3.0L no heat

[wcbarker]

I know I know the first thing you are going to say is air lock.
I can say for sure there is no air lock.
Let me tell you what happens.
I changed the block from a 98 sable to my 95 Ranger.
Used the heads off the ranger and all the other goodies.
The only thing I replaced was the block.
I changed all the gaskets head, intake, valve cover, and oilpan.
Truck runs great except after driving for 8km or so it starts to blow cold air.
I filled the rad and let it run till operating temp then topped it off.
I did this 3 times and still same issue, hot air until I drive about 8km then cold air.
Any ideas???????

 

[McCormack]

Once it starts blowing cold air open up the hood and feel the heater coolant lines to see if they're warm or not... if they are warm, then your core or control valve need to be checked out, if they're cold then you might have thermostat that's sticking open or some type of obstruction in the lines.

 

[JP02XLT]

If the control valve fails, will it default in the open position so it allows flow to the heater core? Possibly an easy test would be to disconnect the vacuum to it and check for heat in the return hose / core.

JP02XLT

 

[Cody Ray]

On a side note, is the 98 sable engine mounted transversely or longitudinally? The blocks are different depending on how the engine is mounted on the chassis... don't know if that matters to you. Is the vacuum supply to the (I'm a bit drunk and don't remember the correct term) the valve that allows coolant flow to the heater core compromised?

 

[Cody Ray]

If the control valve fails, will it default in the open position so it allows flow to the heater core? Possibly an easy test would be to disconnect the vacuum to it and check for heat in the return hose / core.

JP02XLT

When you remove vacuum from the valve it should close unless there is debris keeping it from closing. Tomorrow I will do a short video of how the valve operates with and without manifold vacuum. Also when you disconnect the vacuum source you might set a code because off the vacuum leak you just created.

 

[Sasquatch_Ryda]

The thermostat in my 3.0L fell apart inside the intake on mine and was causing this.

Also...isn't there different head gaskets between the 2 engines for cooling purposes?

 

[JP02XLT]

When you remove vacuum from the valve it should close unless there is debris keeping it from closing. Tomorrow I will do a short video of how the valve operates with and without manifold vacuum. Also when you disconnect the vacuum source you might set a code because off the vacuum leak you just created.

I purchased a valve last night, When no vacuum is present the valve is wide open, if you select a function on the heater control that passes vacuum like A/C then with vacuum the valve closes. I expected this but did not know until I had it in my hand to see for sure.

JP02XLT