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Heater Blows Warm Air

Discussion in 'Early CJ-5 and CJ-6 Tech' started by Renegade ll, Jan 9, 2019.

  1. Jan 9, 2019
    Renegade ll

    Renegade ll Member

    Thayne Wyoming
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    Well I need some ideas for making my heater blow hot air. Here's what I have. 1971 cj5 with 225 V6 freshly rebuilt. New aftermarket heater from Vintage air. 180 degree thermostat. Here in Wyoming it gets cold in the winter. On most days my jeep runs at 150* . I would prefer it to run between 180* and 190*. I do not want to block the airflow in front of the radiator if I can help it. I was thinking of trying a 195* thermostat or a 205*. Has anyone found a good fix for the say 0-30 degree weather.
     
  2. Jan 9, 2019
    ITLKSEZ

    ITLKSEZ Volvophilic

    Post Falls, ID
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    You might want to pull your thermostat and make sure it's closing all the way. I never had a 225 that ran cooler than the thermostat rating, even at -20.
     
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  3. Jan 9, 2019
    timgr

    timgr Jeepin' Nerd Sponsor 2019 Sponsor

    Medford Mass USA
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    You may have to block off part of the radiator to get up to temperature in really cold weather. Possible your thermostat does not have enough gain to drive the system to full operating temperatures when the outside temps are around zero. By definition, negative feedback systems only approach the set point (ie the thermostat "value"). The more gain the closer the approach is, though too much gain becomes oscillatory (unstable). You could try a different brand of thermostat.
     
  4. Jan 9, 2019
    PeteL

    PeteL Member Sponsor 2019 Sponsor

    Hills of NH
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    I'll repeat my cautionary experience here... from a F-head jeep, but the exact same situation.

    I put in a high temp thermostat, then had engine boilovers when the weather got extremely cold. I surmise the cold ambient air around the thermostat housing kept it from ever opening, even as the block boiled.
     
  5. Jan 9, 2019
    tomasinator

    tomasinator Member

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    The engine-not-coming-up-to-temp happened to me, too. On New Year's Day, my wife and I put on puffy coats and gloves and drove no-top-style in a '70 CJ5 to town. The CJ5 has the original heater plus another heater on the passenger side. I've plumbed them both in series. The engine temp gauge never got up to normal on the drive. Maybe the thermostat wasn't working or the two heaters were enough of a radiator so the engine never warmed up to normal operating temperature.
     
  6. Jan 9, 2019
    colojeepguy

    colojeepguy Colorado Springs Sponsor 2019 Sponsor

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    I tried a 195 Stat in my 225 & it didn't work well...the temp kept swinging from 180-220 degrees. This happened with two different 195 stats. Switched back to a 180 & all is well. Why? I don't know.
    But I have found that to get good hot air out of the heater you need to be around 195 degrees or hotter. I have half of my radiator blocked off in the cold weather.
     
  7. Jan 9, 2019
    Twin2

    Twin2 wasn't me Sponsor 2019 Sponsor

    Virginia Beach, VA
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    same here . if you want heat :D
     
  8. Jan 9, 2019
    Jw60

    Jw60 Recovering Jeepaholic

    Sedalia MO.
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    Don't run the heaters in series. split the hose or better run seperate lines and get more flow. If the original is clogged it won't let the other work either.
    On my f-head I had to get a heavy duty thermostat that has v notches in the opening. Another trick is to drill a small hole in the flange of the thermostat to allow trapped air to pass and allow a small amount of water to constantly flow around the bulb allowing it to sense better. Did the rebuild remove any exhaust dampers or block any exhaust crossovers in the intake? The exhaust damper when used forces air to cross under th carb to allow the fuel to vaporize and burn completely. Is there any lack of power or fuel economy?
     
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  9. Jan 10, 2019
    47v6

    47v6 junk wrecker! Sponsor

    Washington DC.
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    I am running a 165 thermostat in my 225 V6.
    In summer my temp fluctuates 185 to 195 and 200 on long drives in 95 or 100 degree weather. Now in 40 degree weather it fluctuates 175 down to 150. Its never constant. I have put in 4 different thermostats too. 165 and 185s.

