another pump and get it swapped out asap? How bad is it?

sailingdog 12-15-2008 02:19 AM

Ain't broke, don't mess with it.... Carry a spare and the tools to swap it out though. :)

Rockter 12-15-2008 06:49 AM

The man is right. If it works, then leave it. Change the oil from here on.

rrh 12-15-2008 08:46 AM

If it continues to be diluted with diesel, you will want to have it serviced. It could be as simple as o-rings or a cracked diaphragm. Even so, there is probably a vent on the side (maybe the backside) of the pump. As diesel invades, it will push out the oil, dumping diesel and oil in the bilge. I don't agree with the "if it ain't broke, don't fix it" theory. If it is leaking diesel into the oil, it will wear out sooner, much sooner. I had a 4 cylinder Bosch pump rebuilt this summer for a little over $700. That sounds high, but for my application there are no new ones available and to purchase a rebuilt one would have been double or more. Why wear out the cam, pistons, etc by continuing to allow the oil to be diluted? In my book, a diesel injection pump is too valuable to "just let it work as long as it will". Yes, I'd try it with a reasonable oil change period. I'd check it regulary. If it is filling with diesel, I wouldn't hesitate to pull it or have it pulled and serviced by a qualified shop.


jrd22 12-15-2008 09:54 AM

I'm not familiar with the Lehman diesel but I've never seen a diesel engine that had a seperate oil sump just for the inj. pump. That's a new one on me.

rrh 12-15-2008 10:25 AM

Oil Sump in Pump?
Many of the older pumps, (all that I have worked on) have self-contained oil sump. Maybe a diesel mechanic will provide a more definitive answer. The newer, common rail system don't seem to have their own sump but operate off of engine oil - at least my Ford/International DIT does. I tried to post a picture of the type but only wound up with a lot of garbled link info. The type I am talking about is bolted to the side of the block and usually has to be rotated against the block to set timing. The oil level has to be checked and oil does need to be changed.


dem45133 12-15-2008 11:21 AM

The semi truck units I'm familiar with were all lubed by the engines oil. Nothing in the world says that it has to be that way though. If it has its own lube system/sump, than change it regular. I expect than even a new unit of this type will get a small amount of diesel in it. I'd watch that real close. Since the oil you references had been there forever... the fact that it did have some diesel in it may not really indicate issues. As the man said though, change it out, watch it like a hawk. If after a few hours runtime your still getting significant diesel in it... you may need to service it. If its only a tiny trace amount... I'd probably just keep using it.

The amount of wear may or may not be as big as you think. If its a slow running engine or if routine operations were slow ops, then there may not be as much wear as the above gentleman suggests... fuel oil in itself in a fully immersed operating part at slow speeds may not have worn it all that bad. Hard to say... just how black or nasty was the oil /fuel mixture you drained? If its isolated from the main crankcase... it should have remained fairly clean. Was there any metallic filings/shavings present (trace amount would be normal). Was the oil dark with non-oil contaminants (metal or otherwise)? If you showed reasonable sign of foreign materials at all, and it truly is isolated from the crankcase oil system.... then I say it will have internal issues. If the oil was clean and only had fuel oil present... I like run it a bit and see.


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