Motor oil replaced by Diesel - what do I need to fix?

[Jordan]

The diaphragm in the fuel feed pump ripped in my Yanmar 3JH2CE and the motor oil mixed with the fuel to the point where it was basically the same viscosity as diesel.

After I realized the problem I stopped using the engine for any amount of time, but I had to use it for maybe 30 minutes total to get into the marina.

I replaced the diaphragm and changed the oil/oilfilter/fuel.

Its still producing enough blue smoke to matter. Its sounds smooth and good.

How much damage could it have done? Am I looking at a re-ring?
I'm thinking I should start with valve seals and maybe have the injection pump rebuilt. The latter will be hard since I'm in Patagonia.

Any advice from diesel experts would be much appreciated!

[a64pilot]

Very unlikely excess fuel dilution of the oil resulted in excess ring wear.
If damage occurs, it’s very most likely in the bottom end, the bearings and shows up in low oil pressure when engine is hot and usually at idle, and a low, deep knock is really bad.
I guess it could have harmed the valve seals, which would have you burning oil.
Thing about Diesels is burning oil isn’t necessarily a bad thing, they can burn considerable oil for a very long time. It’s not until compression gets so low that they are hard to start or don’t make decent power that you have to do something about it.
If it were me and it had good oil pressure and it started normally, I would leave it alone until I got somewhere else.
Now if it has abnormally low oil pressure or has a hollow knock, better deal with that now.

[_andi_]

Farmers of the old used diesel to flush engines, running them at idle for a bit.


Was the engine massively overfilled by the diesel? That could be a problem.


Being as curious as I am I'd probably try to pull the injectors to have a looksie with an endoscope cam. Maybe measuring compression at the same time if possible.



But as long as there were no metal bits in the oil and the oil pressure is good (both hot&cold) I'd just leave it as it is.

[_andi_]

... and a friend of mine used old oil as fuel for his diesel bmw, nothing I'd recommend but that's also something which can be done in a pinch (if mixed with a little diesel if I remember correctly). So I wouldn't be too worried about oil entering the fuel system as well.

[boatpoker]

Originally Posted by a64pilot

Very unlikely excess fuel dilution of the oil resulted in excess ring wear.
If damage occurs, it’s very most likely in the bottom end, the bearings and shows up in low oil pressure when engine is hot and usually at idle, and a low, deep knock is really bad.
I guess it could have harmed the valve seals, which would have you burning oil.
Thing about Diesels is burning oil isn’t necessarily a bad thing, they can burn considerable oil for a very long time. It’s not until compression gets so low that they are hard to start or don’t make decent power that you have to do something about it.
If it were me and it had good oil pressure and it started normally, I would leave it alone until I got somewhere else.
Now if it has abnormally low oil pressure or has a hollow knock, better deal with that now.

I'm with A-64

[Jordan]

OK thanks everyone - I feel better now. I'll replace the valve seals when I get farther north because that's pretty easy, and just keep feeding her oil for now.

[NYSail]

I’d change the oil again before I did anything else.

Greg

[Lepke]

Some times the rings will "sort of" reseat after a couple days. I bought my current boat knowing I would overhaul the mains. Warming the engines before starting my trip home, the smoke was so bad someone called out the fireboat thinking I was on fire. Except for using oil, they ran hundreds of miles coming home without missing a beat. They had way over 20,000 hours.

[Pete7]

Originally Posted by Jordan

I'm thinking I should start with valve seals and maybe have the injection pump rebuilt. The latter will be hard since I'm in Patagonia.

What? don't even think about it. Warm the engine up and then take it for an Italian tune up for an hour.

Pete

[MCOS]

I would just change the oil. If it starts ok it probably has good compression and since it didn't just seize up and stop the engine most likely did not overheat and score
Cylinder walls. Zen out, run it. I've flushed engines with diesel to clear out gunk.

[a64pilot]

Rings require very, very little lubrication.
Two strokes live long lives with the rings lubricated with a 50 to 1 mix of oil and gasoline for instance.
They of course have needle bearings because your not doing that with sleeve bearings.

[LooseGoose]

Cut open the oil filter to check for metal filings.....and save that bit of oil for a subsequent oil analysis....both will tell you a lot about whether you had significant abnormal wear during the incident period....good luck.

[captmikem]

Originally Posted by _andi_

Farmers of the old used diesel to flush engines, running them at idle for a bit.
.

I still do this, cleans the internals and gets rid of the carbon etc laying on the bottom of the pan. I have done this for many years.

Basically, you still had oil, it was just diluted with diesel. even a 50/50 mix as long as you did not run it hard should not harm your engine. Oil provides two functions, it lubricates and cools, as long as you had oil pressure pumping the oil/diesel mix through the bearings they were being lubricated and cooled.

If your engine is turbo, and you had high rpms, the turbo bearing may have taken a bit of wear, especially if you did not let it idle abit after running hard, IF you ran it hard.

I just would not worry about it. but, that is my opinion.

M

[Almost-There]

I'm with A64 and as LooseGoose suggested try and find a way to send in a oil sample. I've used a aspirin bottle when I was stuck with my Maule. I really wanted to see an oil sample before we tried to fly out after swapping a cylinder. Once it got to the lab we had results emailed to us that day. If possible send in a sample after its been run for some time too.



Also as suggested change the oil again if you only did it once.Chances are the smoke will clear up and dont be afraid to use a little thicker oil as a crutch.Or an additive like Lucas or Camguard etc that is available locally. Just do a little research on who makes what and chances are you'll find something decent. I'm not trying to open a can of worms but I've used Camguard in both aero and marine engines for years with great success,I've found it in multiple 3rd world countries without a problem and last but least is it is FAA certified to do what they say it does. So unlike most snake oils it actually has been tested and certified ;-)

[Louis Simon]

I had the same problem with lift pump diaphragm on my Perkins 4-108. Cost me $5000 and a lot of work. Changed oil and found sump holding about 3gal of diesel/oil. Started engine -noise. Turned over by hand(rocked back and forth) CLUNK= bad bearing. Pulled engine & rebuilt. Had a lot of problems with fuel pump timing as gears had several (factory?) markings- so which is correct? Finely got 18 degrees before TDC by disconnecting fuel line to # 1 cylinder & hand turning till fuel appeared. The oil dipstick is flat on the bottom 1 inch or so-I thought (wrongly) the upside down oil filter was letting excess oil drain into the sump & I couldn't see the level on the dipstick wire rod above the full mark. Lessons learned-(other than being dumb) Lift pump diaphragm that allows diesel to drain into the sump when ruptured is a BAD design. REPLACE with an electric pump. About $15 on line. Running fine for last two years.