Yanmar 3GM cooling problem.

[capnsensible]

Anyone ever had and solved this??

Fresh water header tank slowly filling when engine is running. Is it possible for sea water to leak across from the cooling tubes to the fresh water side, or possible seal or gasket leak??

Any advice most welcome!!

CS

 

[Cloven]

Is it actually overheating or just a case of expansion of the cooloing water into the header tank?

Anyone ever had and solved this??

Fresh water header tank slowly filling when engine is running. Is it possible for sea water to leak across from the cooling tubes to the fresh water side, or possible seal or gasket leak??

Any advice most welcome!!

CS

 

[capnsensible]

Hello!

Engine runs at normal temperature, not overheating. Overflows about a cup /hour ish. Read of similar on a Yanmar troubleshoot forum, but no answer to the fault!

 

[pagoda]

Hello!

Engine runs at normal temperature, not overheating. Overflows about a cup /hour ish. Read of similar on a Yanmar troubleshoot forum, but no answer to the fault!

Other than tasting the cooling water (spot on finger) - the other way of testing for salinity ( and Chloride ions) is to drop into a sample a few drops of Silver Nitrate. If you get a rapid pure white precipitate, you have salt present. Where you get Silver Nitrate these days I'm not sure. As chemical wizz kid of 15 - I had a massive collection of stuff in the garage, including Silver Nitrate..

Just a thought..?

Just discovered you can acquire it on Ebay. Do take great care- wear rubber gloves -it is a very caustic material -and used to be used for spot killing off warts !

 

[vyv_cox]

In theory it is not possible for cooling seawater to leak into the fresh water side due to pressure differences. The coolant is normally at about 12 psi (less than 1 barg) whereas the seawater is nominally at atmospheric pressure, being open-ended. However it has been reported several times with Volvos that an exhaust manifold partial blockage can increase the seawater pressure sufficiently that it blows past the seals into the coolant. This is partly a result of the somewhat difficult seal arrangement in the Volvo heat exchanger. I have not heard of it on a Yanmar but cannot discount it.

Another cause can be a perforation in the heating coil of a calorifier. Domestic water systems are controlled at a pressure somewhat higher than the coolant (2 bar v. less than 1 bar) so leakage into the coil will result in overflow of the coolant.

I have been told recently of a case in which a leaking head gasket has resulted in overflow of the coolant into the bilge but I know no details. Also a Volvo, not Yanmar.