2000 F150 had problems all winter with little to no heat. The heat has worked great prior to this last winter. We tried flushing the radiator and no improvement. Lack of money forced us to deal with having no heat. Now the temps are starting to warm up in Oklahoma and the truck is getting hot at highway speeds and especially when pulling a trailer. Slow down through town and the temp comes down. I am desperate at this point! Our F350 (the real farm truck) is down needing a new water pump that we also cannot afford and I can't afford to have this one down also. Have had it suggested that it could be a clogged heater core and it could be bypassed for the time being. So I guess my question is, where do I start? Do you all think that could be the likely culprit? Will it hurt anything to bypass the heater core? How hard is it going to be to do this? I can't afford to pay someone so I will be doing it myself. Yes I am female, yes I am a country girl, and no I am not afraid to get dirty! Any advice you can provide would be greatly appreciated!!!

 

Have you tried changing the thermostat?

 

You can bypass the heater core with no harm coming from it. Ran my last truck (2000 F150) bypassed for 4 years...but that is in Phoenix proper where a defroster and heat are not too critical. That's your big drawback on that route.

No heat to me sounds like heater core. Gotta pull the dash for that one. No nasty smells?

 

Sounds like the cooling water is too low. That will cause both of those problems. You may have a leak somewhere. Fill with water and use it right away and see if that fixes the problem. (You may have to go through some fancy tricks to purge air from the system). If so then that's your problem. If the problem returns later then you have a leak! Also leak could be inside of the engine and you may not see it! A TRUE radiator shop should have equipment to test cooling system to see if it has a leak (even if the leak is internal).

 

While you can bypass the heater core, it won't solve the overheating issue.
Question is, is the radiator becoming blocked in it's lower section causing a loss of system capacity.
This will show as you increase the load on the motor from towing when that extra cooling is needed and road speeds may be slower.
If you open the drain and nothing comes out, it is likely plugged.
The heater core could also be plugged under this condition.
Fan clutch, is it still working as normal?
Has the thermostat been changed?
Have you been running straight water in your trucks all spring, summer and fall? If yes that is a no-no and invites system corrosion.
Air trapped in the system must be purged when filling.
Head gasket leaking into the cooling system adds heat.
Any external leaks?
Pressure cap still good? It raises the boiling point of the coolant besides keep the system closed and under vacuum as shut-down cooling occurs.
A leaking water pump will let air back into the system at cool-down.
.
Consider a system pressure test.
Whether the truck is out of service from lack of resources or some other reason, it is still lost to use until issues gets corrected, so you have a decision to make..
Sorry for you circumstances.

Good luck.

 

Bypassing the heater wil only solve the problem if the heater is leaking. Still it's one way to troubleshoot the problem. And it eliminates a part of the system that you usually can't see.

FWIW I think HF sells the radiator pressure test kit. It should be cheap. Nothing to it except a radiator cap connected to a pressure gauge and a handpump. Put it on your radiator, pump it up and watch to see if the pressure drops. If there's fluid in the system, you should see it leaking (without running the engine!) if the leak is external. If the leak in internal then the water will still go into the oil, into a cylender, out the tailpipe (or more likely settle in a cat).

Bluegrass is right, don't forget to check the fans, belts, clutches, etc. If there's not enough air getting through the radiator the engine will over heat and, most likely, boil out the coolant and that could make the problem look like a coolant leak when it's really not.

 

Yes when this first started we replaced the thermostat, sorry I forgot to include that. Water and coolant are both fine and no leaks anywhere. Haven't seen puddles under the truck, or excess water from tailpipe. Also the oil looks good and no water in it. Fan, belt, etc are also all in working order. Haven't noticed any strange smells in or out of the truck. I think that answered the majority of them but I will check again. Looking into the radiator pressure test kit right now. Thank you all for all of your help!!! If you all can think of anything else please let me know and I will report any updates also. Thanks again, yall are the greatest!!!!

