So I have a question, my truck was taking forever to warm up, and I changed out the thermostat with a higher opening temperature. I ran it and it takes about 30 mintues to get warm, and never really blows out hot air out of the heater core.
my question is can the fan clutch be broken where it's always spinning at the maximum cooling. When I spin the fan there is no difference between the resistance when its cold or hot. Could that prevent the truck from warming up?
Also, my heater core has a leak which I added bars stop leak, would that have any effect on the heater or engine warmup time.

 

Ugh... you likely now have a plugged heater core and that stuff can also plug up your radiator.

In a short answer - yes.

Time to replace not only your heater core, but now your radiator from using that stop leak stuff. Make sure to thoroughly flush all passages before installing the new radiator and heater core.

 

Yes, I noticed the heater core is not heating up, so its probably clogged with the stop leak. The stuff almost works too good.

 

If you have a leak, fix the leak. All stop leak is fit for is ruining everything it comes in contact with.

 

I once plugged a heater core by just using tap water in the coolant. The tap water was full of minerals/hard. I removed it and took it to a radiator shop to get it cleaned out and was told to replace it, there wasn't much hope of cleaning it out. On our vintage trucks, removing the heater core is a major operation.