Was the gasket an O-Ring?

 

No, it was a blue cardboardish thing.

Turns out I had the housing sealed fine. A clamp on one of the hoses had failed allow coolant to leak. The guy fixed that and backflushed heater core.

However, wife says it is still just luke warm air. Gonna pull it up on ramps and run it with cap off to be sure there is no air in it and that coolant level full.

 

Did you use the 195* one? They sell colder ones down to 165*. OEM was 195*.

 

I got a Duralast from AutoZone and I told her I wanted the OE spec one, but that doesn't mean that's what I got. I see they have 3 on there website. I still have the box. I'll check the part# to be sure I got the right one.

Thanks

 

Did you ever discover anything else about your problem? I have a 97 F-150 with the exact same problem. I changed the heater core and coolant myself last fall, and the truck's heater worked perfectly until this past Friday night when I lost the vast majority of my heat in the middle of a 3-hour drive. I immediately assumed the thermostat was my problem. The temperature gauge remains in the same exact spot it has for years--just below halfway but slightly above 1/3 of the way (follow me?). I purchased a 195 thermostat at Advance and swapped it out this weekend. Now my heat is better, but obviously not like it was before. I just stopped driving my truck about 20 miles. I immediately raised the hood and checked. The heater hose going into the core is hot, and the output hose is hot, but slightly cooler than the input hose. But I was able to grab and hold either one without much difficulty. The same exact scenario of approximately 5 seconds of good hot air before it cools down happens with my heater too. Any more ideas? Could my problem have originally been the thermostat, and now I've created an air pocket because I had to drain some of the coolant to change out the thermostat?

 

You shouldn't get an air pocket just dropping the level and then topping it off. Mine has all kinds of issues...heat...no heat...gauge spikes to hot and stays that way for a min ute....then a blast of heat and gauge goes to normal. Mine is a head gasket issue that I am just milking along. I have sealer in it and once it does "it's thing" ...it settles on normal and my heat is good until I shut it off and restart it...then it starts over again. As long as I keep the level about 3" lower than the lowest mark on the tank, it doesn't puke any out as it decides what to do.

 

Well, I did get the right thermostat (OEM Spec). I put it on ramps to try and get out any air pockets. Truck still has luke warm air. After driving longer than you should, occasionally the air will be warmer than luke.

Not sure on your year of truck, but on the '02 they are notorious for having "Blend door" issues because Ford went with cheap plastic on the pivot points and they break (don't want to get started on automotive engineers must be the worse). However, I don't think mine has this issue because if I turn to cold and AC it is cold and turn to heat and I get some. If it was broke, I'd think I'd get one or the other.

If I fill the plastic coolant tank above the recommended level, will it damage something or is there an overflow and it will just push out the extra if need be?

thanks,

 

Here's the thing that speaks against a blend door with my situation--I replaced my blend door with the heater core 14 months ago, and it had the "improved" metal band around the hinge point. I can turn the temperature control **** in my truck to all points around the dial with corresponding changes in temperature. I can also place mine on Max AC setting, and the recirculating door above the passenger floorboard is working as it should. Bottom line--something happened abruptly to my heat right in the middle of a 3-hour drive. My new thermostat did indeed seemingly help a little, but I'm still driving around with lukewarm air just like you.

I changed the heater core, blend door, and coolant 14 months ago, and drove it all last winter with great heat. And I had great heat right up until it stopped the other night. I am at a loss for what might be wrong. I also started the truck last night, got it warmed up, then shut off the engine but left the heater running with the key switch. As expected, the hot air ran out in about 5 seconds or so, but started back when I restarted the engine (and the water pump). So I don't think I have a clogged core either.

 

I am as perplexed as you on my truck. This fall, I flushed the cooling system and back flushed heater core. Then I replaced the thermostat. Had a leak I couldn't find, thought it was thermostat housing, took it to a garage and it was a hose clamp. But while there, they also flushed the heater core. I've ran it with the coolant cap off on an incline. And still just luke warm air. It didn't have warm air when we bought it. When I replaced the thermostat I noticed previous owner had replaced it, but he put it in backwards. Thought when I put in a new one correctly, that was the fix. Unfortunately, it had no effect.

They don't have more than 1 thermostat do they?

I'd think if the heater core was plugged you'd get no warm air at all.

After I double-check the coolant or overfill it, if that doesn't work, I may have to resort back to putting cardboard in front of the radiator to see if that helps. Weather is in the teens here and wife is getting cold - it's her truck. We have another 02 with the V8 5.4 liter and it heats up fine - 150K+ miles on it. I've only changed coolant on it.

 

Last year, I had the same problem and it was around for about 2 years. Changed the thermostat and that did nothing at all. Long story short at some point I had switched out the ***** on the dash. The one that operates the fan speeds was cracked and it wasn't gripping the small peg. I had that one on the temp and at the time I did not realize that it wasn't turning the peg. It would stay in the 12 o'clock position so the cab temp would only be 60*F instead of about 145-160*F. So when my dad and I were trying to figure it out last winter, I decided to swap the ***** around and then I got a blast of hot air.

At that time we were thinking about ripping the dash apart and fixing the blend door. This would've been very costly. Apparently the blend door is a problem on some 1997-2003 trucks.

 

Yes, the blend door is a regular problem on these trucks. When I swapped mine out just over a year ago, the original one had started forming a crack at its pivot point. It would have eventually failed. And, yes, it is a huge job to swap out (unless you hack up your dash).

Well I had a flash in the pan last night coming home. The "Panel Vents" setting is right beside the off setting on the control ****. I have discovered that if I turn the heat off for about a minute or so, then turn it back to panel vent, it will blow very nice hot air for about 20 or 30 seconds or so. I kept doing that, and, low and behold, it stayed hot for the rest of the way home. When I got home, I popped the hood and checked the hoses. Nice and hot on both sides. I loosened the coolant filler cap and the system gave out one big nice burp of air. I tightened it back, and had good heat on my to work this am. It was working so well that I actually turned down the temp control **** to about the 2:00 position. Well.......that did something. By the time I got to work, it was back to the lukewarm air. It's getting better, but still not completely right. Just thought I'd share the latest in our little saga here.

 

Interesting. Thanks guys for the various **** advice. I'll check that out.
I checked the wife's truck last night and the coolant was not up to the "Cool" fill mark. I added probably 1/3 gallon of coolant to bring it up to the line. She has not drove it far enough yet in the 3 degree temperature to see if it made a difference. I'm not real hopeful though. After a good run I'll check out the **** situation if I still only have luke warm air.

thanks

 

Low coolant will for sure cause a low heat condition. If it pukes it out after you topped it off.....it's the head gasket leaking..I'm in that boat.

 

I don't know what mileage is on your vehicle but maybe the water pump fins have corroded away leaving little power to move the coolant.

 

That's another good point. Thanks.

I have an infrared thermometer. With my truck warmed up completely, the fan at full speed, the temperature of the air coming out of the panel vents is anywhere between 113-120 degrees. So if one of you guys is driving your truck currently with an infrared thermometer in your hand, we'd both probably appreciate a comparison reading. Lol.