1. Home
  2. Ford Explorer Forum
  3. Thermostat

Thermostat

I just took my new-to-me '94 Explorer on its first backroad trip. It did GREAT! Gravel roads, fording a foot-deep stream, a steep, muddy, rutted road- it handled it all. This is just what I wanted.

However, I noticed that on long downhills the temp indicator dropped to cold. I had noticed that the temperature gauge normally read low, the needle right at the line between "cold" and "normal" but figured that could be typical.

I've seen this on other vehicles, and wanted to get it fixed before it gets cold and I need the defroster/heater.

I figured it was stuck open, but when I got it out (good thing I had a wobbly adapter and various extensions!) I found it closed.

So I put it in a pan with the new thermostat, fired up the burner, and watched. The old thermostat opened sooner than the new one, and once they were opened, I turned off the heat and started adding cold water to the pan. The new thermostat promptly closed, but not the old one. I removed them from the pan and the old one was still open slightly, though it was cool enough to touch the brass part that contains the wax pellet.

I don't know what goes wrong- if the spring weakens or what, but the new thermostat works great. There's only two needle widths difference on the temp gauge between going up a long hill and going down it, and it reads well into the normal range instead of at the bottom end.

-Paul

Reply to
carbide
Loading thread data ...

I've been through two thermostats in my '94 XLT and need to put another one in. I don't know why they keep "Sticking Open" but it seems to be a common occurance.

Rob

Reply to
Rob Burtz

Think about what would happen if it stuck shut...

Reply to
Mike Iglesias

I've heard of it happening, but of the 5 thermostats I can remember replacing over the years, it was always for running too cold. The opening force provided by the thermal expansion of that wax pellet is pretty irresistable.

Of course they make the body of stainless steel now. I think they used to be brass in the olden days, that could corrode and break...

BTW, I think my old thermostat might have been the original, with 164K on it. I don't see any mention of a thermostat change in the records the previous owner gave me.

-Paul

Reply to
carbide

Well heres what my 94 explore did ( and a friends also ) . Regardless of the outside temperature the gauge always said it ran real cold ,used lots of gas too. My friend said to remove the heat sensor that is just tucked in frt of the a/c compessor on 4 L engines and clean it ,I did and now run at normal temperatures .Get much better gas milage too . The sensor tells the computer the engine is still cold and computer tells the choke to stay on and the guage to register cold ..This is rather common on early Explorers.

Reply to
xcaret

Well heres what my 94 explore did ( and a friends also ) . Regardless of the outside temperature the gauge always said it ran real cold ,used lots of gas too. My friend said to remove the heat sensor that is just tucked in frt of the a/c compessor on 4 L engines and clean it ,I did and now run at normal temperatures .Get much better gas milage too . The sensor tells the computer the engine is still cold and computer tells the choke to stay on and the guage to register cold ..This is rather common on early Explorers.

Reply to
xcaret

Your '94 Explorer has a choke????? In 1989 I purchased a five year old LTD, with throttle-body injected V6. A bit of black smoke was visible in the exhaust and I pointed it out to the salesman. "It's the choke sticking a bit", he said. "A choke, on a fuel injected engine?", I wondered, knowing next to nothing about fuel injected engines. "Yes, they still have them", he replied with great confidence (it turned out to be the infamous carbon clogging of the EGR valve). I still have the vehicle. Haven't found the choke yet, but I keep trying.

Reply to
Happy Traveler

Mine has two sensors, right behind the thermostat. The one on the left is for the gauge, the right one tells the fuel injection the coolant temperature- according to my Haynes manual.

It does say that the fuel injection "runs open loop" when cold, i.e. it doesn't use the oxygen sensor to fine-tune the mixture, which will cause poor fuel economy.

-Paul

Reply to
carbide

The temp gauge on my '92 was reading low so I took out the thermostat, put it in a pan along with a new one, and the new one opened sooner (around 185 degrees) so I put the old one back in and put the new one on the shelf. It still reads a little on the low side but better than overheating ;-)

The old Explorers go through a lot of thermostats and it doesn't seem to matter what brand it is.

Reply to
Ulysses

Good tip. I'm gonna try that.

Reply to
Ulysses

snipped-for-privacy@draco.acs.uci.edu

If it's stuck shut there should be a little emergency bypass in the thermostat.

You can tell when it's stuck shut if you're always running hot and under a load, realy hot.

Reply to
michael

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.