Edmunds Answers



  • MrShift@Edmunds 10/06/11 2:22 pm PST

    Gee with that much rust in the block (if you're sure that's what's going on) there's not much you can do externally I'm afraid. I suppose you could remove the thermostat, stick a garden hose in there and reverse flush the block and see what comes out, but I think that's only going to be a temporary fix (and a big mess).

    I think you can also buy a water filter to trap junk before it gets to the radiator, so you might look around for one of those.

  • thomis 10/06/11 3:12 pm PST

    Can you explain how to "back-flush" from the thermostat, that could possibly clear out the heater core?

  • MrShift@Edmunds 10/06/11 3:42 pm PST

    I doubt it. In fact, you should by-pass the heater by disconnecting the two hoses going to the core and then joining them with a tube that takes the place of the core. You can't really backflush through that tiny heater valve with any success.

    By "backflush" I mean in the opposite direction of normal coolant flow.

  • thomis 10/07/11 8:50 am PST

    Well, Auto Zone sells a backflush kit. I picked one up on my way home last night but I ended up not using it. A very helpful technician at Auto Zone told me to disconnect both hoses to the heater core, the inlet and outlet. It was easy to distinguish between the two because the inlet was hot when the vehicle was running. The heater core was clogged so the outlet was only warm. Anyways, I waited for it to cool then disconnected the two hoses. I took the spray nozzle of my garden hose and backflushed through the OUTLET hose and all kinds of gunk came flying out of the heater core, then clear water. I re-connected the hoses, started it up and let it run for a while. Heat restored.
    "In fact, you should by-pass the heater by disconnecting the two hoses going to the core and then joining them with a tube that takes the place of the core." NOT SURE HOW THIS WOULD HAVE SOLVED MY NO-HEAT PROBLEM MR SHIFTWRONG

  • MrShift@Edmunds 10/07/11 10:29 am PST

    Well first off I'm glad to hear you got your heat back---the reason I told you to bypass the heater core was because you have been working on the symptom, not the cure. The rust in your heater core came from your block, not vice-verse, so if you don't clean out the block first, then it will re-pollute the heater core and you'll be doing this dance again.

    But since you bought the kit (good move) and you're comfortable with the idea of back flushing, you should proceed and clean out the block.

    If I had not told you to bypass the core while cleaning out the block, all the junk from the block would have lodged in the core, possibly so much as to be incurable.

    I feel confident that what I told you to do was correct, not wrong at all.


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