Unclogging Heater Core?

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

  1. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    With a 180*, it'll be hot, but you won't need to let go immediately. But if you go down in temperature, it'll play havoc with the temperature from the core, even if it isn't plugged.
     
  2. colnago

    colnago In Overdrive

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    Well, I'm stumped again. The system did have a thermostat, which I replaced. Both old and new thermostats passed the "boiling water on the stove" test; they opened up around 185, and closed around 165. The hoses got hot as above, but the heater didn't. So now I'm down to two possibilities: either (1) the PO bypassed the heater core, or (2) the water pump isn't pumping anything through the heater core.

    Any other ideas?

    Joseph

    On edit, I don't think the heater core was bypassed, because the "out" line is not as hot as the "in" line, and I know the heater core isn't clogged.
     
    Last edited: Jan 27, 2019
  3. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    I think there's one point you're missing: heater cores will bypass hot water when plugged. If you look at a core's top tank, it's not sectioned, so when the hot coolant hits the crud, it just follows the path of least resistance. I think you need a core. Hell, Babe's put out good heat for its age, but when I went to remove the hose from the control valve, the whole nipple just 'popped' off the tank. Having an old core may be an invitation to a disaster; had that nipple waited until after I finished all of Babe's engine work, it could've made my efforts all for nothing.
     
  4. colnago

    colnago In Overdrive

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    I am by no means discounting this as a possibility. But if this were the case, wouldn't the line going back to the water pump be warmer? Maybe not as warm as the line to the core, but closer in temps? Heck, it's possible that I have two issues: a blockage at the water pump, and a clogged heater core.

    You are correct, though, that I stated above that the core was not clogged. The top could definitely be clear, and the core itself plugged up, giving me the impression that the core is fine. Which puts me back to square one. It's a good thing that spring is around the corner!

    In other news, my odometer stopped progressing this weekend. Now it just makes a clicking sound. So the speedometer needle is going crazy. I just ordered a new unit from Scott Drake, so hopefully he does good work. Swapping the new unit in will probably keep me busy for an afternoon.

    Joseph
     
  5. Basstrix

    Basstrix In Maximum Overdrive BRONZE MEMBER

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    Is it possible that the door under the dash is not routing air over the heater core? If you're convinced air is blowing over the heater core, the next step I'd take would be to remove the return line and place it in a catch bucket and have someone start the engine to see if you're pumping fluid.
     
  6. beerbelly

    beerbelly In Maximum Overdrive SILVER MEMBER

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    Maybe early on this has been done/discussed, but here's my take:
    I'd avoid disconnecting the heater hoses at the heater box inside the car. It's tough & messy to do, since the connections are inside the car.
    It seems to me you could diagnose the water pump issue by disconnecting the heater hose going to the core at the water pump outlet; if you get a good flow of water when you turn the engine over, that would tell me the pumps is OK. If not, something is snafu in the pump or cooling system.
    Then, re-connect that hose and disconnect the return heater hose at the intake. With the heater control at full open, turn the engine over again, and see if you get any water out. If not, the core is most likely plugged. If you do get water, then I'd start looking at the control cables and the attachments at the heater box.

    The other option if the funds & time are available is just bite the bullet and get a new pump, heater core, hoses and a heater box seal kit. Been there, done that. Then you know all is good and you can move on to whatever the next issue these old cars always have!

    IMG_7062.JPG IMG_7068.JPG IMG_7114.JPG
     
  7. colnago

    colnago In Overdrive

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    I'm not 100% sure it is blowing over the core. I know it is blowing. I know water flowed through the two lines going to the core when I stuck a water hose to each end. I know the water pump was pretty grucky where the hose attached. I know there is some sort of sediment in the cooling system, because I took off the water neck to check/replace the thermostat. The rest is speculation. The core may very well be plugged, with only the top able to channel water. Or, the PO may have bypassed the core, and just ran a hose through the firewall. But if this were the case, then the temps along the two heater hoses would be more universal, and there wouldn't be any gruck at the water pump (it's almost like the water/coolant had pooled there, stagnated, and started to mold).

    So the flow is FROM the water pump, through the core, and back TO the intake? If that's the case, then the water pump is the problem. I was assuming that flow was in the opposite direction (I'll pull out my manual tonight and verify direction of flow). The hose between the heater core and the intake manifold is warm (cool enough to hold, but warmer than when the engine is off). The hose between the water pump and core is cool, except for the last foot by the firewall where it gets close to the engine/exhaust manifold.

