I just recently installed a 170 degree thermostat in my 97 jimmy 4x4. She runs great but a couple of UTI kids were filling my head with stuff that it is bad for my engine.

Will i lose MPG?
Is it bad for my engine?
Do i have to have my computer relearned?
Is it best to run colder or should i go back to a oem?

On my 97, the gauge sits below the first quarter mark but never goes over it. It runs perfect but i think i maaay be losing MPG. i just dont want it to damage my Jimmy. I love this thing more than anything.

 

You will not be getting optimum MPG running a colder thermostat. The engine is designed to run most efficiently at a certain operating temp. Also running colder will lead to higher levels of internal carbon build up because your combustion chambers won't be getting hot enough, and your oil will dirty up faster than normal. Your computer is calibrated for a certain operating temp, and until the coolant sending unit shows that its at operating temp your fuel/air mixture will be rich, if you are dead set on a colder stat then you will have to set the computer for it.

I'm not sure if there are any benefits of running a colder thermostat to be honest. I could be wrong though. I would stick with OEM. Mine is a 210 stat. My temp gauge remains pointing straight up at the middle mark when warm.

 

In my 2k zr2 I run a 195* stat. and it sits 2 lines under 210

 

Ive been running a 180 in my 1st gen for almost a year now. No issues i know of yet. I run cleaners,etc in my oil,seafoam in the tank. So sludge issues is at minimal. I DID notice a drop in gas mileage when i did the swap. I do notice it drives better then when it was at 210. Cant win em all!

 

same with my 97. Ive been advised that 195* is the best to use.

 

Most vehicles dont go into closed loop until at least 180 deg. So your system is always in warm-up mode.

did you notice a performance difference once you reached 190 degrees before you changed the stat?

Is it bad for your engine? Well.. the mfrs must think so, maybe that's why all of them install 190 deg tstats. They're concerned about getting through the warranty period without paying dealers money to fix problems.
- that's the bottom line.

Also long term.. I have a feeling that when you put the stock temp tstat back in you might find O2 sensor problems and wouldnt be surprised if the cats fail early. That's a feeling.

hotter the engine the quicker it boils out condensation in the engine. So you better keep a close eye on it if you dont drive long trips.


Of course.. it would be interesting if Chris posted money spent for seafoam and oil treatments per year.

 

Haha...Well the marvel i run maybe 2-3 times a year 100 miles before a oil change. so,12 bucks right there($4 per bottle). Then i put 1/2 bottle of seafoam in a tank of gas once a month.
$48+$12=$50 bucks extra a year,which probably helps anyways even without the 180. Im OCD about my maintenance. Especially since im so rough on my blazer. Is it helping? I dont know,im not having any sludge issues etc. So im happy.

 

These engines love to run hot its kinda weird but i let them win =)

 

hmmm unlike your math. $60!
Well, there ya go. And if you're 'rough on the car', that helps in the 'sludge' and cylinder deposits dept too.

Believe it or not I am not a believer in preventive additives.. though I certainly look like a Lucas and Red Line (water wetter) shill sometimes. I only add when I SEE a NEED for it.
If you only ran Speedway gasoline, you wouldnt need the Seafoam.
I know for a fact from a 180 kmile teardown. No deposits on intakes or cylinder heads. Took injectors to a NAPA with inj cleaning system. They reported top shape.
Or Mobil1 oil.. know for a fact from the 180K teardown and bearing/ cyl wall inspection. No sludge anywhere in engine. And I am hardly 'ocd' on my oil changes.. go longer than 25 Kmiles often. Though THAT one {84 Mustang SVO Turbo} I made sure to change at least once a year. If you can pull a piston just scraping top of cyl with a box knife, and still see mfr cyl wall crosshatch, you got no oil problems.

That's just my opinion, again. Why would I lie.. not getting paid by either mobil OR Speedway.

 

Thank god for the good guys on blazer forum!