New heater core installed - Summer operation?

Hello all,
I finally installed my new heater core in my M931. Ended up taking out the entire heater box to remove and replace it. Now that warmer weather is here (finally) I plan to shut the coolant flow to the heater core using the 2 shut-off valves. Is it OK to leave the coolant in the core or flush and drain it out. Or is it wise to open the valves every once in a while to move the coolant inside and out of the heater core.

BTW, lesson learned... When I flushed and replaced the coolant last year, I forgot flush the heater core!

Thanks!

I don't shut off my valves in the summer time. I do though have a cable operated valve that is inline (that I installed on my deuce) on the hose that is designed to not completely close. The reason for this is so that the coolant still flows through the core to keep the core in good condition and not have stagnant coolant stay in the core. Also if you shut off both valves, it does not leave any room for expansion and contraction of the coolant in the core during heat cycles. Maybe its the engineer in me talking, but I would only want to shut off (or partially shut off) one of the valves, preferably the one on the return side of the system. Your heater core is under the hood and just closing the damper would probably be enough to keep the heat out. Its up to you though. I prefer a little bit of coolant going through my core even in the summer time though.

If you flushed the coolant before in the truck, were the heater valves open when you did it? Some would still drain out of the core because the core is mounted on the side. So all is not lost.

Thanks very much for the detailed reply!

What I found my heater core was leaking can I safely shut both valves to run it? I'm guessing coolant would still circulate?

DEAD THREADS ARE AWESOME!

You can shut off the heater core, and safely run the engine.

74M35A2 said:

DEAD THREADS ARE AWESOME!

You can shut off the heater core, and safely run the engine.

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Better to bring back old ones than start new ones , makes searching easier.

Completely agree.