Yanmar 2GM head gasket

[Roberto20010]

last week I noticeable amount of "smoke" came out of the starboard side of the engine, looked like it came from the head gasket.It did not seem like we were losing power, the boat was moving at a good pace; I slowed down and had to continue powering for a while at lower speed(we were in a really tight part of the IC) the smoke diminished with the lower RPM.
How hard is to change or fix the head gasket?
What else could it be?

 

[Alan]

First you need to verify that you do have a blown head gasket. Clean the area in question, check the oil for water contamination and run the engine again. Do not run the engine if the oil is contaminated with water/coolant. If you can see oil or water escaping from the head/block joint the gasket is leaking. This job is best left to a professional if you are not experienced with engine work.

 

[Roberto20010]

Alan,
I cleaned the area, mainly dried up oil, and the back of the engine, oil not dry.
I looked at the oil, black and shiny..how can you tell if there is water in it?
I ran the engine at the dock for about 40 minutes and I couldn't see oil or water or smoke coming out from anywhere..the exhaust looked gray/whitish, it was hard to see,too windy.

 

[MOTHER OCEAN]

Make sure your sea water strainer is not restricted causing the exhaust and head to overheat. Also check the antifreeze level th make sure that is not low, you may have overheated the engine.

 

[Alan]

Robert,

Black and shinny oil is a good sign. If it were contaminated with coolant the oil would look various shades of milky brown/black. I would run the engine again and keep an eye on the engine as it warms up. Use an infrared temp gun to read the engine temperature at various points on the head. They should all be relatively even after full warm-up.
Infrared temp guns are fairly cheap (around $40) and immensely useful tools for diagnosis.

 

[jtm]

I agree with Alan- I doubt you have a shot head gasket. On a car (ask me how I know) if you had a shot HG you would check your oil dipstick- and if it has got thicky "toothpaste" on the stick and in the oil in general ( assuming its just not some normal(minor/minimal )water condensation running down the stick then you are having the antifreeze and its water component mixing with your engine oil. On the 2GMF the upper center pulley pumps the antfreeze thru the internal system- 4 years ago I found that pulley shaft had broken( it was wiggly in the bushing) and it was leaking antifreeze thru the bushing unto the engine- I wonder if you are "steaming off" the antifreeze as it dribbles onto the hot engine and that will feel somewhat oily/slippy. BTW the replacement pump/pulley part was about $175 but an easy DIY fix.

Let us know how it turn out.

 

[Roberto20010]

My engine is cooled directly by seawater, so no antifreeze levels to worry about it;
and there was plenty of water coming out of the exhaust.
Tomorrow I'll get a infrared temp gun and check the engine temps.

 

[jtm]

roberto -In this engine there's an internal antifreeze side and the freshwater side - the freshwater cools the antifreeze side in the heat exchanger. the impeller for the antifreeze side is the upper center pulley. the impeller for the freshwater side is the small pulley on the bottom of the facing side.

 

[Roberto20010]

you are thinking the 2GMF, F for fresh water; I have the 2GM, no heat exchanger no antifreeze.

 

[Alex Dare]

Roberto,
Any chance the smoke you were seeing could have been from a seeping valve cover gasket leaking oil onto a hot part of the engine? If it was seeping, its possible the leaking positive crankcase pressure would blow the smoke making it look worse than it was. Just a thought....

 

[Roberto20010]

Alex,
I did find oil on the back of the engine when I cleaned; and the smoke was partly due to the oil burning, but there was also some steam blowing out the starboard top side.

 

[MOTHER OCEAN]

Could be your mixer elbow cracked or rusted thru alowing hot water to shoot out.

 

[Airframe]

It really isn't that difficult to change the head gasket. All you need is the correct tools, Yanmar shop manual and a torque wrench. There are no special tools required. The shop manual is pretty good at explaing the process. While you have the Head off take the fuel injectors in for cleaning and testing also have the valves redone on the head. Beware a head gasket is expensive $175

 

[Alan]

Airframe,

I agree that it's not brain surgery to replace a head gasket but it does require a certain level of knowledge to do it correctly. Screw it up and you could spend a lot more money fixing a bungled job. I've seen my share of butchered mechanical work.