Collant System Flush

motormayhem · May 7, 2009

Ok well i was checking the level today as my expansion tank is cracked and noticed that after driving the coolant is rust-brown so I think it is time for some fresh stuff. I don't have a overheating problem so I am debating weather I should remove the hoses and flush it or just drain it using the petcock on the radiator. Also what is the best way to flush it? Just poor water into it till it comes out clean? Also i heard it is bad to use hard water in it so should I go get some bottled water and use that or distilled. First time doing this so any help is greatly appreciated.

thedeliverator · May 8, 2009

I'd remove and replace the lower radiator hose unless you know how old it is. Not a good thing to have go out on you.

If you've got rust flakes coming out or an oily sheen on the drained coolant, you'll need to flush the system out, first with a detergent to get the oil, then with something like citric acid to deal with the rust.

Hard water is fine to flush out with, but when you fill do so with distilled water. Just my opinion but the bargain basement coolant/antifreeze isn't worth it. You'll just end up changing it again in a year when the corrosion inhibitors stop working... or you won't, and in another year you'll have a block rusted from the inside out.

GoHot229 · May 8, 2009

Heres something I did, it will only work with brass radiators though as aluminum causes a reaction. I used 'muriatic acid' after taking the radiator out and laying it flat and filled with water from a bucket that I had poured in 6-8 oz's of the mixed solution. Watching it for a fiew minuates bubble and clean, I then poured it out, in the DIRT, as it will stain asphalt or concrete and kill plantstuff's, but then put the hose in the bottom outlet and let it run for a fiew minuates to rinse. Afterwards, looking inside it appeared like new, literaly. My whole reason to do this radiator was because the car was running hot, and after this cleaning, it never overheated again. Ihe Muriatic acid will disolve calcium and rust in short order, however to use it on aluminum radiators will not work, take my word, if you try it you WILL destroy aluminum radiators........

motormayhem · May 8, 2009

GoHot229 said:
Heres something I did, it will only work with brass radiators though as aluminum causes a reaction. I used 'muriatic acid' after taking the radiator out and laying it flat and filled with water from a bucket that I had poured in 6-8 oz's of the mixed solution. Watching it for a fiew minuates bubble and clean, I then poured it out, in the DIRT, as it will stain asphalt or concrete and kill plantstuff's, but then put the hose in the bottom outlet and let it run for a fiew minuates to rinse. Afterwards, looking inside it appeared like new, literaly. My whole reason to do this radiator was because the car was running hot, and after this cleaning, it never overheated again. Ihe Muriatic acid will disolve calcium and rust in short order, however to use it on aluminum radiators will not work, take my word, if you try it you WILL destroy aluminum radiators........

Lol when I was cleaning the gas tank out on my model A my friend borrowed some and put a aluminum gas gauge in it and left for 15min and when he came back he asked me where I put it and I said I hadn't touched it. Turns out it just completely dissolved. Lucky he had a box of them.

I guess I will just pull the hoses and give everything a thorough rinse and put it back together. So distilled water is the best?

RockyM1028 · May 9, 2009

remove thermostat, rinse radiator,fill with 3 bottles CLR from grocery store, top off with water. run until operating temp has been reached than an additional 10 minutes or 20-25 min total...... drain system 2 twice to be sure all CLR is gone.. replace radiator hoses and new themostat..... This will also clean out the block!!!! "BUT" If you have extreme corrosion in the block and it hits your water pump well you might need one off these as well.. I've done this to several cars+trucks and it's amazing, have yet to have a pump go! CLR " Calcium Lime and Rust Remover in the household cleaning section!!!!

motormayhem · May 10, 2009

I did the rinse before I had a chance to read your post, but I removed the hoses and flushed the radiator untill I had clear water coming out of it. I realized after I had it apart the thermostat would be closed but I didn't take it out. I just gave the radiator a thorough rinse with water and put everything back together as I didn't have any issues with overheating I didn't think I needed to use anything but everything is back in place and working as it should. :-D

Collant System Flush

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