Heater Core Flush for Dummies

Discussion in '60-Series Wagons' started by ColoradoLC, Mar 6, 2008.

  1. ColoradoLC

    ColoradoLC

    Messages:
    423
    Location:
    Centennial, CO
    So after reading up on several of the heater core threads, I decided I'd undertake this procedure to try and make the heat being generated from my heater a little hotter.

    Prior to this procedure, it was running about 95° from the front and rear heaters of my 1986 FJ60.

    Thanks to all of those that posted and helped in the other threads.

    NOTE: Due to the difference in hoses that have been used to replace the original hoses on your rig, as well as other changes that may have occurred, I recommend you confirm your setup before diving into this.

    Materials needed:
    1 gallon of muriatic acid
    Replacement screw clamps
    Extra coolant
    clear flexible hose (approximately 3 feet), I think I got 1.25" hose
    Bucket
    Funnel
    Flat head screwdriver
    Air compressor (optional) or bike tire pump

    Steps:
    1. The hose pointing up in the picture below is what you want to disconnect to feed the acid into the core. The hose below that, you will disconnect to drain out the coolant and acid. Facing from the front, these are on the firewall just to the left of my engine.
    [​IMG]

    2. Remove the retaining pin and pull down the hose on the upper hose, then unscrew the screw hose clamp on the lower hose as indicated in the picture below.
    [​IMG]

    3. At this point, attach the clear hose to the metal host insert and drop the lower end into your bucket under your rig. Initially, this will drain some coolant, then you'll blow even more out with your compressor or pump.

    Here are a couple of pictures of this:
    [​IMG]
    [​IMG]

    I stuffed a blue shop paper towel in the removed hose so coolant wouldn't drip out in case you were wondering what that is.

    4. At this point, put your funnel in the top hose and start pouring acid into it. Pour a little at a time so you can make sure it doesn't get everywhere since it is pretty reactive. You'll start to see or hear some bubbling coming from the outlet hose and it may start displacing brown liquid, which means it's working and removing deposits from the heater core.

    I have seen a post where someone had to park uphill to get the core filled, but mine was only on a slight incline so I don't know if this will make a huge difference. If you get done with this process and don't notice an increase in the temp blowing out, try it again on a hill, with the front of your rig pointing uphill.

    5. Once you have filled up the core and the liquid coming out is clear, it's time to drain it out. I had to tape my air compressor hose nozzle to the top of the hose (take the funnel out of course) so that acid didn't spray everywhere. Go lightly on the pressure and it should flush all of this out. I would recomment flushing with water, then add half and half water/coolant back into the top hose.

    6. After that started to come out the bottom hose, I attached both hoses with new screw hose clamps, rinsed everything off and started the engine.

    Depending on your results you may also want to park on an incline to burp the core of any air. You should only need to detach the upper hose to get this done.


    My temps are now a good bit hotter. I don't know the exact temperature, but for the first time, I've actually had to turn the heat down.

    One other thing that could have an impact with heating is the thermostat. I changed mine before attmpting this procedure and although I didn't see an increase in the temps, I did start getting warm air sooner (5 minutes as opposed to 20).

    I did not do this procedure for the rear heater, but if anyone wants to post steps for this with pics, I'll be glad to add it.

    Try this and let me know if you have any questions!

    Winston
    Last edited: Mar 7, 2008
  2. Jan-78FJ40

    Jan-78FJ40

    Messages:
    3,268
    sounds great, thank you!

    my only comment would be that I think rinsing with plenty amounts of water/coolant would be a good idea. Otherwise you will retain a good amount of hydrochloric acid in the system (despite blowing it out), and the pH of your coolant will be wayyyyy low, rendering it corrosive.
    I think you might want to check the pH of your coolant.

    cheers,
    jan
  3. If you're wondering how to do that, I get Ph strips from my local Carquest Auto Parts store for checking the diesels................


    a pool supply place may also have them.......................



    :beer:
  4. ColoradoLC

    ColoradoLC

    Messages:
    423
    Location:
    Centennial, CO
    Good call. I edited #5 to indicate that. I'm planning on doing it again this weekend to see if I can flush any more out of it, so I will take care of that then.

    I want to make this process referencable, so if you have any suggestions to improve the process I'm all about the kaizens.
  5. Zack1978

    Zack1978 SILVER Star

    Messages:
    2,617
    Does the process that you used isolate the heater caore so that no acid gets into any other part of the cooling system? Also how dirty did the acid come out? Did you dilute the acid?

