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FM 118 cooling system

Montermahan

Registered
I'm getting ready to fire up a 118. Adding water, I notice there is no provision for preventing cooling system from over pressurizing.
I guess the radiator will allow for expansion, but what would happen if something like a head gasket leaks.
 

KidDynamo

Subscriber
Last Subscription Date
02/18/2020
If it is similar design to my little 52, the condenser isn't full of coolant like a "radiator" so there is plenty of air to compress without allowing pressure to build up much.

My unit had a fill port that would be filled to the top and then the pipe plug installed. The resulting fluid level was approximately to the top of the water hopper.
 

Reed Engine

Subscriber
Last Subscription Date
07/10/2019
In the middle of the radiator near the bottom there is one tube that has an ice pick hole punched in it. That same tube is soldered shut on the bottom (open on top). This allows pressure to be released without letting the coolant out.

If you blow a head gasket its not going to run.

Only fill the water tank half full. The original radiator is a vapor phase condenser. Steam goes up into it and is cooled then condensed to fall back down into the water tank / hopper.
 

AKMark

Subscriber
Last Subscription Date
04/02/2020
I have been wondering about this myself. I have a Z 739 and while running the thermometer tops out at about 200 but the condenser doesn't even get warm. I have it filled to the top with antifreeze. Should I drain some out?
 

dkamp

eMail NOT Working
uh... Yeah... unless your 739 has been set up for some other cooling plan, the radiating portion is not intended to be full of liquid. It's based on evaporation, and filling it to the top defiles that principle...

but I'll bet if you run it long enough that way, under a heavy load, it'll probably empty itself in an embarrassing way. Park it near a fire hydrant... it'll scare the neighborhood canines away.:brows:
 

Andrew Mackey

Moderator
Last Subscription Date
05/14/2017
Not a good idea to run with antifreeze. The 'radiator is actually a condenser. The water boils at 212F and turns innto steam. The fan cools the condenser returning cool water to the hopper. Antifreeze raises the boiling point to 250+ and when antifreeze is boiled it turns caustic which may eat the brass out of the condenser.
 

Reed Engine

Subscriber
Last Subscription Date
07/10/2019
We use FM in the oilfield here in Okla quite a bit. We use 50/50 water antifreeze. Yes it does raise the boiling temp but water freezing and busting the cylinder or head is not good. If you don’t add 50/50 keep it drained.
 
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