Unclogging Heater Core?

Discussion in 'Ranchero Tech Help' started by colnago, Jan 6, 2019.

  1. colnago

    colnago In Fourth Gear

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    Bottom line, my heater doesn't ever get warm, no matter what. This is in my '64. No matter how I adjust the valve, the lines to/from do not get any harder. I figure that there's most likely some obstruction. Is there any good way to flush out the lines? Am I missing something else that I should check?

    Joseph
     
  2. kaytbugsdad

    kaytbugsdad In Second Gear

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    I would unhook both hoses from the heater core and see if you can get water through it with a garden hose...…. Use low pressure to make sure you don't blow the heater core apart, just in case there is some kind of blockage in there...…. If it's the original one, I would look into replacing it.....
     
  3. Huevos

    Huevos In Maximum Overdrive

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    How does the radiator look?
     
  4. colnago

    colnago In Fourth Gear

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    Unhooking the hoses is probably what it's going to take, but it's going to be a real PITA. The hoses go through the bulkhead, and connect to the heater core behind the heater assembly. I'll probably start by disconnecting at the engine, and see if there is a blockage. It won't tell me where the blockage is, just whether there is a blockage or not.

    The radiator looks pretty clean. I did drain the system, because the PO only had water in there, and I filled it with the 50/50 pre-mix. I expect that if there was just water, it was probably from the garden hose, not distilled. I suppose this may mean that there's corrosion that has created a blockage.

    This morning, I was wondering if this could be caused by not having a thermostat installed (I don't know if there is one, or not; this is just speculation on my part). So, the water is taking the path of least resistance, and bypassing the heater core, maybe? Is there any way to see if the coolant is flowing at all? Maybe run the engine with no radiator cap, and seeing coolant flow? I'm just grasping at ideas.

    Joseph
     
  5. plumcolr

    plumcolr In Maximum Overdrive SILVER MEMBER

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    Is the upper radiator hose getting more than warm? Is the temp gauge showing anything? Should go about half way. You could block the radiator airflow with cardboard and see if temp climbs. Just don't leave it blocked too long.
     
  6. colnago

    colnago In Fourth Gear

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    Location:
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    I'll check the radiator hose tonight, after I get home. The temp gauge is probably 1/4 - 1/3, when I think to check. I've never seen it climb too high, but then I just mostly putter around town. I also haven't seen it ever drop, like when the thermostat first opens. My morning/evening commute is only ~7 miles, and it's all in-town, so it never has a chance to get too warm.

    Joseph
     
  7. cbolt

    cbolt In Overdrive SILVER MEMBER

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    With the engine at operating temp you should be able to feel the hoses for warmth, both to and from the heater core. That way you will know if water is indeed flowing both to and from, and know if you have blockage or not. If one side is warm and the other cold I would say blockage.
     
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  8. Clark

    Clark In Maximum Overdrive

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    So replace the heater core! I don't think they are that difficult to change in a '64.
     
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  9. colnago

    colnago In Fourth Gear

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    Location:
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    When I did it in my '67, the manufacturer had changed the design just enough that it wouldn't fit properly in the brackets. So I had to shim here, trim there, and spend the afternoon swearing at it while standing on my head working under the dash. With the '64, I have lines coming through the bulkhead and into the cab area, nearly guaranteeing that I will get radiator fluid all over my fairly new carpeting. And there's no guarantee that anything is wrong with the heater core itself.

    Joseph
     
  10. TestDummy

    TestDummy In Maximum Overdrive SILVER MEMBER

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    A compelling argument. Is there a valve in the line somewhere? A few cars have them to keep the hot water out of the cabin in the summer months.
     
  11. Basstrix

    Basstrix In Maximum Overdrive BRONZE MEMBER

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    Have you removed the valve to verify that it is opening?

    Also, if you have an old-school radiator shop in your area, they can rebuild your heater core (if you're concerned about it not being a fully compatible replacement). My first job out of high school was at a shop that included radiator work....they had bulk "core" material and would simply unsolder the end caps and solder them onto the new core.
     
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  12. TestDummy

    TestDummy In Maximum Overdrive SILVER MEMBER

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    Could be as simple as a vacuum leak, assuming it has a valve,...and it's vacuum operated not linkage. I have no idea.
     
  13. colnago

    colnago In Fourth Gear

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    I haven't pulled the valve (it's on the firewall side of the heater box, under the dash), although I verified that the cable was hooked up and moving a lever. I think my best course right now is to take cbolt's advise, and feel my hoses (man, that sounds kinky). I'm afraid that I will have to pull it all out. If it's blocked, it's blocked, and it doesn't really matter where. It's still gotta come out in order to clear it.

