In this video I show you the process I use to flush a heater core using CLR. I have done this many times in the past few years and it works extremely well. Obviously use at your own discretion. This is for entertainment only. -Enjoy!
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49 thoughts on “Heater core flush: using clr”
  1. Avataaar/Circle Created with python_avatars Seraphim401 says:

    70 people need a brain flush.

  2. Avataaar/Circle Created with python_avatars Bart Massi says:

    Great vide!, very informative, we will be doing a Honda CRV heater core flush tomorrow, thanks for the insight.

  3. Avataaar/Circle Created with python_avatars boostedsil40 says:

    if the heater is plugged then wouldnt the radiator also have buildup and could you run it in your radiatoer by turning on the enging for a minute every 10 minutes for a hour or 2?

  4. Avataaar/Circle Created with python_avatars Austin Foster says:

    Hey quick question. Does having a clogged heater core cause any cooling issues with the engine itself? Could you just cap it off if you had to?

  5. Avataaar/Circle Created with python_avatars Josh Smith says:

    Could you pull the thermostat and run the CLR through the whole cooling system?

  6. Avataaar/Circle Created with python_avatars Rorick Eulavea says:

    Your awesome. I wish I was there when you made this video!! I thought it was hilarious!! But the CLR worked for cleaning my heater core!! Thanks for video!!!

  7. Avataaar/Circle Created with python_avatars Keith Harris says:

    Where did you get that air and water hose combination gun at

  8. Avataaar/Circle Created with python_avatars dnl machine says:

    Boutta tree-fiddy??!?
    Thats a durn good price, I can get with that.
    Nice work again Mr O.
    Stay gold.

  9. Avataaar/Circle Created with python_avatars Tim Gifford says:

    CLR label states "Do not use on Aluminum "

  10. Avataaar/Circle Created with python_avatars Jarod Q says:

    Giving this a try on my 2012 Outback. Confirmed actuator works, so it's likely a partially clogged core. If I can fix it for ~$100 in tools and a Sunday afternoon I'll be thrilled.

  11. Avataaar/Circle Created with python_avatars Tyler Brown says:

    Eric, usually, at the end of your videos when you say, "if I can do it – you can do it," I l laugh and say, "you're so very wrong Eric O. I can't do that." But this time, being out of better ideas to try to remedy my wife's no passenger-side heat in her 09 Highlander Hybrid, I said, "I think I might be able to do that." And it freakin worked.

    Now, it was a pain in the backside to get TO those hoses on this car. But I got there. I also didn't have the pump. So I ended up flushing thoroughly with water (disposing of the coolant responsibly); then with a funnel to one of my hoses, I filled the core with CLR, set a timer, came back and flushed it out. Repeated that probably like 4 or 5 times (I wasn't seeing big clunks of evil coming out). Also changed the direction of the flushing each time. After running out of CLR, I flushed again with water, put everything back together, said a weak prayer, and took 'er for a shake down the road. 100% success! Passenger side heat went from ice-cold to nice-and-hot.

    I can do it, Eric. I can do it.

    Tyler

  12. Avataaar/Circle Created with python_avatars Samuel Spade says:

    Look like a diluted CLR solution as he added to water circulating through the system… is there a mix description. It may have been 1 to 1 CLR to water, but that was my guess. Yeah… I am that guy that doesn’t listen well or find things obviously in front of me.

  13. Avataaar/Circle Created with python_avatars The Four Eyed Fabricator says:

    I just used your method on my wife's '08 MKZ heater core. The heat comes out hot enough to melt your face now! CLR and SMA for the win!!!

  14. Avataaar/Circle Created with python_avatars mike hall says:

    I think you fixed it and didn't lie to the customer!

  15. Avataaar/Circle Created with python_avatars Jason Cruise says:

    💯💯👍👍

  16. Avataaar/Circle Created with python_avatars John Anderson says:

    I have a 2013 Dodge blows one out of 1 side cold as a what could it be

  17. Avataaar/Circle Created with python_avatars Mazda626gtturbo says:

    How long with the pump on each side?

  18. Avataaar/Circle Created with python_avatars Kazil Ziya says:

    Sadly , ethical mechanics like yourself are far and few in between. As for using CLR , i've used it with no problems and have seen others use it with no problems.

  19. Avataaar/Circle Created with python_avatars claymore cluepile says:

    i tried CLR…..then i found using heinz white vinegar worked better

  20. Avataaar/Circle Created with python_avatars BackBay_Boston says:

    I did this to my Ford escape, used standard toilet bowl cleaner. Had to do it 2x but it worked like a charm

  21. Avataaar/Circle Created with python_avatars John Ridley says:

    With the "Drano method" – the "black stuff coming out of the heater core" is probably dissolved aluminum oxide – what used to be the heater core.

