Heater core replacement- Jeez!

Discussion in 'Lounge' started by beerbelly, Mar 22, 2022.

  1. beerbelly

    beerbelly In Maximum Overdrive SILVER MEMBER

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    So I rebuilt my heater box a few years ago; the box had been busted by the previous owner, so I patched it with fiberglass and added a new foam seal kit. I also pressure tested the core, and it held pressure fine- until it didn't a couple days ago. Ordered a new core from Summit; got here in 2 days! Those guys are awesome.
    Just buttoned it up, with new heater hoses, took it for a test drive, and it's good as new. But this is not a job a 71 year old guy wants to do very often! It's nothing but heat pad/sunny deck/iPod/brewski time now.

    But knowing I was still able to fix that old Ranchero made me smile. Love these old cars.
     
  2. Clark

    Clark In Maximum Overdrive

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    I got tired of replacing heat cores in my '75 GT. Following my boss's suggestion I tried a 6 psi radiator cap instead of the usual 14 psi cap and NO MORE heater core failures! The 460 ran cool enough even at idle with the A/C on BUT I did have to install a much larger coolant recovery tank. Ok, had installed a 3-row copper radiator but still I was amazed that it ran cool enough anyway with a 6 psi cap.
     
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  3. beerbelly

    beerbelly In Maximum Overdrive SILVER MEMBER

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    Interesting Clark; tell me more, especially coolant recovery tank size. I have a large capacity Cold Case radiator with a 1 quart recovery tank.
     
    Last edited: Mar 24, 2022
  4. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    13 PSI is factory pressure. I've only had failures in the radiator or the heater core when I didn't keep up on maintenance. That came to light when I had to replace the radiator back when I pulled and resealed Babe's engine. I think the last heater core failure was long before I started wrenching for a living. Same for the water pump, for which both were in my '78 Malibu.
     
  5. beerbelly

    beerbelly In Maximum Overdrive SILVER MEMBER

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    My Cold Case calls for a 16 lb. cap, but RockAuto's 1965 289 listings all say 7 lb., lending credence to Clark's statement:

    Screen Shot 2022-03-22 at 5.50.13 PM.png
     
    Last edited: Mar 22, 2022
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  6. beerbelly

    beerbelly In Maximum Overdrive SILVER MEMBER

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    Weird; when I search RockAuto for the same engine in a 1965 Mustang or Falcon, they show 13 lb. caps. Odds are 13 lb. is correct, but I ca't find the spec in my shop manual.
    Screen Shot 2022-03-23 at 5.21.28 AM.png
    Screen Shot 2022-03-23 at 5.25.24 AM.png
     
  7. pmrphil

    pmrphil In Maximum Overdrive GOLD MEMBER

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    Hell, NO pressure still works, albeit not quite as well. The pressure in the cooling system keeps the coolant from developing "pockets" or hot spots in the engine. The higher the pressure, the higher the boiling point of the coolant. It's that simple. I believe it's approximately 3 degrees for every pound of pressure. Big whoop. Water boils at 212 degrees or so, and that makes a 16 lb. cap capable of reaching 260 degrees before boiling. A 7 lb. cap will get you to over 230 degrees. Ya really wanna run your stuff over 210 anyway? That's where the big reserve (overflow) tank comes into play, along with a recovery style cap. I run 7 to 9 lbs. in all my stuff with no issues.
     
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  8. beerbelly

    beerbelly In Maximum Overdrive SILVER MEMBER

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    Thanks Phil, good to know. I'm wondering if the 16 lb. cap contributed to the core failure like Clark said.
     
  9. Hillbilly

    Hillbilly In Maximum Overdrive

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    I would bet the higher pressure cap was the main cause of failure.
     
  10. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Pressure higher than recommended, very likely. But recommended pressure, only if something compromised it, and poor parts build quality is part of that. Phil's point that higher pressure prevents steam pockets is correct; it also ties in with 'cavitation,' the formation of bubbles in a high-velocity fluid. If you pull a bad water pump, and you see damage to what the pump was mounted to (except in certain designs), directly behind the shaft end, that is cavitation damage. You not only need the proper pressure, you also need the proper coolant-to-water ratio, because the coolant has additives that changes the water's physical properties, to stave off freezing, boiling over, corrosion and cavitation.
     
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  11. pmrphil

    pmrphil In Maximum Overdrive GOLD MEMBER

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    yup, I'd say probably so.
     
  12. plumcolr

    plumcolr In Maximum Overdrive SILVER MEMBER

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    Found on the 'net:

    [​IMG]
     
  13. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    The image didn't come through.
     
  14. plumcolr

    plumcolr In Maximum Overdrive SILVER MEMBER

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    Basically says water, 212@0 lb, 233@8, 242@12, 252@16. Add about 15 degrees to those numbers for a 50/50 mix.
     
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  15. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    And why you *never* open a hot cooling system. Ask my right arm and torso about it.
     
  16. plumcolr

    plumcolr In Maximum Overdrive SILVER MEMBER

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    Used ta be the old guy would warn you, hand you a rag if he was being nice, or let ya learn the "hard way" if he was in a bad mood or you were a slow learner. Ask me how I know.
     
  17. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Ouch. What'd you do, or not do, to not get the rag?
     
  18. plumcolr

    plumcolr In Maximum Overdrive SILVER MEMBER

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    Hard-headed in general. Teenage know-it-all. nineteenfiftymumble. PS: well-deserved, now that I'm the old guy.
     
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  19. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    "Nineteenfiftymumble." I'll have to steal that, pretend like I made it up.
     
  20. Clark

    Clark In Maximum Overdrive

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    Stainless steel overflow tank for my '75 GT. Of course there is lots of room under the hood of a '75 Ranchero.

    [​IMG]

    [​IMG]
     
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