Here we go... I replaced my thermostat awhile ago and during this time I noticed a difference in the thermostat valve areas. Size mostly...

Anybody have any coments on this? I use the Napa thermostat and notice it holds a even 190F* on the stock gauge until I put my foot into it then it will rise to a needle width of the 190 mark but that's it.

No problems with that just curious what you guys have to say...

 

please ask hulin in dixie!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

mopar1973man. Last winter my truck was not warming up enough in the cold, it was always showing 183* to 185* no matter how long the engine was running, so I bought a new 190* thermostate from Carquest and installed it. After installing the new thermostate the guage varies from a needle width above 190* to a needle width below 190* when the thermostate opens to change the coolant. The old thermostate was allowing the engine to reach about 195* and then dropped to about 183* when it opened in warm weather, too slow reacting.
Even towing my 32' 5er the engine stays between a needle width above or below 190* which is what you want.
RETOOC

 

I was given an updated part number for a thermostat from Cummins by another member. Supposedly takes care of the variances in temperature.

Cummins Thermostat - 3934373

 

Retooc - Your running the same as me. It was cold in the winter time with a high rising needle (above 190F*) then open suddenly and dropped to 180's F*

The only difference was this summer it was rising to above 190F* and staying there and not dropping. The radiator is clean no oil/dirt in the face of it. Fan is cycling normally (loud fan).

So I change the thermostat and the picture above is what I used. To also find out that others where having the same problem I was with the stock T-stat being to wide in the valve and allowing to much flow of coolant.