Little to no heat dilemma….

[Domterry12]

As the title says, I am blowing little to no heat. Last winter I recall having decent heat, this year I pretty much have nothing.
Here is what I’ve done/checked before posting here:
antifreeze level is full.
Thermostat is in place, it’s the hockey puck style, and opened and closed in a pot of boiling water.
Removed return hose that goes from heater core to radiator, removed at rad and blew into it and was able to blow air thru it and the air was coming out at thermostat housing (stat removed)
Put back together, fired it up cold. No flow from heater core return line (was able to see with lowered antifreeze level) no flow until thermostat opened and then had good flow back into rad from heater core
Removed glove box and made sure heater box door was as far as it could go towards heat; even unscrewed cable and moved it as far as could go.

im stumped, any ideas?

 

[Barrman]

Do you have a way of measuring the actual coolant temperature? Besides pulling the radiator cap and looking for steam from the heater core return when it dumps into the radiator.

My next thought is heater core condition. You wrote there was flow. But if it is just a single tube, heat won’t get transferred to the air.

 

[nyoffroad]

If you have access to a radiator thermometer just drop it in the filler neck and see what the actual temp is. Or if your not old school like me and have an inferred thermometer use that. Those engines take a long time to warm up at low idle and the colder it gets the worse it gets. I use a piece of plastic type cardboard wire tied to the grill to close off most air flow. Never had a problem with any of my trucks over heating either.

 

[Domterry12]

Do you have a way of measuring the actual coolant temperature? Besides pulling the radiator cap and looking for steam from the heater core return when it dumps into the radiator.

My next thought is heater core condition. You wrote there was flow. But if it is just a single tube, heat won’t get transferred to the air.

I could run the truck with the cap off for 10 mins or so and then measure with a thermometer. I can no longer see the heater core dump because it’s full of coolant.

 

[Domterry12]

If you have access to a radiator thermometer just drop it in the filler neck and see what the actual temp is. Or if your not old school like me and have an inferred thermometer use that. Those engines take a long time to warm up at low idle and the colder it gets the worse it gets. I use a piece of plastic type cardboard wire tied to the grill to close off most air flow. Never had a problem with any of my trucks over heating either.

I do have a temp gun. Just not as accurate and a real thermometer. But I can tell you after trucks been running a while I can grab all rad hoses and heater core hoses. They are hot, but I can continually hold them, they aren’t burning hot.

 

[87cr250r]

If you're not seeing 180°F on the upper radiator hose your thermostat has failed.

 

[Domterry12]

If you're not seeing 180°F on the upper radiator hose your thermostat has failed.

just drove 30 mins to work. After the drive at idle with my temp gun highest reading I could get off upper hose was 108…looks like thermostat tricked me.

 

[nyoffroad]

just drove 30 mins to work. After the drive at idle with my temp gun highest reading I could get off upper hose was 108…looks like thermostat tricked me.

I think they are all fail open vs fail closed, that would be real bad!

 

[Domterry12]

I think they are all fail open vs fail closed, that would be real bad!

Just strange because I put it it in a pot on the stove and watched it open and then close in cold water……either way new stat was delivered today, will install tommorow

 

[Domterry12]

She’s blazin heat! New thermostat did the trick. Like I said I tested stat in a pot on the stove and it still opened and closed even tho defective, so be careful future no heaters!

 

[79Vette]

Do you remember the part number of the thermostat you used?

I've had the same problem for a long time and have tried several different thermostats with no success.

 

[Domterry12]

Do you remember the part number of the thermostat you used?

I've had the same problem for a long time and have tried several different thermostats with no success.

I used duralast part#42995, the hockey puck style