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New Thermostat affect heater?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 76_Cheyenne, Oct 31, 2002.

  1. 76_Cheyenne

    76_Cheyenne 1/2 ton status

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    My Truck has a new 4 row radiator and since then the engine never gets very hot, and my heater hardly puts out any air worth calling warm, I might as well have the windows open. And here in Montana it was 7 degrees this morning and I really want some heat. So Im thinking that the new radiator is keeping my engine to cool, and maybe A different temp thermostat would help? Could this be right? Thanks
     
  2. bklynlifted

    bklynlifted 1/2 ton status

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    what temp do you have in there now?? you should have a 195 in there if it's good then put the cardboard in front of the radiator a small piece should do ? but my guess is you have the wrong temp stat or its stuck wide open ?? /forums/images/graemlins/thumb.gif
     
  3. HarryH3

    HarryH3 1 ton status Author

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    Yep, a 195 degree thermostat will help a bunch. You can also cover up most of the radiator with cardboard in the winter. Leave a 12 inch hole in the center, so the fan doesn't cavitate, and you'll be good until spring. I've got a Lund Winter Cover kit on my wife's '94 Suburban. It covers the grille so the monster radiator in it actually gets a chance to get warm in cold weather. Without the cover it takes a VERY long time to get heat. I got it from www.autoaccessories.com .
     
  4. 76_Cheyenne

    76_Cheyenne 1/2 ton status

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    Im not sure what Themostat I have in there. I belive it is the original one, but I will pick one up a 195 this weekend and some cardboard, Thanks Guys
     
  5. TWISTEDJACK

    TWISTEDJACK 1/2 ton status GMOTM Winner

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    It probably has a 180 right now. I am changing mine to a 195 'cause I froze today on the way to work.
     
  6. TopOff

    TopOff 1/2 ton status

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    If you have A/C make sure your heater core vacumm valve opens. This is a vacuum actuated flow control to your heater core. I usually see these on the passenger side firewall with a vacuum line attached. I believe they open WITH vacuum. So if they are disconnected or leak, they will not allow water to flow to your heater core.

    Good luck.
     
  7. Mr.Chevy4x4

    Mr.Chevy4x4 1/2 ton status

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    I'd be willing to bet that when you pull the water neck you will find that there isn't a thermostat in there. A lot of people will pull them out completely when they are having overheating problems.

    Mike
     
  8. HarryH3

    HarryH3 1 ton status Author

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    I don't think any of our trucks came with a water valve. The water runs through the heater core all the time on them. They just have a door in the plenum that determines the temp of the air coming out of the vents.
     
  9. TopOff

    TopOff 1/2 ton status

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    That's interesting.

    My '71 with Ac has one. My friend's '72 Blazer has one.
    And my '73 Blazer has one.

    I wonder when they stopped putting them in.

    I would think there would be some way you would want to stop the heater from making heat, before it hits the condensor on an AC equipped truck.

    Good luck.
     
  10. HarryH3

    HarryH3 1 ton status Author

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    My '75 doesn't have one, my '77 and '87 didn't, nor does my '90 Suburban or '91 S-Jimmy. The internal control door on the '75 lets the heat get past it, probably due to worn or missing seals, so I installed a manual valve in one of the heater hoses so I can just shut off the circulation in the summer. /forums/images/graemlins/cool.gif
     
  11. imiceman44

    imiceman44 1 ton status

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    Like harry said, I had a 73 and a 74, now have 76, 79 and 82 and all of them don't have a valve, it's just air redirected.
    Actually you don't want a valve system, I had them on my mercedes and after a long summer you try and open it and it's rusted or full of gunk that it doesn't work, so you pull it out and clean it or change it, every year.
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    I see the grille opening "blockoffs" in trucks used in cold climates (semi's included) but I'm curious as to why those are necessary if you have a thermostat?

    It would seem near impossible that even below freezing, that the engine could dissipate all of its heat with the t-stat still closed...I'm not saying it doesn't happen, because I certainly see many people running around with blocked off grille openings, but even at 7 degrees this past week, my dads engine temp never dropped below t-stat rated temp, and thus, the heater was never cold.
     
  13. HarryH3

    HarryH3 1 ton status Author

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    Diesels need them the most. If a diesel isn't working hard, it doesn't generate much heat. It's a much more efficient engine than a gasoline engine, thus less of the fuel is wasted as heat. But for gas engines, blocking off the extra airflow lets the engine warm up much faster. Our '94 Suburban has a huge radiator, and an equally huge grille opening. It takes a very long time to warm up when the temps get below 30 degrees or so. The Lund Winter Cover made a nice difference in how quickly we get heat inside, yet the engine never overheats with it installed. /forums/images/graemlins/cool.gif The temps on that truck never get over 210 in the summer, even on the hottest days with the dual a/c cranked up to high, so it just doesn't take much air to cool the radiator when the outside temps are below freezing.
     

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