Ordering NEw Tstats soon, thinking of going with the 195's as I'm not sure whats in there now, but pretty sure at least one of them is stuck open.

Spent last few hours in T-stat threads.

Any new opinions on an old topic?

195 and get them from GM with the o rings. May as well swap out the coolant for new, pull the rad and clean it all out, change the temp sensor on the head, helps drain the coolant. Get her clean and ready for the summer heat.

I have a buddy running a 180° on a 1995 single stat. He is really happy with it : before the swap, his truck was running usually at 192~194 °F. With the new T-stat, she runs at 175°F and grows up at 195° when pushing hill climbing, no more...
I will soon put a 180° + a 190° on my dual mount ( 1996) to replace my 2 old 195° and I will tell you.

190's

Depends on what you need, as I'm sure the threads revealed. From my perspective:

* 180s if you are planning to do a lot of heavy towing, or are concerned about summer heat. The 180s will be fully open around 200-205.

* 195s if you need best fuel economy and don't expect to do a lot of towing, and want to keep the temps up higher.

Don't forget, once the stats are fully-open, either one is fine. The fan and fan-clutch will control the cooling. Point is, when the stats are fully-open there is no difference in flowrates between 180s and 195s.

I run the 180 on the Tahoe because I have NOT upgraded the water pump nor the thermostat housing. I have found with the 180 and the electric fans, it does a pretty good job keeping it around 195-200 most of the time, unless I'm going up a very steep hill and getting on the throttle (which is fun).

I believe the 'burb has stock 195s, and it does just fine with the upgraded dual stats and bigger water pump. I'm pretty happy with both of them.

If I were to upgrade the Tahoe to a new water pump and dual-stat, I would move to the 195s.

Have fun.

Rob :)

That looks like a work truck in your avatar picture. I run the 180's. The truck ran fine with the factory "F" ECM program and runs better with the reflash. I have never had a problem keeping warm in the winter either. The regular cab trucks do not require much of a heater anyway. Some guys say you will get better fuel mileage with the 195 thermostats but I could not tell any difference when I changed to the 180's. I vote for keeping it cool.

i run 195 as i like the winter heater option. summer it still stays below 200ish and if necessary on them long hills i turn the heat up high and roll the windows down. ED

Twin 195's here. Like Ed ^^^^^I like heat in the winter.

I never thought about mixing/matching, but I seem to average about 10,000 mi a year, and havn't even worried about overheating since I replaced my fan clutch last year as it was kicking on way too late.

As a side note for peeps reading this, MUCH MUCH of an improvement having your fan clutch kick on at 210 faithfully. If yours is worn out, replace it.

Anyhow, I want mileage gains, don't plan on towing much, if anything, and nothing heavy.

DOn't plan on using Sander next year at all, in fact, selling it for $300.00 bux if someone around MASS wants to buy it.

So I think i'm going with the 195's.

Getting them from Kennedy, and they come with new o-rings. Is there anything else that needs a gasket/seals while doing this job?

So I think i'm going with the 195's.

Getting them from Kennedy, and they come with new o-rings. Is there anything else that needs a gasket/seals while doing this job?


Nope. No extra gaskets. The T-stats have a seal around them already.:)

This Indirect Injected Diesel runs best with the 195's, according to Bill Heath - do the coolant mods to keep temps within livable range under full loading

Also gets better fuel economy from greater efficiency running ~150deg IAT's

when i had my t-stat housing off to get my lower intake mani off it i didnt see any gasket on the t-stat housing between the two haves, is that a metal on metal seal?

I've got 180's in there now....(No complaints), but a lot of the Guru's say AC Delco 195's are the way to go.....but of course, cooling system needs to be 100%, Dirty rads, condensors and tired fan clutches will out weigh any T-Stat heat problem.

Louis

I am running dual 190's but one is a fail-safe that will stay open if it ever fails, but in past two years not a single problem and never heats up (but I also did other mods at same time like new clutch fan and duramax blades).

The seal is a split-o'ring around the t-stat flange............

I just replaced mine today in my '98 K2500. I used Stant brand, 88*c (195*f ?) and they didn't have a seperate gasket, the entire 'stat was coated in a gasket. Which way was the little bleeder valve supposed to face? I put them in with the little bleeder facing down ( towards the ground) I hope I got that right...

At least the truck has the correct Dex-Cool in it now

Don't tell me you changed from the green to the orange dex-cool?.............That stuff is NG, get rid of it ...........do a search........many people have changed back to the green.
Has something to do with the dex and aluminum and corrosion....check it out.

Louis

Don't tell me you changed from the green to the orange dex-cool?.............That stuff is NG, get rid of it ...........do a search........many people have changed back to the green.
Has something to do with the dex and aluminum and corrosion....check it out.

Louis

My understanding is that Dex-Cool has had some problems with 'sludging' when a chemical reaction occurs due to the water used, typically water with high levels of dissolved solids, such as calcium, etc. Using DexCool with distilled water is supposed to be just fine.

Rob :)

P.S. That said, I used plain tap water for my change out a couple of years ago... I didn't know this back then.

I run an OEM t-stat. I think it's 195. I pull heavy and don't overheat, but I've got a new radiator and Heath fan clutch (running green anti-freeze)

The majority says Green.........Usually when 9 out of 10 people say it's a horse, it's a horse.
Thats just me.

Good Luck,
Louis