'72 w/ air heater shutoff valve

[Tom L.]

I am considering adding a heater shutoff valve on my LS-5 W/ A/C. I searched the archives and found many threads discussing this. However, none of them (that I found) mentioned wheather they had A/C.

The reason I ask is the water flow through the expansion tank. It is piped on my car (and in the AIM) so that the hot water goes from the engine to the heater core, to the expansion tank and back to the engine.

My question is this, if I put a valve in that line, won't any air in the system be prevented from following the described path to the expansion tank where it belongs? Thanks!

[John H.]

Re: '72 w/ air heater shutoff valve

Lynn -

Just put the valve in the 5/8" hose from the intake manifold to the heater core inlet - that's where the factory put it; it'll work fine.

[Michael W.]

Re: '72 w/ air heater shutoff valve

I think there's a small diameter hose coming off the top of the radiator going to the expansion tank for this purpose.

[Tom L.]

Re: '72 w/ air heater shutoff valve

John, thanks for the reply. I was not sure that the hose routing was the same in other years in the same app. My AIM only shows model year '72. I think I'll give it a try and report back if needed.

Mike, I had brain fade after many years without working without a car with an expansion tank. When working with late model stocks we were diligent in making sure there were no dips in the vent line that could serve as a trap. I forgot that, checked the line on my car and found a HUGE dip before entering the expansion tank.

Hopefully I'll put the valve in the 5/8" line and correct the dip and be cooler in the cockpit!

Have fun!!!

[Joseph H.]

Re: '72 w/ air heater shutoff valve

Another idea is to bypass the heater core altogether. Someone did this to my 69' prior to me owning it, even putting caps on the heater core to protect it. It only gets driven in nice warm weather and this really helps cool the inside down, especially since I do not have air, but my top does come off................