2 different thermostats (180/195) in a dual housing?

[mgray]

Is there any reason to run two different temp thermostats (180/195) in a dual housing? A little warmer than 180 but cooler than 195? Just curious as the previous owner of my truck I believe removed both thermostats as it ran cool in summer, and now in winter it barely warms up and threw a p0126 code indicating stuck open themostat. I’ve also lost some boost I’m hoping is due to the code?

 

[dieselolds]

First I’ve heard of it to be honest.In my previous 97 6.5 engine I’ve always just purchased two acdelco thermostats from rockauto.Never bothered to see if they were 180 or 195.

 

[ak diesel driver]

I've heard of engines using different temp stats in a dual setup. Never seen or heard of anyone doing that in the 6.5

 

[dbrannon79]

it does make sense for hard working engines. the KW rigs at work use two different stats in them but I think the way there setup is one opens first and if when temp rises the second opens giving full flow if coolant to keep the engine in check.

 

[JMJNet]

From my understanding by reading over 16 years of ownership.
Diesel engine needs heat.
Being in Vancouver, BC which is generally colder climate compare to TX, why would you want to run a cold diesel engine.

Moral of the story, get the 195 T-stat if you can.
Make sure they are ACDelco OEM (more expensive).

 

[Will L.]

An engine has an acceptable low operating temperature, correct. But ask why is all temperature adjustments ended at 160°f- because there all the required heat for good operation is met.
While the company location I worked at was in LasVegas for the fleet- the company had trucks throughout Nevada, Utah, Az. So I didn’t have to do the “won’t start because it’s too cold” outside of 3 cold months- we did do monitoring through the fleet in the Sierra Nevada’s, Salt Lake City, etc.

It is possible that some modifications make better mpg possible at 195 than 180, we found same mpg and actually better power output* at 180 than 195. Depending on the turbo, timing changes, fueling changes, etc. - sure many people say they get 1 more mpg at 195 than 180. But with stock or slightly modified tunes- and slight bigger turbo (no more than hx35 basic sizes) we never got ratings of 1mpg or more increased from 195 in the thousands and thousands of 6.5 rolling.
* watch any power tv shows, reading any of the magazines, talking to most dyno shops- Almost all of them agree more power is produced at lower temperatures and often dyno test in modern gas engines are done at 135°f now because of it. All the diesel dyno shops do them at the minimum temperature the computer or sensors removes limiters or timing alterations. (Again 160° for 6.5).

If you want really hot heater- yes running a 195 stat (or 2 for most folks) your ur engine will stay hot and therefore your cab heater will work better.

I suggest you make sure your 20+ year old heater core doesn’t have debris damage on it first and not risk engine over it. All our fleet that wasn’t in testing went to 180 stats because when something went wrong like heater hose rupture or something- there is more headroom for the engine to deal with the added heat and not be destroyed.

adding a low coolant sensor for ones not equipped, and adding an audible alarm and maybe a flashing light for low coolant and/or high temperature.

I don’t want to make it sound dangerous to run at 195, that is fine. But:
Know that the dash gauges often are off-read a quality temp gauge.
Learn about balance flow issue. And ALWAYS:
at 200 be worried
at 210 watch the gauge more than the road
at 220 pull over, stop, let idle until back down to 195

 

[MrMarty51]

Just My theory : cooler cylinder temps, slows combustion and the delayed combustion gives a longer power stroke as the piston is retreating from the head.

 

[THEFERMANATOR]

Just My theory : cooler cylinder temps, slows combustion and the delayed combustion gives a longer power stroke as the piston is retreating from the head.

And cooler cylinder temps at low load also leads to wet stacking which can kill your engine. I know many like 180's, I like 190-195's myself for the majority of engines, and for cold weather run as hot of a stat as you can.

I know the Duramax used to use a 180 & 185 tstat in them, but the newer stats(l5p+) don't seem to open until 190 & 195.

 

[MrMarty51]

And cooler cylinder temps at low load also leads to wet stacking which can kill your engine. I know many like 180's, I like 190-195's myself for the majority of engines, and for cold weather run as hot of a stat as you can.

I know the Duramax used to use a 180 & 185 tstat in them, but the newer stats(l5p+) don't seem to open until 190 & 195.

Yup, I am running twin 195s in My truck. Now that I got the clutch fan figured out as faulty, it now cools perfectly fine. Thanks to @Will L. for teaching Me about locking the fan clutch for test purposes.

 

[Will L.]

And cooler cylinder temps at low load also leads to wet stacking which can kill your engine. I know many like 180's, I like 190-195's myself for the majority of engines, and for cold weather run as hot of a stat as you can.

I know the Duramax used to use a 180 & 185 tstat in them, but the newer stats(l5p+) don't seem to open until 190 & 195.

Wet stacking any diesel isn’t good, and is a clue you idle too much or run to cold. But if your 6.5 engine gets to and maintains over 160°F- it won’t wet stack. All the 6.5 generators I ever worked on run 180 stats. And generators usually are the worst for it because they are either idle or or 2500 rpm. idi doesn’t usually do it because they use so little fuel. The more powerful the engine is capable, the worse wet stacking gets. But that because it shoves boat loads of fuel into the cylinder. Fuel sippers like the 6.5- not so much.

But that’s my experience in the desert. If in the really cold weather you get it- ring up the temp if you have to idle a lot. But I would strongly suggest doing a high idle mod to try eliminating it first.