Running too hot

General Discussion

  1. Tori

    Tori Well-Known Member

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    The new to me '71 RR w/ 318 , Auto, is running a bit too warm. Running around town..... even at a constant 45mph it was getting to 210-215 on an 85*-90* day.

    Here's what i know:
    - Has no fan shroud. (i know it needs one)
    - Has a skinny bladed flex fan
    - Has 13# radiator cap, that probably wasn't sealing.
    - Looking into radiator, veins i can see look great. Clean, and no mineral build up. Fins are in great shape, radiator overall looks very good.

    I pulled the thermostat, was a Gates 195*. I boiled it and watched it operate and at what temp it opened. Worked perfectly. I bought a new one, did the same test and while it operated the same, it clearly didn't open near as much as the Gates. I installed the new one looking for a different result and really saw no change.

    I've replaced the radiator cap with a new 16# cap. But have not run the car again since.
    I will check timing also but have a feeling it's probably not the cause. Engine starts well, and does not ping,.....

    Anyway, I'd like to get a fan shroud on it. Do they make reproductions? How do i measure to see which radiator i have ? Is it just a width measurement ?

    Also, looking at several cars this weekend at a local show, almost all of them were running fan clutches and steel blade fan. Would a 71 had a fan clutch ? I'd like to run one if it's recommended.
     
  2. polywideblock

    polywideblock FBBO Gold Member FBBO Gold Member

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    how long did it sit ? check your waterpunp the vanes corrode off
     
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    • Car Nut

      Car Nut Mopar Master FBBO Gold Member

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      Get a infrared thermometer and check it.
       
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      • 65RoadRacer

        65RoadRacer Well-Known Member

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        I'd start with a 180ยบ Thermostat in warmer climates. Something I have always done with any 'new to me' car is to have the radiator rodded out, replace the water pump (whether I think it needs it or not) and flush the cooling system (straight water until it runs clean) and replace hoses if they're shoddy. The only time I can remember overheating is when a water pump failed on me after 1600 miles (it was a name brand).

        Flex fans aren't all they're cracked up to be, the blades are supposed to 'straighten out' at higher speeds for less drag but unless you're racing that drag is minimal and not really worth the cost of the flex fan. If you're sticking with mechanical fans you should probably stick with the factory fan as it will be sufficient on a stock motor. Fan clutches, when working properly, will 'free wheel' when the engine is cold to allow the engine to warm up quicker, then engages when it's warmer to 'lock in' the fan. I've seen fan clutches that failed - didn't lock up fan - and that also caused overheating, so I would get a new fan clutch just to be on the safe side.

        Just suggestions...
         
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        • 747mopar

          747mopar FBBO Gold Member FBBO Gold Member

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          Have you driven it at higher speeds for any length of time? Cruising down the freeway should tell you if the shroud will help although I don't argue that it definitely needs one it just doesn't do much at highway speeds. I'd suspect the pump, build up in water jackets, collapsed hose, lean fuel mixure or timing.

          As far as the thermostat goes, going cooler makes no sense. If you have a thermostat that opens at 195 and your car is getting up to 215 the cooling system isn't up to the task.
           
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          • Mike67

            Mike67 FBBO Gold Member FBBO Gold Member

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            There are many things you can check as posted here but it sounds like your problem to me is a fan without a shroud.
            If your fan is more than 2" from the rad, you are not going to pull enough air through it at low speed. JM .02.
            You can supplement with an electric pusher until you find a shroud...
             
            Last edited: Jun 19, 2017
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            • steve from staten island

              steve from staten island FBBO Gold Member FBBO Gold Member

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              I agree with Mike a fan shroud is necessary. Is your engine stock bore?
               
            • Bruzilla

              Bruzilla Well-Known Member

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              Mike67 is right on. :) Without a shroud, all your fan is doing is grabbing hot air from the engine bay and swirling it around. You're not getting full convective cooling from the radiator, which needs the fan to pull outside air through it to work, and you're not getting much in the way of direct cooling from the fan blowing on the engine.

              Get a shroud and you should be good to go.
               
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              • Ranger16

                Ranger16 Well-Known Member

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                • Zeppelin264

                  Zeppelin264 Well-Known Member

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                  Mancini makes reproduction fan shrouds.

                  I built one out of sheet metal myself and it made a big difference in the cooling driving around town.

                  That 16# cap will show if you have any weak spots in the hoses etc..
                   
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                  • Tori

                    Tori Well-Known Member

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                    I have. .........and check what, for what ?
                     
                  • Tori

                    Tori Well-Known Member

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                    Thanks for the links for shrouds. I'll call them and figure out which radiator i have and get one coming. That was the plan all along as i knew i needed one for optimum efficiency. I'll start there and see how it goes.

                    Thanks
                     
                  • Tori

                    Tori Well-Known Member

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                    Any tips on where to measure the radiator to figure out the size ? Measure just the core ? Measure to the flanges ?
                     
                  • Mike67

                    Mike67 FBBO Gold Member FBBO Gold Member

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                    Core should be what you need
                     
                  • Ski 61701

                    Ski 61701 Well-Known Member

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                    Have you checked your timing? If its waay retarded your motor will run hot, any motor will run warmer than normal. All of the suggestions people have given are very good and are needed for really efficient cooling. But since you just got it and want to play with your new toy a little try and advance your timing some and see if your temps come down. With the car running, see if a piece of paper will stick to front of radiator. If it does, you know youre pulling air through and focus on a good tune up. If the paper doesnt stick, focus on getting a proper fan clutch assy and shroud in addition to cleaning rad out and back flushing motor.
                    Try and get a thermal fan clutch set up for your car, they are the most efficient. The flex fan is a hp gobbler. Get on youtube and search engine fans and david finkbiner from hotrod and steve dulcich did a test of fans on a dyno. Very interesting viewing.
                     
                  • PurpleBeeper

                    PurpleBeeper Well-Known Member

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                    Point the IR gun at the thermostat housing to get a true temperature reading. Definitely add a fan shroud & I believe all you need to know (on a stock radiator) is 22" or 26" wide (you probably have a 22"). I "think" the clutch fans came out in '73, but don't quote me on that. New fan clutch for sure. Yep, swap the water pump (heck, they're like $35 only). Cooling system flush too (I had a "good looking" radiator what was plugged up). Also, maybe take off the radiator cap & warm up the engine to look inside the radiator for an occasional "big bubble" (head gasket). Radiator cap was a good idea (15lbs. stock I believe). And yes, distilled/deionized water + "water wetter" or similar runs cooler than 50/50, which reminds me, if you have 100% antifreeze (not 50/50) that can make a car run hot too, so pull out that little "floaty ball" or "floaty lever" hydrometer & check your coolant blend.
                     
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                    • green 66

                      green 66 FBBO Gold Member FBBO Gold Member

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                      Clutch fan (5 blade) and shroud-no problems for me
                       
                    • Tori

                      Tori Well-Known Member

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                      Anyone reading this have an extra stock fan you'd like to sell ?
                       
                    • Mike67

                      Mike67 FBBO Gold Member FBBO Gold Member

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                      I might have one at the shop...I dont know if I can make it by there before I leave on vac though...
                       
                    • Tori

                      Tori Well-Known Member

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                      I can wait Mike, The car is down right now for steering column repairs anyway, then we'll be out of town this weekend.. so i can wait a bit.