Hey everyone, I'm new to the F150online forums, although every truck I have ever owned has been F150's and 250's. I'm familiar with other forums, and before I get into my heater core issue, I did search through pages and pages of threads regarding heater core issues, so I didn't just bypass everything and skip straight to asking questions. But I have some confusion regarding some of the posts made about heater core issues, as compared to other heating issues.

Background on truck- Its a 2007 King Ranch 4x4 Supercrew. I bought it with 88K miles on it about 3 months ago from an older man that owned it for 2 years. He purchased it with 82K miles on it, so he only put 6,000 miles on it in 2 years, which was another reason he was selling it. Just never drove it.

So I drove the truck home, and it performed perfectly. Motor runs great. Truck is super clean, well taken care of. A week into owning it, it over heated on me. Light came on, saying Reduced Engine power. Temp guage was hot. I immediately shut it off and checked coolant levels... Empty... I let it cool down, bought some antifreeze, and filled it back up. Drove to Autozone, they said thermostat got stuck more than likely where the truck hadn't been drove much. Changed out thermostat, topped it back off with antifreeze, and kept an eye on the levels. After 2 weeks, I would notice my coolant level would drop, to where there was nothing in the reservoir, so I started adding water because I knew I was losing it somewhere. I would let the truck warm up, checked underneath it, but no water was dripping from anywhere that it shouldn't have been. We checked the water pump, radiator, etc. All seemed good. Drove it to Michigan, done fine, but before I came home, I had to fill it back up again with water.

So the other day, temps finally dropped a bit here in Southern Ohio, so I turned the heater on. All worked well, until I came to a red light and was idling. It started blowing out cool air.. But when the light turned green and accelerated, it went back to warm air. So that's when I thought heater core.
So I get home, lift up the cabellas mats on the passenger side, and sure enough, the floor is wet. Now here is my confusion from all the other threads I have read. The truck does not have a "sweet smell" and my window does not immediately fog up like everyone has mentioned. In fact, theres no smell at all really, and defroster works fine.

So before I sink a ton of money into replacing the heater core, is there something else it could be?

if it is the heater core, are there any specific tips or things to be careful of. I have read about the A/C recharge thing and Air Bag concerns. I also read where someone stated that the Haynes manual does not give specific instructions about replacing the heater core.

Any tips or suggestions would be appreciated. I do not plan on doing this myself. I have a mechanic that works on our farm equipment and vehicles when its something we cant do, and he's gave me a heck of a deal on doing the work for me. But I wanted to give him as many tips as possible.

If I overlooked or didn't read the correct thread regarding this, I apologize.

Thanks!

 

I would make certain that you have coolant on the floor and not just plain water from a leak around the windshield. You could look closely at the color of it (dab a clean paper towel in it and look for color) or..... I don't recommend this, but I would get a tiny bit of the suspected coolant on the tip of my finger and taste it. If it's sweet it's coolant and then the heater core is probably the cause. Maybe the newer safer coolants don't taste sweet so this may or may not be helpful. It is possible the leak (if it is the heater core) is away from the flow of air that passes through the core itself and that may or may not explain why the windshield doesn't fog up. Something else you could do is pressure up the cooling system with a pressure tester and watch for coolant dripping or running onto the floor.

 

If you had coolant in the cooling system and no sweet smell in the floor and no interior fogging and you never saw sign of all that lost coolant, what's in the floor under the mat is from the AC condenser core run off drain that has apparently leaked back into the floor from the drain exit in the fire wall pass side .... there is a short pipe into engine compartment and a 90 degree elbow on it. If Elbow is missing, water condensed can dribble back into interior.

TSB 07-13-5 PASSENGER FRONT FLOOR WATER LEAK – A/C CONDENSATION LEAKING

And to find the real coolant leak, start with a pressure test with the proper tester. Advance Auto Parts has the testers in the loaner tool program.

There's also this:

https://www.f150online.com/forums/hv...-side-tsb.html

https://www.f150online.com/forums/ar...ater-leak.html

 

Thanks for the info tbear! I have already printed those links for reference!

I can fill up with antifreeze and 2 weeks later, the reservoir will be empty, but theres definitely no sweet smell in my cab, and my windshield does not fog up. That's why I keep researching what I can to narrow down the issue. I hate to spend all that money on heater core replacement, if its not truly the issue. But like I mentioned, the heater works fine, but sometimes when you come to a red light or sit idle for a minute, it starts blowing out luke warm air, but as soon as you take off driving again, it heats right back up. And the Air conditioner would do similar things when I used it. Cold air while driving, luke warm at idle or stopped.

So forgive this stupid question, but would the AC condenser leak antifreeze? and could that be where I am losing my coolant?

I will probably have my mechanic perform the pressure test first and see if he can narrow down the issue.

Thanks again for both replies guys!

 

Pressure test the system

 

The A/C system has nothing to do with the cooling system. It uses refrigerant, not coolant.

Also have your mechanic do a hydrocarbon test on the coolant, you might have a leaky head gasket.

 

Ok- We'll be doing the pressure test this evening. I called our local auto parts places. (AZ & Advance) and they acted like they didn't know what I was talking about when I mentioned the hydrocarbon test. But i'll at least get the pressure test out of the way and let you all know how that goes. Hopefully I can pinpoint exactly whats going on.

Thanks again for the feedback, and I definitely welcome more.

 

Well, i cant thank you guys enough for the suggestions of pressure testing my coolant system.

Rented one from Autozone and after getting it home and realizing they did not include the correct adapter- my father in law and I went back and got the adapter and checked it right in autozones parking lot. Then we heard the water hitting the ground and looked down near the radiator and seen water spraying out of the lower radiator hose where it connects to the motor.

Got the new radiator hose for $20 and the next day- we replaced it..... But when we went to remove the clamp from the old hose- thats when we seen that the clamp had rusted and broke.. The hose was fine(we replaced it anyways.) so we assumed thats why i never seen antifreeze leaking there because at idle, it probably wasnt putting enough pressure on the hose to make it leak.

Long story short- trucks been fine all weekend, and coolant level stays the same.

So now- i have to do some research to find out whats leaking in my passenger floorboard!

Thanks again everyone!

 

That's why I prefer worm drive clamps instead of those spring clamps it comes with. I'm old school, a lot of people here will turn their noses up at worm clamps.

 

They are morons.



O'Reilly's has them in the store.

 

glc- We used worm clamps to replace the old spring clamp or whatever its called. I don't like them either.

And we just had an O'Reilly's open up about 30 minutes from us, but I didn't even think to call them.