New to site, new to Mopar overheating issues

Small Block Mopar Engine

  1. moparmat2000

    moparmat2000 FABO Gold Member FABO Gold Member

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    A/C cars use a smaller water pump pulley for packaging everything on the front of the engine. As such, they use a different water pump based on the smaller pulley size to maintain a similar flow to the non A/C setup. This is done so both A/C and non A/C engines heat up and operate similarly regardless of A/C or not.

    If the stock pulley ratio is so badly matched that the cars ran hot with it, i doubt the factory ever would have used it. If he has an overheating problem speeding up the pump is a bandaid fix if theres something else going on there. Non A/C water pumps have 8 vanes because they spin a little slower. A/C car water pumps only have 6 vanes because they spin a little faster.

    It's a mild 340, not some fire breather. I still say if this thing has a properly reading gage that theres either 1 or 2 things going on. Either the radiator is partially blocked, or the thermostat is too high or sticking, or both.

    If these things are good, it could also have the wrong water pump for the pulley ratio. Looks like in the pix that the pump was recently replaced. If it's running a replacement 6 blade A/C pump sized with pulleys designed for the 8 bladed pump then theres your slow flow issue.

    Non mopar types and some mopar types go down that same rabbit hole thinking an A/C water pump must be heavy duty and must flow better because of the stresses on the engine of running the A/C. That's the furthest thing from the truth. Both pumps vanes are designed to flow similar numbers based on the pulley diameter it's designed to be matched to.

    Ok yellow rose He could throw some A/C pullies on there as a bandaid for a possible incorrect water pump if that's what's in there, and speed it up, that will certainly work. But then he will have to figure out a hacked up alternator bracket setup to keep the belts in line and tracking straight since his car is a NON A/C setup, and A/C pulleys have a different offset compared to what he has. This will throw the pulley alignment from the pump to the alternator off. Requiring some creative bracket making and washer stacks to get the alternator to line up. That my friend is what is called a HACK job.

    These cars ran around for years without overheating problems with these stock non A/C pullies. So what if he does all that your recommending and it ends up being a partially plugged radiator and he "reinvents the wheel" for nothing so to speak. All he did was a work around, a bandaid fix, and not really correct the problem. If the pump is incorrect for the pulley setup, it's much easier and less aggravating to just change the pump out for the correct one. Ditto if it's a plugged radiator.

    D's Nuts and Bolts , i recommend to have the radiator checked and boiled out, make sure the thermostat is a 180° and it's got a new radiator cap since this is the easiest and most common places where there will be an issue. If it still runs hot, remove and check the water pump to see how many blades are on the pump. 8 blade pump for non A/C pullies is what you should have. If you have a 6 blade pump, its incorrect and will cause it to run hot.
     
    Last edited: Jul 23, 2020
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    • cudamark

      cudamark Well-Known Member

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      It’s not complicated. The OP is down on flow somewhere. Speeding up the coolant is never bad.

      That's not always true. I've seen many cars that had too much flow causing an overheat problem. Running straight antifreeze can cause overheating too. The proper mix of coolant needs to take a certain amount of time in the radiator to transfer heat to the tubes and fins. If the coolant moves too quickly through the radiator, that doesn't happen and the coolant is back inside the engine before it cools properly. (removing the thermostat altogether can cause that) You can also get cavitation in the pump if it churns the coolant too fast. That's why the A/C cars used a smaller pulley with only a 6 vane pump. The 8 vane on that smaller diameter pulley made too much flow in some cases. I know, there will be many on here that will say they've done it without problems, and that may be true in their particular application, but, it's not always true in others. There were lots of pulley combinations and different capacity coolant systems with different flow characteristics to make a blanket statement that applies to them all.
       
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      • D's Nuts and Bolts

        D's Nuts and Bolts Active Member

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        The radiator? It measures 22"s x 3.5 wide
         
      • cudamark

        cudamark Well-Known Member

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        How many rows of tubes does it have?
         
      • moparmat2000

        moparmat2000 FABO Gold Member FABO Gold Member

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        It's a correct sized V8 radiator for a 67-69 A body. If it's a 2 row core radiator and your radiator shop says the core is shot, then see if they can recore it with a 3 row core. Some places call em "desert coolers".
         
        Last edited: Jul 23, 2020
      • D's Nuts and Bolts

        D's Nuts and Bolts Active Member

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        Thank you Thank you! So the non A/C cars had a larger pulley with the 8 blade pump. I should probably still get a better fan though it sounds like, possibly with a fan clutch. I'll check the thermostat and replace the cap.
         
      • moparmat2000

        moparmat2000 FABO Gold Member FABO Gold Member

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        Yes. The larger non A/C pullies required an 8 bladed pump. I have an aftermarket flexalite 6 bladed 18" diameter fan that's made for a clutch. You can use a stock depth fan clutch for an A body V8 car with your copper/ brass radiator. Should you decide to put a thicker aluminum radiator you will need a shorter fan clutch. The Hayden 1990 jaguar XJ6 fan clutch is shorter and is a direct bolt on. It comes with a centering bushing so it can center on a mopar water pump. It uses SAE thread holes to mount the fan. Hayden also makes a shorty mopar muscle car fan clutch for cars with aluminum radiators that's a little shorter than even the jaguar one and is of a heavier duty design.
         
