Water temp and MPG

[2TimingTom]

Lately I've been noticing that my temp gauge is about at 1/3 and my gas mileage has been lower than normal- like 11-13 mpgs. Granted I do have a SAS/SOA, but still...... The temp gauge is really my concern.

Today I hooked up my ScanGauge that normally resides in my Mariner. My Mariner's water temp will reach 190-210 or so depending on driving conditions. My Explorer today didn't get above 182, spent most of the time in the upper 170s.

My thermostat was replaced with a 190 degree several years ago- but only like 20,000 miles ago.

Where is your temp gauge? I seem to remember mine being at 1/2 after I replaced the thermostat. Anyone with a ScanGauge, what temps are you seeing?

 

[DJRockit69]

I havimy a similar issue I still really can figure it out I have a new radiator new t stat new water pump and all new hoses. My factory gauge on the dash plummets when the T stat opens. My temp is around what Ur is and I'm still clueless

 

[SoNic67]

What's the temperature outside? The clutch fan will still pull some frigid air over the engine block. Put a cardboard in front of 1/2 of radiator.

 

[2TimingTom]

It was 50 degrees as I was driving around yesterday.

A piece of cardboard is a bandaide. A thermostat that's working properly will get the engine up to proper operating temp in all but the coldest of weather.

 

[SoNic67]

Yes, sure...
Today was 15 outside in the morning and my engine warmed only to 1/3 of the gauge (highway driving). I have to leave at noon for a short trip (around town, 21 deg) and the temperature raised to 1/2.
I guess the T-stat was broken and fixed itself in a day...

 

[2TimingTom]

Or your cardboard fell out......

So if what you say is true, if your gauge at 15 degrees is at 1/3 and 1/2 at 21, then when the weather is actually cold (sorry, but 15 is not cold) then your gauge wouldn't even register if you were in -20 in upper Minnesota. And it should be I the red if the weather is in the 80s. And we all know that simply is not the case.

 

[SoNic67]

When the T-Stat is completely closed... it cannot close more that that.
So if at 15 is already completely shut, at -20 it will still be as shut as before. This is not a matter of being defective.
Air flow at 60mph is different than at 30mph and that made the difference in cooling.

 

[masospaghetti]

If the thermostat is working the engine has almost no cooling capacity until it warms up except for the heater core. Unless you're talking seriously extreme weather, like -50 F with the heater on full blast, the engine will heat up just fine.

 

[Varsity]

It been -4 with wind chills at -20 the last couple of days and my temp is usually around 182-185ish. When the temperature is actually positive, I'm usually between 185-190. The temp gauge sits directly in the middle.

I'm not much for the cardboard idea either, but I see the purpose.

 

[Turdle]

after replacing several thermostats, I finally dug deep and went to the dealer for a genuine ford replacement. Now my scangauge says my engine runs at 191 degrees.

Before, it was having a hard time reaching those temps with cheaper units.

I know, I know, it shouldn't be so, but that is my .02 to throw in.

When I tried a failsafe, the heat soak after turning off the engine ran it up to the hold open point. AT that time it would not get over 160, and it was only about 3 weeks old.
Just FYI.

And I might add, it is possible for a thermostat to "hang up" or not close completely, intermittently. Been there back in the day-

 

[colintrax]

Or your cardboard fell out......

So if what you say is true, if your gauge at 15 degrees is at 1/3 and 1/2 at 21, then when the weather is actually cold (sorry, but 15 is not cold) then your gauge wouldn't even register if you were in -20 in upper Minnesota. And it should be I the red if the weather is in the 80s. And we all know that simply is not the case.

15 IS cold lol

I think you know your problem. Your tsat is bad.

 

[2TimingTom]

I agree. I'll pick up a genuine Ford replacement. Change the coolant while I'm at it too.

 

[97xlt4.0]

I had this experience on my '97 several years ago, the temp gauge was as you described, and i did notice a decrease in mileage....i was bone stock at the time, save for a set of 30x9.50 tires.

What I found, after replacing my water pump, and several months down the line, was that my plastic thermostat housing had failed completely, and looked to have been failing for some time.

As I was crunched for time, I opted to purchase from the Ford dealer for my replacement, and it came complete with thermostat, and since then i've had no problems....

 

[PAExplorerXLT]

Here is what I see everyday. I have good amount of heat though. My coolant temp is 175 and the thermostat is new but don’t know what temp. It is going to be 0 tonight.

 

[colintrax]

^that's too cold. Your coolant should be 190ish

 

[MtrJunkie]

And your check engine light is on.

 

[Turdle]

At 191 (scangauge temp) my temp gauge needle sits right on the thermometer symbol in the middle.

 

[PAExplorerXLT]

And your check engine light is on.

At this age you should not buy one of these without the check engine light on. There is something wrong! Seriously, it is a lean condition that nobody can figure out.

 

[MtrJunkie]

Hahaha!!! That's so true it's almost NOT funny.

 

[ZWilson07]

At this age you should not buy one of these without the check engine light on. There is something wrong! Seriously, it is a lean condition that nobody can figure out.

Exactly why I finally just bit the bullet and ordered a smoke pro. I CAN'T WAIT to finally have a evap smoke machine lol.