Temperature Gauge? (1 Viewer)

[TexYoung]

1973 FJ40 Stock 1F. Vehicle sat for a few months since last driven. At idle the temperature gauge is going all the way to the left within 10 minutes. I took out thermostat and tested in boiling water, opened fine. Replaced the sending unit - no change. Ran motor with no thermostat and cap off. The water was circulating but not a lot. I took my heat gun after it had been idling for about 15-20 minutes and got these readings: Water temp at radiator with cap off 175, Radiator 180, Hoses average 170. Heater hoses 160-180, Thermostat housing 181, Right side of head 176, Right side of block 145, Top of head where manifold connects 220-250, sending unit 225. I think the water pump is OK, bc it was circulating. Maybe bad gauge???

 

[charliemeyer007]

Sending unit are cheap, get the correct one is important. If you disconnect it the meter should read above hot IIRC. The meter I think you can get rebuilt units or perhaps used, or fix it your self.

 

[Pighead]

Maybe bad gauge???

Or maybe bad wire between sender and gauge

 

[TexYoung]

Thanks. I checked and have voltage on both sides.

 

[TexYoung]

Sending unit are cheap, get the correct one is important. If you disconnect it the meter should read above hot IIRC. The meter I think you can get rebuilt units or perhaps used, or fix it your self.

I'll disconnect and see what happens.

 

[Ozpall]

New temp gauge

 

[TexYoung]

New temp gauge

View attachment 3730803

Is that where they are located on the 2F? Mine is in the head right next to the exhaust manifold. I would like to get that thermostat housing.

 

[Ozpall]

Is that where they are located on the 2F? Mine is in the head right next to the exhaust manifold. I would like to get that thermostat housing.

No same spot as yours I drilled the tstat housing and put an aftermarket gauge.

 

[45Dougal]

Start by measuring the resistance of the sender hot and cold.
if that checks out then check the feed voltage at the temp gauge - should be regulated to about 7V. maybe your fuel gauge needs a clean up?

 

[Millardo]

1973 FJ40 Stock 1F. Vehicle sat for a few months since last driven. At idle the temperature gauge is going all the way to the left within 10 minutes. I took out thermostat and tested in boiling water, opened fine. Replaced the sending unit - no change. Ran motor with no thermostat and cap off. The water was circulating but not a lot. I took my heat gun after it had been idling for about 15-20 minutes and got these readings: Water temp at radiator with cap off 175, Radiator 180, Hoses average 170. Heater hoses 160-180, Thermostat housing 181, Right side of head 176, Right side of block 145, Top of head where manifold connects 220-250, sending unit 225. I think the water pump is OK, bc it was circulating. Maybe bad gauge???

TexYoung, came across your thread as I was looking for info on temperature readings, but for the opposite reason. I "feel" like my 1972 FJ40 Stock 1F is running HOT while the gauge never reaches higher than center of Cold and Hot. I planned to get a temp laser gun this week and take readings in the same locations.

Are the readings you recorded in the normal range? Does anyone know offhand what would be appropriate readings for these locations should be?
I am currently running without a fan shroud, so there's that...

Thank you in advance, Chris

 

[45Dougal]

If you measure the resistance of the sender when it's hot and cold, then you'll determine that you have the right sender, and you'll be able to establish if you're running too hot.

I assume that you have an electrical multimeter given that you have a 40

If it's misreading, then it's most often the gauge and it's supply voltage, but this is independent of the sender resistance.