Merc 165 engine cooling system used to feed a heat exchanger.

[DonL]

I've installed a heat exchanger in the vessel's cockpit and feed it with hot water from the engine water pump. The return is connected to the exhaust manifold.
Unfortunately, no hot water seems to enter the hose at the engine.

I suspect that there is insufficient pressure. The total hose length is about
30'.

Another consideration is back pressure at the manifold?

Have not yet tried a booster pump.

Thoughts?

DonL

 

[ken_23434]

Re: Merc 165 engine cooling system used to feed a heat exchanger.

I am pretty sure the water going to the heat exchanger from the engine should come FROM the thermostat housing, not the water pump. Once the engine warms up, the thermostat will open and allow the water to go to the heat exchanger. The big hose at the water pump (talking the one on the front of the engine) is a suction to the pump, NOT the discharge.

If you download the service manual that is in the link at the top of the forum called Adults Only, there is probably diagrams for the engine that will identify where all the hoses go to/come from.

 

[ken_23434]

Re: Merc 165 engine cooling system used to feed a heat exchanger.

I found a diagram. It says it covers the 165, so hopefully it covers the engine you are trying to work on.

 

[Bondo]

Re: Merc 165 engine cooling system used to feed a heat exchanger.

I've installed a heat exchanger in the vessel's cockpit and feed it with hot water from the engine water pump.

Ayuh,.... Do you mean as in a Heater, or Water Heater,..??

The circulating waterpump on the motor is the Low-pressure point,+ is where the water is Returned to....

You need to find a plug in the Head, Before the T-Stat to get Hi-pressure Hot water...
I've done it on V-motors,... I donno if there's an available port on the head of your motor or not...

 

[DonL]

Re: Merc 165 engine cooling system used to feed a heat exchanger.

The heat exchanger is a cabin heater.

The feed comes off a small fitting on the engine circulating pump, just above the large hose.

The installation was done by a marine mechanic - with NO experience in this endeavour. From comments, I'm beginning to see the light - now to find a high pressure fitting!!

DonL

 

[Bondo]

Re: Merc 165 engine cooling system used to feed a heat exchanger.

The feed comes off a small fitting on the engine circulating pump, just above the large hose.

Ayuh,... As noted above,... That's the Return...