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  #31  
Old 03-13-2014, 06:44 PM
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Originally Posted by KATOOM View Post

So with all that said, I would suggest getting a warmer thermostat. I know I've heard that the 12 valves only have a 180* but like I said before, I could swear that I've heard that there is a hotter one available, like a 190*, from somewhere. Or what you're finding is that your $12 thermostat is cheap and isnt calibrated to the proper 180*. What do you expect for $12. No matter which way I say it.....you need another thermostat.
I have a Cummins stat in my garage that did the same thing, so I don't know where I would find a 'better' one. I have not ever seen a hotter thermostat for the 12 valves, but would really like a 190* one.
On another note, I played with my thermometer and the results were disappointing. I had two probes (my meter can watch three temps at the same time) on the steel heater lines right close to each other, but driving there must have been to much breeze because the highest temperature I saw was 156*. I am questioning the calibration of my thermometer because the hotter reading was on the return line. The line coming right out of the head was only 139*. When I parked my truck I tried to get it to warm up to open the stat, but the best I could do was get the temp up to 165*. Even the gauge in the cab wasn't moving. I tried blocking the radiator with cardboard and kicked the A/C on to try to load the engine a little more, but I just could not get the temp up any higher. I also tried different RPMs to see if it would help. I had it up to 2000+ RPM and it actually started to cool off! The best heat I saw was with the RPMs at about 1200. Anything above that and it was trying to cool. I did figure out the low line on the gauge must be 140* and the center one is 190*. With 165* water temp the needle was just about exactly half way between the two marks. I am going to see if I can figure out how to get a more accurate temp reading.........
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  #32  
Old 03-14-2014, 10:42 AM
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If you have or know someone with a IR thermometer that might work better for you. As for the temps you were dealing with, it sure sounds like that thermostat just isnt staying closed like it should. Maybe there's more to all this than it seems. Maybe the Cummins water pump and water passages creates to much force on the thermostat and it has a hard time holding the pressure back. Because I've never seen anyone have so much trouble with engine temps on other vehicles than what some guys go through with these engines in these trucks.

On a side note, I remember a thread not to long ago where the discussion was regarding the rear freeze plug and the problem with some trucks blowing that plug with higher HP. Generally the problem is from a combination of higher HP (higher EGT's) and higher than normal RPM's because as the RPM goes up, so does the coolant pressure. So what happens is the force of the coolant literally blows the back freeze plug out because the coolant flow design is so that the back cylinders dont get the return flow they should. Therefor the cramming affect of all that coolant trying to go somewhere pops that plug if the pressure is too great. With that said, there has been some people (including me) who tried to incorporate bypass systems so that the back cylinder gets more flow. I could go on and on about the various ways this is accomplished but my point is that some of those bypass systems only bypass through spring pressure, and that set pressure is surprisingly high. Something like 50+ psi before any bypassing takes place. This led to a member trying to get answers by performing a road test with a pressure gauge mounted on the head in various coolant ports. The results were staggering whereby simply the increase in RPM caused his coolant pressures to get up to and above 50 psi if I remember right. Thats crazy as one would think that the pressure in the coolant system is always below 16 psi otherwise the radiator cap would pop. Well not the case. The pressure is actually much greater and I say this because it seems that maybe the pressure and force of the coolant coming from the water pump is shoving the coolant past the thermostat. So maybe some thermostats are just stronger than others.
I know it took a lot just to say that.....
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  #33  
Old 03-14-2014, 11:17 AM
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You got me thinking..... See if you agree or disagree with my line of thinking. What you said about the pressure generated by the water pump generates is probably pushing water past the t'stat while sitting still hence the reason it was cooling with higher RPM. I did not know the pressure would get that high and that explains why they will push coolant out at the headgasket by the water pump. You have heard of clipping the water pump? What are your thoughts on doing this to help cut back on the coolant flow? Next question is how would clipping the pump work with a truck that tows with a CGVW of about 17k? I wonder if the modifications that Dodge required had something to do with this 'problem'.
Unfortunately I have this one that can't be clipped:


Far as using an IR thermometer, I have a small one, but it is real difficult to monitor the engine temperature when it is near the t'stat temp then goes to the bottom of the temp cycle while driving. The thermometer I have is this one:

There has to be a way to do what I want, just need to figure out how.....
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  #34  
Old 03-14-2014, 01:04 PM
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I think we're on to something.....

