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Discussion Starter #1
What are the pros and cons of running 180 degree thermostats vs. 195 degree?

Would this be a good option for keeping coolant temps down while towing? Will there be a downside when not towing?

Thanks,
Dave
 

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I have a 180 Robert Shaw sitting on the shelf in my garage. I had to swap in a stock 195 to set the timing last fall and never swapped the 180 back in again.

So one disadvantage of the 180 is that it's hard to reach the operating temp required by the time setting functions.
 

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180 pro's

Lower under hood temp - benefits the FSD/PMD if under the hood and all the other underhood plastics/rubber and various components.

Cons

Lower engine temperature. Diesels like a warmer block; it makes the engine more effiecient to run at 195 as long as intake air charge is the same (cool as when engine is at 180).

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Thermostats temp should not cause or solve an overheating problem (if they are working correctly). But may reduce temp swings that will engage the fan. I run (2) 180F thermostats and my truck usually runs about the 180-185 (dang GM odd ball tick mark on gauge is hard to remember exact number) and rarely moves normal driving. When towing it fluctuates according to load. It can go up ~10-20 degrees also depends on if A/C is on. That shifts the pivotal operating temp a little higher.

Now if they were 195F and you add 20F the fan might start to engage and take more power from the crankshaft (guesstimate 10-20 HP). I think the AC compressor robs about 6 hp and I can feel that engage so I don't want up to 3 times that taken away when I am working the engine hard.

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I don't know but I feel like there is a reasonably significant difference in a 20F swing across 212F. I know ECT is only one measure other areas are hotter and cooler but something still bothers me about too much moisture steaming as I think steam can super heat differently than water. I have no science to back that up as to how or where this moisture can act but something I think is different there.
 

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OK I know it can get hot up north too but for how long. Down here depending on where you are at it doesn't cool off until 10PM and seems like never sometimes.

Once when I had a stuck open thermostat did I have a problem getting over 160F ECT within the time limit and set an SES light but even in dead of winter (ha not so cold or long here) with 180F I have heat pretty quick and no problem holding ~180F.
 

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Our montana friend has a feature article on his web site that take all the mystery out of what works for cooling.He found the 195's pushed the temp over 212+ before they were fully open. He recommends & uses the RS 180's. Now with the new screw on marine pump & duramax fan clutch & duramax fan blade the temperature swing problem is a past issue. Do you guys know the Duramax radiator is the same size dimensionally as the stock6.5 radiator ? It is!!! Stop the wide temperature swings ,stop the block cracks,I say!!!
 
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180's and cold weather?

Can't help with a pro or con comment however I recently upgraded my fan and clutch and it was recommend by the vender that 180 F thermostats be used with this new setup. I've had the fan in for a couple of weeks, but I just installed thermostats today. I'm in Ontario, warm summers, cold winters, do people with trucks in the north run the 180's all year, or do you have to change them out as the weather gets cold ? My truck had good fast heat in the winter with the 195's. Thanks
 

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Discussion Starter #7
I saw that on the SS website yesterday when I was checking the price of the 180* stats. It sounds like you might be the guinnea pig for the 180 stats :) Are you planning on towing anytime soon? I'd be very interested to see if you notice a difference.

My truck heats up nice and quick in the winter also. With some of the stuff I've read about the 180 stats, it has me a little worried about winter temps. I don't use a winter front but maybe that would be the solution.

Dave
 

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Discussion Starter #8
4doorTAHOE6.5TD;1878730; said:
Our montana friend has a feature article on his web site that take all the mystery out of what works for cooling.He found the 195's pushed the temp over 212+ before they were fully open. He recommends & uses the RS 180's. Now with the new screw on marine pump & duramax fan clutch & duramax fan blade the temperature swing problem is a past issue. Do you guys know the Duramax radiator is the same size dimensionally as the stock6.5 radiator ? It is!!! Stop the wide temperature swings ,stop the block cracks,I say!!!

Are we talking about Heath? I can't find any articles that talk about 180* stats. Can you point me to the article you're talking about.

Thanks,

Dave
 

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Even with 195's I can't keep my truck warm in the winter. I've been running 180's for over a year now. The only benefit of 195's in the winter as far as I know would be that the heater blows hotter air. And if you can tell the difference between 180 and 195..your a better man than me :p:

I could be wrong though, so I take no responsibility for this response :D
Jay
 

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Remember that t-stats control the MIN. operating temp. not the max, thats up to the rad and the rest of the sys....
 

