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Stuck thermostat?

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Truck is my wife's 2011 3500.

 

Lately I've noticed that the coolant temp never gets above the low 180's.  Ambient today was in the 60's and driving it never got above 174.  Truck has 80k miles and is bone stock.  Possible stuck thermostat? Or something else?  Heat blows nice and hot.

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  • IBMobile
    IBMobile

    One way to tell if a t-stat is stuck open is to start the vehicle cold and let it run at idle. If the upper radiator hose at the radiator slowly warms up until it is hot the t-stat is stuck open.. Wit

  • 98whitelightnin
    98whitelightnin

    I, like Mike, have always used napa. I see people recommending cummins only and it makes me mental. I went to cummins for a 190* for my 98 24v and they wanted $90. I went to napa and got one for $22 a

  • dripley
    dripley

    Cummins and Mopar are not the only companies that have others manufacturing for them. It is fairly common practice. The manufacturers get specifications to build by from their customers. If Cummins or

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Picked up this one up for the Ranger. Glad to see where it was made.

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There are few things I will buy at the dealership. I bought a Mopar 200f t stat for an 2008 Dodge 3500. It works great.

  • Owner
On 1/13/2020 at 9:26 AM, kzimmer said:

I've had good results with Gates thermostats.

 

Last Gates 200*F I bought didn't last 1 week. Very wild up and down swings in temperature. Down as low as 168*F and the way up to 220*F on open.

 

28 minutes ago, Mopar1973Man said:

 

Last Gates 200*F I bought didn't last 1 week. Very wild up and down swings in temperature. Down as low as 168*F and the way up to 220*F on open.

 

That's very strange. I had a couple Stant thermostats that were pretty wild. Never gates though. I'm running a gates 180 right now and it's smooth as hell even below -25°c ambient temp. Even initial opening is a less than +/- 10°F swing. When stabilized, less than +/- 5°F swing.

    • Like 1
    • Owner

    Yeah I want to try the 200*F thermostat. NAPA doesn't stock any 200*F thermostats. I jumped on RockAuto and spotted the Gates thinking great name to buy. Week later I was pulling it out because of wild temperature swings and install a 190*F NAPA. Back to the 192-194*F solid temperature. 

     

    Still want to try a 200*F but not sure where to buy it. Nope don't say Cummins or Mopar. Not happening... I don't want the crappy fall apart Robertshaw design.

     

    Even NAPA has two series for the 1996 Dodge. The 192 and the 195*F for the V8 gas engines. Rock solid temperature right at 195 to 197*F. Too small for the Cummins. 

    35 minutes ago, 98whitelightnin said:

    Mike, im almost positive a 6.7 thermostat is the same size as your truck. My 2012 came factory with a 200 and rock auto has stant for under $9

    https://www.rockauto.com/en/catalog/ram,2012,2500,6.7l+l6+diesel+turbocharged,1502371,cooling+system,thermostat,2200

     

    Yep, I'll second that, I've used a factory 200° stat for a 6.7 in my truck before. 

    • Owner
    On 1/20/2020 at 8:58 AM, 98whitelightnin said:

    Mike, im almost positive a 6.7 thermostat is the same size as your truck. My 2012 came factory with a 200 and rock auto has stant for under $9

    https://www.rockauto.com/en/catalog/ram,2012,2500,6.7l+l6+diesel+turbocharged,1502371,cooling+system,thermostat,2200

    I did the Gates 34212 on that listing thinking Gates was a good quality T stat. Mine failed the in the first week.

     

    Went back to Napa... Haven't tried again since. Money is tight and time is even tighter.

    I would like to confirm that the 6.7l t stat is the same size as our stats in the VP trucks. 

     

    I do believe that my 200f t stat came from Cummins, it was just a relabled Cummins stat.

    • Owner
    1 minute ago, pepsi71ocean said:

    I do believe that my 200f t stat came from Cummins, it was just a relabled Cummins stat.

     

    No true. Cummins does NOT manufacture any thermostats.

    4 minutes ago, Mopar1973Man said:

     

    No true. Cummins does NOT manufacture any thermostats.

    It was a Cummins box. I'm not sure who the MFG was. But the Mopar label was over the Cummins label. I wish I bought two at the time Mike. I would have gladly sent you an extra one.

    • Owner

    After doing my research Cummins or Mopar has never manufactured thermostats. Cummins has changed at least 4 to 5 times different manufacture they sell. Then digging to the manufacture of the actual thermostats you find out that Cummins used companies like Motorrad, Mr. Gasket, Robertshaw, etc. Funny how everyone claims that Cummins or Mopar Thermostat is better but NO ONE has even checked on who manufacturing said thermostat. As for specs the only spec is the temperature. Being that opening size and volume restriction has changed every time they changed companies. I've replace a few stock thermostats for people and always shocked at all the different designs...

     

    Now for my 200*F like I said was a Gates. It only lasted 1 week or so. I think I've chucked it out already.

    Edited by Mopar1973Man

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