What Thermostat temp is best for Dodge Ram/24v Cummins?  Just wondering if I would get better fuel mileage with the 190* thermostat.

What temp do you have and mileage.

Thanks, Kerley

 

190* is the factory temp. 200* (From a 3rd gen) has been experimented with. NAPA or Cummins, only, as they always fail open & provide a steadier temp.

Ed

190* is the factory temp. 200* (From a 3rd gen) has been experimented with. NAPA or Cummins, only, as they always fail open & provide a steadier temp.

Ed

I believe only the 6.7L 200* thermostat will work in these trucks.

 

I run a Napa 190* and average 23.xx on the highway. I considered it myself but the summers here get pretty hot so I'm going to stick with the 190

I'm also running 190*F here.

 

Highly NOT suggested to run 180*F this will reduce the efficiency of the engine. Diesel engines require a certain amount of heat to properly function. 200*F themostat from what I've heard so far will will run you coolant temperature about 197-202*F and bring slightly higher IAT temperatures too which you want to aim for about 100-140*F worth of IAT for good MPG's.

I think I have a 180* thermostat based on the factory dash temp guage. I have installed new Intercooler boots, Donaldson air filter and just had Dodge program my computer. The computer program made a big improvement in power wise, It runs sweet, best since I've owned it. All Battery Cables, Batteries, Fan Belt,Alternator,Oil, Air and fuel filters, four new tires, shocks and Crank shaft Sensor were changed about six months ago and been driven about five hundred miles. WOW, no wonder my wife thinks I need a new truck. I have not changed the Injectors or run the valves. My truck does not burn oil. Fuel pressure is 18 to 20 psi. so why such poor mileage of 14mpg .

Cold air and cold coolant are counter productive to a diesel engine. You need enough heat energy to convert atomized diesel fuel to a vapor then ignite the fuel. If its too cold then it lags in conversion and then to ignition. So with the colder temps you got to run higher cetane fuels but high cetane fuels are lower in BTU's. So if you run warm air intake (100-140*F) and warm coolant (190*F or 200*F thermostat) then you should gain back MPG some. The rest is driving style and how fast you drive.

Man,   over on   lostjeeps,   and  all the newbie to  diesels  are  fretting about  how  HOT  their  machines  can run...  and  the blizzard of  threads  at keeping it cool  are countless.

 

...   electric fans,  lower temp thermostats (which there are none)  unless you gut the  stat housing and  put in a  aftermarket  inline.. 

People  over there  don't realize  that  those jeeps are fitted  with 170 stats,  and  generally hold  that temp on the gauge.   kick it in the rear, go up  a long incline,  and  then  they are finding the radiator  is  FINALLY  being  utilized!     But  those  guys are  fretting  over a  'spike' of  maybe   25 degrees.   (195-200).    whooptee doo.  to me,  that's a non issue.

 

When I  tried  to explain  that  diesels  are more  concerned with  their  MINIMAL  temp they run,  as  opposed  to the   MAX   that gasoline  engines  require..   it fell on deaf ears.   

My  very expensive   summer  a couple years ago  were all  from   too cool  running.  (160)    I had to lug the snot out of  a  cummins  903  to get it  'up' to  180.   big mistake.    I  didn't  lug it  to  keep it  hot,  but  the few times  I did,  it  would.     

After the rebuild,  I replaced the stats  with the  180's  ,  and  now it  holds   that   no matter  the conditions.    idling,   over lugging..   you name it.   

 

Our  Rams  are   way over engineered  on  the    cooling  capacity..  which is  good!        That big ol radiator,  (when in good shape  )     does  a  great job at keeping the  MAX   in hand.  

Start to open temps  are  more important  than   fully  open temps      and unless I'm  wrong,  isn't   that how  diesel  stats  are  rated?

 

So,  I look at   engine temp  management as    the  stat  is  for keeping  a  minimum  temp,  and  the  radiator  is for keeping   things  under control.

 

I have  digressed again...

how are you using your truck  most of the time?    If it's like mine,  and  is  down n  dirty  90%  of  the time,   I'm  staying with the  oem 190.

If  it  was   a  DD,   empty most of the time,  then   I'd  go  190.

