Cooling System Towing Test Results, Before/After Mods

Jon A · December 23, 2018

Unfortunately I don't have enough time to work on my own truck as much as I'd like, much less work on others'. But if you pick up HP Tuners (which is good for lots of other things as well) I'd be happy to walk you through it. It's easy enough a caveman can do it.

If your trans is running hotter than it used to, that suggests something changed. The thermostat might be going bad, debris may be blocking the cooler, etc. The biggest single thing you can do for trans temps is getting rid of the stock thermostat. Makes a huge difference. I'll be posting some results as soon as I have the chance.

CyaDwnthaRd · March 15, 2019

I'm searching for an alternative GM 180 thermostat?

I've researched the reviews on Jet, and other aftermarket low temperature thermostats and ALL seem to have a very low rating, poor gasket design or material prone to premature failure.

I've seen the GM 197 degree part # 12674634

I really prefer a lower thermostat is anyone is aware of a GM OEM .

Thanks

Pearl2017 · March 25, 2019

FWIW, I put the summit 180 degree in about 9 months ago. I believe it is Summit branded Jet thermostat and I also had read that the seal can become detached and the stat not fully close. The rubber seal appeared to be thermally fused onto the disk very well. I just traveled 2000 miles to Dallas and back and scanned using hp-tuners some of the way and the temp stays rock solid at ~186 degrees. If you don't trust the Jet get the gm 196 one and use an old Chevy trick and drill a small hole in the disk. I believe a 1/8 or 3/16 hole is all you need to allow a bit of bypass and drop the temps. I don't think GM makes a 180 for any of the new motors as they are supposed to run much hotter.

kennerz · March 26, 2019

Great thread. Any consensus on what the best low temp thermostat for the transmission is? Or has anyone experimented with different trans fluids? In a built 700r an expert I know recommended lubrication engineers (not an apples comparison) but they seem to have an impressive array of quality lubricants.

Currently my trans hardly ever runs much over 185deg, and seems to struggle to get up to temp on short (less than 20min) trips. I almost think that the ECM is programed not to go into "closed loop" type functions until it hits over 130 deg. Is my thermostat stuck open/closed?

I have the shroud inside the grille removed so I'm not sure if that is having in impact on the cooling (overcooling in some situations. When hot it works well, but want to understand what I can do to manage heat and have it get up to temp in a consistent way, and cool predictably.

Sounds like the GM (coolant) 197deg thermostat is a great option for those that want OEM build quality vs risky aftermarket junk. Also the takeaway from this thread is aftermarket coolers are not necessary for most unless you are placing your truck in extreme conditions. A intelligently modified , well set up/maintained factory set up seems to be adequate depending on use.

Also not sure of the pros/cons with the exception of potential start up wear, but I've been running 0~w40 (Castrol full syn, not a brand loyalist just have not seen the evidence that one is so far superior, rather change more frequently and use a quality filter (Wix, K&N, or mobil 1))European formula for some time now and it maintains pressure when hot much better than 0~w20. Just seems too thin especially when the camaros and vettes run it or offer it as an upgrade in the same platform (LT). If there is something MUCH better please let me know just always get the same amsoil, Royal P responses.

I want to hit the 300k goal.

Pearl2017 · March 30, 2019

Kennerz,
I was talking about engine coolant thermostat and not transmission thermostat. From what I've heard the 160 degree engine tstat is too cold and will cause problems for closed loop operation. 180 should be lowest you go. The 196 is still way better than the higher one the truck comes with and the massively high engine, IAT and under-hood temps that go with it in the Arizona summer where i live.

Some people are removing the thermostat from the transmission and not replacing it. A turbo 700r is vastly different to what we have now. Even using the recommended GM fluid there are issues and they are working to reformulate it for better operation. If you want to experiment with other fluids and let us all know what you find i'm all ears.

Grumpy Bear · March 30, 2019

Jon A, You ever finish collecting the 160 F trans stat heat profile? Would love to see it.

truckguy82 · March 30, 2019

On 3/15/2019 at 10:15 AM, CyaDwnthaRd said:

I'm searching for an alternative GM 180 thermostat?

I've researched the reviews on Jet, and other aftermarket low temperature thermostats and ALL seem to have a very low rating, poor gasket design or material prone to premature failure.