        Last edited: Jul 23, 2020
      • yellow rose

        yellow rose Overnight Sensation

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        The “it overheated because the coolant flow was too fast” is as wrong as setting power valve opening based on idle vacuum. It was wrong when it was first said, it’s wrong now, and it will continue to be wrong.

        I realize the OP isn’t running a fire breathing anything. So I wouldn’t correct the pulleys. What he has isn’t OE. Go back to OE everything because that worked 50 years ago. When fuel was better, when the OE tune up wasn’t changed or anything else.
         
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        • moparmat2000

          moparmat2000 FABO Gold Member FABO Gold Member

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          If he has a 6 bladed "AC" pump on a car with non AC pullies theres the slow flow problem. Providing that the radiator doesnt have a partial clog, the easiest way to correct that issue is to put the correct 8 blade pump on.

          I have seen people put 8 bladed non AC pumps on cars with AC to run the coolant thru faster. But putting an AC pump on a non AC engine works completely opposite.
           
        • moparmat2000

          moparmat2000 FABO Gold Member FABO Gold Member

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          Ok yellow rose So it has a 70 up water pump, alternator brackets, and radiator based on the look of the pump and inlet outlet locations on the radiator. It has 67-69 non A/C water pump pulley and crank pulley. Regardless how this was put together it has "Factory" 67-69 NON AC diameter pulleys, and as such it requires a NON AC water pump.

          I said nothing about OE tune, fuel, etc. You did. What I do know is the stock pulley ratio he has is non A/C, it needs a non A/C 8 bladed pump weather it's running a correct 67-69 style pump or a non correct 70 up pump does not matter. The pulley diameters on a non AC 67-69 small block are the same diameter or extremely close as a 70 up non AC small block, and what matters is enough flow right?

          67-69 non A/C cast iron water pump 8 vane impeller
          70 up non A/C cast aluminum pump 8 vane impeller

          Only difference between the 2 pumps is casting design with outlet location, and material used. Both are 8 vane pumps. So regardless of what year the different pieces are the pump needs to be sized to the pulleys being used on the engine.
           
          Last edited: Jul 23, 2020
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          • yellow rose

            yellow rose Overnight Sensation

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            Geeeesus. When I get to pick the cooling system, I pick an high flow pump and speed it up.

            Again, the OP has a FLOW problem. Why you keep arguing it makes no sense.
             
          • D's Nuts and Bolts

            D's Nuts and Bolts Active Member

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            The casting # is
            2780930 340-3 – 1968-1973, 340 LA-series small-block, Not T/A or AAR

            Yes unfortunately the guy I bought it from know nothing about the car, I contacted the guy he bought it from (another dealer) and he doesn't know anything either. Honestly, it's a good car, but I missed several things while looking it over. Missing kick down cable/linkage, dash lights don't work, radio, heater didn't work (fixed heater), they had the transmission fluid way too full, and obviously the over heating issue. Granted some of the stuff you can't spot or don't think to look. Happy with the car just kind of pissed the guy wasn't fully truthful.
             
          • moparmat2000

            moparmat2000 FABO Gold Member FABO Gold Member

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            I am arguing it because your the one who mentioned swapping out the pulleys, and all the other BS. It may have the wrong sized pump making the flow too slow.
             
          • moparmat2000

            moparmat2000 FABO Gold Member FABO Gold Member

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            D's Nuts and Bolts when you get this figured out please let us all know what you find in regards to this issue. I am curious to how close I am to being right with what's wrong with this thing.
             
          • yellow rose

            yellow rose Overnight Sensation

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            This is right out of the 1973 Factory Service Manual. You can see for yourself what the factory did when it wanted max cooling. I always want max cooling. You can run more compression, less jet, full timing and more IF you control the temp at 180 or a bit less. I use 170 for temp if I’m running a heater. Otherwise it’s 160. It won’t wear out quicker if you get the tune up correct. I want to be able to run the most compression as I can, on pump gas, and STILL me able to drive through downtown hell and not get hot.

            Some of this doesn’t apply to you, but really it does. The better you control coolant temp, the more forgiving everything is.

            The columns from left to right are 198-225-318-340

            182E55FB-8640-49DD-9F42-754E7681A901.jpeg
             
          • yellow rose

            yellow rose Overnight Sensation

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            I posted a picture right out of the FSM about water pump speed.
             
          • Demonic

            Demonic Well-Known Member

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            Welcome to the forum, D. Hard to tell from your pic, but is the inside of the radiator dirty if you drain it down a few inches? It looks somewhat rusty. Bad plan to have a fan on both sides, it just restricts air on the inlet. My rule of thumb is, the inside of the radiator is dirtier than you think. Flush it with Evaporust Thermocare for 3 days and rinse it 2-3 times after that. Follow the above advise regarding flow - start with a good high flow thermostat. They have an port size of about 1 3/8" or slightly better. Check the driver side mount carefully.

