I have a 97 f150 4.2l over 237,000 miles on it with no heat. The hose to and from the heater core are little warm but not HOT. The airdam door in the heater box is working properly. I replaced the thermostat already but noticed the antifreeze is a heavy rust color. I also noticed that it seems the antifreeze isn't circulating as the lower radiator hose and over flow tank fluid are still cold after driving to work one way for 18 miles. For the hell of it today I drove to work with the cap off the over flow tank and nothing came out and still cold fluid. Note the truck doesnt over heat and the top radiator hose get a little past warm but thats it nothing close to HOT. I cant rely on the temp gauge as its on cold for about 3mins when i first start the truck then BAM right to H until the next day or 8hrs later when I drive it home.

I believe it maybe the water pump or air lock when I changed the thermostate....any ideas???

 

Did you flush the cooling system when you changed the thermostat or did you just refill it?

 

Did you install the thermostat backwards? You may also need a new water pump. I would just do both and since I have the truck apart, inspect and replace idle & tension pulleys, and go with all new belts & hoses. And since you've got the fan off, think about an electric fan kit.

I just went through the same thing with my '97 Explorer. New pulleys, belts, hoses, hose clamps, water pump, thermostat, gaskets, thermostat housing (old one was cracked), radiator, fluids, electric fan, and cold air intake.

Once I started taking things off, I just didn't see the logic in putting the old parts back in. The initial project was just to replace the water pump. Maybe I went a little overboard. But now I have the peace of mind that everything is brand new. It wasn't cheap though. But do I want to deal with belts, hoses, & pulleys coming apart later? Then I would just have to perform the same labor all over again.

 

Good point. Make sure that you clean everything out. Otherwise, your brand new coolant would just be contaminated by the old junk that is in there.

 

Take it to a professional - you need a heavy duty flush job. Hopefully your radiator and heater core aren't already plugged beyond help.

 

Well I just bought the truck like a month ago and they installed a new radiator as the truck was involved in a minor front end collison. Idk why they didnt flush it then. All I didnt was refill it after the thermostat change which is installed correctly. What I think I may do is a complete flush and install new water pump just to be on safe side, but dont have the $200 bucks to spend on it right now but its prolly best i do it. Luckily the belts and hoses are new as well.

 

It's a '97. You'll have to spend money on it whether you like it or not. My local shop rates are about $150 per hour. I just put about $1,500 into parts, and at least 20 billable hours worth of labor in under the hood of my '97. It's all part of owning a used car. Remember? It's because you don't have a $10,000 down payment, and can't afford to pay $500 a month on a new car. Every year, there is some sort of maintenance and upgrade to do. My next project is going to be exhaust. Headers, catalytic converters, and a cat-back system (plus all the little things like gaskets, anti-seize, thread locker, nuts & bolts, heat socks, new spark plugs & wires) will be about $2,000. This is a work in progress. I start planning now, and I'll have the money to do the work by the end of next year. Or, I just buy the parts as I can afford them, one part at a time, until I've got all the parts I need for the build. Let's not even mention transmission, braking, and suspension.

 

"no heat issues" means you aren't having heating issues? good, me either

 

Come to find out it was multiple issues.

1. Thermostat was in backawrds...Note spring goes towards engine block
2. Fuse for the blender door wouldn't stay in the fuse box, kept falling out so a quick bend and twist of the fuse tabs its firmly in place.
3. Water pump had two fins broke off
4. Heater core needed a good flushing.

6hrs in the back yard and $175 later all is fixed and it now cooks you out of the truck!

Now if i only can get the temp gauge to work right.

 

Have you replaced the coolant temperature sender?