Grey smoke, fuel in oil?

[NYSail]

Hello all,
Towards end of last year I started noticing a slight bit of white smoke from exhaust after years of no smoke at all..... This year I have a steady white smoke from exhaust which and left my dingy line dark. Also when I checked oil it appeared to be above where I typically fill.... Still slick and no smell of fuel and definitely not water, however.....
I changed my mechanical pump last year. Another thing I noticed while inspecting is a small leak around one of my injectors that I saw due to a slight bubbling around where is inserts into block. No smell in engine compartment and engine runs fine. Had valves adjusted right before I left on trip (on block island until Friday).
Any suggestions? Could worn injectors cause smoke and fuel leaking into oil?
Btw engine is a 1986 yanmar 3HM35F.

Thanks as always for advise

 

[coolista]

There is a mechanical seal @ the bottom of the injector - usually a copper flatwasher. It becomes deformed when the injector is tightened-down to create the seal. This is typically the only seal around the injector, isolating the combustion chamber from the outside world. If worn or corroded, will leak but if it is there (nobody forgot to drop it into place) and does leak, usually it is loose or leaks from foreign material accidentally dropped in during assembly, forcing a crevice. As you can imagine, not much opening is required to get bubbling, and is solved by replacing the relatively cheap seal washer. On the other hand, if the injector itself is leaking, then it must be serviced/replaced. Primarily fuel in the crankcase is blow-by from worn rings allowing unburned fuel to migrate down one of the cylinders. Smoke can come from worn valve guides allowing oil to travel from crankcase to exhaust header, but this vector does not put fuel in the crankcase, like the rings bleeding. I am not sure about your model, but a mechanical (primary) fuel pump may leak fuel past the diaphragm and into the crankcase. Your injector pump might theoretically (rarely) do this, and this would be investigated properly by a professional.

 

[NYSail]

Thanks...... Yes I just purchased three new injectors to be installed when I get home. I had to replace the copper ring and heat insulator when I first bought boat but injectors have never I assume been serviced (1986). Mechanic said compression seemed good when he was adjusting valves..... Anyway, have made an appointment to have him change injectors and check system when I get back... Just run a bit slower going home.

 

[Benny17441]

The answer to both questions is yes but they are not the only cause for either not the most likely reasons for the event. An injector atomizes fuel creating small particles that mix with air creating an ideal mixture that will ignite and burn thoroughly. When an injector is fouled it can spurt raw fuel that being thinner than oil can blow its way past the rings into the crankcase. Burnt oil is mostly bluish in color with white reserved for water as steam but the dividing line can be hard to read. Bubbling around an injector is not normal and points to an air leak under pressure. That injector could be going bad. I would say if smoke is white go ahead and check the cooling hoses, tight the belt and replace the impeller. Other than that check the viscosity and level of the engine oil and finally re-seat that injector with a new seal to try and eliminate a reason for the bubbling. Whatever ails your engine does not seem to be critical so just do a little maintenance and continue to observe to narrow down the system that is creating the smoke.

 

[kloudie1]

I think you are heading in the right direction, NY Sail. You may be able to isolate which injector by engaging a decompression lever while the engine is running at a smidge above idle. If one lever does not change the engine RPM as much as the other two, that is the one cylinder with a problem..

 

[Nelsonhow]

Similar problem on my 2GM- whiteish grey smoke

IMHO:

Replaced injectors - no change
replaced all washers and filters in fuel system- no change
replaced head gasket- no change
Finally at the end of last season running hard my temp alarm went off.
I pulled the head and cleaned the water passages, cleaned the carbon from the head valves and exhaust, replaced the thermostat and descaled the motor with RedyLyme. When I put it back together it started up but I could not get my raw water pump to prime. I thought I had found the problem. I replaced the impeller and the pump cover plate and gasket. Now the pump worked great. With the boat out of the water I disassembled the valve and fittings to the engine raw water intake. The line between the thru hull and the ball valve was full of tiny muscle shells.

It turns out that I was running a little hot...hence the white smelly steam.....it got progressively worse until that last rub if the season......are you getting cooling water out the rear?

My advice would be to check the cooling loop first....it easy to check and if it ok then move on to other things.....

 

[NYSail]

Hello all... Thanks for the input. Yes I do have a good flow of water. Was advised also that elbow may be internally clogged causing back pressure into engine.... Mine is 9 years old and due a replacement this weekend. Will report back after and prior to injector change

 

[NYSail]

Solved. Replaced the mixing elbow. I run engine hard every time I take her out. Replaced elbow 9 years ago. Last year noticed slight white smoke. This year on long trip slight smoke turned to a good stream of grey smoke.... More at higher rpm's. Water flow was perfect. Upon inspection water chamber was perfect however exhaust chamber was 98% blocked by a black lava stone like blockage. New elbow no smoke at all. Engine sounds happy. Just shows what stress these engines can operate under. Love my yanmar! Note to self (and anyone else).... Water flow does not indicate health of elbow. 5 years check / replace. Small price to pay and easy "do it your self" job.

 

[Nelsonhow]

Great Going

Thanks for the report on the cure. It helps us all.