I think the 165/170 t-stats are for the v-8's. use the search engine here for "thermostat". its been mentioned many times that the 187's are really 195's. something to do with new emissions standards in 2007 when the 2.9's/3.7's came out. is your truck getting hot?

 

When I replaced my thermostat a few years ago, 195 was all I could find for my 2005 I-5.
I would LOVE to replace mine with something a little cooler...

 

Ive tried searching already and can't seem to find any good part numbers that are verified to be a direct replacement in the factory housing..

Truck isnt technically getting "hot" per GM's specs but for what I use it for, I need something thats fully open and flowing coolant at 180-185 degrees.

Truck gets ran pretty hard in 120 degree heat with the a/c cranked and once it gets hot, its hard to cool down.

 

Gotcha ... This seems to be the hot topic )) during the summer every year, maybe someone can make a list and sticky ? 

Here’s a few ideas that come to mind, they are stand alone or you can combine them …

Check to make sure both radiator hoses are hard (this indicates no air bubbles)
Check to make sure the antifreeze is around 50/50, anything outside the blue zone is too much antifreeze and cooling becomes counterproductive. With the engine cold, use a Prestone tester and pull directly from the radiator.
Have more water to antifreeze ratio (I’m at 60%water 40%antifreeze) (you need at least 10% antifreeze for water pump lubrication/anti-corresive properties) #656 for pictures. https://www.355nation.net/forum/i4-...net/forum/i4-i5-engine-drivetrain/i4-i5-engine-drivetrain/sfan...an-kit-33.html
Make sure the OEM Clutch Fan is in good condition
Make sure the radiator fins are clean (shinning a flashlight at night is a good test)
Swap to a V-8 radiator
Add a spacer to the t-stat (currently using a .60 spacer) https://www.355nation.net/forum/how-performance-maintenance/188762-how-shim-your-thermostat.html
Add Water Wetter or Blue Ice, etc. (currently using Water Wetter)
You could remove the rubber seal near the windshield, some concerns are that it interrupts the air flow/turbulence under the hood. i ran mine for a while and didn’t notice anything, but its back on …

add a transmission cooler to reduce the transmission temp https://www.355nation.net/forum/how...et/forum/how-performance-maintenance/39738-how-install-transmission-cooler.html
switch to a high quality or racing synthetic oil for the engine and driveline

 

Gotcha ... This seems to be the hot topic )) during the summer every year, maybe someone can make a list and sticky ? 

Here’s a few ideas that come to mind, they are stand alone or you can combine them …

Check to make sure both radiator hoses are hard (this indicates no air bubbles)
Check to make sure the antifreeze is around 50/50, anything outside the blue zone is too much antifreeze and cooling becomes counterproductive. With the engine cold, use a Prestone tester and pull directly from the radiator.
Have more water to antifreeze ratio (I’m at 60%water 40%antifreeze) (you need at least 10% antifreeze for water pump lubrication/anti-corresive properties) #656 for pictures. https://www.355nation.net/forum/i4-i5-engine-drivetrain/sfan...an-kit-33.html
Make sure the OEM Clutch Fan is in good condition
Make sure the radiator fins are clean (shinning a flashlight at night is a good test)
Swap to a V-8 radiator
Add a spacer to the t-stat (currently using a .60 spacer) https://www.355nation.net/forum/how-performance-maintenance/188762-how-shim-your-thermostat.html
Add Water Wetter or Blue Ice, etc. (currently using Water Wetter)
You could remove the rubber seal near the windshield, some concerns are that it interrupts the air flow/turbulence under the hood. i ran mine for a while and didn’t notice anything, but its back on …

I just completely overhauled the entire cooling system with new everything except the thermostat.. V8 full aluminum performance radiator, spal 16" e-fan with an extremely nice shroud, all pre-deluded 50/50 dex cool & new hoses.

Just want to find a lower t-stat..

What does the shim do?

 

I took the thermostat apart and started by cutting an 1/8 " of coil off, then put it back together and tested it in the house. Used a meat thermometer to check the water temp on the stove. Ended up getting it to crack open at 160* and fully open by 180*.

It may take more or less trimming on the spring for different tstats so just cut what you need to adjust the opening temp.

 

cool idea just have to watch out for the P0128 code for running too cold ... or maybe disabled with your HP software?

DTC P0128
CONDITIONS FOR RUNNING THE DTC
DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0502, P0503 are not set.
The startup ECT is less than 80°C (176°F) .
The intake air temperature (IAT) is more than -7°C (+19°F) .
The engine run time is between 30 seconds and 30 minutes .
The vehicle is driven more than 0.8 kilometers (0.5 miles) at more than 8 km/h (5 mph) .
The mass air flow (MAF) is between 20-75 g/s , with the average more than 30 g/s .

 

Back in the day , all of us that lived in the rust belt and only drove our muscle cars in summer , would not run a thermostat at all. We could buy what amounted to a large washer that fit in place of the thermostat allowing constant coolant circulation. It worked quite well in that circumstance. You could try something like that by removing the spring and innards of your thermostat and give it a shot . Worst case it doesn't work as well as you wanted and you go stock or try the shim one. Some time old school is the best school.

 

 

I think I am gonna try the 1/8" 304 Stainless Tig rod. lol

Seems to be the ticket from what I read!

Thanks guys!

 

Like OldTime suggested, I've run many hot rods without a thermostat. I've run some electric water pumps on them too. The only problem with that in a daily driver is that your heater will never work very well.
Another thing that offers the best of both worlds is to take the thermostat out and drill a couple of holes in it. drill holes on the flat part. I'd drill a couple of 1/4" holes, but if there's no room for that, smaller holes will work too. You'll have some constant flow, but it will restrict flow enough reach enough of a "standard operating temperature" to prevent codes and have a functioning heater also.

 

Do you have a manual overide for the fan?
What are your temp settings for the fan to come on?