    Pretty sexy heater box (well, as sexy as a heater box can be, anyway).

    Joseph
     
  8. beerbelly

    beerbelly In Maximum Overdrive SILVER MEMBER

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    My bad Colnago; I just checked my manual, and the hoses are opposite of what I told you. TO the heater from the intake, FROM the heater to the pump. But same theory applies.
     
  9. colnago

    colnago In Overdrive

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    Ah, well, I found one legit diagram on Google. It also said the coolant flow is intake -> heater core -> water pump. I'm still suspicious of the water pump, though, since it looks like I have a spot where it seems to have stagnated. I suppose that could be from air in the line; though - there just isn't anything to pump, so it just thrashes the coolant that's in that one spot. The line between the core and the pump goes over to the fender, then back down to the pump. Could it be a gravity thing, where an air bubble is being created in the line because it's higher than the top of the engine? If that's all it is, then it will be really easy to re-route the hose.

    Joseph
     
  10. Basstrix

    Basstrix In Maximum Overdrive BRONZE MEMBER

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    Are you able to run water into the port on the water pump (to check it for blockage)? If the top radiator hose is flowing water when the t-stat is open, the water pump is pumping. The supply port for heater core is fed by the same pressure that pushes water through the top heater hose. At this point, you need to know if the port at water pump is plugged and/or if air is blowing over the heater core.
     
  11. colnago

    colnago In Overdrive

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    Well, I do know that the water pump is pumping. It's keeping the engine temps in check (my temp gauge is ~1/3 of the scale), and the hose at the top of the radiator is toasty after a drive. I just looked at the return hose from the heater core. It comes from the heater core, under the diagonal support, then along the top of the inner fender before dropping back down to the water pump. I'm wondering now if there could be a huge air bubble in that upper hose (since there's probably a two-foot section of the hose that's above the top of the engine), and that's causing that circuit of the water pump to cavitate since it doesn't have any fluid to pump. I'm speculating here, but IF I have a huge air bubble, and IF I lower the hose to remove the trapped air, then maybe I will get the heater circuit to start pumping. Assuming there are no restrictions, will the water pump be able to push coolant into the heater core, or does it pull coolant from the heater core? Or does it need to do both?

    In answer to your question, I have not checked to see if I can pour water into the port on the water pump.

    Joseph
     
  12. Basstrix

    Basstrix In Maximum Overdrive BRONZE MEMBER

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    The pump pushes water into the block, where it passes through the block and into the heads then to the front of the intake manifold. Once the t-stat opens, it flows through the upper radiator hose.

    The pump is a centrifugal type and is better at pushing fluid than pulling, so the suction at the water pump may not be significant.

    I am doubtful that you have an air pocket, but it's easy enough to check. Running the hose into a bucket and cranking up the engine for a moment will tell you right away whether or not that's the cause.
     
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  13. colnago

    colnago In Overdrive

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    You make it sound too easy! Run the one hose into a bucket, hook another hose with a funnel to the water pump, and fill it up with gin. Whatever doesn't move is where my problem is. If they both move, then it's the core itself. Easy-peasy. I probably won't find the time until Saturday, though.

    Thanks for the tips!

    Joseph
     
  14. colnago

    colnago In Overdrive

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    I got it! I figured it was a blockage at the water pump, so I disconnected the heater hose, stuck a screwdriver into the water pump, pushed gently ... and suddenly had coolant all over me! I'm not sure how sediment could have started collecting in that particular spot, but it did. Maybe it was algae from the PO using water instead of coolant.

    Anyway, the heater works ... just in time for spring.

    Joseph
     
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  15. Basstrix

    Basstrix In Maximum Overdrive BRONZE MEMBER

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    Great news and glad you got it solved.
     
  16. beerbelly

    beerbelly In Maximum Overdrive SILVER MEMBER

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    Great! I wonder if it was some kind of stop-leak gunk?
     
  17. colnago

    colnago In Overdrive

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    Probably. Which means I'll have another clog to deal with sometime in the future. :rolleyes:

    Joseph
     
  18. TestDummy

    TestDummy In Maximum Overdrive SILVER MEMBER

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    And yet another car problem solved on Ranchero.US!!! Or is this the first one?
     
  19. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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  20. colnago

    colnago In Overdrive

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    The first? For me? Not even close!

    Joseph
     

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