Loosing Coolent

[rlmvallen]

2000 Bayliner with 5.0 liter MerCuiser with closed coolent system. Engine was rebuilt in 2004 and this summer noticed that water in closed coolent system was loosing coolent by a quart or a bit more every hour of operation, which in turn activated the alarm. Once I refilled system I could run some more. No water or antifreeze in Oil. Enging runs great. Have no idea where water is going. There is none in bilge area, none on intake. I see no sign of it anywhere. <br />ANY IDEAS?<br />THANK YOU

 

[Haut Medoc]

Re: Loosing Coolent

Welcome to iboats Well you know its going somewhere.......If the coolant is not in the bilge or oil, then the only other thing I can think of is blown head gasket from the cylinder to the water passage.I would pull the plugs and inspect them, for evidence of water....JK

 

[21270]

Re: Loosing Coolent

I had a problem close to youres, one of my 45 degree necks out of the manifold was leaking. I didnt know it, my resovoire tank would be empty at the end of the day. J.kopec pointed me in the right direction and now the problem is solved. I could atleast see the antifreeze in the bilge which is alot easier than not knowing where its going. Good luck.

 

[rbezdon]

Re: Loosing Coolent

if it is not in the bilge then it is almost certainly being consumed by the engine and exhausted out through the exhaust system. Usual culprit for this is a head gasket as suggested by one of the pros above. Not too many other options. JK suggests pull the plugs and inspect them. I would add a compression test and a check of the engine oil for any evidence of water/antifreeze.

 

[rodbolt]

Re: Loosing Coolent

last one I did that showed those syptoms was a bad riser gasket, the one before that was a popped headgasket. with no coolant in the oil or bilge it rules out an intake or external block leak. your most likly down to a headgasket or riser gasket. an automotive radiator pressure tester can help ya find it.

 

[Don S]

Re: Loosing Coolent

Since it has a closed cooling system, it could be a leak in the heat exchanger it self.<br />When the pressure builds up in the antifreeze side, it pumps it into the raw water side.<br />Pulling the heat exchanger and blocking the ports on the AF side and pressurizing with a coolant tester should locate the leak.<br />Put it in a tub of water, the bubbles will tell the story.<br />If no leaks found, then look for a head gasket.