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Diy Radiator Flush And Clean Suggestions?

Discussion in 'Early CJ-5 and CJ-6 Tech' started by J.P. Thal-Larsen, Oct 7, 2018.

  1. Oct 7, 2018
    J.P. Thal-Larsen

    J.P. Thal-Larsen New Member

    Potomac, MD
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    I'm pretty sure the radiator in my '62 CJ5 (Dauntless conversion) is from the mid 60's. I've flushed it once with a single application of Blue Devil Flush. After draining, flushing with water, filling with the flush product and driving around for a few days, it did come out muddy brown. There's still a good bit of corrosion/deposits in the passages however. I haven't ruled out another flush with a specialized product, but my guess is that they have less aggressive acids so that they can be used in aluminum radiators.
    Unfortunately the neighborhood radiator shops are few and far between around here so the old rodout method is probably not an option.
    Does anyone have a chemical/procedure for aggressively cleaning the crud out of old copper and brass radiators?
    Muriatic acid?
    C-L-R?
    Vinegar?
    Oxalic acid?
    Sulphamic acid?
     
  2. Oct 7, 2018
    timgr

    timgr Jeepin' Nerd Sponsor

    Medford Mass USA
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    There's a thread on a Corvette forum that features a GM service bulletin and describes how to make the old-school radiator flush from wood bleach (oxalic acid) and neutralize with washing soda (sodium carbonate). Oxalic acid will dissolve rust by chemical means. I can't find the thread right now - maybe you can look for it. Here's the service bulletin - radiator flush (GM Bulleton) - Car Forums and Automotive Chat - as I recall the 2-part kit contained oxalic acid as the flush and sodium carbonate to neutralize. Maybe if you search you will find some advice on sources and quantities for these chemicals.

    I believe the main problem with the 2-part kits involves how to dispose of the drained fluids.
     
  3. Oct 7, 2018
    gunner

    gunner Member

    Washington state...
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    I'll go down and check, but recall I used citric acid in the fhead. Worked great. It caused the water pump to leak for a little while but then it stopped. I figure it loosened up some crud around the shaft but the seal did eventually seal back up and it's been fine for a few years now.
     
  4. Oct 7, 2018
    71CJ54WD

    71CJ54WD Member

    DC
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    May 3, 2018
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    Fresh water running through the block will get enough of the gunk out that it will be good. Flushing water through there until it runs clear in both the radiator and the block does wonders.
     
  5. Oct 7, 2018
    dparker650

    dparker650 New Member

    Pennsylvania
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    A bottle of The Works toilet bowl cleaner in the radiator and fill it up the rest of the way with water. Let it soak for about 20 minutes and flush. All kinds of things will flush out and the brass will shine like brand new!
     
    Hellion likes this.
  6. Oct 7, 2018
    Daryl

    Daryl Sponsor Sponsor

    Bonney Lake, WA
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    I have had some luck with filling the system up with vinegar, bringing it up to temperature and letting it sit over night before flushing it out. Fairly mild and no worries about run off.
     
  7. Oct 7, 2018
    nickmil

    nickmil In mothballs. Sponsor

    Happy Valley, OR
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    If you have any aluminum in the system like intake manifold, thermostat housing, water pump, timing cover, The Works can cause real damage. Try putting some aluminum in a steel pan of The Works and see what happens. Make sure you wear a respirator and have lots of water or a fire extinguisher handy.
     
  8. Oct 8, 2018
    70cj5134f

    70cj5134f Member

    East Tn
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    After I flush with whatever acid, I flush with water,
    Then I like tide powder laundry det .
    Bout half cup.
    Start up and idle or low rpm driving in yard , 20 min.
    Then rinse with water 3-4 times.
    Laundry det is low suds!
     
    Hellion likes this.
  9. Oct 8, 2018
    dparker650

    dparker650 New Member

    Pennsylvania
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    Sorry I should have specified, I pull the radiator out for this and only use it there. Just use fresh water I the block.
     
  10. Oct 8, 2018
    47v6

    47v6 junk wrecker! Sponsor

    Washington DC.
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    I have never flushed my coolant system on pretty much anything. I mean I have replaced coolant for repairs and what not... is this a thing that has to be done?
     
    71CJ54WD likes this.
  11. Oct 8, 2018
    J.P. Thal-Larsen

    J.P. Thal-Larsen New Member

    Potomac, MD
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    Thanks for the input/recommendations. I think I found the home brew that Tim is talking about here. I'm now a graduate of Introduction to Home Cleaning Chemicals 101 ;)
    It's likely that the acids mentioned in this DIY flush are the bases of some of the products that are mentioned in this thread, without the more harmful acids/cleansers that might be contained in these household products. For example, Sulfamic acid is the main component of grout cleaner/grout film remover. It removes scaly deposits.
    The toilet bowl cleaner is probably effective on our brass core radiators, so long as the radiator is removed, but I have no idea as to its effect on seals, gaskets, etc. in a closed system. I'm looking for a flush method for the closed cooling system/rad installed so that I can benefit from the heated solutions circulated throughout the system.
    I'll follow up with the results.

