Stock thermostat - What is "Normal" gauge indication

[TDG]

What is generally a 'normal' gauge reading for a stock thermostat? (With the heater off)

I've been using the cheapo 'cold' thermostats for years and have grown used to the gauge always being well to the left side usually floating somewhere between the line and N to O in normal.

Today I changed everything (hoses / pump / radiator / sensors / thermostat etc) and went back to the OEM thermostat and the gauge is now about half way to a tad past halfway up... as expected with a hotter thermostat.

Just trying to gauge what is normal when all things are normal (stock) I would install a real temperature gauge but I'm trying not to chop this Explorer up (again) as it is in good stock shape.

 

[yostyexplorer94]

I have a 180 degree in mine and it is around the n to o. Stock thermostat was right around the middle.

 

[roscoe 0202]

the computer likes 195.
roscoe

 

[Craggles]

What is generally a 'normal' gauge reading for a stock thermostat? (With the heater off)

I've been using the cheapo 'cold' thermostats for years and have grown used to the gauge always being well to the left side usually floating somewhere between the line and N to O in normal.

Today I changed everything (hoses / pump / radiator / sensors / thermostat etc) and went back to the OEM thermostat and the gauge is now about half way to a tad past halfway up... as expected with a hotter thermostat.

Just trying to gauge what is normal when all things are normal (stock) I would install a real temperature gauge but I'm trying not to chop this Explorer up (again) as it is in good stock shape.

I'm new to the forum so let me say I'm VERY happy to find a Gen1-specific page! (I have a '93 Explorer XL 4WD...)
Specifically, I have a problem with my ECT. The temp gauge hasn't gone above ice-cold in years and results in a check-engine light. The engine "seems to" warm-up normally, and recently I tested the thermostat (still installed in the vehicle using a meat thermometer to verify the water in the radiator is "still" until the thermostat opens) before replacing the sender, all to no avail.
Bringing my electrical engineering skills into the mix while looking at the ONLY diagram I have which shows the sender connected to the PCM at Pin7 through a LtGrn/Red wire, after measuring an "electrical open" from the end of the sending wire to Pin7 with the PCM cable bundle disconnected (and battery disconnected for some time first), I re-routed a new completely new sending wire to Pin7 (using the existing connection; I just snipped the existing Pin7 wire near the PCM, for access).
This didn't fix the problem either. The CEL, which usually doesn't come on until 5 minutes or so of freeway driving, came on immediately. Also the gauge was absolutely dead, while normally there is the tiniest deflection. (at this point I restored the original connection, although I haven't reconnected the sender, which is pointless, perhaps save for a floating logic input somewhere. The vehicle is running normally, pretty fair actually but with the CEL on and, I'm worried, with potentially reduced fuel mileage as the computer could make decisions with bad information).
So, here's my thoughts:
1. How/where are the gauge/sender connected to the PCM? My apparently "wrong" picture doesn't show the gauge at all. I'm wondering if the connection is actually THROUGH the gauge, and wondering if I need to remove the instrument cluster (which, fortunately is what allowed me to find this forum
2. But, after reading your post, I'm wondering if I'm waaaaay off track. Maybe I should just replace the thermostat after all, and hope for the best! Also sounds like I should throw away my new O'Reilly thermostat and get one at Ford?
HHHHEEEELLLLLPPPPP tia

 

[roscoe 0202]

the computer sender has two [2] wires going to it the guage sender has one wire going to it. I think you are playing with the guage sender the engine coolant sensor [ect] is on the other side of the manifold.
roscoe

 

[Rhett]

Mine is always on the left side, N or O.

I think there's a wide range of quality with thermostats...some will open too soon, or too late. Next time I'm going to make it a point to buy a Motorcraft 195 degree thermostat.

 

[Craggles]

the computer sender has two [2] wires going to it the guage sender has one wire going to it. I think you are playing with the guage sender the engine coolant sensor [ect] is on the other side of the manifold.
roscoe

Oh my
That's totally something I could do. How embarrassing, but it would certainly explain my results. As Iike to say; "sorry I gotta tell you this, but happy I can..." I'll file it in that category.
So, we'll see. Thanks!!

 

[Craggles]

Btw it also seems to suggest the engine is legitimately cold. But it really seemed like the thermostat is working. The radiator is perfectly still, until "something" happens. What else could it be besides the thermostat opening. Maybe I'll constrict a hose with a clamp so it will heat up. I would die to see the gauge move! Yes, that's another thing I'm capable of attempting...