 

Recently in my 94 f150 I started having problems with little to no heat and overheating. Prior to this I was in an accident and had to replace my radiator and hoses. The heat was worked before the accident and started getting sparse after the repair. So when the temp gage spiked I replaced the thermostat. When this did not work I started read through the post from other owners and decide to try just removing the radiator cap and running it to temperature. That worked and i have been driving it for past two days w/o it overheating. thanks to the person who put that post out there

 

There are only 3 things I can think of, mainly because this happened to my truck and I replaced two of the three.

I replaced the thermostat, and then figured out I had a cracked head gasket. Got that fixed and solved my problem. The other thing that our mechanic said was that it might be the heater core, or a fuse.

 

I've seen two bizarre failures of things that you don't oridinarily think of but that can also cause over heating. First one was the spring in the radiator cap gradually rusted away and the cap wouldn't hold enough pressure so engine would over heat but only sporadically. Easy to spot if you LOOKED at the spring in the cap! Pressure test should also find it. Second was the water pump blades that rusted away so that even though the pump was turning, it wasn't pumping enough water! You may be able to tell by looking in the top of the radiator and checking the water flow AFTER the engine warms up but taking the cap off of a hot engine can be dangerous! And on some engines and radiators it's hard to judge the water flow. The only reasonable thing to do here is to replace the pump, "just in case".

Cracked head or bad gasket should show up with a pressure test!

 

Couple of things:

1) I have swopped hoses on my heater core with luck in the past of restoring flow. You can also flush with a garden hose, in both directions.

2) I have bought bad new thermostats on two occasions in my life. You can test it in a pot of boiling water on the stove to see if it will open.

3) Check your main radiator hoses, they can suck shut. If you can push them together with two fingers, you need to look at replacing them. Most OEM hoses have a spring in them to prevent this, most aftermarket do not.

4) Getting all the air out after you flushed it can be tricky, look up how to do it. You may just be fighting a big air bubble.

 

I have a 97 expedition with the 5.4L motor. I've changed the heater core, radiator,water pump. Heater core failed and showed leaking under truck and the smell in the dashboard, radiator had a cracked plastic side and leaked fluid, changed water pump cause I had already had the radiator out so why not. Just recently I had a boil over. Not an overheat but just a boil over. Every forum was saying head gasket. My first thought was thermostat. I changed it. Again I had a boil over. Guess what? The thermostat it calls for is 195 degrees. Could it be to hot? Did I really have a blown head gasket? Cheapest fix would be to install a colder thermostat. I installed a 160 degree and Bam FIXED! No boil over! Please guys before you invest a lot of money try the simple things first.

 

The normal Thermostat spec is 195.
Your 160 is not recommended for at least 3 reasons.
1. The PCM may set a code for slow warm up or temp to cold below about 175 as detected by the cylinder head temperature sensor.
2. It will affect cold start warm up time.
3. It will likely result in a drop of fuel mileage.
Best to find out why you cannot use the 195 thermostat.
You must be sure all air is purged from the system at fill up.
Thermostat should have a bleed hole in it's rim to help this.
.
Head gasket issues:
1. If cylinder combustion pressurizes the system, overheating can result from additional coolant heat.
2. If the leak is in the other direction a loss of coolant finally causes overheating from the loss.
.
These motors are touchy about air in the system but run forever even as high as 212 in the summer without overheating as long as there are no faults.
Be sure the pressure cap is good.
Without the additional system pressure the coolant will boil at a much lower temperature.
Good luck.

 

BS - Yea DON'T install one below 192. Iknow for a fact the 187's won't take. Please guys, don't listen to 97expychuck's post unless you want problems. Perhaps irreversibly ones..

 

Like Brew said! If a 160* thermostat fixed a boil-over problem, that was a sheer coincidence. 195 is not too hot as bluegrass explained. Gone are the days of running the coolest thermostat you can get! Got a buddy that works for a famous race team and if the race car starts running a water temp lower than about 200* on the track at WOT, they start taping up the front end to cover airflow over the radiator. I have actually seen a hotter thermostat fix a overheat problem on an old hot rod. I may be wrong, but my theory is the cooler thermostat was letting water run at max flow and thus not spending enough time in the radiator to dissipate enough heat. Hot water was immediately returning to the engine.