I've seen the GM 197 degree part # 12674634

I really prefer a lower thermostat is anyone is aware of a GM OEM .

Thanks

Katech just released some for the camaro and vette. Not sure if they work on our trucks.

flyingfool · March 30, 2019

excellent write up, only problem I have with the 180 t-stat from the aftermarket is it's very unreliable..... I would recomment taking a factory t-stat and drilling out a few bi-pass holes to lower the stock temp control, instead of using the aftermarket parts for a 180 temp

my origional plan was to use an inline thermostat housing to replace the factory t-stat, this way i can use the old style 350 chevy t-stats from AC/Delco wich come in a range of temps from 150, 165, 170,175, 180-210 F , something like this part..

https://www.amazon.com/Meziere-WN0072-Inline-Thermostat-Housing/dp/B003NDHHAW/ref=sr_1_1?crid=16XGJRKSXVSYZ&keywords=inline+thermostat+for+car&qid=1553956190&s=gateway&sprefix=inline+thermostat+%2Caps%2C230&sr=8-1

it should be noted, these engines are machined and built for the higher temps, so the colder they run, the diamentions of the parts are not fully expanding , thus your clearances will be sloppier. take the pistons, for example. they are a special metalurgy and if not at correct temp, will make a sound like piston slap in the bore witch might trigger knock sensor, and pull timing = lower power., then you have bearing clearances for the oil gallery. Half a thou diamention can really change lube control to the crankshaft

also I notice you haven't deleted the thermostat in the tranny yet, , this is a must do for towing!

Edited March 30, 2019 by flyingfool

kennerz · March 30, 2019

13 hours ago, Pearl2017 said:

Kennerz,
I was talking about engine coolant thermostat and not transmission thermostat. From what I've heard the 160 degree engine tstat is too cold and will cause problems for closed loop operation. 180 should be lowest you go. The 196 is still way better than the higher one the truck comes with and the massively high engine, IAT and under-hood temps that go with it in the Arizona summer where i live.

Some people are removing the thermostat from the transmission and not replacing it. A turbo 700r is vastly different to what we have now. Even using the recommended GM fluid there are issues and they are working to reformulate it for better operation. If you want to experiment with other fluids and let us all know what you find i'm all ears.

Flying fool - was pretty right on regarding the 160 deg water coolant thermostat. That may have been a good mod on the original small blocks, but has been a bad idea for a long time. Even the 87' up hydraulic rollers tolerances were tight enough to have problems not coming up to temp and increasing wear from running too cold (not enough material expansion) or not going into ecm closed loop operation and washing the cylinders down with gas. Every generation since has gotten increasingly tight tolerances using different expansion rate (aluminum/sleeves/etc..) material. The LS's like to run hot (were designed to run hot) and the Gen V LT is the most extreme so far when it comes to design intent. Meaning they made it that way for a reason (usually low emissions) to run hotter.

There is obviously some room for improvement from a performance perspective by making slight changes - just more is not really better with these newer engines.

If you can find a quality 180 coolant stat probably would be OK, 195 would probably be more in line with the ECM parameters and engine design. Surprised no one's mentioned an aftermarket radiator. For the trans I would think a 160 stat would be good since the old adage that automatics live longer when cool still holds true.

Really appreciate all those contributing to this discussion as I'm trying to figure out the benefits myself and what and how much to mod and for what uses (towing/daily).

Grumpy Bear · March 30, 2019

Call Mark Johnson at IPSCO.org upper hose inline thermostat housing. Gut factory housing. Do not block or remove return hose to tank. It keeps the pump happy. Drill bleed hole in flange .0625 to .0781. This is not to make it cooler but to provide some water movement past the min flow bypass in the stock housing to give the wax pill something to work with.

Stant Supersant 160 F Part # 45356 Requires some tuning. Mainly used on boosted motors. Not really a street item otherwise.

Reische 170 F Part # NB54 I expect this is the Dayco part. a $10 part Imported from Australia with silly shipping charges.

Dayco 170 F Part # DT14E Both Dayco and Reische are over $50 this side of the world.

Stant Superstat 180 F Part # 45358 My favorite. Removes 20 to 30 F from the system, Very ECU friendly.

