Air lock in coolant

[Jim]

I have just changed the anti-freeze in my 1984 2GM Yanmar and seem to have an air lock in the cooling system. I do have a heat exchanger for the water heater. The engine gets hot. I noticed a plug with an allen wrench insert on the water pump. Can this be removed to bleed the system of air? It looks like the plug has never been removed and I would imagine it would be very tight. I have filled the hoses to the water heater but that didn't help. Also the hoses are not getting hot and neither is the coolant in the engine heat exchanger. I have seen some similar stories in the archives for other engines but not the 2GM engine. How do I get the air out?

 

[Gene Barton s/v Paradigm]

Thermostat?

I'm certainly no engine expert, but it seems to me that even if you had some air in the lines, the exit cooling line hose would still get hot unless the thermostat is failing to open. I'd suggest checking that. Even if the pump goes and there's no circulation, the hose should still warm up. But if the thermostat isn't opening, that would match your symptoms.

 

[Jim]

Found the slution

Well I will answer my own problem. First of all I have a 2 GMF engine. I detached the forward hot water heater hose at the engine. It is the one directly behind the engine water pump pulley. I then cut a 2 ft. piece of garden hose and slid it on. I then took off the fill cap on the heat exchanger and added coolant via funnel to the hose. When the coolant filled the heat exchanger I capped it and removed the hose and reconnected the water heater hose [make sure the water heater hose is also filled before reconnecting] and presto, it worked perfect.

 

[Ernie Rodriguez]

Another way

I had the same problem with my modified Yanmar 3GMD, originally a sea water cooled engine with the SENDURE mod kit that added a heat exchanger and an engine driven Jabsco pump, identical to the Yanmar sea water pump which is used for circulating the sea coolant. Long hoses between the heat exchanger and the hot water tank made it difficult to get all the air out of the system. I used a simple hand operated pump to pump the anitfreeze 50/50 solution through the engine drain plug. This forces all the air out of the system . You simply connect the hand pump hose to the engine drain hose, open the valve on the engine, open the filler cap on the water resorvoir, (or watch the level in the overflow tank if you have one) then work the pump until you have clear antifreeze solution coming out of the cap (or into the overflow tank), then close the drain valve on the engine, and you are done. The pump I used is one of those small ones that are sold in automotive parts stores for pumping oil from a quart container. Fits right on top of the antifreeze container and the small output hose of the pump fits right into the drain hose.ErnieErnie