    Thanks,
    Zack
  6. calphi27

    calphi27

    Messages:
    1,136
    Location:
    Denver
    Great write up and thanks!!! They only thing I would add is that you use distilled water for the final flush and use it again to mix with the coolant.
  7. ColoradoLC

    ColoradoLC

    Messages:
    423
    Location:
    Centennial, CO
    Yes, those two hoses only go through the firewall to the heater core.


    I did not flush at all the first time, but I am going to do it again this weekend for the second time and flush. I would highly recommend using distilled water.
  8. ColoradoLC

    ColoradoLC

    Messages:
    423
    Location:
    Centennial, CO
    Hey Zack sorry, I forgot to answer part 2 of your question.

    My acid was brownish looking. I did not dilute it.
  9. farflung

    farflung

    Messages:
    14
    Location:
    Bonney Lake, WA
    It looks to me like you have the clear hose hooked up to the downstream side of the T that sends fluid to the rear heater core. Isn't that going to allow the acid/vinegar to mix in with the fluid in the line at the bottom part of the T?

    Seems like a better place to hook up the clear hose is upstream of the T. I hooked my flush hose up right next to the firewall. You'll lose less coolant that way too.
  10. ColoradoLC

    ColoradoLC

    Messages:
    423
    Location:
    Centennial, CO
    It may be a little hard to tell from my picture, but I am draining out the bottom line into a bucket. It wasn't really mixing with anything. It was an in the top and out the bottom process. Once I flushed it out with distilled water a couple of times, I hooked the system back up to the rest of the cooling system and was back in business. I did have to add some coolant as expected.
  11. ntsqd

    ntsqd technerd

    Messages:
    4,807
    Location:
    Upper So. CA
    I found that an old school all brass twist type hose nozzle fits into the stock hose like it was made to go there. I tightened the clamp down on it, turned on the water and slowly opened up the nozzle by twisting the hose. House pressure is 40 psi minimum and you really don't want to take the core to that high a pressure, so go carefully here.
    I'm doing it backwards ("do what you otter, add acid to water") but from the start it is diluting the acid and not risking it spraying out randomly.

    Doing it that way meant that the acid could only come out where I wanted it to do so. And that I could flush the core thoroughly. I ran the water forwards for a while and then backwards for a bit

  12. erikgil

    erikgil

    Messages:
    395
    Location:
    NW NJ and Western MA
    Well I just did this about an hour or two ago. Burped it on a hill that was intense and the rad cap was the highest spot and coolant tank full. Still tepid heat from front heater and the rear heater is a bit warmer than that but still, not what i call "heat".
  13. John McVicker

    John McVicker SILVER Star

    Messages:
    1,418
    Location:
    Big Pine, CA
    T-stat plus upper t-stat 'o' ring.

    Replacing them will likely fix you up.

    John
  14. erikgil

    erikgil

    Messages:
    395
    Location:
    NW NJ and Western MA
    Thanks for that. I forgot to mention I did those 2 weeks ago.
  15. John McVicker

    John McVicker SILVER Star

    Messages:
    1,418
    Location:
    Big Pine, CA
    By mistake it's easy enough to put t-stat in upside down ?? Throwing ideas out.

    John
  16. erikgil

    erikgil

    Messages:
    395
    Location:
    NW NJ and Western MA
    Could be. I thought I checked that and the o ring would only fit one way. Aftermarket gauge reads 170 - 180 most of the time. Fan clutch after sitting overnight spins with limited resistance when off continuously.
  17. John McVicker

    John McVicker SILVER Star

    Messages:
    1,418
    Location:
    Big Pine, CA
    You might be right about 'o' ring upsidedown thing. Can't remember

    170-180 is cool for sure but you should feel more heat than what you describe.

    How about the heater valve on the engine side firewall. Are you SURE that is is opening fully & letting a full stream of water to your heater core ??

    John
  18. cruiseninak

    cruiseninak

    Messages:
    319
    Location:
    Germany
    OP or anyone else. How do you contain the acid so you don't make a mess/spill? I am thinking about doing this but am unsure about how to properly treat or dispose of the waste acid. Any thoughts I think would be helpful for all of us.

    Pat
  19. brian

    brian SILVER Star

    Messages:
    5,711
    Location:
    lebanon,pa
    just keep a jug of water/baking soda handy to dump on acid spills.
  20. erikgil

    erikgil

    Messages:
    395
    Location:
    NW NJ and Western MA
    Yeah, it actuates quite nicely. No slop and no restriction. Seems to be "just right" in feel both at the inside level and moving it under the hood.

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