The Stovebolt Site Forums The Shop Area Engine Shop Close heater circuit for better cooling???

HI...I was told that closing the valve to our 55/235 heater lets the engine cool better during the Summer months as the water circulates faster???? I have always kept the heater valve open Winter and Summer. In Winter we need the heater and Summer a longer path for more cooling??? What gives????? T/C Steve

flow rate won't be any different open or closed .... the heater isn't "inline" with the main block flow, and doesn't affect that much larger flow .... OTOH, in the cab you don't really want any added heat in summer, which is the only reason to have a shutoff on it

Bill

I think you have the right idea; letting the water circulate through the heater core would cool the engine more than the radiator alone. Turning on the heater fan on will help even more.

But if you have to leave the heater on in the summer to keep from over heating there is something wrong with the cooling system.

You only need to have water flow in the heater on when you want heat.

Grigg

NO problem with over heating. I was told it was better for the heater core to keep the valve open all the time....OK.....Then I was told / read to close it for better cooling.....NOW...I will close it during Summer and once in awhile during Summer I will open the valve to keep the heater core from getting Gradoo inside..agreed? T/C Steve

sounds fine, but shutting it for a couple months a year won't be a problem if you keep the system fairly clean

Bill

I have an original old round heater in my 46 and am about to put a shutoff on the heater hose leading to it because the cab gets very warm on a hot day...not good. You should be fine just closing it off for a few months a year.

OK...you guys have me convinced that what I heard / read is a Chevy truck urban legend..... thanks to you for the help and a cooler cab! T/C Steve

I thought the heater served as a bypass which prevents hot spots before the thermostat opens & that's why the 261 has a by-pass thermostat. Also it doesn't dead head the pump when the thermostat is closed.

Harold - why would they have made these trucks standard with no heater if it served a vital purpose other than heating the cab? the use, or not, of a heater should have zero effects on the functioning of the engine

Bill

I don't know for sure. Small block chevys have an internal bypass. Big blocks use an external bypass. Many other late model engines have an external bypass hose. Isn't that why people drill small holes in the thermostat - to prevent hot spots in the head prior to the thermostat opening up when there's no bypass system? Is it possible hot spots in the head on warm-up with no bypass was discovered after these engines were designed?

Harold makes a good point.
With the heater valve ON, the coolant can circulate through the head before the thermostat opens.
The 261 bypass thermostat housing does the same, even if the heater valve is OFF.

A small hole on the thermostat helps bleeding off steam bubbles during warm-up.

I leave mine open and I've noticed the gage reads cooler.

Now when it s 95 degrees out, I do not want the heat in the cab but with the vent open it really doesn't matter as it blows out. I have it closed when I on the open road but in traffic around all the stop in go stop lights, I'll open it. I don't know the real value of how the system works but in my rig, open reads cooler for the motor.