Stant OE Type 195 F Part # 13359 Could also use the factory housing and GM # 12674634 actually 197 F.

Stant OE Type 205 F Part # 13352. A choice if you swap thermostats with the seasons....

Flepro #35710 Seal required and supplied with one of the Stant thermostats of your choice by IPSCO.

After three gasket failures from OEM type replacements, JET, Summit, Mishimoto, etc I quit. Whipple has a 160 F all brass gasketless for the stock housing for boosted motors. I do not have a part number for that one. Great idea that needs a few more choices.

The fancy machine work is not standard. Mark did this at my request.

Clip from my build thread: pg 24:

[First outing today 184-186 F water. 153-163 F transmission. 204 - 210 F engine oil. 82 - 87 F air temperature. 60% humidity. 55 - 60 mph. 12 - 15 mph wind on my 12 then on my 6 round trip.]

Trans is thermostat delete.

flyingfool · March 31, 2019

after deleting the trans t-stat i run 120-135 all day long, no aux trans. cooler nessecary, even with a 7500 lbs trailer towing in the desert, I never got past 150F after 120 mile drive with the trailer, I do have 3.73 gears

Edited March 31, 2019 by flyingfool

flyingfool · March 31, 2019

heres a 170 i want to try out https://www.amazon.com/gp/product/B072JQ57Y1/ref=ox_sc_saved_title_6?smid=ATVPDKIKX0DER&psc=1

cheaper housing

https://www.amazon.com/Meziere-WN0072-Inline-Thermostat-Housing/dp/B003NDHHAW/ref=pd_bxgy_263_img_2/131-5166147-3637010?_encoding=UTF8&pd_rd_i=B003NDHHAW&pd_rd_r=4463fe89-540e-11e9-9f39-25571fcafcbf&pd_rd_w=88Qw6&pd_rd_wg=Hios7&pf_rd_p=a2006322-0bc0-4db9-a08e-d168c18ce6f0&pf_rd_r=ABA38AMZ059QP0VNYE37&psc=1&refRID=ABA38AMZ059QP0VNYE37

Edited March 31, 2019 by flyingfool

flyingfool · March 31, 2019

On 3/30/2019 at 11:29 AM, Grumpy Bear said:

Call Mark Johnson at IPSCO.org upper hose inline thermostat housing. Gut factory housing. Do not block or remove return hose to tank. It keeps the pump happy. Drill bleed hole in flange .0625 to .0781. This is not to make it cooler but to provide some water movement past the min flow bypass in the stock housing to give the wax pill something to work with.

Stant Supersant 160 F Part # 45356 Requires some tuning. Mainly used on boosted motors. Not really a street item otherwise.

Reische 170 F Part # NB54 I expect this is the Dayco part. a $10 part Imported from Australia with silly shipping charges.

Dayco 170 F Part # DT14E Both Dayco and Reische are over $50 this side of the world.

Stant Superstat 180 F Part # 45358 My favorite. Removes 20 to 30 F from the system, Very ECU friendly.

Stant OE Type 195 F Part # 13359 Could also use the factory housing and GM # 12674634 actually 197 F.

Stant OE Type 205 F Part # 13352. A choice if you swap thermostats with the seasons....

Flepro #35710 Seal required and supplied with one of the Stant thermostats of your choice by IPSCO.

After three gasket failures from OEM type replacements, JET, Summit, Mishimoto, etc I quit. Whipple has a 160 F all brass gasketless for the stock housing for boosted motors. I do not have a part number for that one. Great idea that needs a few more choices.

The fancy machine work is not standard. Mark did this at my request.

Clip from my build thread: pg 24:

[First outing today 184-186 F water. 153-163 F transmission. 204 - 210 F engine oil. 82 - 87 F air temperature. 60% humidity. 55 - 60 mph. 12 - 15 mph wind on my 12 then on my 6 round trip.]

Trans is thermostat delete.

what size is the upper gm rad hose in inches?

Grumpy Bear · April 1, 2019

2 hours ago, flyingfool said:

what size is the upper gm rad hose in inches?

Ah...well...it's metric but Mark knew the closest SAE size and it works well. I can't remember. Great find on the T stat. 170's are rare this side of down under. I see it already has the pilot hole too.