Martec Freshwater system

[Simon054]

Hello,
I have a Yanmar 2GM20 engine fitted with a Martec freshwater system with an electric circulating pump and a calorifier. At around 4/4.5 knots (2000 revs) the system works well and the water temperature does not set off the alarm however above 5 knots (2300 revs +) and the water temperature slowly creeps higher and has triggered the alarm. The sea water pump is new with a new impeller and I have replaced all of the hoses due to their age and some minor leaks. If I fit another circulating pump with a higher flow rate across the calorifier will this keep the water temperature down at higher revs or should I fit a small radiator in the system similar to an oil cooler radiator across the air intake hose? Or has anyone solved the issue another way other than buying a new boat!!

 

[vyv_cox]

Has this condition always existed or come on recently? Have you checked that the heat exchanger is not fouled? Is the thermostat working correctly at the right temperature?

 

[Simon054]

It has always tended to run on the hot side, the flow through the heat exchanger seems fine both salt and fresh water but I have not checked the thermostat which is set a 75 degrees.

 

[vyv_cox]

Are you sure about seawater flow through the heat exchanger? You cannot judge it on what is coming out of the exhaust, which also includes bypass. Especially if the thermostat is not opening fully.

 

[Simon054]

My system does not have a bypass, the hose from the seawater pump comes into the heat exchanger then out to the exhaust manifold to the discharge point.

 

[kellys]

Did you ever resolve this problem? As I am considering adding a Martec system to my MD11A and have heard of this problem before.

 

[GrahamM376]

Did you ever resolve this problem? As I am considering adding a Martec system to my MD11A and have heard of this problem before.

I fitted one to an MD11C and had no overheating problems but the engine had been stripped and all waterways cleared out beforehand.

 

[kellys]

Thanks for the feedback, my engine is a MD11C not A. Currently I have a bit of a temp problem as the temp gauge does the usual rise and fall routine.
A few years ago had the heads off and gave it a good cleaning, but did not remove the cylinders (should have). The problem disapeared but has just started to show up again. I need to change the cylinder seals to stop oil leaks and this time will remove the sleeves from the cylinders and give it a clean. So to prevent the blockage again I was considering the martec system or rigging up some sort of system to be able to flush the engine with sweet water. The martec is a bit expensive but seems like it would have advantages over raw water cooling such as hotter consistant operating temps and no more clogging problems

 

[GrahamM376]

Thanks for the feedback, my engine is a MD11C not A. Currently I have a bit of a temp problem as the temp gauge does the usual rise and fall routine.
A few years ago had the heads off and gave it a good cleaning, but did not remove the cylinders (should have). The problem disapeared but has just started to show up again. I need to change the cylinder seals to stop oil leaks and this time will remove the sleeves from the cylinders and give it a clean. So to prevent the blockage again I was considering the martec system or rigging up some sort of system to be able to flush the engine with sweet water. The martec is a bit expensive but seems like it would have advantages over raw water cooling such as hotter consistant operating temps and no more clogging problems

Quite often it's a blockage in the manifold causing overheating. IIRC (thinking back 15 years) there's a plug somewhere under the thermostat cover which blanks off the long waterway. This can be drilled out and the passage cleaned out, then resealed with plastic metal or similar.

 

[kellys]

Quite often it's a blockage in the manifold causing overheating. IIRC (thinking back 15 years) there's a plug somewhere under the thermostat cover which blanks off the long waterway. This can be drilled out and the passage cleaned out, then resealed with plastic metal or similar.

Just a update, I have found the reason for the temperature gauge cycling. The small hole that is in the part of thermostat that moves was completly blocked. After cleaning this out it seems the engine temperatue gauge cycling has stopped and the display stays more or less around the ¨T and E¨ on the display. Of course this was found after numerous other things were done with litte change. I had done the wire in the drains with only a tiny bit of crud coming out, removal of exhaust manifold, very little crud, new impellor (no change), flushed cooling pasages in reverse gear, not much gunk at all. I will check this first next time.

Shane

 

[scottie]

Did you ever resolve this problem? As I am considering adding a Martec system to my MD11A and have heard of this problem before.

MD11A does not exist
It's either MD2 or 11C or 11D

 

[scottie]

Remember to check that alarm is set for fresh water thermostat

 

[kellys]

typo