12 valve cummins thermostat

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Billy's picture
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Joined: 08/11/2009

I had the stock 180 thermostat installed in my truck. The problem was I was only seeing temperatures of about 170 on the dash gage and 165 at the vege filter, which didn't seem warm enough. So I just installed a new thermostat in my 97 cummins. Napa Superstat 532090. Many people recommend it for this truck even though the thermostat is designed for a big block 440 gas engine. Now my dash gage reads about 200-205 and vege filter sensor reads about 184 at highway speeds and ambient air temperature 70-80 F. The 184 is much better for heating the vegetable oil. But my question is is 200-205 too hot for the block. The stock coolant temperature sending unit is clear in the back of the block on my truck, and I just replaced it, but I think they moved it to the front of the engine in 98.

I don't want to hurt my truck by running a thermostat that is not designed for my truck. My only other alternative is buying a cummins 190 F thermostat but they want a ridiculous price of like $75.

Any help would be greatly appreciated

Thanks

Billy's picture
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Joined: 08/11/2009

I was just curious if any of the 12 valve owners had tried this 195 degree stant thermostat. And to see if the temperatures I am seeing from the temp sending unit (200-205) could be a problem. Its hard to say what sensor is sending the most accurate temperature. 200-205 on the dash and 184-185 at my heated veggie filter.

slatemd's picture
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Joined: 11/26/2007

Quote:
Originally posted by: Billy
I was just curious if any of the 12 valve owners had tried this 195 degree stant thermostat. And to see if the temperatures I am seeing from the temp sending unit (200-205) could be a problem. Its hard to say what sensor is sending the most accurate temperature. 200-205 on the dash and 184-185 at my heated veggie filter.
I have a 92 12-valve Intercooled.

Is you engine an intercooled engine?

Depending on how you are driving, I have my oil at around 150 to 180 with no problems at all.

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81 VW Rabbit Caddy (Adolf) blending.

92 Dodge 250 extended Cummins Inter-cooled Turbo (Mad Max) 2-tank system.

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Billy's picture
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Joined: 08/11/2009

Yes my engine has the big intercooler in front of the radiator. Are you using the stock thermostat? I'm not sure if the 1st generation cummins has the same 180 degree stock thermostat or not. I've been hearing that these diesel engines like to run hot so maybe it's okay to run them up to 205 with a 195 degree thermostat.

Thanks for the response

slatemd's picture
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Joined: 11/26/2007

Yes, I am completely stock.

-------------------------
Mitch Rapp for president.

81 VW Rabbit Caddy (Adolf) blending.

92 Dodge 250 extended Cummins Inter-cooled Turbo (Mad Max) 2-tank system.

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Billy's picture
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Joined: 08/11/2009

I took out the experimental thermostat and put the 180 degree stock back in for the time being. It's fine during the summer but during the winter here in Montana I will have to try something different. I might try the same thermostat but buy a new one. The frybrid forum says you shouldn't see temperatures much over 190 with that thermostat. So we'll see.

slatemd's picture
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Joined: 11/26/2007

Quote:
Originally posted by: Billy
I took out the experimental thermostat and put the 180 degree stock back in for the time being. It's fine during the summer but during the winter here in Montana I will have to try something different. I might try the same thermostat but buy a new one. The frybrid forum says you shouldn't see temperatures much over 190 with that thermostat. So we'll see.
In the winter, I install my custom diamond plate grille delete plates for a nice toasty engine.

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Soylent Green is PEOPLE!

81 VW Rabbit Caddy (Adolf) blending.

92 Dodge 250 extended Cummins Inter-cooled Turbo (Mad Max) 2-tank system.

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Billy's picture
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Joined: 08/11/2009

Hey Slated

Do you have any pictures of your diamond plate delete plates or can you describe how you made them and how they work. I would like to find something like that for the winter. I have a winter front cover but it doesn't work great.

Thanks

slatemd's picture
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Joined: 11/26/2007

Quote:
Originally posted by: Billy
Hey Slated

Do you have any pictures of your diamond plate delete plates or can you describe how you made them and how they work. I would like to find something like that for the winter. I have a winter front cover but it doesn't work great.

Thanks
Billy:

Yes, I posted my trucks pictures on this forum, however, I cannot find them. I know it was around the spring time when I posted them, but I cant find them. I simply cut diamond plate to fit in the four grill openings. I usually cover the two bottom openings in the winter and/or all four if I am only doing city driving. I have 1 square nose 1992 Dodge. Remember, if you cover the grill with delete plates, make sure you leave an area open for the transcooler to get air. As you are looking at my truck, it would be the top right hand grill. I only cover half of this grill opening.

-------------------------
Soylent Green is PEOPLE!

81 VW Rabbit Caddy (Adolf) blending.

92 Dodge 250 extended Cummins Inter-cooled Turbo (Mad Max) 2-tank system.

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slatemd's picture
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Joined: 11/26/2007

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Billy's picture
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Joined: 08/11/2009

Cool Slatemd, that looks nice.

slatemd's picture
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Joined: 11/26/2007

Cool Slatemd, that looks nice.

Thanks.  Depending on what I am experimenting with, I can configure any pattern from the delete plates.  The diagonal pattern was to see if I had any difference with heat and/or intercooler performance because I normally install two delete plates on the bottom two-grill sections horizontally.  Soon I will keep the bottom two plates on for the next 5 months.  As it gets colder, I simply add more delete plates, but I am sure to monitor my temperature as I am cruising down the road.  If I am running too hot (say @ the ¾ mark on the factory gauge), I simple remove the plates as I need to.  I would like to invent a cable operated louver system for the front grill.  This way, I can open or close them as my temperature warrants without stopping.   I like it when my temperature gauge is dead center.  This seems to be the ideal operating temperature for this truck.  Also, my ideal cruising speed is 72 MPH.  It is just the way it is with this truck.

 

 

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Billy's picture
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Joined: 08/11/2009

Any 2nd generation 12 valvers have any luck with an aftermarket thermostat? Have a brand name and part #?  It's been a long cold, wet Spring here in Montana and I'm getting frustrated trying to keep me truck warm.  I have found that covering the grill drops my mileage by 2-3 mpg, figure that could be a result of either warmer air going to the turbo or the extra cycling of the radiator fan. Thought I could get warmer temps by covering the radiator behind the intercooler but that doesn't seem to do a thing unless I completely cover it and then it will easily over heat went under load.  Too damn bad cummins doesn't make a warmer thermostat for these trucks. Seems like that is the only solution.

philipvitale's picture
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Joined: 09/20/2013

Hello, did you ever figure anything out with that thermostat? I have a second generation cummins and i have the same issue. My coolant temp is 170 and my wvo temp is 120. I thought about installing a fphe, but i would rather not with such limited space.

Thanks,
Phil

veggpwr's picture
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Joined: 09/27/2010

I would try a 190F thermostat.
A winter front would help some in keeping the coolant temp close to 190F.
I have a FPHE and my WVO temp would be around 160 to 170F.

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Billy's picture
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Joined: 08/11/2009

Yeah I put another 195 in of same make and model and it works great. I also run a winter front for all seasons except summer.