Engine Coolant Expansion Tank

[Interlude35]

We added an engine coolant expansion tank to eliminate the possibility of an air lock in the hot water heater and the engine. “Eye Balling” the elevation of the hot water heater to the top of the engine radiator cap It appeared the hot water heater may be slightly higher,which could create air blocks forming in the coolant system. The hot water heater did not make hot water from the engine but worked great when using shore power. The engine coolant now makes hot water and the engine running temperatures are very consistent . As part of this change we eliminated the coolant overflow tank at the engine. The coolant expansion tank is located in the port aft cockpit locker.

John & Marilyn Ferguson
“Interlude” 2005 hull #316

[wolfe10]

John,
Please describe exactly what you did.

Did you "T" in at the water heater and then run a line up to the new reservoir? If so, which line at the water heater?

[Interlude35]

Hi Brett- added a "T" to the engine cooling hose stern connection on the hot water heater(HWH) I replaced the HWH with an ISOTEMP HWH but the connection location to the engine coolant hose would have been about the same as with the original HWH. Then connected a 3/8" hose to a commercial MOROSO coolant expansion tank which I mounted in the stern cockpit. The MOROSO coolant expansion tank now becomes the engine fill tank with a 7psi rating radiator cap. Mounted and connected ,via a hose, the now unneeded plastic overfill tank near the MOROSO expansion tank for any overflow from the MOROSO coolant expansion tank. The radiator cap on the engine manifold must have a higher psi rating than the radiator cap on the coolant expansion tank( the original was 14 psi which was adequate). Eliminated the storage shelf for now (maybe always) increasing access to the HWH, refrigeration unit and steering cables.

I am attempting to send you some pictures but have not mastered the process to attach them.

John & Marilyn Ferguson
Interlude
2005 Hull 316

[russp]

Hi John,

This is going back a bit, but wondered how you closed off the coolant bleed at the engine block radiator cap? As I read your article you only have the one bleed point from the coolant circuit and that is aft above the hot water heater?

Regards

[Interlude35]

Hi Russ - I left the old radiator cap (14 PSI rating) on the engine. I installed a 7 PSI radiator cap on the remote coolant expansion tank. I removed the connection to the overfill tank and left the connection hose open to the bilge. It has never discharged any coolant. John