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Lower than stock thermo

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Panther, Mar 19, 2001.

  1. Panther

    Panther 1/2 ton status

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    Hey Guys. I just replaced my thermo in my 90 with a 350. I got the lowest temp I could (165 I believe). I thought the cooler the better, but doing on a search on here seemed to produce limited, but mixed opinions. Just wanted to do a consolidated poll on what people think.

    Is it ok (or even better) to put a thermo with a lower temp than the stock one?

    <font color=blue>"It's just a differentialator....Totally unnecessary" [​IMG]</font color=blue>
     
  2. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    Here is my experience with lowering thermo temp in a 5 words or less:

    Gain power, lose mileage...
     
  3. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I've heard that its better to have the motor running in its proper operating range. It will run more efficiently...
    Doesn't the computer controlled EFI set-up use a coolant temperature sensor? Wouldn't a lower temp thermostat fool the computer into running the truck a little rich?

    Rene

    [​IMG]<A target="_blank" HREF=http://jules.coloradok5.com>http://jules.coloradok5.com</A>
     
  4. Triaged

    Triaged 1/2 ton status

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    You don't want to run a lower thermostat unless you change the chip. At that temp w/ a stock chip it will run in open loop (not closed loop). This will cause bad gas mileage, a pluged cat, and no more power (maby even less). If you want more power with that thermo put in a Hypertech ThermoMaster chip. They even have a CARB EOD # for use in CA.

    '71 Blazer CST with alot of rust
     
  5. lowlevell

    lowlevell 1/2 ton status

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    Yes, What Triaged said. I can vouch for this first hand.Only run cooler thermos in trucks pre TBI.

    One From None
     
  6. mudpuppy89k5

    mudpuppy89k5 Registered Member

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    I have an '89 that I have owned since it was new. When I bought it, a friend who was a mechanic for GM suggested that I remove the 195 degree t'stat that it came with and replace it with a 180. As I remember, his concern was that 195 was too hot. At the time, we were playing with early '70s Camaro's and Firebirds and running 180 degree t'stats in all of them.

    I've run a 180 degree t'stat in the Blazer ever since. That was twelve years and 200,000+ miles ago (I'm getting to be an old fart) and the motor is still running good, doesn't leak or burn oil. I've never had any engine or exhaust problems (wish I could say the same for the transmission) and all the components are the original equipment. We have to have emission tests (metro Atlanta) and I've never had a problem passing. Just my .02

    John Perry
    http://www.mudpuppy.coloradok5.com/
     
  7. lowlevell

    lowlevell 1/2 ton status

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    My 89' TBI 350 had a 180 in it i believe because the previous owner pulled a friggn huge trailer. Less than a month ago i replaced my radiator, hoses, and thermo (195 degree). I could tell the difference immediatly. I believe the computer didnt like the 180 thermo. The truck "seems" to run better(smoother) now.


    One From None
     
  8. Pookster

    Pookster 1/2 ton status

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    I have a 180 in mine. Im acutally getting pretty good mileage, but the lower temp seems to make combustion incomplete. Consequently, I end up with a richer smelling exhaust and more fowled O2 sensors. Granted, an O2 sensor from autozone is only 12 bucks or os. Long trips or towing makes the 180 worthwhile. But unless you have cooling problems, I'd stick with stock.
     
  9. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Hay BigJBear it\'s one of them Southeners again!

    Hell like you southerners know anything! them there trucks were built in Detroit by Yankee's ahahaha
    Just giving you a hard time.
    Really you just got lucky. Most trucks respond negativly to the lower theromostat by not going closed loop. Your bud must have worked at Anderson :) no wonder they closed LOL. J/K. If you haven't figured it out yet I don't live too far from you. I'm about 3 miles north of Marietta on 5.
    I didn't know Drive shaft service did springs. I need to have them rebuild a Dirveshaft for my Wifes 79 soon. I'll have to see what he's selling. They have given me more than fair prices in the past. Here is another place good for parts for the transfer case. http://www.gbr4wd.com
    See ya around.


    Diging it in the dirt with my K5's
    Grim-Reaper
    <A target="_blank" HREF=http://grimsk5s.coloradok5.com/>http://grimsk5s.coloradok5.com/</A>
     
  10. 90K5

    90K5 1/2 ton status

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    I have a Hypertech Thermomaster chip and probably a 160 or 165 deg thermostat that was in the truck when I bought it. Does anyone know what I'm gaining from this? Does the chip do anything except make the 160 work right for the truck? I mean does it raise shift points, etc.?

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>
     
  11. muddin4fun

    muddin4fun 3/4 ton status

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    I think mine's either got a 160 if it even has one. I'm gonna replace it with a 180. It's better for the engine to operate at a normal temp in my opinion.

    [​IMG]


    <A target="_blank" HREF=http://muddin4fun.coloradok5.com>http://muddin4fun.coloradok5.com</A>
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    anything lower than 180 degrees causes undue wear on the engine components. They are set up with 195 for more than one reason, but 180 is a good compromise.

    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
     
  13. jarheadk5

    jarheadk5 1/2 ton status

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    I've seen it written quite a few places that TBI computers don't like any thermostat below 180 without a chip change. I don't know if the Thermomaster chip does anything other than allow a cooler 'stat.

    [​IMG] Semper Maintenance!
     
  14. Triaged

    Triaged 1/2 ton status

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    The ThermoMaster chip does allow you to run a lower temp thermo and they say is the most powerfull chip you can run on the street.

    '71 Blazer CST with alot of rust
     
  15. Panther

    Panther 1/2 ton status

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    Thanks much guys. Seems like it's back to ABC for another thermo. I gather the stock one is 195 then?? I didn't see it written on the old one when I pulled it out.

    I guess this might explain why I did even worse on emissions when I got it tested this AM [​IMG] .

    <font color=blue>"It's just a differentialator....Totally unnecessary" [​IMG]</font color=blue>
     
  16. Emmettology 101

    Emmettology 101 3/4 ton status

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    I was told by a very reputable engine builder not to run anything lower than a 175 in a pre-EFI engine. When you go lower that water/coolant doesn't have enough time to stay in the radiator and cool, thus staying warm/hot all the time and then the temps will not lower.

    I would run only a stock thermo or a 185 in a EFI vehicle.

    Mike [​IMG]
    See <font color=green>EMMETT</font color=green> -&gt; <A target="_blank" HREF=http://emmett.coloradok5.com>http://emmett.coloradok5.com</A>
     
  17. ken

    ken 1/2 ton status

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    I have been running a 160 in my '90 Sub for 8 years and 226,000 miles. When it had the junk 700r4 overdrive tranny in it, I would routinely get 14 MPG on long freeway trips. I have since swapped in a 400 trans and she still gets about 11 MPGs or so. As a side note, I feel the redcued mileage is OK because I've been thru 6 700r4s!!!!!

    ken
     
  18. dyeager535

    dyeager535 1 ton status Premium Member

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    Try a Robertshaw/Mr Gasket High Flow Thermostat. Everyone on all of my car lists with "oversized" engines loves them, and has nothing but good words about them. Just stick with a 180 or 195.

    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
     
  19. jarheadk5

    jarheadk5 1/2 ton status

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    Where do you get one of those high-flow thermostats?

    [​IMG] Semper Maintenance!
     
  20. dyeager535

    dyeager535 1 ton status Premium Member

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    I *believe* you can get them from Napa. I'm not positive, I haven't had the inclination to get one yet. You could probably even do a search online.

    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
     

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