2.3L ('83-'97) coolant flow (path) through heater core

[racsan]

I was under the impression that coolant went through heater core from thermostat housing to core then to the water pump, Tonight I had switched hoses on the heater core then ran it in case there was a air pocket to be found. I ran it for about 20 min at idle, with my lazer temp scanner tool I observed 130 at the hose connection from the water pump and 95 at the other connection (going to thermostat housing) I noticed by feel that the hoses weren’t the same temperature at the core connections and decided to use my more accurate tool on it. Since its quite a difference in in vs out hose temps (no matter what way it’s supposed to flow) it looks like I need to try a heater core, glad its easy on this and fairly cheap. even though the current core is only about 4 years old, something is not right here.

 

[Uncle Gump]

You should drop in temp across the hoses as the heat is being transferred to the incoming air.

 

[racsan]

true, but I wouldnt think there would be that much of a temperature difference as the blower motor wasnt on at all during this running time. I will see what it does tomorrow on the drive to work.

 

[RonD]

You are correct about the flow direction

The heater hose near the thermostat is the OUT to heater core
Water pump connection is the return from heater core

The water pump pushes coolant thru the block and up to the heads then thru the intake(V6 engine)crossover to thermostat area
Coolant always flows thru the heater hoses back to water pump, and thermostat, even when wide open, can't handle all the flow of the water pump so coolant is always "forced" thru the heater hose

 

[racsan]

ok, I thought so, so why would my “outlet” hose at the core be 30 degrees warmer than the “inlet” hose? Thats what really confuses me.

 

[Uncle Gump]

I missed that part in the original post...

My guess is the devil lives in your heater core. Or the dash is on fire!

 

[racsan]

it has been a “hell” of a truck! lol

 

[RonD]

Water pump is spinning backwards

Or the engine is, maybe you thought it was odd there were 5 Reverse gears but only 1 forward gear?

It is a 2.3l so maybe it is plumbed different