Edited January 25, 201510 yr by rancherman

I'm sorry to say you look back at old school cars back in the day and I use to run 160*F and 180*F thermostat in my Dodge Charger. Now my 96 Dodge is a 195*F thermostat and the 02 Cummins 190*F. But the technology of the engines, oils, etc all have improved and making things tighter and lasting longer. Heck look at my 73 Charger it was wore out at 100k miles and now look at the 96 its 159k miles and still rolling strong.

 

As for thermostats typically the marked number on it is the opening temperature but usually in about 10-15*F more degrees its fully open. I think it more about proper operating temperatures than when the thermostat opens or is wide open. As long as the engine is in operating temperature which is typically above the stock thermostat rating, that's what matters.

I'd like to add   to the list of   things  making  today's  engines  living longer...    the  fuel itself.

 

I've  2    1960's and  1970's    era  PROPANE  engines,   still lugging along...  on  the original   rings and  bearings..         Shoot,    I know  of  one  of my tractors  is  just on  it's  second  set of  sparkplugs!   

 

Most  diesels,  even built back in  the dark ages,  would routinely  rack up  a minimum  of  10k  hours,  and  with   really good maintenance,  20k  was  quite possible before  a major.     I don't think oils  were  THAT  bad  back then.. or  quality of    materials  in the  engine.

Gas  engines,  on the other hand,  were  face it..   really   throw away type  engines.     sure,  we could rebuild em,  and  did a lot of them!     Cars  had   what?  20k  warrantees,   and  as  the  warrantee  race  heated up to 100k,   something needed  changed!    quality  improved!      

 

    'enter stage  right...  egr  type  diesel engines'... circa 2006 ;   at least the light duty versions  were  mandated.     who knows   where  this  path leads us in overall   lifespan...

Edited January 25, 201510 yr by rancherman

 

    'enter stage  right...  egr  type  diesel engines'... circa 2006 ;   at least the light duty versions  were  mandated.     who knows   where  this  path leads us in overall   lifespan...

 

Actually it start back in 1994 with the California Emission 12V Dodge Cummins. Really strange to see a EGR valve on a 12V Cummins...

 

Even with the high teck cardboard winter front I am only getting 160 or so after a 20 to 25minute drive.

Don't even ask me about cab heat....brrrrrrrr.

Going to try a new Napa 190 today.

Chris

I would say your thermostat is shot.

I put in the new 190 from Napa. Looking at the old one it is date coded 02 of 99 and its a 180.

Made by caltherm.

Original to the engine I would say.

Chris

180*F isn't stock. It should of been a 190*F thermostat.

Well, I can't explain why the 180 was in there.

However with the 190 in ...I had heat coming out of the vents after 4 kilometers. 

I have never had heat that fast. I picked the wife up on the way home and she was impressed too.

By the time I got home the IAT was 97...don't see it up there that fast either.

Very Very happy I put in the thermostat...I should have listened 2 years ago. 

Chris

Early second gens came stock with 180 just like 12v. I went to cummins for a new thermostat and parts guy had to order one, when it came it was a 180 and I said I wanted a 190. The 180 was like $45 and the 190 was $90. I got a Napa 190 and it was perfect. Put the 180 in my 2005 so it wouldn't run so dang hot. I just ordered a 195 for the 12v, got it off of eBay and it's supposed to stop the temp swings.

Yes, 180 is OEM (at least on the early 24 valve engines).

Next time you want to buy an OEM 190 stat, order one for a 3rd gen. Don't ask me why because I don't know, but the 2nd gen 190 part number is different than the 3rd gen 190. They all drop right in, even the 200 for the 6.7, and the 3rd gen 190 is almost half the price as the 2nd gen 190.

True story!

Nice tip... Thanks.

Well, I can't explain why the 180 was in there.

However with the 190 in ...I had heat coming out of the vents after 4 kilometers. 

I have never had heat that fast. I picked the wife up on the way home and she was impressed too.

By the time I got home the IAT was 97...don't see it up there that fast either.

Very Very happy I put in the thermostat...I should have listened 2 years ago. 

Chris

Just wondering how you know what the IAT is. Do you a temp probe somehwere on the intake & a guage?

 

Thanks

Any live data tool should display IAT temps. Like my ScanGauge II does this job for me.

http://www.scangauge.com

Very cool! Thanks for the info.