[rustyescott]

ok stats 93 7.3 idi 5spd . just changed ip , now notice on hwy running 55/60 mph ,temp guage needle reads at the R/M of normal. speed up to 65/70 plus guage reads at the L of normal, do i have a pending problem?
rusty

 

[cdnsarguy]

My first question is what Tstat brand is installed........ must be Ford or IH.

CAUTION:
The specified/required thermostat does not contain an internal bypass, since the bypass is located in the cylinder block. Whenever the thermostat is replaced, it is mandatory that only Motorcraft E5TZ-8575-C or Navistar 1807974C94 thermostat be installed.

Diesel engine coolant temperature at the top of the radiator where hose attaches after high rpm or under load condition for 20 minutes should be (195-237*F) 91-114*C nice time to have a temperature reading point and shoot tool.

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Coolant temperature guage...

Connect a 73 ohm resistor between the guage lead at the sender and ground. The center line of the needle should fall within the band around the C mark.

If guage tests within calibration replace the sender.

If guage still tests out of calibration replace guage.