yanmar 2gm20f coolant leak

[SandIsland]

Hi. this is my first post and have found a lot of helpful ideas over the years on many topics. However, I am not that good with technical mechanical stuff except for the basic maintenance so I could use some help.

My 1987 yanmar lost its fresh water coolant over the winter during storage on the hard. My engine also has a heat exchanger for the sea water cooling. The engine has about 1200 hours and I do not believe the fresh water pump has ever been replaced. If that may be the problem, is it much of a job to do and would you trust a boatyard to do the job or should I find a yanmar certified mechanic. I hate the thought that is might be a head gasket. Any thoughts would be appreciated. Thanks.

[DeepFrz]

Unless you know where the water leaked from I would advise that you not start replacing parts. Was there an antifreeze water mixture in the engine? If you had straight water there is a possibility that the water froze and possible popped an expansion/frost plug. But of course that is just a wild a@@ guess.

Find out where the water escaped and work from there.

There are many horror stories of shoddy workmanship done by "yards". I would suggest that if you have them do any work that you act as your own project manager or have someone who is qualified act as your project manager.

[boatbod]

First things first. Do a pressure test of the coolant system and find the leak. If you saw no sign of spilled coolant, it's likely a failed heat exchanger.

[SandIsland]

I live in Maine, so yes the antifreeze and water were mixed. The coolant probably leaked out over several months and there were no telltale signs as to where the leak originated. I did notice that a gasket may be at fault, but the location of the gasket is terrible. The gasket appears to be located on the main cylinder body behind the crankshaft V-pulley. If so, looks to me like the engine may have to be pulled. Ugh! All the hoses for the cooling system seem to be fine.

[SandIsland]

Would the leak occur in the heat exchanger if the engine had not been running since last Fall?

[Diesel Bill]

I agree with boatbod, Start by doing a pressure test of the cooling system. Top off the coolant and pump up the pressure tester to a safe test pressure, usually less than 20 PSI
and then start looking for the leak. Also the system should hold the gauge pressure for a while with out leaking down to quickly. Sometimes it's just a loose hose clamp needs tightening. No sense in throwing parts at it till you have an idea what the problem is.
Good luck.

[CAR54]

My boat has the same year and engine in it. If you the mean raw water coolent is lost the glass raw water strainer would likely crack, if winterizing of the engine had not been performed. If you mean the closed loop cooling system where engine anti freeze is added and is low just add yamar anti freeze and fill to to the very top. then put news paper under the engine and look for wet areas on the paper leave over night if necessary to locate the source of the leak around the engine. This will also give you an idea of the leak rate by gauging how far the coolent has dropped. A pressure test is the best way but you said I am not that good with technical mechanical stuff so this is the simplist way I can think of to trouble shoot this problem. The heat excharger is very well built on this engine so finding a fault in it seems highly unlikely.