Water in spark plug tubes

[Capt_Mike]

Hey guys!
Customer brought his boat to me after his 2008 DF115's low pressure fuel pump failed and injected gas into his oil which filled up.
Engine failed after he noticed white smoke coming from exhaust.
Saltwater had been present in spark plug tubes for 2 and 4 cylinders where I found the salt granules and rusted spark plug tops.
I looked through schematics for engine and called various places...nobody can figure out how water got into the spark plug tubes
Replaced fuel pump, plugs and oil.
Customer says that water did not hit engine power head at all.

Does anyone know why seal could have been blown to cause this?
Any help is appreciated...

[artdf175]

sounds like a couple of problems and maybe there is a mechanic that can explain this better
gasoline in the oil -- that does not sound like a bad low pressure fuel pump..
the low pressure pump feeds the high pressure side that feeds the fuel injectors
the only thing discussed here is when the float valve in the high pressure side fails and the overflow runs into the oil pan.
then you can have problems when the oil level gets too high and I suppose feeds into the engine where it is not suppose to ..

salt in the spark plugs holes, not internal, condensation maybe. water spray from running and rough water getting through cowling vents
doesn't sound like a major problem unless engine is covered in salt water
seems like you should be able to see any water source upon getting the engine running again
Art

[catacom225]

Fuel pump

Low Pressure Fuel Pump Is Cam Driven. Just changed mine , seal failed causing fuel to leak back into oil pan

[artdf175]

Good observation had not run across that problem before vs lots of stuck floats
Capt. Mike
Did you get the engine running?
If it is built like the 150/175's there is nothing but a valve cover
Any failure in the cooling system would blow fresh/salt water over everything
You might get a clue after watching it run
Let us know what you find for future reference

[Harper]

Ruptured diaphragm on low pressure fuel pump has been addressed a number of times in the forum. On all units DF175 and smaller, the low pressure fuel pump is a cam driven diaphragm-type pump, and if the diaphragm ruptures, fuel goes from there to the crankcase. DF200 and larger have electric low pressure fuel pumps and will not encounter this problem. Only possible exception is the new I-4 200 HP that uses the same block as the DF150/175.

The water in spark plug holes is a puzzle, since the coil-on-plug attaching is gasketed, and there should be no chance for water intrusion, or even condensation. Did the affected plugs seem to be properly torqued?

Capt Mike, what do you mean by "engine failed"? Has it seized, or need to be rebuilt for some reason, or did it just quit running?

[Capt_Mike]

Good observation had not run across that problem before vs lots of stuck floats
Capt. Mike
Did you get the engine running?
If it is built like the 150/175's there is nothing but a valve cover
Any failure in the cooling system would blow fresh/salt water over everything
You might get a clue after watching it run
Let us know what you find for future reference

I did not get engine running properly yet. It starts up when cold and it seems that as soon as it gets to operating temperature and the thermostat opens, it bogs down and throttle has to be increased to keep it running...water is being injected somewhere...
I did a compression check and all cylinders are up to where they should of be for the age of the motor...

[Capt_Mike]

Ruptured diaphragm on low pressure fuel pump has been addressed a number of times in the forum. On all units DF175 and smaller, the low pressure fuel pump is a cam driven diaphragm-type pump, and if the diaphragm ruptures, fuel goes from there to the crankcase. DF200 and larger have electric low pressure fuel pumps and will not encounter this problem. Only possible exception is the new I-4 200 HP that uses the same block as the DF150/175.

The water in spark plug holes is a puzzle, since the coil-on-plug attaching is gasketed, and there should be no chance for water intrusion, or even condensation as a problem.

I'm trying to figure out if there is a gasket or ORing that is blown where the tube end closest to the spark plug and head...

[Harper]

The only gasket that I know of effecting the spark plug tubes is the gasket between the cam cover and head. Not much chance there for leaks of anything but oil.

[artdf175]

after you had it running for a bit.. did you take another look at the oil?
did changing the l.p. fuel pump fix the gas in the oil problem

[nelbur]

Another common way to get gas in the oil is a problem with the float/needle & seat in the vapor separator. I wonder if the water in the tubes could have come from poorly seated spark plugs. Exhaust gasses have a high level of water that might have condensed in the tube. What looks like salt could be corrosion of the aluminum, but a taste test could determine if it is salt or corrosion. Corrosion would be gritty. Salt would not be, plus it would be salty, duh.

[artdf175]

I did not get engine running properly yet. It starts up when cold and it seems that as soon as it gets to operating temperature and the thermostat opens, it bogs down and throttle has to be increased to keep it running...water is being injected somewhere...
I did a compression check and all cylinders are up to where they should of be for the age of the motor...

Question because not familiar with that exact engine
Does this one have the 'idle air control system"? Parts page seems to say yes
Part of the IAC system is to improve starting and warm up performance
I believe there were several threads about cleaning this valve
Just a thought
One more thought how good is the battery?
It has been discussed how sensitive these engines can be to the right voltages

[Capt_Mike]

after you had it running for a bit.. did you take another look at the oil?
did changing the l.p. fuel pump fix the gas in the oil problem

Yes. No more gas going into oil after low pressure fuel pump changed.

[Capt_Mike]

Another common way to get gas in the oil is a problem with the float/needle & seat in the vapor separator. I wonder if the water in the tubes could have come from poorly seated spark plugs. Exhaust gasses have a high level of water that might have condensed in the tube. What looks like salt could be corrosion of the aluminum, but a taste test could determine if it is salt or corrosion. Corrosion would be gritty. Salt would not be, plus it would be salty, duh.

The vapor separator is a separate contained unit and doesn't come anywhere near oil...how do you figure has gets into oil from there?
Spark plugs were seated correctly.

[Harper]

While your "oil-making" problem was obviously the low pressure fuel pump, the other most common such problem stems from the needle and seat in the VST not closing properly, causing the VST fuel bowl, in which the high pressure pump is immersed, to overflow and dump raw liquid fuel out the vapor line and into the crankcase. Normally the vapor line that runs from the VST to the engine crankcase just carries vapors, which are drawn into the intake to be burned (much like a PCV system) but the stuck float needle in the VST will cause the fuel overflow. The bowl in the VST is fed by a needle and seat arrangement just like the fuel bowl on a carburetor. Filling that bowl is the function of the low pressure fuel pump. Controlling the fuel level in the VST is the function of the float and needle/seat valve.