  22. Avataaar/Circle Created with python_avatars Andygeofri says:

    Came for the info, stayed for the show. Hope you'll be here all week? LOL. Humor cracked me up.

  23. Avataaar/Circle Created with python_avatars Mrcaffinebean says:

    I followed this exact procedure last weekend and it worked PERFECTLY! I now have full heat again! Thanks for posting this excellent video!

  24. Avataaar/Circle Created with python_avatars Sam Savill says:

    "The rust n the dust n the crust…" 😅

  25. Avataaar/Circle Created with python_avatars 97warlock ismyname says:

    all this stuff is great ideas ……. My issue is ….. Heater hoses inaccessable. one goes to the thermostat housing & one goes along back & under engine & dissapears mysteriously into darkness, Ive heard it goes to the water pump but do notsee it on the water pump. – THIS i sthe line I need to access its cold after running 15 minutes but can not get to where it becomes rubber hose again, ……its rubber off the core for about 8 inches then fits on a metal tube, which that metal tube dissapears into the void . this is my second year without heat. starting to suck.

  26. Avataaar/Circle Created with python_avatars David Ashabranner says:

    Eric I believe you fixed it too good while your face is melting.

  27. Avataaar/Circle Created with python_avatars Nameless Noone says:

    Eric O is a MF'in life saver! Big thanks to South Main Auto for making this video. My wife's Sebring has had heat in only one vent ever since she acquired the car….I tried everything I could think of aside from tearing into the dash to replace the heater core which is an all day job. This was my last hope and after going through all the steps…..the CLR not only broke up all the blockage and get the heat coming out across all vents but just about doubled the output temperature so the hear is nice and hot. Thank you so much Eric!!!!

  28. Avataaar/Circle Created with python_avatars Karl Schmitt says:

    so my young son pulled off the vent grill on our dodge van and sent a couple match box cars for a ride and blocked the blend door from closing …. that took me 8 hrs to find …

  29. Avataaar/Circle Created with python_avatars Gator Dave says:

    Where did you get the air gun that can put water through it

  30. Avataaar/Circle Created with python_avatars RabidDogEOCF says:

    Howd you prime this? got the same pump and cant figure how to prime it?

  31. Avataaar/Circle Created with python_avatars Resilient says:

    That's cool I liked the clr part it's the small things that count.

  32. Avataaar/Circle Created with python_avatars Randy Jeffery says:

    Very smart and honest.

  33. Avataaar/Circle Created with python_avatars Gunk says:

    But about how long did he circulate the CLR? 10 min, 2 hr?

  34. Avataaar/Circle Created with python_avatars nowr2run says:

    I used VANISH TOILET BOWL CLEANER but you can't leave it in there that long. That stuff will take your FREAKIN SKIN OFF, HELL EAT YOUR RUBBER GLOVES, worked great on my 97 & 99 Jeep Grand Cherokee's.

  35. Avataaar/Circle Created with python_avatars Josh C says:

    I Bought the pump from the link. How do you prime the darn thing? No instructions.

  36. Avataaar/Circle Created with python_avatars David Timmel says:

    Should have tried this on the Grand Prix "extreme flushing" that needed a water pump and his old dextron coolant had turned to mud. Or told him to do it himself. (I doubt that he would have)

  37. Avataaar/Circle Created with python_avatars John Johannemann says:

    Good job as always. Just with repairing the vehicle properly, but taking care of the customer as well.

  38. Avataaar/Circle Created with python_avatars Joe Ramirez says:

    CLR great idea , back flushing helps remove particles that may have clogged the heater core.

  39. Avataaar/Circle Created with python_avatars N C T says:

    What tool did you use to blast air and water??? Amazon link plz…

  40. Avataaar/Circle Created with python_avatars Wings an things says:

    CLR; in Canada we put that Sh%t on everything.

  41. Avataaar/Circle Created with python_avatars Death Cooties says:

    Brilliant!

  42. Avataaar/Circle Created with python_avatars Blazer 123 says:

    thanks eric

  43. Avataaar/Circle Created with python_avatars Darrin Purkis says:

    Class act sir

  44. Avataaar/Circle Created with python_avatars Ben V says:

    Good tip. If my wife's high mileage Volvo's heater doesn't blow heat, I might give the CLR flush a try.

  45. Avataaar/Circle Created with python_avatars Patrick Young says:

    Eric I love the show – this one should be called "Extreme Heater Core Flush" :0

  46. Avataaar/Circle Created with python_avatars RetiredIntelGuy says:

    You gotta change those fluids! Your car will give you a lot less trouble if you do!

  47. Avataaar/Circle Created with python_avatars Dathan says:

    I'd much rather flush a heater core as opposed to having pieces of plastic trim break while replacing the heater core.