Temp Gauge Not Rising (engine Not Reaching Operating Temp.)

ChristianLance

New Member
Jun 12, 2017
5
0
1
22
I have a 5 speed 1990 Mustang LX 5.0: Stock 302, New distributor, thermostat, spark plugs, Spark plug wires, New cam sensor. It's entirely stock.

When I start the car for the first time while it is cold it stalls. Upon second start up it almost dies and then picks back up again. I'm not sure if this is related to the problem that I'm currently having but when I run the vehicle for over 20 minutes the temp. gauge hardly rises above 140/150 - no matter how hard I push it and no matter how long I let it idle for. I replaced the thermostat hoping this would fix the problem but it has only gotten worse. Prior to the replacement, It was running at a good 160/170.

I was thinking the fan clutch or even a broken gauge.
I've gotten a check engine light but it only appears for a few minutes and I cant get a chance to check it.
I made sure that the thermostat was installed correctly. It's not leaking and everything seems to be running fine except for the engine being too cool.
 
  • Sponsors (?)


Mustang5L5

Mod Dude
Feb 18, 2001
30,982
7,350
224
Massachusetts
The sensor for the gauge is right here.

IMG_1762.JPG


Verify the wiring is intact, and perfhaps replace it as I believe it's cheap.

The coolant temp sensor for the ECU is in the pass side coolant hard pipe. If you really want to see if you have temp issues, get the car warmed up and pull codes. If coolant not to temp you'll get a code 21 at under, I believe, 150 degrees
 

mikestang63

SN Certified Technician
Aug 27, 2012
9,821
6,602
204
In the garage
uh. wondering how you replaced a cam sensor on the engine that doesn't have one? These motors use distributors.
Running at even 160-170 is too cold and your computer is operating on the edge of closed/open/ mode. The engine operates better in the 180-200 range. What temp thermostat did you install. Stock is 192. . Chance are your stock temp gauge or sending unit is bad.
As Mike said- get the car warmed up and then run the KOER codes. The stalling could be a number of issues. If you get a 21 the ECT sending unit may be bad
 

ChristianLance

New Member
Jun 12, 2017
5
0
1
22
uh. wondering how you replaced a cam sensor on the engine that doesn't have one? These motors use distributors.
Running at even 160-170 is too cold and your computer is operating on the edge of closed/open/ mode. The engine operates better in the 180-200 range. What temp thermostat did you install. Stock is 192. . Chance are your stock temp gauge or sending unit is bad.
As Mike said- get the car warmed up and then run the KOER codes. The stalling could be a number of issues. If you get a 21 the ECT sending unit may be bad
It was the cam sensor inside of the distributor. First I tried one of the cheap $4.99 O'riley ones. The thermostat didn't sit flush with the housing and so I ended up using a Mr.Gasket aftermarket "high performance" thermostat that opens at 180 degrees.