Coolant flow direction?

RyanEAS

Active Member
Does anyone know which direction the coolant flows, not only through the engine, but also the heater core? Especially the rear heater core? Or any available diagram would help to. TIA!!!
 

AWD V8

Well-Known Member
Well, the pump provides the suction, so a heater hose connected near the pump would draw coolant from the heater core.

The hottest coolant is taken from the cylinder head, so that hose delivers coolant to the heater core.

Following these hoses back to the heater core will tell you which is the heater core inlet.

As far as the rear, the hoses will be tied into the front heater hoses. At the rear heater core I don't know, unless you can physically follow it with your eyes.

I know this isn't the short answer but I hope it helps.


Also knowing Envoy or TB and what year and engine might help with a short answer.

4.2 engine
#3 is out of the head, so that is the hottest, flow is out of the engine.
#7 is at the back of the water pump, so that is suction, into the engine.
 
Last edited:

Mooseman

Moderator
You having problems with rear heat? Could be the diverter valve. It turns coolant flow on/off to the rear heater core. It's not shown in the diagram above as that is a SWB.
 

JayArr

Well-Known Member
Hi All

I know this is an old thread but it was the perfect place to add the question I've been googling.

According to the aqbove diagram and description there is no metering valve in the coolant system. Is that correct? Does hot coolant run through the heater core 24x7x365?

On the XL versions there is an extra valve not shown in the diagram but it only allows the coolant to the rear heater core, it doesn't meter the front heater core.

Am I missing something here???
 

Mooseman

Moderator
Answered in the other thread.
 

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