273 overheating after new timing chain set and waterpump

Heating / Cooling / AC

  1. Wally-T

    Wally-T 64 Signet

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    Hi again guys. I had a problem last fall with overheating so I installed a new thermostat and it ran nice and cool again, under half on the temp gauge even in hot weather in heavy traffic.
    A couple of weeks ago I installed a new timing chain set, new manifold gaskets and a new water pump. Now it runs nice and cool on the highway and about half on the temp gauge in town but when I'm in traffic it moves 3/4 way up the gauge and would keep going if I didn't pop it into neutral and raise the rpm. I noticed that the old pump had a plastic impeller and the new one has a steel one. Does anyone know if the plastic impellers flow more water than the steel ones.
    Thanks again for all your help folks, I'm gaining much knowledge here. Wally
     
  2. Garrett Ellison

    Garrett Ellison Amateur driver on public roadway, do not imitate.. FABO Gold Member

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    Do you still have your old water pump and can you post some pictures of it if you do?
     
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    • Plymouth 65

      Plymouth 65 Floorable Deplorable

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      It depends on how many impeller veins there are. The plastic one I have has more veins than the stamped steel one I have. Cooling is about flow, typically more flow more cooling if everything else is functioning properly. 65'
       
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      • Rmoore

        Rmoore Well-Known Member

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        Sounds like your radiator maybe stopping up !! Is there a fan clutch on your motor ? Is there a fan shroud on your radiator ?
         
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        • Dartsun

          Dartsun Mopar Dude

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          My 273 did the same thing in traffic or waiting for a train even with a factory shroud. I replaced my original radiator with a champion aluminum one with no shroud and 0 over heating issues. A re-core I’m sure would’ve fixed my problem but was twice price.
           
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          • Wally-T

            Wally-T 64 Signet

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            I'll try to remember to take some pics tomorrow
             
          • Wally-T

            Wally-T 64 Signet

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            If memory serves me correctly, I do believe the plastic impeller had more veins. Bummer
             
          • Wally-T

            Wally-T 64 Signet

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            I've been thinking of getting a new rad anyway and it's easier than doing the water pump again. Thanks
             
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            • moparmat2000

              moparmat2000 FABO Gold Member FABO Gold Member

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              Theres 2 types of impellers. 6 blade and 8 blade.

              The 8 blade impellers are for non A/C cars because of a larger diameter water pump pulley that turns the pump slower. The 2 more blades is to increase the coolent volume because of the larger and slower turning pulley..

              The 6 blade impeller pump is for cars with A/C as the water pump pulley is a smaller diameter and turns the pump faster at the same given engine RPM.

              Metal or plastic bladed pump does not matter. What matters is you have a pump with the right number of blades or fins for the given pulley diameter and its subsequent pulley RPM.

              Putting a non A/C water pump (8 blade) on an A/C pulley equipped car helps increase coolent flow. Putting an A/C water pump (6 blade) on a non A/C pulley equipped car does the complete opposite and slows the coolent flow down further.

              Hope this helps.
              Matt
               
              Last edited: Jul 6, 2020
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              • SGBARRACUDA

                SGBARRACUDA ROY FABO Gold Member

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                My 69 Dart has the original 273 radiator in it with a 360 in it now with factory A/C. My car would do the same thing, cool great as long as I was moving, but slowly climb in temperature when I was at a red light. The radiator looked very clean but I pulled it out and took it to a old school radiator shop that removed the tanks and Rodded it out. Man what a difference, it cools in traffic even with the A/C on. The guy at the radiator shop did tell me it was pretty clogged up.
                 
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                • SGBARRACUDA

                  SGBARRACUDA ROY FABO Gold Member

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                  I forgot to mention that since my Dart was a factory A/C car, it did come with a three core radiator.
                   
                • RedFish

                  RedFish Well-Known Member

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                  Years ago, I replaced a broke slant 6 with a rebuilt 318 in our 1st 67 fish. On the interstate daily to work and back. Someone would screw up, I would get caught in slow traffic and over heat. Somwhat puzzled because the slant had never over heated. New radiator cured it.
                   
                • Wally-T

                  Wally-T 64 Signet

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                  I wish I'd been thinking more critically when I was putting it together. My car is non A/C and I'm pretty sure the new pump had fewer blades. If that's the case then it looks like I'm looking for the correct water pump or a smaller pulley. I bet you can guess which one I'd rather change lol.
                   
                • Wally-T

                  Wally-T 64 Signet

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                  Did these Valiant's come with a factory fan shroud? Mine doesn't have one on it.
                   
