I just wanted to post my recent experience since there's always a lot of discussion here concerning truck problems with no heat and motors running cool. Like many others have stated, our rig was running cool, little heat in front, but the rear heater was reasonably warm. This was strange since you wouldn't think either heat source would be warm if the thermostat was the problem!
Until now, our truck had never warmed above the 1/4 mark on the temp gauge during cold weather. I decided that replacing the thermostat would be a cheap place to start troubleshooting the system. I picked up a new Toyota Thermostat and gasket and started in...As soon as I got the top off, I saw part of the problem - no rubber seal on top of the old thermostat! Scraping away the old gasket took more time than anything and there was also a lot of mineral build-up where the seal should have been on top of the thermostat. This prevented the new seal from seating properly so I had to scrape away that heavy scale also.
Luckily when taking the 4 bolts out, none of them snapped (soaking in liquid wrench probably helped) and I was super happy about that! By the recommendations of others here, I replaced the bolts with studs and used nuts to secure the top housing - what a great improvement for future repairs! Studs in, new thermostat in place with rubber top seal, and RTV on both sides of new gasket...Top on thermostat and lightly tightened down the new nuts! I let everything sit for about an hour then cranked the truck, checked for leaks and pulled out of the garage. I knew I was in good shape when the truck quickly started warming much more quickly! I parked on a fairly steep incline with the radiator cap off and ran the heat for a while...Even with the system down about 1/2 gallon of coolant, it still quickly got the air out and warmed even more. I added more coolant and we threw the dogs in the truck to go for a ride and see how the heat was going to be when running normally.
I was amazed how quickly the system warmed up, the heat started flowing (actually hot) and within 10 minutes I was actually turning the heat down (definitely a first for this rig) even though the outside air temp was about 10 degrees F for us last night. Truck temp went to the middle of the temp gauge and stayed there! What a huge win!!
I highly recommend anyone with heating issues replace their thermostat and see what happens...
Until now, our truck had never warmed above the 1/4 mark on the temp gauge during cold weather. I decided that replacing the thermostat would be a cheap place to start troubleshooting the system. I picked up a new Toyota Thermostat and gasket and started in...As soon as I got the top off, I saw part of the problem - no rubber seal on top of the old thermostat! Scraping away the old gasket took more time than anything and there was also a lot of mineral build-up where the seal should have been on top of the thermostat. This prevented the new seal from seating properly so I had to scrape away that heavy scale also.
Luckily when taking the 4 bolts out, none of them snapped (soaking in liquid wrench probably helped) and I was super happy about that! By the recommendations of others here, I replaced the bolts with studs and used nuts to secure the top housing - what a great improvement for future repairs! Studs in, new thermostat in place with rubber top seal, and RTV on both sides of new gasket...Top on thermostat and lightly tightened down the new nuts! I let everything sit for about an hour then cranked the truck, checked for leaks and pulled out of the garage. I knew I was in good shape when the truck quickly started warming much more quickly! I parked on a fairly steep incline with the radiator cap off and ran the heat for a while...Even with the system down about 1/2 gallon of coolant, it still quickly got the air out and warmed even more. I added more coolant and we threw the dogs in the truck to go for a ride and see how the heat was going to be when running normally.
I was amazed how quickly the system warmed up, the heat started flowing (actually hot) and within 10 minutes I was actually turning the heat down (definitely a first for this rig) even though the outside air temp was about 10 degrees F for us last night. Truck temp went to the middle of the temp gauge and stayed there! What a huge win!!
I highly recommend anyone with heating issues replace their thermostat and see what happens...
