180 Deg Thermostat

Discussion in 'Engine Performance + Maintenance' started by wb292, Nov 14, 2019.

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  1. Supercharged111

    Supercharged111 I'm Awesome

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    I run 180 stats in both trucks. I saw a difference in performance in my 88 when it ran stone cold with a stuck open stat, but I really run the 180s now to give my cooling system a head start when it comes to towing up a giant assed hill. That said, my temps rarely deviate from the stat temp. All I really get is peace of mind, but that could be all for naught.
     
  2. RichLo

    RichLo E I E I O

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  3. Supercharged111

    Supercharged111 I'm Awesome

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  4. Mark Gilbert

    Mark Gilbert Newbie

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    So, my logic on this is pretty simple.

    Coolant in the radiator with the thermostat closed will spend more time cooling down and therefore reach a lower temperature. When the thermostat opens you have a cooler charge of coolant to reduce the engine temperature.

    Yes, more flow will cool better, not because the speed of the coolant itself, but the fact that a larger amount of it is providing cooling in a shorter time. But circulating hotter coolant reduces the advantage. If flow was the only concern then why wouldn't the manufacturer make a thermostat that flows more. Even when fully open they have a pretty small area for coolant to pass through. Along those same lines why have a thermostat at all? Why not just have a valve that opens once the vehicle is up to temperature and never closes again. On a typical engine that is running properly if you leave the radiator cap off and put a thermometer in the water neck you will be able to watch the cycling of the thermostat.

    Obviously a larger radiator and/or more airflow across the radiator will increase it's ability to provide cooler coolant to the engine, that wasn't the question that the OP asked.

    Many situations have been mentioned, but the OP is living in Phoenix and gave a specific example. 120 degree weather, Now in AZ this means dry air as well, it is reasonable to assume that the air conditioning would be running meaning you aren't pulling 120 degree air (by the way that is in the shade) through the radiator it will be much hotter because the A/C condenser is heating up the air before it gets to the radiator. If the coolant is (we'll say a higher number) 230 degrees coming out of the block and into a radiator and the coolant and the air temperature is going to be closer to 160 degrees because of the condenser, how much will it be able to cool passing through the radiator?

    I get it higher flow is good - in the block, but higher flow rate through the radiator is not so good. The thermostat helps on that end.
     
  5. Mark Gilbert

    Mark Gilbert Newbie

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    If I were you, I would first make sure your radiator is performing properly, if your engine is getting old your likelihood of having some clogged cores internally are much higher, you may also have debris blocking the airflow either at the radiator itself or in the condenser. If your fan clutch is not working properly then you will get the same result, poor airflow. Now I may be wrong about this, but I was under the impression that even thermostatic fan clutches will disengage at a high enough RPM. Climbing a 6% grade with a tired motor probably requires high enough rpm's to disengage it.

    I would still recommend keeping the 195 thermostat, but again, obviously increasing the capacity of the radiator will help. You could also get a small electric "helper" fan. My 99 454 suburban had one from the factory so it shouldn't be too hard to adapt to your truck.

    I am of the opinion that most people that setup electric fans that complain about them is that they don't setup a way for the fan to free spin when the vehicle speed is high enough and it will actually slow the air through the radiator.
     
  6. L31MaxExpress

    L31MaxExpress I'm Awesome

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    Fan clutch working properly will definately engage atleast partially at higher rpm. I had the Express van on the dyno a while back in 80°F weather. Ran 2 pulls. Then an abreviated 3rd pull that was cut short when the trans started to downshift. On the 4th pull the clutch fan engaged at 3,500 rpm and stayed atleast partially engaged up past 5,000 rpm. The fan sounded like a medium duty truck taking off in traffic. Lost more than 10 ft/lbs across the duration of the pull when it coupled. The datalog showed the coolant dropped more than 10°F in a matter of seconds at ~5,000 rpm when the clutch engaged.
     
  7. 90 Silverado

    90 Silverado Newbie

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    My 90 was always running hot in AZ untill I upgraded to a larger factory type radiator.( Has the factory built in oil cooler and trans cooler like mine had)

    Can't remember the part number, but I got it from O'Reillys in Wickenburg.

    Had to modify the top plastic holddown to make it fit, still ran the 195* stat with no problems, even when towing.

    Doug in P.R.:cool:
     

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