I have a 87 Pickup with a 22RTE. I purchased this truck about 6 months ago. I am slowly fixing all the messed up crap on this truck. I just recently routed and made sure all the coolant hoses were correct. It was a none turbo truck with a turbo motor dropped in it. I brazed a nipple onto the top of the radiator and got the turbo coolant lines routed correctly. The truck never really gets hot. This winter the air was warm but not hot. So I pulled the thermostat and tested it in a pot of water and my temp gun. The thermostat opened at 195°. So I reinstalled the thermostat. The coolant is 50/50. The heater core is clean and flows good water. You can drive the truck around for hrs and stop and test the temps. At the thermostat housing its 165°. At the top radiator hose its 165°. At the bottom of the radiator its 165°. I pulled the cap and it was 165° inside the radiator as well. I am lost as to why the truck will not heat up. I pulled a heavy car hauler trailer for 20 mins and it then tested 195°. So the truck is capable of getting hot when loaded really hard. What could be my problem. I am 100% correct the hoses are routed right.

 

You're complaining that your cooling system is too efficient? Lol, sorry I don't mean to be a jerk, can't help much but that was the first thought I had.

 

Did you closely inspect T-stat? Someone drilled a bypass hole that's too big in the thermostat? Search for that.

 

Sounds like coolant is bypassing the thermostat somehow. Since the PO left you with a lot of "messed up crap", I'd check to see if they "redesigned" the coolant flow path and added a hose or two that, among other things, routes coolant around the t-stat. Could be in the heater circuit somewhere.

 

If this truck did not have AC installed, alot of debri gets in thru the cowl in front of the windshield and goes thru the blower and straight to the heater core. Also if take off your front mudflaps and find alot of debis behind the inner fender that can be sign of trash blocking off the flow. Even with AC dust can get into the core like below.

Here is what I have ran into and either earlier or later in my thread I show it in worse shape then this https://www.yotatech.com/forums/f199...l#post52151096 The ventilation system gets dirty in these. The debris could even block off the condeser and keep air from moving thru the system. I would look at what others have suggest first and if that doesnt fix your problem see about the gunk in there.

The one on the left is new, the one on the right has the fins clogged. You could feel the hot water cicrulating thru the pipes on the firewall but no heat to the cab. If this isnt the problem, I have flushed my cores with CLR.

 

Along with all the other info if your coolant level is to low you won`t get heat .
The air intake has to be set for fresh air to get the most heat output.

The heater valve is free and working like it should??