But in saying all that MnTom, I would most certainly explore as many thermostats as I could before ever considering clipping the water pump impeller. The cooling system on these trucks is huge and therefor offers a greater level of cooling while towing heavy in hot weather.....with the A/C blasting. I guess if it has to fluctuate then it has to fluctuate but not getting warm isnt acceptable.

I know its far more than you probably care to spend but here's a "claimed" hotter thermostat for the 12 valve. http://puredieselpower.com/internal-...g-o-rings.html
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  #35  
Old 03-14-2014, 01:12 PM
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I've read of guys using this thermostat in the 12 valve. http://www.napaonline.com/Catalog/Ca...090_0183704642

Its the same size as the 12 valve thermostat but it can get the temps up to about 200*-205*. Some have suggested drilling a couple 1/8" holes in the flange like the Cummins thermostats so that you get the proper flow which should help regulate temps better.

Its a thermostat for a 440 gas engine. Search for threads about the 440 thermostat if you're curious.
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  #36  
Old 03-14-2014, 01:12 PM
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WOW! That thermostat had better have gold in it! I know that a lot of guys that pull and race their trucks clip the pump to run a higher RPM to keep from pushing the headgasket out, but I wonder if it would work for towing. I am not sure about that. I know mine started to warm up when the outside temperature was 88*, A/C on high, fully loaded (5er, family, etc.), and clibing a 6% grade 18 miles long. I kept the RPMs up and that is when I had my headgasket start leaking. It never did get hot enough to kick the fan on.
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  #37  
Old 03-14-2014, 01:15 PM
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Quote:
Originally Posted by KATOOM View Post
I've read of guys using this thermostat in the 12 valve. http://www.napaonline.com/Catalog/Ca...090_0183704642

Its the same size as the 12 valve thermostat but it can get the temps up to about 200*-205*. Some have suggested drilling a couple 1/8" holes in the flange like the Cummins thermostats so that you get the proper flow which should help regulate temps better.

Its a thermostat for a 440 gas engine. Search for threads about the 440 thermostat if you're curious.
What about the 1/4" by pass/bleed hose already installed? Wouldn't that do the same thing?
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  #38  
Old 03-14-2014, 01:46 PM
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I haven't found anything about guys towing with the hotter t'stat. Now that I am retired I am hoping to be doing lots of towing with my truck.
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  #39  
Old 03-14-2014, 02:23 PM
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At this point MnTom I'm just throwing darts in the dark hopping that I can hit something for ya so really I'm not sure. As I already mentioned, I would rather not clip the pump but if you're blowing head gaskets then thats maybe another topic. I cant imagine the hydraulic pressure of the coolant at 50+ psi lifting the head before it popped out a freeze plug. Rather that be more a problem with high boost and excessive drive pressure pushing the heat bolts past their limits. Thus the reason why people run ARP studs.

As for the thermostat and the bypass, with the thermostat closed there is supposed to be no flow into the radiator. That is other than the amount which squeezes through the thermostat jiggle pins. So the bypass is only going to keep the coolant moving but only in the engine. The jiggle pins will allow some coolant purging into the radiator even though the thermostat is closed and probably allow for any air burping as well. So I'd say its not the same.
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  #40  
Old 03-14-2014, 02:32 PM
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The bleed/by pass on mine is a 1/4" line that goes around the thermostat. Like this (not my truck!!):

So it goes from one side of the t'stat to the other. I have been told that the water pump moves such a volume of water it will push coolant out of the headgasket right below the thermostat and that is exactly where mine leaked. It is a super slow leak (I went over a year before I fixed it) so it is not a critical leak.
I have even thought about shutting the bypass off to see what happens, but I haven't yet.
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Duct Tape can't fix stupid, BUT it can muffle the sound
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