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I believe running 180 therms would cause greater temps swings than 195 therms. as KGT says the therms only control the min temps not the max. The max temps will be the same between the 180 and 195 therms. I believe it is the sudden temp swings that is the greater threat of cracked heads and not contiuous high temps. You can only heat and cool metal so many times before having trouble, the greater the temp swings the sooner you with have it.

The vast majority of every engine manufacturer recommends 195f operating temps and thats what they have been designed to run at.
 

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I believe that using the 180 gives the cooling system a 15 degree headstart on keeping everything under the max temp. I run 2 RS and have heard the Factory dual stat run one of each, I can't verify that but I thought that might even give you the best of both worlds. My 95( before I sold it) love the 180's running right at 185-190 unloaded and 195-200 loaded. No big swings, temp gauge would get to temp and hardly every move. Before the upgrade and Rad cleaning I would swing from 190-220 with the fan clutch kicking in around 210 and pulling it back to 190 range.
 

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It may give you a head start, but for how long, the max op temp is going to be what it is no matter where you start from, you start from a stone cold engine and the max is still gonna be the same. now the max operating temp is controlled by the rad and its ability to shed the heat from the hot coolant passing through the core and the ability of the fan to draw it throught the rad when req....
 

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Looks like this thread is going to end up in another "clean your radiator" argument.

I do not care what you guys say. I take my radiator right out of the truck and clean it properly. That is the biggest problem with cooling on these or any other trucks. I know this for a fact, I drive a diesel highway truck for a living and if you do not keep the radiator clean it overheats too! I am 100% sure that my radiator does not control the operating temperature of my engine in any of my vehicles.
 

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Quote: Jasonsmack wrote: "I tried hard but you are going to have to explain this one to me."

The rad., water pump, and every other component in the cooling system is used to keep coolant temp down except the t-stat. T-stats are only used in a cooling system to keep the temp. up to a min operating temp., 180 or 195. If a engine is going to over heat to lets say 220f with 195 t-stat it will overheat to the same 220f with a 180 t-stat., a t-stat has no ability to make a overheating engine run cooler (except for a bad t-stat of course)
 

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kgt;1879511; said:
It may give you a head start, but for how long, the max op temp is going to be what it is no matter where you start from, you start from a stone cold engine and the max is still gonna be the same. now the max operating temp is controlled by the rad and its ability to shed the heat from the hot coolant passing through the core and the ability of the fan to draw it throught the rad when req....

Exactly, so max temp is determined by the ability of the cooling system to get rid of heat. If the engine is overheating to 220f on a hill, it will be with any t-stat that might be installed. The problem is the temp swing is greater with a 180 t-stat, there is a 40f increase and going down the hill it will drop very quickly 40f. back to 180f. But with a 195 t-stat you will only see a 25f temp varience. It is these large temp swings that will give the head a workout/crack not high sustained coolant temps.. (to a point of course)
 

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Whoa, big guy. (talking to Jason).. actually, your rad DOES limit (not control) the cooling ability in all of your vehicles... but not because it's dirty, or because of anything you do. I pulled outta Brooks with Joann for a few years, and my KW got cleaned out lots, too.

I mention this because it ties in with the whole 180/195 thing...

Thermostats open up once their activation temperature is passed, and let the coolant circulate freely. From that point forward, it's a race... can the engine build heat faster than the rad can diffuse it to the air? If so, things cool off. If not, then the temps continue to climb until boilover - the heat input exceeds the cooling capacity of the rad.

When does that happen? That depends on a few things, too... the volume and heat-carrying capacity of the coolant (which is a good reason for using antifreeze in the summer) are factors because it ALL has to heat up, so more coolant = longer time, and better coolant = longer time. Another thing that influences it is the starting temp - when the thermostats open. With 180 therms, all that coolant has to heat up from 180* on... with 195s, all the coolant has to heat up from there. The end is at the same place, obviously.
The last variable is the fan - how much air it moves and when it kicks in are both factors, but the fan only gets into the game when the heat input exceeds the cooling capacity.

When you're pulling heavy and steady, the thermostats are only responsible for the bottom temperature, not the top... something we need to keep in mind when pulling hard into the wind or up hills... if it's heating up, and our rad and fan can't stop it, the only thing we can really do about it is put less heat in - let up on the foot feed, change gears, make sure the TCC is locked, etc.

When you're not pulling steady, the lower thermostats let the engine cool off to a lower temp between the hard pulls, which gives us a little more room to play with, but ultimately doesn't affect the whole thing.

The last thing is the continuing argument over temp swings, and I'm not getting into that one, other than to say the temp has already swung from 65*F to 195*F today... a 20* swing isn't that much, really.

Big truck, little truck, the same rules apply.
 
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