Diesel Fuel in Crankcase Oil

[casual]

WOW,Now I find out the engin is a 4JH3E,and the hours are approching 6000.All the responses only concur my beleifs that with the oil dilution and nobody certain how long it's been going on,and to top it off this morning when looking at the engin my self even the oil filter is Badly Rusted,I know buyers are responsible for checking everything but the word from the broker prior to me travling a thousand miles one way was the engin was 100% and running fine,and they talk about Used Car Salesman.A little levity thrown in,New Engin is there any other choice?
Many thanks again for all the help.

[delmarrey]

It could have an accumulation of errors with 6000 hr and a lack of maintenance. By the time you fix one thing, something else goes wrong. The money you spent on the drive saved you a whole lot later on.

[Charlie]

My boat had a 4JH2E in it originally with only 3800 hours on it. When I saw how slap dab the maintenance was on the rest of the boat I priced in replacing the engine. Mostly b/c I didn't want any surprises. I sold the engine for half the cost of a new one so it worked out well. I have bought two boats long distance now. I ask the broker to take pictures of specific areas of concern on the particuilar type of boat -- the engine being one of them -- and ask that the pictures have a date time stamp on them. If the broker is not willing to provide these for me it is not worth going to look at the boat.

[Charlie]

Originally Posted by delmarrey

Maybe these pictures will make better sense. The red arrow being the flow of the fuel.


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I just want to get this straight. The red lines represent the fuel flow if the seals are bad in the injection pump. If I disconnect the lube oil line while the engine is running it will make a mess. but the diesel should be easy to spot and if I shut the engine down quickly after disconnecting the lube oil line and capture the fluid that comes out from the lube oil line I will know if the injection pump is leaking and not destroy the engine.

OTOH if the lift pump is bypassed from the system and the engine does not make oil that also eliminates the injection pump as a source for oil dilution and the only other option would be that the injectors are leaking fuel into the cylinders. This is unlikely b/c my engine does not throw out smoke.

Is my logic correct?

[delmarrey]

[QUOTE=Charlie;828069]I just want to get this straight. The red lines represent the fuel flow if the seals are bad in the injection pump. If I disconnect the lube oil line while the engine is running it will make a mess, but the diesel should be easy to spot and if I shut the engine down before quickly after disconnecting the lube oil line and capture the fluid that comes out from the lube oil line I will know if the injection pump is leaking and not destroy the engine. There would be fuel in the line vs lube oil.

Yes

OTOH if the lift pump is bypassed from the system and the engine does not make oil that also eliminates the injection pump as a source for oil dilution Yes

and the only other option would be that the injectors are leaking fuel into the cylinders. This is unlikely b/c my engine does not throw out smoke.
Not necessarily.

If the injector is leaking after shutdown, from residual pressure, then it would just drain past the piston while sitting. The amount of oil would depend on how many start ups & stops.

I might add; if the lift pump is leaking there needs to be enough pressure to over come the 100 psi oil pressure (when cold). So, in some cases it may be just leaking from gravity or back pressure into the lube line while the motor is off. Does your electric pump shut off with the motor?

If you look at the pump specs chart I posted it shows 2.9 psi for the lift pump, not enough to over come the oil pressure, unless the injection pump is leaking just enough to force fuel backwards. In that case it could be both, with the injection pump only leaking slightly or creating some sort of pressure in the cam cavity (heat or motion).

It's really hard to nail it down w/o being there to open up systems to see what's going on. The only other way for fuel to get into the crankcase is past the pistons!

[casual]

I may be posting twice,The engin turns out to be a 4jh3e not 4 e.Any way the compression is good,my main concern going forward is the ware internally.The engin hours are not 100% clear maybe 3000 maybe 6000,After replacing the lift pump and if this clears up the problem,can I trust the engin,I only plan to uses this boat for offshor sailing,Many thanks again for all the education

[delmarrey]

Originally Posted by casual

I may be posting twice,The engin turns out to be a 4jh3e not 4 e.Any way the compression is good,my main concern going forward is the ware internally.The engin hours are not 100% clear maybe 3000 maybe 6000,After replacing the lift pump and if this clears up the problem,can I trust the engin,I only plan to uses this boat for offshor sailing,Many thanks again for all the education

I would have a yanny mechanic do an engine survey. There are too many things that can go wrong. And if you can't track the hours it sounds like deception. Do you really want someone else's trouble? Can you afford a new motor soon? If your going off shore, you do want a dependable motor and clean fuel tank!

[delmarrey]

There is one more leak path that I over looked and noticed when I was checking my motor today. It's the front seal on the injection pump cam shaft, circled in the picture. It goes in the front gear case cover where one can pour in oil.


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[Charlie]

Thanks Del.