VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 need thoughts on cleaniing out cooling system

I'm gonna try and do a concentrated flush of the block/radiator and I guess the heater box before going full tilt into replacing my antifreeze with Evans Waterless Coolant. So, would removing the drainage plugs, I guess on the block? or elsewhere be a big pain? enough to warrant just taking to my mechanic and have him do it in case its a royal pain to get them off? I need to really flush it out...then blow it with compressed air to get all of the water out and hopefully gunk.

thoughts?

You should really consider removing all the expansion/freeze/cleanout plugs and do the rod through the holes deal. Otherwise you will only remove some loose flakes from the system.

The best products made will not remove the old caked rust. Only following Ray's suggestion will do that.

Do the block, heater core and radiator separately. Reverse/Back flush each with water and air pressure. Then fill it back up with 50/50 of whatever. You're done.

You can do it if you have an air compressor and a garden hose. Tale the thermostat out whilst doing the block.

Don't worry about the casting plugs (sometimes called "freeze plugs"). You can scratch around in there all you want but if the block is so rusted up that it is causing problems you're not going to fix it with a coathanger.

Charlie

I disagree with the above.

I don't know if this will help much...
But I just flushed my '66 Chev this weekend... over a two day period. I ended up with a petcock that wouldn't open or close (the arm broke loose and just spun around) -- but that's another story, although it caused me to loose a day waiting for a new one to arrive.

I followed the Prestone Flush instructions - but wish that I hadn't.

STEP ONE: It said to drain your old coolant. Then add FLUSH and fill with water. Warm up the car for at least 10 minutes. Turn the heater on full. (I drove it for 10 minutes after it idled for 10 minutes.... I wanted to make sure that the thermostat was wide open.)

STEP TWO: Let the engine cool off. Drain the FLUSH mixture. And refill with water. Warm up for another ten minutes. (Again I did that and then drove it for 5 minutes.)

STEP THREE: Let the engine cool off. Drain the water. Then add antifreeze and water. Done.


So what do I wish that I'd done differently? I think that after two fill-ups, and a limited driving warm-up, that the water in the engine AND the radiator was mixed pretty well. BUT!! By waiting for the engine to cool off, the thermostat closed and when I drained the water, only about 2 1/2 gallons came out. My entire system is suppose to hold 16 quarts (4 gallons). So I'm a tad concerned that SOME of the mixture was still in the engine after I was done draining it.

I WISH THAT I HAD REMOVED THE THERMOSTAT BEFORE THE PROCESS. It would have been some additional effort, but I think the results would have been even better. More "old" water/rust would have come out during the flushing.

--Bill

If that was that two part powdered flush it is useless except for a light coat of rust. Years ago it was much stronger and better but like everything else the EPA didn't like it.

If I were trying to clean out a badly rusted cooling system today I would use good old Drain-O lye (EEK). You got to be careful how you dispose of it. Years ago the instructions for cleaning out a radiator was right on the container of lye.

When every thing is opened up..after your flushes..use the magnet on a wand..you will be amazed at the flakes you can still get out..

"I disagree with the above."

Gene,

You weren't specific, so I guess you disagreed with all of it. Accordingly, I can only assume that everything in my post was BS. Or, was there some bit of it that you did agree with? If so, I'd like to know what it was. Mercy!

The poster didn't say he was having any problems. Just wanted to flush the system and put new antifreeze in it. Or did I miss something.

Your statement "I disagree with the above", without more, to me seems unwarranted, puzzling and unsettling. Please explain your rational for such a bare statement.

Charlie

The only flush that I have found useful is muriatic acid (HCl). You can buy it in concentrated form for swimming pools. Dilute 10 parts of water to one part HCl by carefully adding acid to water. Circulate it until hot several times, drain, rinse a few times. Then put in box of baking soda dissolved in water to neutralize any remaining acid, drain and fill with coolant of your choice. That is the summary. For more complete description use search option for muriatic acid. Previously posted discussions have at included the safety equipment needed to do the flush safely and more details.

Lye is effective on oils and grease but not rust. Acids will solubilize rust.

When I was doing my motor I filled the block with 5 parts water to 1 part Molasses and left it for a few weeks. A lot of gunk came out and it seemed to work though not everyone believed that it would. We had a badly rusted up anchor on a coastal steamer in Sydney Heritage Fleet. The quote was about $5000 to free it all up. Anyway I stuck it in a skip filled with water/molasses and three weeks later we lifted it out and it all swung free. Anyone else use that?

Just want to comment on Bill's post:
I recently had my '28 cooling system flushed at a local, reputable radiator shop. The thermostat was left in and he was able to backflush with a water hose hooked up to the thermostat housing and have the water/junk exit the bottom radiator hose at the bottom of the water pump. Of course, the radiator was not hooked up to the hoses for this block/head flush.

So, when the flushing liquid is running counter to normal flow, it will push the thermostat open and flush the head and block.

Dean

Thanks Dean. That would have accomplished a better flushing than what I did.

I haven't flushed an engine with a thermostat in it, for at least 20 years... A long, long time ago, I stopped adding thermostats to my '31 and never installed one in my "other" two 31s. So I kind of forgot about it when I wanted to flush the '66. My bad.

But... at least it's better than it was. And I suspect that after my 5,310 mile tour of Route 66 in May, that anything that I have done to it, has made it better.

Also, I've gotta admit that I have used a magnet in an older engine and was AMAZED at the stuff that it found -- AFTER I thought that it was clean and ready to go. I'd say that the older the engine is, the more likely you should do that.

And... (sorry for the follow-on's), if the engine is old, -- YES, remove the freeze plugs. And throw them away. Otherwise you may kick yourself in the near future after all of your hard work.

That's it. Now I'm just waiting for my new aluminum petcock to arrive so that I can take the temporary brass one out.

Hi rivstg1,

Most of us don't remember back to June 17th, 2014 when we had a previous discussion of his issue. So here it is.

Overheating issue, I am stumped

We have an index of past posts to help you discover a lot of info on topics we have covered. When you are ready to give it a try follow the Advanced Search steps and hints, and ask further for how the process works.


Best wishes Mike,

Hi I should have written that I AM having overheating issues....detailed in another posting. This is why I was going to go this route of flushing and better coolant. If I removed the freeze plugs (are they hard to remove with the engin in the car?), does anyone know how difficult it would be to install new ones with it still in the car as well? I really didn't want to have to remove the engine!!!!

thanks for all the responses from everyone....I'm learning!!!

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