Follow-up to previous post.
I changed my thermostat today all by myself! The previous one (pictured) was a 190-degree. My Quadzilla Commander sensor was spiking sometimes as high as 220, so I figured the old one was going bad. I replaced it with a 180-degree Cummins T-stat from www.scheiddiesel.com. and I like it allot. Test drive showed the temp at 178-182 on the sensor. But here's pic of the old one. Notice on top/inside on the "dome" there is (was) a rubber-type cap. Much of the cap is deteriorated. I tested it in a pot of boiling water and it does indeed open, but somewhere between 195-210 (according to my digital turkey temperature tester). I'm guessing this was the original t.stat. How long do thermostats typically last?

 

The one I replaced last November was in there for about 8 years. Still worked fine, but the seal for the outside edges was starting to get tired. Similar to yours.

 

The probable cause for overheating was the road draft bottle. If so, the radiator fins are still plugged and the overheating will continue.

 

they last a long time and if they do fail they are reversed popet design to fail in the open position. when they go bad they remain open not closed and u experience longer and longer warmup times.

 

My 2001 has been gradually increasing in temp - thinking this is from the puke bottle clogging up the backside of the radiator. Even so, while making a 3 hour drive yesterday, the temp hit just over 190, while driving over one of many mountain passes, and then dropped way off to like 150, and is now staying around that temp - needle just withing the min temp range. From reading the last post, when the thermostat fails, it fails open. Do I need to be concerned with having the thermo replace right away, or could the R&R wait until I return home - about 180 miles? Thanks, DD

 

Dodgerdog you should be fine running a short distance like that with temps around 150*. I wouldn't run it like that much in dead winter, but the summer should not cause any problems. When you do change it out, it takes about 5 minutes. Remove 3 bolts, pull old out, drop in new, reinstall 3 bolts and top off coolant.

We had a thermostat fail in our Cat backhoe a couple of weeks ago and it failed in the closed postition. We were in a bind and needed it badly and had already cleaned radiator and thought that had taken care of it, but after running about 10 minutes it started overheating again and this time we decided to pull the thermostat and sure enough it was closed while sitting in the housing at temp around 220*. First one I have seen fail due to not opening at all.

 

Hey thanks for the reply post. Since I wasn't sure about running with a thermostat failed wide open, I found a mechanic on a Saturday even who not only replaced the thermostat (NAPA 190 as OEM), but he clean out the backside (oiled up from puke bottle), and frontside of the radiator - all for about $130.00. The radiator looks great as in clean, and the drive back from Salida to Steamboat over many mountain passes had the temp rock solid just under 190 degrees - best temp stability I've seen in years with this good ole truck of mine.

 

My truck went through major heat befor I jumped on here and was diagnosed with something like this.
My rad was totally covered up from the puke bottles BS location. On one occasion I got out on a job and left it runnin readin 220* to try to let it cool down... 10 minutes later I get back in the the dash coolant temp is pegged in the red at 240* with check gauges light on. I coasted home and it cooled a bit but that weekend took care of it.

I pulled the rad and took it to a self car wash with a can of degreaser. 9.00 in quarters later it looked as good as new.
Changed the t. stat while I was at it, all in all, 3 hours sunday morning and about 50 bucks later I was done and havent seen over 191* since.

 

Must be a common end of the summer activity, I just finished pulling the Rad and washin out the oil and dirt combo. I'm Going to finish it off by relocating the bottle.