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Possible thermostat problem need help

Zeromarine

Active Member
Joined
August 12, 2019
Messages
83
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City, State
Kamloops B.C
Year, Model & Trim Level
2002 sport Trac xlt
On my 2002 sport trac. This may be normal but I just want to make sure. It’s been around -10 c the last few days. In this temp the truck sits outside. I drive a short 3 miles to work so it doesn’t go really far.
I have noticed though the temp gauge goes about 1/4 way up only and when driving at in town speeds it’s sometimes goes a bit lower.
It will move up and down a little when driving not a large amount.
I checked the coolant it’s full. I started it with the rad cap off and no movement so the thermostat is closed. I then went for a half hour drive today on the highway and then back through town. It starts making heat after about 3 min. Once I got on the highway the gauge was at about 1/4 and the heat was very hot so hot that when my hand was In front of the vent it was turning red it was so hot. Ok so good heat. Half way into my drive I pulled over and popped the hood and put my hand on the upper red hose it’s hot. And both of the lines going into the heater core are hot as well.
The heater control valve opens and closes fine also.
Got back o to the road and pinned it up to 70mph. And the gauge went up to half. When I leveled out at 60 it went back down to 1/4 on the gauge again makes wicked heat.
Back in town now going about 30 the gauge stays at 1/4 and at time’s goes a bit lower even if I’m going down a hill or something. When I got home I sat there at idle and the gauge again stayed at about 1/4. (I’ll insert a pic of it where it is most of the time). Anyway at idle the heat was still hot but not as hot as when moving. Still warm though. Granted my wife’s 2012 fiesta cools down from the vents a bit the same when your at idle in this temp and gets hotter when you start to drive. So I’m sure it’s normal. in the summer I believe the heat gauge is closer to the middle.
Tbink this is normal in the winter as it’s my first winter with it. Or should I change the thermostat? To me it seems to be working fine. But just wanted to get ideas from other people if they have the same thing in the cold winter. thanks.

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Sounds to me your thermostat is stuck open replace it with a new stant
While your at it replace your thermostat housing with a metal one
 






Sounds to me your thermostat is stuck open replace it with a new stant
While your at it replace your thermostat housing with a metal one

I agree.
 






Got back o to the road and pinned it up to 70mph. And the gauge went up to half. When I leveled out at 60 it went back down to 1/4 on the gauge again makes wicked heat.

Right here it sounds like you watched the thermostat open on the gauge, when the temp climbs up past half and then suddenly starts to drop that is usually when the thermostat opens
Your fan clutch could be bad causing the fan to drag all the time which will result in over cooling and your thermostat will not open as often because the water temp never gets up to 195
Does it sound like a B52 bomber on takeoff all the time?
Either way it sounds like a good time to do some maintenance to the cooling system, thermostats should be replaced about 60-90K miles
Fan clutches can last the life of the truck but when they go bad the fan will run always = poor MPG
If you only drive 3 miles and its cold outside then your truck is never reaching operating temp and that is actually a bad thing for them water can collect in your muffler and rust it out. It is a good idea to get them warm once in a while........short commutes are killer for these rigs, they need to reach operating temp once in a while
 






Short trips are bad for your oils too, because the oil never get's hot enough to burn off moisture.
 






yes engines will actually make water in the crankcase!! no bueno!!
 






I agree with the clutch fan. Mine finally gave up the ghost by freezing up never free wheeling. Replaced it with an electric fan from a police interceptor crown victoria and all was fine after that
.
 






Ya I can see on the gauge it opening and closing. And when I start it and let it run for a few with the rad cap off there is no flow into the rad. Also when I’m moving it makes burning hot heat. It’s still hot at idle just not as hot.
Fan is easy to turn by hand. It really doesn’t sound loud at all so I think it’s good. These fans are always turning tho correct? I’m going to change just the thermostat with a oem ford one this weekend regardless doesn’t hurt.
thanks everyone
 






Coolant is moving in the system, you just can't see it. Mine does the same thing. Sounds to me like you have a failing sensor on the thermostat housing or the temp gauge on the cluster is failing. The fan clutch is working fine so that's not the problem. My advice change the thermostat then if that doesn't work look at the senor or gauge.
 






Ya that’s the plan I’ll change the thermostat (which looks pretty easy to change) and go from there. Thanks all.
 






Ya I can see on the gauge it opening and closing. And when I start it and let it run for a few with the rad cap off there is no flow into the rad. Also when I’m moving it makes burning hot heat. It’s still hot at idle just not as hot.
Fan is easy to turn by hand. It really doesn’t sound loud at all so I think it’s good. These fans are always turning tho correct? I’m going to change just the thermostat with a oem ford one this weekend regardless doesn’t hurt.
thanks everyone

Fan should not be moving all the time. It sounds like the fan clutch is going bad and your thermostat is bad. My fan clutch went bad, and I let it run all the time, did nothing about it for 2 years and it messed up my intake manifold. I had to replace it. So make sure you take care of it asap.
 






OP - Before you worry about any other possibilities replace your t-stat.
 






Ya I got the tstat today and I’m going to replace it this weekend.
And I’ll let ya all know
 












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