Hotter Thermostat

[MrZip]

The truck is an 03 3500 dually with the high output engine. I just had my water pump, serp. belt, and thermostat replaced yesterday. Today, on way to work I noticed temp gauge at 200 straight up. It used to run around 185 and up to 200 in summer and a little over when pulling 13,000 lb. fifth wheel.

My question is, The mechanic obviously put in a 200 thermostat. Will this affect my temps in the heat of summer or when I am pulling our trailer? Is there anything wrong with having a hotter thermostat than I used to have? Do not want any overheating problems. Appreciate any thoughts or opinions on this.

 

[p-Bar]

I prefer cooler since diesel have a tendency to run this way . The "600"s run hot because they want more complete combustion to meet "smog" . I prefer cooler just for some leeway. Just my 2 cents

 

[Bob4x4]

From the FSM

The thermostat will begin to open at 85. 5 - 89. 4°C. (186 - 193°F ). If the valve starts to move before this temperature is reached, it is opening too early. Replace thermostat. The thermostat should be fully open (valve will stop moving) at 97°C (207°F). If the valve is still moving when the water temperature reaches 97°C (207°F), it is opening too late. Replace thermostat. If the valve refuses to move at any time, replace thermostat.

 

[p-Bar]

From the FSM

The thermostat will begin to open at 85. 5 - 89. 4°C. (186 - 193°F ). If the valve starts to move before this temperature is reached, it is opening too early. Replace thermostat. The thermostat should be fully open (valve will stop moving) at 97°C (207°F). If the valve is still moving when the water temperature reaches 97°C (207°F), it is opening too late. Replace thermostat. If the valve refuses to move at any time, replace thermostat.

Ya that's what I like to see the facts... .

 

[CBari]

OK great facts now for dumbies like me how does one test that. I have one that I was getting ready to replace and I kinda would like to test the new one from the parts store before I replace it. And of course would like to test the old one to see if it was my problem.

 

[SHobbs]

I have heard of people using a pot of water on the stove to test them.

 

[p-Bar]

I have heard of people using a pot of water on the stove to test them.

To add to this take your wife's candy thermometer to monitor it.

 

[Turbo1Ton]

Make sure to suspend it with a string or wire so that it does not touch the pan. This will avoid it opening before the water reaches the correct temperature.



Jeff

 

[steved]

Keep in mind the factory guage does not move linearly... in other words, what appears to be a fairly big increase near the centerpoint is only a couple degrees. Most thermostats are only "close", and not a very precise instrument.



As long as it isn't overheating, you could simply have variance in guage reading or thermostat openings.



As far as I know, there is only one "heat" for our thermostats... perhaps yours wasn't working correctly to begin with??

 

[RKerner]

Keep in mind the factory guage does not move linearly... in other words, what appears to be a fairly big increase near the centerpoint is only a couple degrees. Most thermostats are only "close", and not a very precise instrument.



As long as it isn't overheating, you could simply have variance in guage reading or thermostat openings.



As far as I know, there is only one "heat" for our thermostats... perhaps yours wasn't working correctly to begin with??

there seems to be a long distance between 185 and 200 on the gauge when comparing it to my Quadzilla. 185 starts about two needles above the bottom tic above the 140 mark.

140 |_______200___|

... ... ... . |

... ... ... . | needle is here at 185 on Quad. Normal operating temp is between 195-202.

 

[steved]

I have three numbers on mine... 140, 200, and 260. Not sure where the 185 comes from?

Between my Granatelli and OE guage, the 140*F to 200*F will cover anything from ambient to 200*F, a swing of seven to eight degrees from 200*F is about 1/4 of the scale between 200 and 260, 226*F (seen this one time) is about halfway between 200 and 260.

The guage is not linear... 8 degrees is 1/4 scale, and 18 degrees for the next 1/4 scale...

 

[rbattelle]

I've been monitoring my temperature closely the last few days. Last Thursday it was 86° ambient and I drove home from work at 70 mph with the A/C on (non-recirculating). Maximum water temperature was 196.

The next day, same ambient conditions, driving home at 70 mph with the A/C off, maximum water temperature was 190.

These numbers are for an empty truck.

Sounds like my truck runs a little cooler than some others on here. I don't mind high temperatures (better efficiency), but not if it runs hot because something is wrong.

I'm planning to give the condenser/intercooler/radiator a good cleaning soon. After 6 years they may be significantly down on airflow due to dirt. MrZip, you might want to try that too.

Ryan

 

[sag2]

Actually depending on the capacity of the cooling system to get rid of heat, with a thermostat that is 10 degrees hotter than you had, you might actually see more stable temps in the summer. The reason is the engine is going to stay 10 degrees warmer, so the coolant should be passing through the radiator slower, allowing it to give up more heat to the atmosphere, and keeping the engine temps more stable in the process.

In reverse, think of a cooling system sized too small. Adding a colder thermostat will just allow it to open fully and the coolant never slows down in the radiator release the heat from the engine. The system just gets hotter until it can't stay below the boiling point of the coolant.