H41 losing coolant somewhere

[Nachismo]

2008 H41DS with 4JH4E. Some tiny amount of coolant disappears without a trace. Never goes over 175 deg under way, but every 5-6 hours about 4oz lower in the reservoir. Already tightened every obvious connection, including the water heater loop. No puddles, no vapors, NADA! Where is my coolant going?

 

[Nodak7]

2008 H41DS with 4JH4E. Some tiny amount of coolant disappears without a trace. Never goes over 175 deg under way, but every 5-6 hours about 4oz lower in the reservoir. Already tightened every obvious connection, including the water heater loop. No puddles, no vapors, NADA! Where is my coolant going?

Nach, I had the same issue for awhile. I found one of the coolant drains in the rear of the engine had loosened a bit and was cracked open. never had a puddle or anything but the slightest of leaks. Also I have found a known problem with the coolant filler nozzle attachment to the top of the engine had a small leak. That one has been more persistent and difficult to repair. One other item you did not mention is how does your exhaust look? Does it have lots of white smoke. Is there stuff on the hull where the exhaust comes out. Both of these might indicate a leak into the engine. Good luck!

 

[dmax]

Along with checking out the exhaust, look at your oil to make sure it's not contaminated with anti-freeze (will get milky).

 

[Nachismo]

Nodak7 nailed it! A tiny crank of the aft drain valve & no more disappearing coolant! THANKS!

 

[senang]

Just for the record of possible leaks of cooling water don’t forget the hot water tank heated by the engine coolant!

 

[splax]

on the 34 the water heater hose wears on the hull ribs. check the bilge for coolant