                • 69FBCuda

                  69FBCuda I'm so confused! FABO Gold Member

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                  Pictures would be a great start.
                  What does 1/2 or 3/4 equate to in Fahrenheit?
                  Is it actually over heating to the point of releasing pressure from the cap?
                  Have you temped it with a temp gun?
                  Have you looked into the radiator to see if there is circulation?(dont remove a hot cap please)

                  You live in Canada and you really think the pump is going to make that much of a difference.
                   
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                  • toolmanmike

                    toolmanmike Moderator Staff Member FABO Gold Member

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                    Exactly! It doesn't sound like it's overheating. That doesn't happen until the coolant boils out onto the street. Did you replace the thermostat? Sounds like it could be a bad cap not holding pressure.
                     
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                    • moparmat2000

                      moparmat2000 FABO Gold Member FABO Gold Member

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                      He stated engine was fine after a T stat change last year, and did not start getting real hot until "right after" he replaced the water pump. I am betting they sold him an A/C type 6 bladed pump. Y'all are shooting down the wrong snake hole. If it was a plugged radiator issue it would have gotten hot before and after the water pump change. It's getting hot only after the pump change. That is the only thing coolent related he changed right before this started to happen. Car is non A/C with the larger slower turning pulley, and probably has the wrong 6 bladed A/C pump on it. It's not flowing enough coolant for the impeller speed.

                      What year valiant?
                       
                      Last edited: Jul 7, 2020
                    • 69FBCuda

                      69FBCuda I'm so confused! FABO Gold Member

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                      Still curious what "real hot" equals in degrees? I run a $9 amazon reman here in Florida and during the summer 95+ degrees, headers, stopped at a light pavement is proly 120 and with a 195 thermo my sun gauge cycles between 190-200, you could set you watch by it!

                      Last fall? what 60 degrees? and your comparing that to the summer heat?

                      "I had a problem last fall with overheating so I installed a new thermostat and it ran nice and cool again, under half on the temp gauge even in hot weather in heavy traffic."
                       
                    • 67Dart273

                      67Dart273 FABO Gold Member FABO Gold Member

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                      Unless the new pump was made defective such as wrong impeller it doesn't matter if it's an AC or non AC pump. EITHER should cool that engine especially a 273. The same pump cools a 340!!!

                      Are you CERTAIN the problem started with a pump change only?
                       
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                      • SGBARRACUDA

                        SGBARRACUDA ROY FABO Gold Member

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                        You have to start with a clean radiator before you start applying bandaids.
                         
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                        • 67Dart273

                          67Dart273 FABO Gold Member FABO Gold Member

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                          Something else I'm sure happened to me:

                          Oldmanmopar has claimed that over time, the tubes can crack loose from the fins and lose heat transfer. The rad can flow lots of water and not radiate very much heat!!

                          My original 273 rad would not cool a 318 or 360. Rad shop claimed it would "cool anything." It is the factory 2 core. I finally swapped in a later 73-74 2 core slant six rad I had and the temp instantly dropped a LONG ways. I'm convinced the old rad suffered this fate
                           
                        • pishta

                          pishta I know I'm right....

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                          dd your new timing set advance your cam timing> Did the new set slide right on when you took the old set off or did you have to turn the cam to line it up? Id run a jug of rad cleaner through and see what comes out. You'd be suprised what that can break up and flush out.
                           
                        • MOPAROFFICIAL

                          MOPAROFFICIAL FABO Gold Member FABO Gold Member

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                          There must be 2 threads on this... or the other I answered last nite at 11 pm and it was deleted.

                          I said you may have swapped a 8 blade for a 6 blade....that explains the traffic overheating. Typically a cooling system that is adequately sized will not boil over at idle with the radiator cap off...so you might gather that the cap is not responsible for the overheating in traffic....the cap issue would show up at speed, higher heat and pressure from the pump and growing temps its fighting along with the radiator.

                          Is or was it an 6 blade and ...what is the new pump 8 or 6?
                           
                        • 69FBCuda

                          69FBCuda I'm so confused! FABO Gold Member

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                          "There must be 2 threads on this... or the other I answered last nite at 11 pm and it was deleted."

                          Was that before or after the 12 pack..........Just kidding
                           
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                          • Rmoore

                            Rmoore Well-Known Member

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                            could be brother !! When I it comes to automobiles anything is possible !! I’ll play the devil’s advocate here !! He has the right pump on there now !! New pump really works well ! Maybe to good to push the water thru the plugged up radiator lol !!
                             
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