Yanmar, 20-Years Young / White Smoke

[dockbumdan]

After 20 yrs, my diesel is starting to smoke. Not much and only when it is started, a puff of white (smoke) not steam. comes out. while running hard 2700 rpm it also puts out some white exhaust. The injectors have been serviced recently. within the past 2 seasons. It's not burning oil, that I can tell. I check the oil level every fill up. And add oil at around 800 sm. maybe 1/2 quart. Should I be worried? The engine has over 3000 hrs.

[Beersmith]

I'm no expert, but I have read that some smoke at start-up isn't anything to worry about.

[Geoduck]

3000 hours isnt much if you've changed the oil once in awhile. You should have about 6000 left if you're lucky - maybe more.
White smoke on start up isnt a worry. The smoke screen left behind you at 2700 rpms might be. Watch your temp gage and back off on the rpms. If the smoke clears, then run the boat at that rpm. If the smoke doesnt clear and the temp goes up, you need to rebuild the head because you have a blown head gasket or a cracked head. Watch for water in the oil. The oil will turn grey if there's water in it.
I also have a Yanmar and I dont run it any harder than it takes to reach hull speed which in my case is 2400 rpms - anything else just works the engine harder and burns more fuel.

[stevensuf]

is white smoke not water in with the fuel? leaky head gasket ?

[delmarrey]

There are two reasons for white smoke. Either water or unburnt fuel. Since you've had your injectors done recently, I'd suspect water. If it's a head gasket, you should be losing water from your coolant system. Or your heat exchanger is bypassing raw-water into the exhaust system, which I'd check first considering the age of your motor.

[Charlie]

Del you know more then I but if it is white smoke at startup that disappears is that really something to worry about?

[stevensuf]

I think unburnt fuel usually turns it black/sooty though in a petrol it can cause a whiteness, but in a diesel usually black sooty exhaust. def check coolant levels and heat exchanger seals. might be a very small leak, allowing it to pool and burns off on start a bad leak will have very white consistent smoke and eventually stall

[delmarrey]

What you could do is with the motor sitting cold, pull off your exhaust elbow and look inside the exhaust (and inspect the elbow). If it's wet or eaten away inside the exhaust manifold, there's your problem. Be sure to replace the gasket with new.

[delmarrey]

Originally Posted by Charlie

Del you know more then I but if it is white smoke at startup that disappears is that really something to worry about?

Here's the kicker......

while running hard 2700 rpm it also puts out some white exhaust.

Black smoke usually indicates an over loaded motor or bad injectors (not atomizing the fuel).

[Charlie]

Originally Posted by delmarrey

Here's the kicker......

Black smoke usually indicates an over loaded motor or bad injectors (not atomizing the fuel).

Ok if I only knew how to read this wouldn't be so bad. One other thought since I had white smoke on a Yanmar at higher RPMS. Check your oil level very carefully. If there is diesel in the lubricating oil and the oil level is too high you may have a problem. Common cause of this is a ruptured diaphragm (sp)on your lift pump.

[delmarrey]

Originally Posted by dockbumdan

It's not burning oil, that I can tell. I check the oil level every fill up. And add oil at around 800 sm. maybe 1/2 quart. Should I be worried? The engine has over 3000 hrs.

Other facts: If white smoke is still visible after the engine has warmed up, the engine may have one or more bad injectors, retarded injection timing or a worn injection pump. Low compression can also be a source of white smoke. Air in the fuel system can also cause white smoke.

Here's a nice lil chart I've picked up.


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