I have a 1998 Dodge Ram 2500 with V10 engine that will not generate engine temperature above 140 deg F, this causes the ECM to choke the engine which sets off the O2 sensor. Assuming the problem was with the thermostat I purchased an aftermarket one & installed it. Engine temperature actually decreased instead of increasing. I have ready many posts about this problem with this engine & aftermarket thermostats. Dodge however no longer manufactures the OEM thermostat so apparently that is not an option. Has anyone found a solution

 

Stant Superstat, or Gates are good. Check the actual temperature, maybe your sending unit is bad.

 

Throw the thermostat in a pot of water and verify that it's opening and closing at the correct temperature. I'm betting you have other problems, like the sending unit.

 

I checked engine temperature with a thermometer, also checked engine block with heat gun, Both were only a couple of degrees different from each other. Also even when the vehicle is running indoors for half an hour it still doesn't heat past 140 deg. Cardboard in front of the rad also doesn't help, Top rad hose is also 140 deg

 

When you changed the thermostat, did you also change the seal at the bottom?

 

Sure did, the thermostat came with the seal & was purchased from Napa but from most of the posts I have read regarding this common problem indicate a lack of success with aftermarket thermostats. When driving on the highway & working the engine hard enough to generate a slightly higher engine temp that is just enough that the ECM doesn't tell the engine to choke but the moment you slow down or stop for a couple of minutes the engine cools down, choke comes back on.

 

How was your dash gauge reading before and after the repair? Did you do anything or anything happen to the truck before this happened? Also wondering what you used to press the new seal in? Was the old one damaged?

 

The temperature gauge had never been much above the 1/4 mark but after I replaced the thermostat with a new 190 deg one it was lower but not by much. The truck was never all that great at generating heat but at least it wasn't so cold that the ECM was telling it to run in "choke" Nothing notable happened, just a gradual drop in engine temp. I am in northern Alberta, Canada where winter temps can get to -30 deg & at that temp the truck is unusable.

 

Plug in with a scanner, and see what temp the PCM thinks the engine is.

 

It turns out that our mechanic installed the seal facing the same way as the old one that we took out which was upside down but to install the seal properly we had to mfg a special seal installer to expand the ID of the seal before dropping in the thermostat. The truck now is heating up correctly. I want to thank everyone who responded to this problem.