Cooling and fluctuating temp question

Discussion in 'Street/strip 400/430/455' started by jaystoy, Apr 20, 2022.

  1. john.schaefer77

    john.schaefer77 Well-Known Member

    I used the mr gasket high flow thermostat and it never wanted to get to temp. liked to stay at 170. Worse in cold weather. I pulled it out and replaced with a standard 180, it has been much better.
     
    Last edited: May 9, 2022
  2. jaystoy

    jaystoy Well-Known Member

    Ugh i am afraid you may be right. I might swap the fan clutch first to see it that helps with temps a bit. Really don't want to swap thermostat again. Makes such a mess
     
    Mark Demko and john.schaefer77 like this.
  3. Mark Demko

    Mark Demko Well-Known Member

    So it runs cooler than you’d like it?
    Sounds like it was the thermostat
     
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    The weather is still cool. Wait until it gets hot, then evaluate.
     
  5. Super Bald Menace

    Super Bald Menace Frame off oil changes

    Im curious. I read an article by an expert from years ago that stated the thermostat controls minimum temp once engine is warmed up and the entire cooling system controls max temp which makes sense to me. but what causes them to run colder if the thermostat is functioning? Is it the bypass? I had the too cold issue during winter in my 70 GS455 years ago
     
  6. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Correct, but if you have a really good (Big) radiator, it can drop below the stat rating. Thermostats can vary in that regard. It's really a crap shoot I'm sad to say. I have a standard 180* stat in my GS for well over 10 years now. The temperature never varies more than 5* from 180*. It most often sits at 180* on the nose no matter how high the ambient temperature is, which never ceases to amaze me. I'm thinking you just have to keep trying thermostats until find a good one. Wish I had a better answer. In the winter, it usually wants to run at 175*. You can also block off part of the radiator with cardboard to get the temps up if you want in cold weather. Easily reversible.
     
  7. Schurkey

    Schurkey Silver Level contributor

    Heck, yes. Hayden suggests NOT using the "heavy duty" or "severe duty" fan clutches with normal automotive fans--they'll never disengage properly, they'll make a lot of noise, and they'll cut power/fuel economy because they don't release like they should.


    I have NO idea how folks can think that there's "air pocket(s)" trapped in the cooling system of these old cars once the thermostat opens. Newer vehicles, where the engine, cooling system plumbing, or the heater core may be higher than the rad inlet hose...sure. They're generally equipped with bleeder screws at the high-point(s) just for that reason. But these older cars...no. Any air in the system is purged into the radiator as soon as the thermostat opens the first time. Then it's seen as "low coolant level".
     
    1973gs and Mark Demko like this.
  8. Mark Demko

    Mark Demko Well-Known Member

    Yep!
    You’ll know it’s “burped” when it belches coolant up out the rad :p
     
  9. techg8

    techg8 The BS GS

    Its not overheating so get out of your head about it my man. Gonna make yourself crazy. or crazier..... LOL
     
    Super Bald Menace likes this.
  10. Stevem

    Stevem Well-Known Member

    Also note that if you have a ribbed type non molded upper or lower rad hose that these have been shown to be 30% more restrictive then a non ribbed hose.
    Having a ribbed upper is more detrimental then the lower at high engine speeds
     
  11. Michael_G

    Michael_G Living the Dream... Fast with Class...

    Interesting. Did not know this. Learning has occurred
    -MIG
     
  12. BQUICK

    BQUICK Gold Level Contributor

    Two things I do.....drill an 1/8 hole in thermostat so bubbles can start working there way out BEFORE the Tstat opens and getting a lever vent type cap to burp it along the way.
     
  13. Mark Demko

    Mark Demko Well-Known Member

    Do some burnouts, you’ll forget everything :D
     
    Michael_G likes this.
  14. jaystoy

    jaystoy Well-Known Member

    Well i am absolutely thrilled. Warm day up here in CT. Again running one of those mr gasket high flow 180 stat, a new TA high flow pump. I swapped the heavy duty fan clutch for the regular duty clutch. Temps stop at about 175 to 180. Never a degree higher than 180. I could not be more pleased. No more temp swings. Thanks for all the input.
     
    FLGS400 and john.schaefer77 like this.

Share This Page