Yanmar 1gm10 coolant poluted

[jeroenarends]

Hi there,

We are having a problem with our yanmar 1gm10 diesel engine.

The engine it self runs fine, however the coolant water is polluted since a film if forming on the water.
I replaced the injector, this did not help.

I also tested the spray pattern of the old and new injector, both were fine.

The oil look oke, no sings of water in the oil.
Are there test I can perform to narrow down the root cause of the problem?
The engine is running on GTL without any problems up to now.

[skipperpete]

A 1 GM certainly reduces the possibilities. So raw fuel in the exhaust can occur from startup. Generally ... but not always, in-line pump governors rest in maximum fuel position for the next startup then pull back to idle almost instantly (and some even have an extra “ overfuel” button “Simms minimec” on fords). Consequently there’s a bit of raw fuel that doesn’t get burnt but vaporizes and ends up re condensing in the mixer elbow and into the Aqualock. Because the (tiny) amount of fuel floats in the aqualock it takes a fair bit of running to clear that from the long run of exhaust out to the transom. This gets worse in cold conditions.... you don’t have glow plugs to get a warmer start on the 1GM.
If you return from a trip out and you still have the sheen on the water it could be just a very cold engine.... do you have a temp gauge? And a thermostat?
Finally, I seem to remember your 1GM having a flange mounted raw water pump, there’s at least a chance that engine oil could get into the cooling water at that point.... a infinitesimally small chance though.
What’s GTL?

[Wotname]

Originally Posted by skipperpete

...............
Finally, I seem to remember your 1GM having a flange mounted raw water pump, there’s at least a chance that engine oil could get into the cooling water at that point.... a infinitesimally small chance though.
What’s GTL?

Gas To Liquid. Converts natural gas etc to liquid hydrocarbons.
Shell makes a range of GTL base oils and fuels.

Yes, the 1GM does have a direct driven raw water pump but usually any leakage is the other way i.e. water into the crankcase. But as you say, there could be a infinitesimally small chance of oil getting into the water.

[Compass790]

Welcome to the forum jeroenarends,
Did the problem happen suddenly or did it get worse over time?
Any smoke with the sheen? Have you ever cleaned or replaced the exhaust elbow?
Does it start quickly? If you answer these questions it may help to narrow it down.

[skipperpete]

Thanks Wottie, I’ve never heard of GTL before.

[Boatwright]

How many hours on the engine? High time could mean bad valve guide seals. Any white smoke at start up?

[Chablis 1]

Originally Posted by Compass790

Welcome to the forum jeroenarends,
Did the problem happen suddenly or did it get worse over time?
Any smoke with the sheen? Have you ever cleaned or replaced the exhaust elbow?
Does it start quickly? If you answer these questions it may help to narrow it down.

Hi, I’ve a Volvo D2-55F, 5000h, and have exactly the same symptoms. First I thought the heat exchanger was rusty. rinced and changed coolant several times. The coolant always becomes rusty again. The phenomenon is increasing by time. Changed also the exhaust elbow 150h ago. The engine starts perfectly, runs beautifully. Never any smoke or oil consumption. Last week after been motoring for 30 min I went WOT for 20-30 seconds twice to eliminate carbon built up. Some black smoke, not much.
At anchor I notice a spoon full of muddy orange cream in the bilge that come out from the overflow hose, same stuff on under the coolant cap. The coolant had some on the surface as well. What’s happening?

[Compass790]

Originally Posted by Chablis 1

Hi, I’ve a Volvo D2-55F, 5000h, and have exactly the same symptoms. First I thought the heat exchanger was rusty. rinced and changed coolant several times. The coolant always becomes rusty again. The phenomenon is increasing by time. Changed also the exhaust elbow 150h ago. The engine starts perfectly, runs beautifully. Never any smoke or oil consumption. Last week after been motoring for 30 min I went WOT for 20-30 seconds twice to eliminate carbon built up. Some black smoke, not much.
At anchor I notice a spoon full of muddy orange cream in the bilge that come out from the overflow hose, same stuff on under the coolant cap. The coolant had some on the surface as well. What’s happening?

