cblankin

I am looking for a diagram of the coolant flow for a small block with A/C 1965 Corvette Does the coolant flow from the water pump thru the heater hoses to the heater core even though the heater "Pull for Heat" **** is not pulled. When I point my non-contact IR thermometer the highest readings are the heater hoses.

Powershift

1. Many of the less expensive IR guns have a set "emissivity factor" that does not account for differences in a black object or a white or silver object. So the IR gun reads a bit off. That may be what you are seeing. Expensive guns have a change mode for this, depending on the surface viewed.

2. For a SB with air conditioning, the coolant flow originates at the intake manifold, and flows thru 5/8 ID hose to the heater core (lower connection). There is (or should be) a vacuum operated coolant valve in this hose near the heater core.

The coolant flows thru the heater core and exists thru the 3/4 ID hose (upper connection) and flows past the expansion tank (where it tires into the tank) back to the water pump on the engine.

When you activate the HOT-out or COOL-in pull **** it opens or closes this water valve in the 5/8 ID hose. Open valve = heat -requires vacuum to the valve. Closed valve = no heat - requires no vacuum to the valve. This same pull **** also opens or closes a door inside the heater box.

This is all explained with diagrams in the Chevrolet Service Manual. The Owners Manual also has some info.

The hose going to the heater (with heater valve open) is probably going to be as hot (or perhaps a bit hotter) than the thermostat housing or the upper radiator hose.

Larry