    The '64 has the chrome levers that are mounted low on the dash, and move up and down. I verified that all of the cables are connected, and moving their proper mechanisms.

    Joseph
     
  14. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Just because the cable moves the arm, does not mean the arm moves the flapper. You can disconnect from the engine as easily as from the core, and if you blow air from your lungs through each of the heater hoses, you'll instantly know if there's a blockage. As for the t-stat, a short trip will never heat up the coolant enough to open the t-stat, but heated coolant will always move through the heater core.
     
  15. cbolt

    cbolt In Overdrive SILVER MEMBER

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    If you drain the radiator and disconnect the heater lines at the bulkhead you should be able to prevent coolant from getting on your new carpet. Most heater cores I have replaced have the inlet and outlet fittings protruding through the firewall. Once you unclamp the hoses from the heater core fittings the lines can be elevated, keeping fluid from draining out. Then you undo the heater box bolts and tip the box containing the heater core forward which will keep the remaining coolant in the heater core during removal. If the system is drained the residual coolant remaining in the heater core should be minimal.

    Another method that comes to mind is to push coolant through the heater core using compressed air into one of heater hoses. If you disconnect the lines at the engine and force air into one side the coolant in the heater core should be forced out the other heater hose, provided there isn't too much blockage. This may be a bad idea if your core is indeed blocked... the compressed air may cause the core to rupture and spill coolant into the cab. I have never had a need to do this, but maybe you want to give it a go.

    Finally, rubber mats, towels, and plenty of paper towels placed inside the cab should prevent your new carpet from getting coolant soaked. A good wet/dry shop vac will remove any coolant you may spill.

    I have done enough heater cores to know it can be done without flooding the interior with coolant. I just hate the standing on my head up under the dash part.
     
  16. DJ Clinton

    DJ Clinton In Second Gear

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    The '64 doesn't have a valve in the coolant line. It uses a flapper to control the amount of air going over the core. I would check for blockage first. If no blockage, the flapper may have come loose from the control arm in the heater box.
     
  17. colnago

    colnago In Fourth Gear

    Messages:
    324
    Location:
    Ridgecrest, CA
    "If you drain the radiator and disconnect the heater lines at the bulkhead you should be able to prevent coolant from getting on your new carpet. Most heater cores I have replaced have the inlet and outlet fittings protruding through the firewall. Once you unclamp the hoses from the heater core fittings the lines can be elevated, keeping fluid from draining out. Then you undo the heater box bolts and tip the box containing the heater core forward which will keep the remaining coolant in the heater core during removal. If the system is drained the residual coolant remaining in the heater core should be minimal."

    That's how my truck was. That isn't how my '64 is. The lines go through the bulkhead, and connect to the heater core inside the passenger compartment (unless the PO put it together wrong).

    "The '64 doesn't have a valve in the coolant line. It uses a flapper to control the amount of air going over the core."

    Very interesting. I know two of the knobs control flappers (one for the defroster, one for a flapper inside the box (but I don't know what it does)), but I thought the last would be controlling a valve. This is how my truck works. The valve is in the engine compartment, by the passenger fender. I'll have to pull out my shop manual tonight, and see how it's all put together. It's kind of surprising how primitive these older cars are.

    Joseph
     
  18. colnago

    colnago In Fourth Gear

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    Location:
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  19. colnago

    colnago In Fourth Gear

    Messages:
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    Location:
    Ridgecrest, CA
    When I got home tonight, the hose between the block and the core was warm, but the hose between the core and the water pump was cool. So, I know there's blockage somewhere between the firewall entrance and exit. Rats! I also learned from those links I posted that the hoses are connected to the core within the passenger compartment. I have to disconnect them at the engine, then snake them into the cab.

    I guess I know what I'm doing this weekend. I bet it will be something stupid, too, like the PO forgot to take the plugs/caps off the core when he replaced it.

    Thanks for your pointers!

    Joseph
     
  20. 1979 RANCHERO GT

    1979 RANCHERO GT In Overdrive

    Messages:
    884
    These heaters are the same as 65-66 Mustangs. There is no valve, you mix hot and cold air for temp setting and you will get coolant on the carpet as the clamps are inside. The heater box must be removed and split open to change to core. After messing new cores, checking the flow rate, thermostats, switching hose connections, new heater box seals with one of my Mustangs with the same problem I gave up and don't use that car if heat is needed.
     

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