    47v6, if you're starting with a clean, well circulating system without rust, scale and crud in it, you may never need to do a flush - at least not to the extent that I'm having to do it. This is more of a repair than a maintenance issue for me. The radiator in my CJ was clearly neglected. Decades old weak coolant mix in a system that sat idle for years. It's my understanding that the anti-corrosive components in coolants these days (Prestone Extended Life for example) nearly eliminate the need for radiator flushes so long as they are used/changed according to the manufactures recommendations.
     
    47v6 likes this.
  12. Oct 8, 2018
    70cj5134f

    70cj5134f Member

    East Tn
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    Dont have to be?
    But it should be done?
    Iron blocks and heads rust and flake and clog rad tubes.
    Flushing helps prevent overheating.
    Sometimes your the windshield?
    Sometimes your the Bug?
     
  13. Oct 10, 2018
    J.P. Thal-Larsen

    J.P. Thal-Larsen New Member

    Potomac, MD
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    Interesting research here that makes me comfortable using the chemicals/acids in that DIY flush:

    The 2 acids used in the 3 step process for radiator flush are Sufamic and Oxalic.

    Products that contain mostly Sulfamic acid (removes lime deposits, scaling, and cleans metal):
    • TileLab Grout Cleaner 60-100%
    • Jet Dry Dishwasher Cleaner 35-45%
    • Aqua Mix Sulfamic Acid Crystals 70-100%
    Products that contain mostly Oxalic acid (used as wood brightener and radiator cleaner)
    • Prestone Heavy Duty Radiator Cleaner (old product) 90-98%
    • Earthborn Elements Oxalic Acid Powder 99%

    The compound used last as an acid neutralizer is Sodium Carbonate (also Soda Wash or Soda Ash).

    A few of many household products that contain mostly Sodium Carbonate (used as laundry detergent, PH increaser and cooling system cleaner):
    • Arm & Hammer Laundry Detergent Powder 60-100%
    • Prestone Cooling System Cleaner (old product) - 90-100%
    • Pool Time PH Up 98-99%
     
  14. Oct 10, 2018
    heavychevy

    heavychevy Sponsor Sponsor

    Danielsville georgia
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    I've learned a lot today from different ways to clean a radiator. One thing that i have used before is distilled water in the radiator. Believe that it goes a long way toward a clean radiator staying clean.
     
    CJMark likes this.
  15. Oct 11, 2018
    NCRenII

    NCRenII yellow fever Sponsor

    Far Nor Cal
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    Sometimes cleaning an old radiator will result in the core leaking (tubes or solder).
    Given that, flushing can help. Believe it or not, I've used cola to flush older vehicles. I drain it down enough to add the big size bottle Run it up to temp and let sit for 2 or 3 days. Remove both radiator hoses and reverse flow radiator, and block separately (remove thermostat). After doing that fill with plain water and run it up to pemp, drain by removing hoses and flush again. Sometimes there will be so much crud the radiator will need to be removed and shaken while flushing. Only after flushing results in clean water reinstall thermostat (drill the lip close to the opening with an 1/8" hole to aid in purging air and also allowing a small flow all the time).
    Again beware as a leak may occur. Cola is less caustic (phosphoric acid), yet is great at removing corrosion without being a haz-mat site in your yard.
     
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  16. Oct 11, 2018
    wasillashack

    wasillashack Member

    Wasilla, Alaska
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    I've used Muriatic acid in coolant system flushes with good results, usually requires 2-3 water flushes with soda to get clean water after an acid treatment. Good luck!
     
  17. Oct 11, 2018
    Hellion

    Hellion Rust covered & junky

    Eastern TN
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    Dec 25, 2016
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    Seems like a complete coolant flush was a major maintenance thing in the past, I did it on my first car when I was 16; used a garden hose. Coolant used to go brown (rusty) and rancid often in older cars. They have advanced coolant a lot in recent years with anti-corrosion inhibitors and it seems to last 5x longer.
     
  18. Oct 12, 2018
    Chilly

    Chilly Member

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    Are you sure its your radiator that is continuing to release mud? My 304 had a leaky core plug so I changed them all. Back of the block was caked with some kind of black mud. Took three treatments with pressure washer before water ran out clear. Never could have changed coolant enough to get that out.

    If you ever have fenders off or engine pulled I highly recommend spraying out the block and changing welch plugs.
     
  19. Oct 20, 2018 at 4:19 PM
    J.P. Thal-Larsen

    J.P. Thal-Larsen New Member

    Potomac, MD
    Joined:
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    Follow Up:
    I went through the 3 step process (Sulfamic Acid/run for 3 hours/flush; Oxalic Acid/run for 3 hours/flush; Soda Ash/run for 3 hours/flush) and the results were impressive. I have yet to flush the Soda Ash and add the distilled water and coolant, but I know I've got a much cleaner radiator.
    From this, where some of the passages were completely blocked:
    2018-10-20 15.25.42.jpg

    To this (taken after the Oxalic Acid flush - before the reinstall and Soda Ash flush):
    2018-10-19 16.24.14.jpg

    It's now running cooler than it has in the past. No need to turn the electric fan on in stop & go traffic.
     
  20. Oct 21, 2018 at 2:50 AM
    70cj5134f

    70cj5134f Member

    East Tn
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    I've used CLR with good results, but rinse,rinse,rinse, afterwards.
     

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