2001 Dodge Ram 1500 5.2L V8, 161K Miles

This problem begins a while back. In June, I had my tranny replaced (with a used one), but then I still had transmission problems. Truck was also running hot. Warmed up quickly, averaged 240-260. Its the hot summer of Houston, so city driving here in 100+ temps does't help. I swapped the thermostat out for a failsafe thermostat from auto zone ($14), replaced the gasket and sealed it. This had no impact on the engine temps - still ran hot. I had 4 check engine codes - 3 for the tranny, 1 for the radiator (low on coolant).

A month ago I took the truck back to the shop to get the tranny valve body replaced. This fixed the tranny problems completely, and they showed me a crack in the radiator that was leaking. Over the next week, the car doesn't run hot anymore. Actually, it doesn't get hot enough - never reaching 180. I take the truck back to the shop and have a new radiator installed, and they replace the thermostat again. The shop tells me they checked the check engine light, and the code was 1281 - engine too cold. They say the new radiator may fix that, but if not, it's probably the temp sensor or the instrument cluster. I get the truck out of the shop, drive it for 3 days, and the check engine light is back on because the truck still doesn't get warm enough. CEL code 1281. So today I replaced the temp sensor. In replacing the sensor, I drained the radiator and filled it back up, being sure to burp it. I got 2 gals of fluid back in. When I drained the radiator, I could see they the shop did not replace the housing, but I could see sealant coming from under the housing, so I assume that's from when they replaced the thermostat.

After replacing the temp sensor, I warmed the engine up in the driveway for 10 minutes, then drove around for another 20, but I still can't get the engine to warm up. The image below is the gauge at the end of a 30 minute drive in the heat of the day.

Could it be a faulty or mis-installed thermostat? I know it could be that, but is that the likely culprit? Or is there something else?

 

That's where mine was reading with a 180* stat. I was also getting the "too cold too long" code.More than likely that is what was put in. Replace it with a 195* and you should be good.

 

My 180 reads 180.

 

Replace the thermostat with a 195 unit. Skip the failsafe fellers. They are too 'safe', and panic easily. (and stick open, which is what it looks like is happening.)

 

Yeah probably a 180* thermo. Either that or its stuck. I had the same issue with mine, at first it was with a stuck thermostat, and the second time was because the parts guys gave me the wrong thermo (180*) and I needed a 195*. I always run Stant thermostats, and always put those into my customer's cars.

 

Thanks for the input. I ordered a Stant 195 thermostat and new gasket. I'll update with the results once it's installed.

 

Yupp as stated most likely a 180 degree stat. I have a 180 degree stat and get that code from time to time, I just ignore it.

 

A quick update on this: I got a code reader and watched the live data as I drove 10 miles to work (80F outside temp). The engine coolant temp never got above 163F until I parked and turned the engine off. At that point. the temp went up to 174F within about a minute.

 

Wrong thermostat in there.

 

Get a Stant Super Stat.