 

[Roadrunner777]

I'm new to the forum so let me say I'm VERY happy to find a Gen1-specific page! (I have a '93 Explorer XL 4WD...)
Specifically, I have a problem with my ECT. The temp gauge hasn't gone above ice-cold in years and results in a check-engine light. The engine "seems to" warm-up normally, and recently I tested the thermostat (still installed in the vehicle using a meat thermometer to verify the water in the radiator is "still" until the thermostat opens) before replacing the sender, all to no avail.
Bringing my electrical engineering skills into the mix while looking at the ONLY diagram I have which shows the sender connected to the PCM at Pin7 through a LtGrn/Red wire, after measuring an "electrical open" from the end of the sending wire to Pin7 with the PCM cable bundle disconnected (and battery disconnected for some time first), I re-routed a new completely new sending wire to Pin7 (using the existing connection; I just snipped the existing Pin7 wire near the PCM, for access).
This didn't fix the problem either. The CEL, which usually doesn't come on until 5 minutes or so of freeway driving, came on immediately. Also the gauge was absolutely dead, while normally there is the tiniest deflection. (at this point I restored the original connection, although I haven't reconnected the sender, which is pointless, perhaps save for a floating logic input somewhere. The vehicle is running normally, pretty fair actually but with the CEL on and, I'm worried, with potentially reduced fuel mileage as the computer could make decisions with bad information).
So, here's my thoughts:
1. How/where are the gauge/sender connected to the PCM? My apparently "wrong" picture doesn't show the gauge at all. I'm wondering if the connection is actually THROUGH the gauge, and wondering if I need to remove the instrument cluster (which, fortunately is what allowed me to find this forum
2. But, after reading your post, I'm wondering if I'm waaaaay off track. Maybe I should just replace the thermostat after all, and hope for the best! Also sounds like I should throw away my new O'Reilly thermostat and get one at Ford?
HHHHEEEELLLLLPPPPP tia

Invest in the factory EVTM wiring diagram manual for your year explorer. They run about $20 on a popular auction site. Every wire, connector, routing, diagnostic tests, color code, wire size... the first time it saves you from buying a part, it has paid for itself.

 

[Dan R]

Motorcraft has a 197F thermostat with a jiggle valve. I didn't notice any difference on the temp gauge. The Motorcraft radiator cap is 16 psi rather than 13 on the aftermarket ones.

 

[Dora 1993]

I thought something was wrong with mine because it read so low. It reads at or Bellow the N all the time. New stock thermostat, coolant, and cap didn't do a thing. I think the gauges are just not accurate.

 

[Craggles]

I thought something was wrong with mine because it read so low. It reads at or Bellow the N all the time. New stock thermostat, coolant, and cap didn't do a thing. I think the gauges are just not accurate.

Well thanks Dora. Although, I hope you're wrong because "low ect" is causing me a CEL; that's got nothing to do with the gauge connection, as I learned recently. That's also when I decided it's running legitimately cold, and my next step was a new stock (or hotter?) thermostat...
I'm lost!

 

[Craggles]

I thought something was wrong with mine because it read so low. It reads at or Bellow the N all the time. New stock thermostat, coolant, and cap didn't do a thing. I think the gauges are just not accurate.

Hi again, I found posts on the forum describing the ECT pigtail connection which is wired INTO the negative battery cable. That's where I'm going on my current ECT problem!

 

[TDG]

The thermostat I used is listed as MOTORCRAFT part number RT1161 - it's list as a 190 degree thermostat with a footnote that it may open at 197...

After a week of daily driving it appears that the new normal for me with this thermostat is between the M and A on the gauge with the old thermostat is around the N and O

 

[Craggles]

Hi again, I found posts on the forum describing the ECT pigtail connection which is wired INTO the negative battery cable. That's where I'm going on my current ECT problem!

Btw I had that WRONG. The poster was referring to the Temp Gauge, NOT the ECT connection. And it became unclear the gauge was actually connected through the described pigtail. So, ignore my comment.

Also, my ECT/O2#1 cel's (#116 and #176, if I remember correctly) (and simultaneous (but likely un-related) ice-cold TempGauge) problem(s) are still driving me crazy, but I have a lot more information (including electrical troubleshooting details), so I'm gonna create a new post.
AND, I'm using the paper-clip method to pull error codes, which EVERY Gen1 owner can easily do!