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OK to pinch off heater core hoses in a 240?


Feb 22, 2010
Portland, OR
I've got a leaking heater valve in my 1993 240, and am waiting for parts to come in. The valve leaks externally a bit, but also internally, so heat is partially on all the time.

I would like to just pinch off the heater core hoses in the engine bay just before they connect to the firewall. Is this OK to do without looping? I know in 740/940 the cooling circuit requires circulation, but I think the 240's aren't affected by zero flow, which happens anyway when the valve is closed.

Am I remembering correctly? OK to pinch these off for a week?
Yes you can, same as turning the heat off, with out coolant flowing through the heater core. I would replace the pinched hoses as the insides can brake down and cause a hose failure.
240's engines are the same as 940. Heater valves are different but not in basic function- they do not bypass. Only GM heater valve conversion lets you have a bypass. I think that means you are OK to pinch. When burping the cooling system after it was opened you are always advised to set to max heat, so may be run it first- then pinch.