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mercruiser heat exchanger plumbing question

dudleypullin

New member
what is the plumbing config when changing over to fresh water cool on small block mercruiser - where do the salt water hoses hook into the manifolds? Rebuild engine adding the heat exchange to make the system closed (fresh water)
Dudley
 
what is the plumbing config when changing over to fresh water cool on small block mercruiser - where do the salt water hoses hook into the manifolds? Rebuild engine adding the heat exchange to make the system closed (fresh water)
Dudley...... we take those who call a Closed Cooling System "FWC" out back and horse whip them.
There is nothing fresh about Ethylene Glycol coolant! :D


I'll assume that you are installing a Half System since you asked where the salt water hoses connect to the exhaust manifolds.
If so, look at your new H/E coolant inlet/outlet as though these were on a car/truck radiator.

The lower port will connect to your engine circulating pump suction port.
The upper port will connect to your thermostat housing outlet port.


Seawater "in" at the H/E seawater inlet port.
"Spent" seawater is then directed to each exhaust manifold via a splitter or T fitting...., unless the H/E is equipped with twin outlets.

A WH or Cabin Heater will connect up as shown below.
It is important that these hoses be connecte as shown. If not, we end up with an unbalanced system and poor coolant heat transfer.



Not recommended if the engine spent any time in salt water, just ask around you'll find out.
Rebuild engine adding the heat exchange to make the system closed

He's OK with a freshly built engine.
But I do agree.... if this was a previously raw water cooled engine, changing over will pose some issues.
 

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