Thermostat Swaps?

[Brad7611]

Currently my truck will run up to 210 degrees before the thermostat opens up and then it drops to 197-203 degrees. Has anyone considered swapping the thermostat out for a lower temp one? Say a 180 or 190 degree thermostat? Is there a specific reason the 6. 7 has a higher operating temp than my old 5. 9? Any ideas or info is much appreciated. Thanks in advance.



Brad

 

[Hoefler]

All Part of the emission system and fuel management system.

 

[Beast2B]

I would think if your truck is deleted it might work fine, but stock they are watching the cylinder temp to assist in controlling emissions

 

[Brad7611]

Would there be any benefit to putting a lower threshold thermostat in to bring operating temps down to say 180 or 190 degrees if there wasn't any emissions on the truck? Or would it pretty much be pointless and only make you feel good when you look at the guage?

 

[Alan Reagan]

The engine operates more efficiently at the higher temps.

 

[EMAC2]

The thermostat doesn't directly control the engine temp, the ECM/PCM does by turning on the engine cooling fan and varying the speed of the fan to ensure the temps stay where the ECM/PCM wants it. The thermostat will only allow the flow to the radiator and this in turn may cause a CEL because the engine doesn't reach the commanded temperature.

I'm curious to see how this turns out in regard to the CEL and the lower temp thermostat. Please keep us informed on this and also the part number of the thermostat you decide to use.

 

[mwilson]

Currently my truck will run up to 210 degrees before the thermostat opens up and then it drops to 197-203 degrees. Has anyone considered swapping the thermostat out for a lower temp one? Say a 180 or 190 degree thermostat? Is there a specific reason the 6. 7 has a higher operating temp than my old 5. 9? Any ideas or info is much appreciated. Thanks in advance.



Brad

Modern On-Road Diesels are all running at 200-210 degrees, for emissions and efficiency.

I would not mess with it. It took a few years for the truck drivers to get used to it and quit *****in' about it, now it is the accepted norm.

If you knock the coolant temp down the ECM may panic and you will be running in an ineffecient loop, which will cost you fuel mileage. . and could affect other functions that you wouldn't even think of.



Big Cats, Cummins and Detroit engines are going up and down the road at 210 degrees evey day with no issues.



JMHO.



Mike.

 

[Brad7611]

Mike

Are the big guys running up and down the roads are at a higher temp due to emissions regulations? I am only asking because it seems the old diesels ran a bit cooler prior to emissions. I know they put a butt load of miles on their rigs in perspective to mine, I'm suppose I'm mainly curious as to the recent design changes that have resulted in a higher operating temperature. I understand they help with emissions, but is there any detriment to the engine relative to longevity and perfomance/economy?



With that said I know the motor will outlast the truck regardless. I just like to understand change when it takes place. So do you think or know if the operating temperature would have been raised without the emissions regulations?

 

[mwilson]

I think that the electronic engine controls have allowed the safe operation at higher temperatures. It is a bonus that it helps with emissions as well.

Plus a more effecient engine equals higher fuel mileage, if you can take a truck engine that was getting 4. 5 mpg and by raising the temp and adding sophisticated engine controls create a gain of 1 mpg multiplied by 150,000 miles per year you have just saved some serious coin for that truck owner. If he has a fleet of 50 trucks you just helped him into the millionare's club.....



Back before reliable electronics it was scary to run them over 180, didn't leave much margin for error. But all we had for heat control was a direct drive fan, air shutters and the thermostat.



Now that the ECM is in control of fan engagement it is a much safer proposition. Big rig fans are air engaged as a rule, the latest trend for even more temperature control are 2-speed clutch fans. The ECM also watches A/C pressure and controls the engine fan according to.



The hotter that engine is, the better the rings seat to the liner walls.



Mike.

 

[Brad7611]

Thanks Mike, appreciate the info. Now on to pondering other things haha



Brad

 

[tempforce]

most of the *ord owners have been putting hotter 105"f thermostats in their diesels for years, claiming more power and fuel economy...
it would make sense that it would do the same for our engines and big rigs...
i know it would clean up the burn of the fuel...