ENGINE DIES WITH WHITE SMOKE PERIODICALLY

[flicka]

HI,
I HAVE 30 YEARS OLD SOLE DIESEL 12 HP SINGLE CYLINDER ENGINE. THE PROBLEM IS THAT THE ENGINE DROPS RPM AND STOPS APROX. AFTER 2 HOURS AT CRUISING SPEED. I CAN START IT IMMEDIATELY, BUT IT WILL RUN ONLY ON MINIMAL RPM, A LOT OF WHITE SMOKE IS COMING FROM THE EXAUST AND OILY SHEEN IS SEEN ON THE WATER, THIS STOP AFTER SEVERAL MINUTES AND AFTER 10 MIN. I CAN INCRESE RPM AGAIN. I HAVE MADE SEVERAL SUCH CIRCLES TO GET HOME. I HAVE CLEANED THE FUEL SUPPLY WITH ALL FILTERS. RECENTLY I GOT WATER IN THE GEARBOX FROM BROKEN SEAL ON THE WATERPUMP-CAN THIS BE THE CAUSE.
THANK YOU FOR ANY ADVICE.

[slomotion]

White smoke is generally a sign of water in the combustion chamber. There are several ways that this might happen, but it’s hard to imagine how this would happen after 2 hours of operation and then go away 10 minutes later.

[mikereed100]

I am not a mechanic, but a faulty head gasket would be at the top of my list of suspects. It is strange that the problem resolves after 10 min at low rpms. Evil demons cannot be ruled out in this case. If you lack the equipment to do a compression test a mechanic (or exorcist) may be in your future.

Mike

[flicka]

THANK YOU FOR ANSWERING, BUT MECHANICS HAVE DONE THEIR JOB
THEY HAVE AN IDEA, THEN THEY FIX SOMETHING THE ENGINE IS OFCOURSE WORKING BUT JUST FOR ANOTHER 2 HOURS. SINCE IT IS A STRANGE SYMPTOM AND I DO NOT WANT TO THROW AWAY MORE MONEY I HAVE DECIDED TO POST IT HERE. ANYHOW IT SEEMS I WOULD HAVE TO CHANGE THE ENGINE.

[TexSail]

The problems you describe sound like a head gasket except for the fact that it later runs OK. Can you look at the sediment bowl to see if any water is coming into the injectors? Blown head gaskets usually don't cause intermittent symptoms.

[Lancerbye]

Say three Hail Marys. Hire a witch Doctor and an exorcist. Hang garlic in the engine room, drive a spike through it's black heart. If that fails take two aspirins and call a better mechanic. You are definately burning water. Don't know what your head gasket looks like. You might try retorquing your head bolts. I have seen this happen when an engine was cold and go away after it warmed up. I have also seen that symptom when water got into the crankcase. Have fun.

[uncle_fred]

Originally Posted by slomotion

White smoke is generally a sign of water in the combustion chamber. There are several ways that this might happen, but it’s hard to imagine how this would happen after 2 hours of operation and then go away 10 minutes later.

sounds the same to me cylinder head gasket get it changed and your problems should be solved, if you keep it running and have bad luck new bearings, or a new engine cheaper to get it done early.

Fred

[slomotion]

Or: is there any indication that this engine is overheating? If so, you may have raw water vaporizing in the exhaust/heat exchanger. Again, there could be several possible causes, but again it's difficult to explain why this would be only a periodic condition.

[ssullivan]

I have problem similar to this on my port engine as well. It's on the list of things to look into this winter.

Mine emits white smoke for a couple hours, then slowly improves. Oddly, it's the same engine that loses RPMs (sometimes a couple hundred, other times 1000) while underway, but bounces back in seconds.

It also runs *ever* so slightly cooler than the starboard engine.

2005 Yanmar 30HP. Quality. NOT.

[mikereed100]

Originally Posted by flicka

THANK YOU FOR ANSWERING, BUT MECHANICS HAVE DONE THEIR JOB
THEY HAVE AN IDEA, THEN THEY FIX SOMETHING THE ENGINE IS OFCOURSE WORKING BUT JUST FOR ANOTHER 2 HOURS. SINCE IT IS A STRANGE SYMPTOM AND I DO NOT WANT TO THROW AWAY MORE MONEY I HAVE DECIDED TO POST IT HERE. ANYHOW IT SEEMS I WOULD HAVE TO CHANGE THE ENGINE.

I've had the same experience with mechanics and as a result now do all my own work. Don't give up on it just yet. It is a fairly simple (and cheap if you do it yourself) process to replace a head gasket. If you are not mechanicly inclined this is a good way jump in and bond with your motor. If it fixes the problem you will feel good about yourself until the next thing goes wrong. If it doesn't fix the problem you will have eliminated one possible cause and can move on from there. Unless you have a cracked block you should be able to work this out eventually. Good luck and keep us posted.

Mike

[Bradley]

A 30 year old engine probably has a lot of problems. Before undertaking any costly repairs, I would price out a new engine.

[never monday]

cracked head?

[Boracay]

Since I never quite worked out what the first three were it must be the 4th that is giving trouble.

Or more seriously it sounds like you have a heat/temperature related problem.

Heat is flowing into a heat sink and when the sink is full the temperature rises.
When it rises past the trigger point the white smoke/lose power event occurs.

My guess is the engine/gearbox is the heat sink and the part that is temperature sensitive is oil related.

Quick and dirty fix : Make sure the oil is topped up fully before starting the engine. Change the oil to one of the newer synthetic types which could reduce heat build up. Check that the raw water intake is clear. Ensure that cool fresh air is reaching the engine, and that hot air is leaving the engine (try without engine cover if this is can be done safely).

Slow clean fix : Totally clean the engine/gearbox. Examine it carefully in a good light for any signs of damage or oil leaks. Carefully tighten (finger tight) all connections with the correct size socket or even a torque wrench if available. If gaskets are available take off the rocker cover and tighten the head bolts in the correct sequence with a torque wrench.

The bad news : You engine is complaining about its age and hard life. Spending large amounts of money on repairs may not be economic. How expensive/difficult is it to replace the engine?

[Ex-Calif]

White smoke indicates unburned fuel - The oily sheen in the water supports the diagnosis.

So you either have too much fuel or the temperature in the cylinder is being lowered causing incomplete combustion.

Temerature in the cylinder can be lowered if oil or water is getting into the combustion chamber.

If you have a fresh water cooling system and are not replacing fluid in the fresh water circuit then water loss might be ruled out depending how the raw water circuit is set up. You can also check to see if there is oil in the fresh water circuit. This could be another indicator of head gasket or (very unlikely) a cracked head.

However, a bad head gasket wouldn't fix itself after a brief shut down so I don't lean that way.

I don't know specifically how the injector is constructed but this could be an injector pump or fuel delivery problem.

Before I would embark on an expensive repower I would want to get to the bottom of things. A compression check, a removal and replacement of the nozzles and perhaps an injector pump replacement would be my first trail of troubleshooting.

As a single cylinder engine this shouldn't be too hard to track down.

[Chief Engineer]

Look for the simple things first.

You said you got water in the gearbox. Does the gearbox and engine share the same oil?

Have you checked your exhaust for blockage?

Do you have a temp gauge on the engine?

It could be any number of things

Remember the triangle of fire Air-Fuel-Heat

Originally Posted by Ex-Calif

White smoke indicates unburned fuel - The oily sheen in the water supports the diagnosis.


As a single cylinder engine this shouldn't be too hard to track down.