"I have a Chrysler LM318 in a
"I have a Chrysler LM318 in a 26 foot cruiser with a closed cooling system.Recently fitted a coolant bottle, hose, and recovery tank cap rated at 13lbs. On some occasions the coolant expands half fills the bottle about 2 litres. I think that is about 2quarts in your terminology, and as the engine cools, sucks the coolant back in over a 7hour period till engine is cool, and all is well.
On other occasions, especially recently, the coolant is expelled, the engine cools, no coolant is sucked back in, and when the engine is cold, remove the tank cap, and find the coolant full to the cap level.
The engine is apparently " making" its own coolant. My marine mechanic says this defies logic. We know the heads, and head gaskets are good. No water in oil, no oil in water, no bubbles in coolant with engine running. Pressure tested cooling system, no drop in pressure. If the heads are good I suspect the only other place is the heat exchanger, however with 13 lbs pressure in the system and no pressure on the raw water side of the heat exchanger, it could only leak out, not leak raw water in, and besides there was no leakage according to the pressure test.
I have had a wild thought brought on by frustration, and am seeking your advice before I start pulling things apart, bearing in mind my boat is about 160 miles away, and not handy to any marina.
My wild thought is that there is a small domestic hot water system for use in shower and galley, which is heated by engine coolant being piped through it after exiting the heat exchanger.
I presume, but do not know, that this works similar to the heat exchanger.
This hot water system is controlled by a pressure pump that keeps the tap water under about 18 to 20 lbs pressure with delivery of about 4 gallons a minute.
Is it possible that if there was a hole in a pipe in the hws, that the higher pressure on the domestic water side may force water into the coolant in the engine,which is only 13lbs, thus replacing the expelled coolant.
Is this a possibility, or am I on the wrong track altogether and there is a perfectly logical explanation that I am missing entirely.
Your comments or advice will really be appreciated, and I hope someone will take the trouble to reply."
"I have a Chrysler LM318 in a 26 foot cruiser with a closed cooling system.Recently fitted a coolant bottle, hose, and recovery tank cap rated at 13lbs. On some occasions the coolant expands half fills the bottle about 2 litres. I think that is about 2quarts in your terminology, and as the engine cools, sucks the coolant back in over a 7hour period till engine is cool, and all is well.
On other occasions, especially recently, the coolant is expelled, the engine cools, no coolant is sucked back in, and when the engine is cold, remove the tank cap, and find the coolant full to the cap level.
The engine is apparently " making" its own coolant. My marine mechanic says this defies logic. We know the heads, and head gaskets are good. No water in oil, no oil in water, no bubbles in coolant with engine running. Pressure tested cooling system, no drop in pressure. If the heads are good I suspect the only other place is the heat exchanger, however with 13 lbs pressure in the system and no pressure on the raw water side of the heat exchanger, it could only leak out, not leak raw water in, and besides there was no leakage according to the pressure test.
I have had a wild thought brought on by frustration, and am seeking your advice before I start pulling things apart, bearing in mind my boat is about 160 miles away, and not handy to any marina.
My wild thought is that there is a small domestic hot water system for use in shower and galley, which is heated by engine coolant being piped through it after exiting the heat exchanger.
I presume, but do not know, that this works similar to the heat exchanger.
This hot water system is controlled by a pressure pump that keeps the tap water under about 18 to 20 lbs pressure with delivery of about 4 gallons a minute.
Is it possible that if there was a hole in a pipe in the hws, that the higher pressure on the domestic water side may force water into the coolant in the engine,which is only 13lbs, thus replacing the expelled coolant.
Is this a possibility, or am I on the wrong track altogether and there is a perfectly logical explanation that I am missing entirely.
Your comments or advice will really be appreciated, and I hope someone will take the trouble to reply."