    Cant help with he heater issue, cause I don't have one, nor a top. Last 2a had a heater, but I never used it. My 77 cj5 had a heater.. I mean it blew air and all... wasn't worth much. Had to have an ice scraper for the INSIDE of my windshield.
     
  10. Jan 10, 2019
    PeteL

    PeteL Member Sponsor 2019 Sponsor

    Hills of NH
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    (y) :rofl:

    Been there. In winter I would drive with the windows open so my breath didn't ice up the w/s on the inside.

    My answer to feeble jeep heaters has always been to simply dress warm. No big deal.
     
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  11. Jan 10, 2019
    3b a runnin

    3b a runnin Sponsor Sponsor

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    In the cj5, 360 has a 180* tstat. Temp runs about 160-170 in cold weather, but inside of windshield stays fogged almost constantly. Factory heater
    In the cj6, 225 oddfire, has a 180* tstat, temp runs about 150-160 in cold weather, but windshield clears up rather well. It has an aftermarket heater.
     
  12. Jan 10, 2019
    colojeepguy

    colojeepguy Colorado Springs Sponsor 2019 Sponsor

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    The V6 has a thermostat bypass hose.
     
  13. Jan 10, 2019
    tarry99

    tarry99 Member Sponsor

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    Close the grill up ...........been doing that for decades in cold Weather.........no way of bringing a motor up to operating temperature when it's 20-30 degrees ambient.
    I'll bet there's not a truck on the road in Wyoming in the Winter that does't use one.............I had one made for my Jeep years ago for hunting Colorado with snaps , that would allow for portions to be opened or closed.......it was still cold inside the Jeep , but that's cause your in a tin can!!...............if your still getting fresh air from the outside....it will never work in cold weather.......need to recirculate already heated air from within the cockpit...

    [​IMG]
     
  14. Jan 10, 2019
    Renegade ll

    Renegade ll Member

    Thayne Wyoming
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    Thanks guy's. Why is there a thermostat bypass hose. You would think that would defeat the purpose of the engine getting hot then the thermostat opening up. What would be the result of blocking the bypass off?
     
  15. Jan 10, 2019
    timgr

    timgr Jeepin' Nerd Sponsor 2019 Sponsor

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    As I recall, the bypass hose allows coolant to recirculate through the engine when the thermostat is closed. When the stat opens, coolant flows through the radiator too. Pretty sure there's nothing blocking the bypass when the stat is open; the radiator just becomes the path of least resistance. In theory, the bypass path can only make the coolant hotter, since it bypasses the radiator. You could block the bypass once the stat is open, and that might provide marginally better cooling. Not sure what would happen if you block the bypass when the engine is cold - there would be a lot of churning with no flow through the engine.
     
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  16. Jan 10, 2019
    Jw60

    Jw60 Recovering Jeepaholic

    Sedalia MO.
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    You need some movement of the fluid across the thermostat or it will not get hot coolant from the engine to open. Some engines have an internal passage, some use the heater hoses, and as colojeepguy reminded the buicks have a dedicated hose. The bypass also allows fluid to travel within the engine without pulling cold water from the radiator into the block.
    Edited for clarity. Thank you 45es
     
    Last edited: Jan 10, 2019
  17. Jan 10, 2019
    Renegade ll

    Renegade ll Member

    Thayne Wyoming
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    Copy thanks. Cardboard in front of radiator.
     
  18. Jan 10, 2019
    colojeepguy

    colojeepguy Colorado Springs Sponsor 2019 Sponsor

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    If you paint the cardboard black, it looks a lot less hokey ;)
     
  19. Jan 10, 2019
    45es

    45es Sponsor Sponsor

    Naches, WA
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    Just for the sake of clarity, what Jw60 and others have stated, that the bypass allows for coolant flow within the engine during warm up and before the thermostat opens is correct. What needs clarifying is the last sentence of the above paragraph. The bypass allows fluid to travel within the engine since the pump is pulling water from the BYPASS and returning it to the block. The pump pulls water from the radiator only after the thermostat has opened.
     
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  20. Jan 10, 2019
    PeteL

    PeteL Member Sponsor 2019 Sponsor

    Hills of NH
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    F-heads have a bypass hose to the head, but it seems many people run without them. :shrug:
     

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