picked up an 81 bronco from a buddy for free. put on a fuel pump and it runs. now i'm driving it after $170 +/-. only thing that's a pain really is the heater. it doesn't get very warm. changed the thermostat it didn't help. tried blocking off some of the radiator it didn't help. being near 0 degrees lately i blocked the entire thing for a short drive and it still didn't get very warm, but also started to overheat. damn i'm just happy i got the rear glass to roll up.

any ideas?

 

First, welcome to FTE and the Big Bronco Forum. We will endeavor to get you the most accurate information we can muster.

Sounds like the cooling system isn't full. (Don't assume that just because the overflow is full that the radiator is too). The heater core is the highest point in the system and since liquid seeks its own level, a system that doesn't have enough coolant in it will starve the heater core first. One way to check this is to run the truck to its normal operating temp. and carefully, with the engine running if you can do it safely, check the relative temperature of the hoses going to and from the heater core right where they go into the firewall. If they are both as hot as each other, then the core is most likely flowing coolant well enough to be working properly. If the hoses are both cool compared to the upper radiator hose or you can hear gurgling and the temperature is erratic, the cooling system needs to be filled.

I would tend to think the latter is more likely and you need to fill the system at the radiator cap, not the overflow reservoir. If you want to be certain the system is as full as possible, start with the engine cold (or at least cool enough that you can safely remove the radiator cap). Start the truck and check the fluid level in the radiator. Top off to within about an inch below the neck of the cap. This leaves room for expansion without overflowing before the thermostat opens. Leaving the radiator cap OFF, allow the engine to reach full operating temp. When the thermostat opens, check the radiator fluid level again. (If the level was at all low it will drop again when the thermostat opens). Top off fully this time and recap the radiator. Turn on the heat and see what you get.

On the outside chance that one heater hose is hot and the other is not, you have a clogged heater core and replacement is about your only option.

 

good info. sometimes i guess people tend to overlook the simple things. it's also been a while since i dealt with an older veh. this one had been sitting for about 6 years so i'm just greatful to have so little invested and it's on the road. i've done a lot of work on my mustang, but haven't had a truck in a long while. it'll be good to get to some trails again.