Gentlemen, 

I have done a few searches and I just want to be sure: That these Cummins engines are the coolest running motors around.  I have driven this truck about 500 miles since owning it and I have learned it takes forever to warm up, and when it does, a red light will knock the gauge back down to lower normal. I think its great, and though the wife wants the heat on full blast in June, once the truck warms up to mid gauge, the heat is HOT HOT HOT!

I already made some homemade winter fronts to fit in the grille with some custom cut black acrylic sheet, so I'm asking- This is normal or no?

AP

If you lose heat at a stoplight, I would agree with the thermostat. If you want to heat the truck up quicker, you can always get a high idle switch... Hint hint. http://www.dieselautopower.com/product-p/high-idle-switch-98-02-cubby.htm

 

Ed

how many of those do you have to sell to turn a profit?

I've seen in the dead of winter with minus temperatures outside just idling I can pull the coolant temperature down to about 185-188*F idling then it seems to stop. But that is rare and rather extreme case. Typically I don't leave the truck idling long periods sitting still.

 

Traffic lights? What's that??? Idaho County only has 1 traffic light in the entire county. Valley county has 2 traffic lights...

Killer, in all honesty, if I counted all of my R&D time, I barely made $10 per hour. Profit will come in on later orders.

 

Ed

If you lose heat at a stoplight, I would agree with the thermostat. If you want to heat the truck up quicker, you can always get a high idle switch... Hint hint. http://www.dieselautopower.com/product-p/high-idle-switch-98-02-cubby.htm

 

Ed

 

I disagree, if there isn't some form of winter front the temp will drop very quickly. By the time the thermostat closes from lack of heat most of the block has already received the cold coolant from the radiator and cooled down, the idling or low power use means minimal heat and the truck can cool down to about 180-185° at a light.

 

A winter front makes a HUGE difference on this, not only does the radiator stay warmer but so does the engine bay. Even on a 10° day once things warm up the engine bay is thinking it's closer to a 60-70° day.

 

I haven't ran my 3rd thermostat without the winter front yet, but my previous two were Cummins and both acted the same.

 

I have seen the temp go from 194-195° while cruising to 180° on an off ramp without a winter front on a 5° day.

I have 180 degrees thermostat and my goes up and down all the time this winter 180 to 165 and when it is summer nerver really goes over 180 even in 90 degrees weather and doesn't ever get below 170 in the heat

I have 180 degrees thermostat and my goes up and down all the time this winter 180 to 165 and when it is summer nerver really goes over 180 even in 90 degrees weather and doesn't ever get below 170 in the heat

 

 

I'm not sure why they even make a 180 degree stat, but I would run a 190. Your engine is not very efficient at all running 165 degrees, it's no where near up to operating temp and may very well be partially sticking or worn out.  I've actually got a 200 degree stat in right now, it's amazing how much warmer the under hood temps are since I installed it.

The minimum temp for full power operation is 160°.

Be aware MPG is affect by ECT numbers too cold and MPG do slump off.

 

I suggest the 190*F be used for all applications and not the 180*F. I'm going to be considering the 200*F thermostat myself for the diesel.

As soon as I get fan control with UDC I plan to run a 200 as well.

After today's run in the Cummins to Ontario with temps as low as +6°F and IAT's down to +21°F. No I didn't put my winter fronts on. Boy did I pay for it. Coolant temps hovered right between 188-193*F and IAT's continued to follow the outside temperatures right at about +15°F to +30°F for the day. The only saving grace was the MPG fooler.

 

So I'm upgrading ASAP to a 200*F thermostat and getting my winter front back on this truck.

My winter front goes on in October and comes off in April.

Cold up there, we where only as low as 20 here.

Just to follow up, I went ahead and called Cummins,$80 + dollars for a thermostat- no thanks.  I got a good quality 190 Stant from advance for 20. Truck heats up faster, blows heat within a few minutes and seems happier after being plugged in.  I did't test the old one but it looked original and was marked cal-therm. If it fails early I'll upgrade to the Cummins.  Until then, I'm happy with the performance. Hope this helps someone. 

AP

There was a thread on CF.com about that and a guy posted a picture of both a Cummins thermostat and a NAPA thermostat and they are exactly the same. The only difference is price. Save you money and consider a NAPA as your next one.

 

Typically I change coolant every 30k miles and thermostat at the same time so I've never really had a bad thermostat.

There was a thread on CF.com about that and a guy posted a picture of both a Cummins thermostat and a NAPA thermostat and they are exactly the same. The only difference is price. Save you money and consider a NAPA as your next one.

 

Typically I change coolant every 30k miles and thermostat at the same time so I've never really had a bad thermostat.

The why do the NAPA ones have issues and the Cummins don't? It seems that there are plenty of threads about non-Cummins thermostats having issues.

Heck the stock valve springs and my 103# valve springs look the same, but we know they aren't. What's to say that the spring isn't different between Napa and Cummins?

Just like everything today there is only a small few companies that produce the same part for all dealers. So on quick search I found Gates, Stant, CST and Thomasnet that product automotive thermostats. So Cummins is most likely the exact same thermostat sold by another vendor name but at a reduce cost without the name. So that being said there is no real reason for high dollar Cummins stat being it fails just as well as any other. Being there is only 4 that I can find that produce these then... Chances are they could be the same.

 

So for argument sake the Stant thermostats could be made for NAPA and boxed as such and Cummins take the very same one and marks it up with their name on the box.

 

But who knows?

It just seems rare to find an issue, aside from age, with a Cummins thermostat. Plenty of issues with all the others. Why is that? They might not allow the company that makes them build ones for 3rd party sales to the same standard, or specs. It could be part of the contract.

My napa (stant) 190 doesn't actually hit 190. Over the summer it was pretty constant at about 188. This winter it hits 188ish, opens and holds 185-188 when i'm on the throttle, but drops down below 180 at a stop light or coasting. Previously I ran a cummins 180 and it dropped down too in the same situations. Last week, I bought a napa 200 t-state for a 6.7 and it doesn't fit, the flange is too big, for an early 6.7. I think I read here to get one for a 2010 or newer, which I may try...and my mpgs have dropped off

Edited February 2, 201411 yr by CTcummins24V

I've Went Through A Handful Of AftermarkeT Stats And They Have All Had TempSwings Of Several Degrees. Cummins Is the Only StaT That Has Been Consistent For Me. I Tried Several BeforeResorting To The Expensive OEM

A cummins 190 will open at 187-193, it's not full open until 207 and has a max allowed of 225. I know I can, and will, hold 215 pulling big grades while towing on on a hot day.

The 07.5-09 6.7 uses the same 190 as the 03-07 5.9. The 200 wasn't OEM until the 2010 model year.

The thermostats should be interchangeable from 98.5-current, but I can't find anything that shows that. I know for sure they are compatible from 98.5-09. The head may have changed in 2010, but I don't recall reading about it, and I known 2010 guys are dropping in 180s and 190s from earlier trucks.

The early 6.7 is the same as your 5.9, sounds like NAPA sold you the wrong thermostat.

Even with my recently installed winter front, the 190 NAPA isn't holding 190. I was only seeing 190 upon acceleration. I just ordered a Stant 200 from rockauto for under $20. If that doesn't work I might be hunting down some electrical bugs.

The early 6.7 is the same as your 5.9, sounds like NAPA sold you the wrong thermostat.