I have a 98 150 with the 5.4. Last year my heat started to get really bad. When I first ran the truck it had absolutely no heat, after driving for a few hours it would get a little better. I really didnt care to much and kind of been letting it go. Well the ol lady put down the ultimatim either get it fixed or buy a new truck. So anyone have any ideas. The only thing I could possibly think of was heater core, but I really do not know much about the heating system. Any things to look at imparticular?? The truck seems to run at normal operating temp, but this year I am getting no heat at all even after driving all day. Thanks in advance!!

lots of things can cause this, incluidng low antifreeze or not enough or too much mix as well.. ( get a tester to check that ) , including the heater cor, or what the call the "heat door?" mine is doing the same thing and I'm checking on it, but he wife just called and said it is now leaking anit-freeze as well. so more work to be done.. Ill let you know what I find out on mine..

Krafty said:

Well the ol lady put down the ultimatim either get it fixed or buy a new truck. So anyone have any ideas.

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I think the new one should be blue.


I'd be thinking plugged heater core, too...or maybe a bad blend door, but the symptoms sound more like a plugged heater core.

Assuming you've got enough coolant, when the truck is up to temperature and the heat turned on for a while...feel the hoses running to the heater core. If you're getting good circulation through the core, they'll both be warm- if it's plugged, not so much.

*Now that I'm thinking about it...some trucks have a valve to shut off coolant flow to the heater when you're not using it. It might be an A/C thing, I'm not sure. (My '09 Ranger has one, my '97 does not. Only the '09 has A/C.)

If the coolant is flowing through the core ok, then the blend door is staying set to cold. Need to see if the coolant is flowing through first, you can do that by just touching the heater hoses. If they are both hot, then the coolant is flowing.

Yep I agree. Check hoses first. If one is hot and the other is not, then shut the truck down, pop off the hot side (remember which one it is) and the cold off the heater core at the firewall ( they are the pair of hoses closest to the center of the truck on the passenger side). Run a hose to the cold side, and a long enough drain hose to the hot side to get it out of the engine bay. Then pour about 2-3 cups of bleach down the cold side and let it sit about 10 mins. then keeping the bleach in there hook the hose up and turn on your water FULL blast. Whatever is in there and blocking your heater core should come out. Also keep in mind that if said blockage is filling a pin hole in the heater core you may end up finding it. So keep a nose out for coolant smell on the inside of the cab.

I had to do this to the wifes a couple years ago and it worked great.

Hope it helps.

Thanks sorry been busy busy lately and forgot about this. After being dumb a just trying to throw parts at it I found out it is the core in fact. The hot side was 164ish and the cool side was 64ish lol so I'm pretty sure that is the problem. I was gonna try flushing it with the hose this week, but I think I might give the bleach Idea a whirl. I will keep you up to date.

P.S. I think a new one will be in order as well but blue just isn't my style trying to find one in white!