Dont know yr engine but did you check your heat ex for leaks? Salt water maybe getting in coolant

Cream could be oil in coolant. Leaking head gasket maybe?
Might be time to try a cooling system tester

[Chablis 1]

Originally Posted by Compass790

Dont know yr engine but did you check your heat ex for leaks? Salt water maybe getting in coolant

Cream could be oil in coolant. Leaking head gasket maybe?
Might be time to try a cooling system tester

I thought about head gasket but supposed that if there was a leak I would lose compression, some oil and have white smoke as well.
Could saltwater make coolant look rusty? I’ve no visible water leaks.

[skipperpete]

Well Chablis1 , saltwater could make the coolant rusty and sometimes if the heat exchanger leaks across from the raw water side to the coolant side it’s possible for this to occur without having a low coolant tank level especially if the engine top is at about waterline level ......but usually the presence of salt in the coolant shows as a rusty pressure cap. It would be useful to pressure test the coolant side and see if it lowers the level of the top tank after maybe 5-10 mins at 5psi.

[jeroenarends]

Thank you al for your help

Originally Posted by Compass790

Welcome to the forum jeroenarends,
Did the problem happen suddenly or did it get worse over time?
Any smoke with the sheen? Have you ever cleaned or replaced the exhaust elbow?
Does it start quickly? If you answer these questions it may help to narrow it down.

The problem started sudenly after som heavy use of the enging ( i used the 1gm10 to get someone of the ground)


there is more smoke prduced than i am used to.


I never cleaned the exhaust elbow, does this part need cleaning?


Thanks agian

[Compass790]

Originally Posted by jeroenarends

Thank you al for your help








The problem started sudenly after som heavy use of the enging ( i used the 1gm10 to get someone of the ground)


there is more smoke prduced than i am used to.


I never cleaned the exhaust elbow, does this part need cleaning?


Thanks agian

Oh hell yes the exhaust elbow & exhaust port does need regular cleaning.
It's a common problem especially acute on raw water cooled Yammers AFAIK

Check your service manual for details on elbow inspection. If you havent got a service manual check CF library.


What colour is the smoke?

[Compass790]

Originally Posted by Chablis 1

I thought about head gasket but supposed that if there was a leak I would lose compression, some oil and have white smoke as well.
Could saltwater make coolant look rusty? I’ve no visible water leaks.

I think getting salt water in the coolant would be the only way it would get rusty quickly if coolant is new. path for that is leaking heat exchanger AFAIK.

Doesnt take much oil to make cream & i still would check coolant for combustion gases. You need to eliminate them

DougR knows volvos, you could PM him for Volvo specific advice.

or Skipperpete may be able to help.


EDIT:Whoops just saw skipperpetes earlier post confirming heat ex possibilty

[skipperpete]

Originally Posted by Compass790

I think getting salt water in the coolant would be the only way it would get rusty quickly if coolant is new. path for that is leaking heat exchanger AFAIK.

Doesnt take much oil to make cream & i still would check coolant for combustion gases. You need to eliminate them

DougR knows volvos, you could PM him for Volvo specific advice.

or Skipperpete may be able to help.


EDIT:Whoops just saw skipperpetes earlier post confirming heat ex possibilty

Nope Compass790, you raised the heat exchanger proposition in post #8, I never noticed it at the time.

[Wotname]

Originally Posted by jeroenarends

Thank you al for your help








The problem started sudenly after som heavy use of the enging ( i used the 1gm10 to get someone of the ground)


there is more smoke prduced than i am used to.


I never cleaned the exhaust elbow, does this part need cleaning?


Thanks agian

Then you have probably stirred up years and years of carbon build up in the elbow, water trap and exhaust hose. Running the engine lightly loaded creates lots of carbon and it gets deposited throughout the exhaust. A hard run loosens it up and pushes some of it out.

And yes, cleaning the exhaust elbow is critical maintenance. They corrode out and then you are in a world of hurt.

The smoke was from overloading the engine (overfueling), I wouldn't worry about the smoke on this occasion.