            About $15.- at Wally world. https://www.walmart.com/ip/Thermocu...R74kXNlqLEIhMSQ1EG3tiCnnzmMVOODUaAkbgEALw_wcB

            Does your car have a purple and white interior?
             
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            • D's Nuts and Bolts

              D's Nuts and Bolts Active Member

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              Thank you I will do that. Is the best place to get the thermo from Jegs/Summit etc. can't find the high flow at local places. The car unfortunately isn't a factory purple car, but the interior is white and the doors, jams, etc. have been painted purple. Actually haven't looked into the factory color yet.
               
            • D's Nuts and Bolts

              D's Nuts and Bolts Active Member

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              Is that chart saying that the pump pulley should be approximately 80% of the size of the crank pulley? I'll admit I'm in the weeds a bit, I've been out of working on cars for almost 15 years. Finally able to jump back in, but getting older and kids has my mind a bit foggy.
               
            • moparmat2000

              moparmat2000 FABO Gold Member FABO Gold Member

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              If I am reading this right your 340 standard cooling in the far right column and maximum cooling for non A/C are both 1.20:1 ratio. And the standard and maximum cooling for 340 with A/C are both 1.30:1 ratio. I fail to see where your going with this. Your FSM is stating that regular and heavy duty cooling without A/C both have the same identical 1.20:1 pulley ratio, and the regular and heavy duty cooling with A/C both have a different but identical to each other 1.30.1 A/C pulley ratio.

              Are you trying to compare this to a 318 pulley ratio? Not sure where your going with this? Plus this is a 73 FSM. You dont know what the pulley ratio on his car is. I know they are at least 67-69. Did the 68-69 340 use the same pulleys as a 68-69 318? If they are a 318 pulley ratio, weather its a 318 or 340 hes still gonna need the 8 vane pump.

              This shit is so fucking simple. Yellow rose your making it harder for this guy than it really needs to be. It's either a partially plugged radiator, incorrect or sticking thermostat, or wrong water pump, or a combination of the 3. For most people there is no reason to go crazy with the pulley ratios. I never have on any small or big block cars I ever had. I never had any overheating problems either as long as I had the correct pump, a good thermostat, and a correctly sized and internally clean radiator. Oh I also know hot environments. I live in West Texas it feels like I am living in a fucking roasting pan 4 months out of the year from june thru september. Yesterday when I got in my daily driver to leave work at 3:30pm the outside air temp on the digital display in the dash said it was 110° F.

              D's Nuts and Bolts , if you find the pump is incorrect and need a water pump for your cuda, you will have to buy one for a 1970 up 340 because it uses a passenger side outlet. This is what your cuda has in it. Also spec it as an 8 vane non A/C
               
              Last edited: Jul 23, 2020
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              • moparmat2000

                moparmat2000 FABO Gold Member FABO Gold Member

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                Hang around here long enough and you will have it all fixed and working good. Pretty car by the way.
                 
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                • Wyrmrider

                  Wyrmrider Well-Known Member

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                  fans (and headlights) should be put on relays and not have power going through dash and ammeter, key or headlight switch
                   
                • yellow rose

                  yellow rose Overnight Sensation

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                  Exactly. And it LOOKS like he is UNDERDRIVING the pump. So if he’s fixing shit, why not FIX it?

                  TEXAS hard headedness isn’t helping you.

                  The OP needs to UNFUCK something someone else fucked up. For some reason, you want a half assed fix.
                   
                • moparmat2000

                  moparmat2000 FABO Gold Member FABO Gold Member

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                  Nope. Same could be said about you. I dont want a half assed fix. Do you know what his pulley ratio is? I can tell you the pulleys are 67-69. Did 68-69 318 and 340 use the same pulley ratio for non A/C ??? I am betting yes. As such it needs an 8 vane pump.

                  And you are comparing pulley ratios on a 73 318 and 340 to what exactly??? The pulleys on his car? Those are not 73 pulleys. Most likely a different ratio altogether. I told you what year to year I believe they are. Why dont you pull up that section in a 68 or 69 FSM and see if the 68-69 318 and 340 non A/C pulley ratios are the same or different. If they are the same, and I am betting they are then he isnt underdriving shit. Unless hes using an A/C style 6 vane pump.

                  Your the one comparing apples to oranges. Not me. What's the pulley ratio on a 68-69 318 and a 68-69 340 non A/C. That's what we are comparing. Not what's in the 1973 FSM which has no relavance to 1968-1969 pulleys which what he has.

                  Oh and while we are at it sizing the pump to fit the correct pulley ratio it belongs with isnt underdriving anything. Its sizing it up correctly. Add in a recored radiator with an extra row of tubes if a desert cooler core will fit the tanks. No overheating issues.
                   
                  Last edited: Jul 24, 2020
                • famous bob

                  famous bob mopar misfit

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                  Running down waren johnson----------------LOL on that one !
                   
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