How To Flush?
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Le Mans Master
Joined: Aug 2000
Posts: 6,273
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From: Austin TX
How To Flush?
I'm about to install an alum radiator and would like to use Dexcool. I need to completely flush the block of all Prestone before installing the Dexcool. any tricks to this?
Le Mans Master
Joined: Aug 2000
Posts: 9,662
Likes: 7
From: Semper ubi, sub ubi
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Re: How To Flush? (flynhi)
Will, I'm contemplating doing this too, a new aluminum radiator would look good in front of my new Spals.
DISCLAIMER: I make no claims that this is acceptable to do on a modern engine:
I did this on a 1949 Packard straight 8, the block was horribly crudded up and this is the procedure I used. It might be overkill, but it didn't do any damage to the old cast iron engine. I don't know what it would do to aluminum, so if you have aluminum heads you might not want to go to the extremes I did.
I found out how bad this block was when I pried out a leaking freeze plug, and saw that there was so much crud inside the block I was surprised that water even circulated through it.
1. After I pulled the old radiator I disconnected the heater hoses and flushed the heater core seperately, with just plain tap water (heater cores scare me and I didn't want to eat it up with my flush routine.)
2. I removed the thermostat and flushed backwards through the lower hose until the water coming out was clear (didn't take long.) Then I went from the top down.
3. Then I got three jugs of CLR rust remover (I think they were about a quart each.) Poured 1 bottle into a anti-freeze jug and topped the jug off with very hot water. I then plugged the water pump outlet and poured the hot mix in throught the thermostat opening, until the block was full. I let it set for about an hour, drained and then flushed with water. Lot's of orange rust and flecks of rust and dirt came out.
4. Repeated the procedure, 2 more times. and gave the block a final flush with a hose. The amount of rust never changed, I'm convinced that if I'd done the procedure 20 times, I'd still had rust coming out.
Warning: The flush water and CLR killed the grass all along my driveway, and my wife was seriously miffed!
5. Now here comes the weird part. :lol: I took a couple of 2 liter Diet Cokes and filled the block up again with the Coke. I let it set overnight and drained and flushed it again the next afternoon. The Coke contains Phosphoric Acid, which is supposed to remove rust or convert it to Iron Phosphate (or Phosphite)
6. After all this I had to replace the rest of the freeze plugs because apparently the only thing holding them together was rust, they were steel and not brass. I don't know how CLR would effect brass freeze plugs, read the bottle and see if it is corrosive to brass or copper before you use it.
When I replaced the freeze plugs I saw that the block was pretty darned clean (compared to what it had been before) and most of the lumps of carbonate and rust were gone or greatly reduced. I'm sure your engine isn't anywhere near this bad, so you shouldn't have to go to these extremes.
Good Luck!
DISCLAIMER: I make no claims that this is acceptable to do on a modern engine:
I did this on a 1949 Packard straight 8, the block was horribly crudded up and this is the procedure I used. It might be overkill, but it didn't do any damage to the old cast iron engine. I don't know what it would do to aluminum, so if you have aluminum heads you might not want to go to the extremes I did.
I found out how bad this block was when I pried out a leaking freeze plug, and saw that there was so much crud inside the block I was surprised that water even circulated through it.
1. After I pulled the old radiator I disconnected the heater hoses and flushed the heater core seperately, with just plain tap water (heater cores scare me and I didn't want to eat it up with my flush routine.)
2. I removed the thermostat and flushed backwards through the lower hose until the water coming out was clear (didn't take long.) Then I went from the top down.
3. Then I got three jugs of CLR rust remover (I think they were about a quart each.) Poured 1 bottle into a anti-freeze jug and topped the jug off with very hot water. I then plugged the water pump outlet and poured the hot mix in throught the thermostat opening, until the block was full. I let it set for about an hour, drained and then flushed with water. Lot's of orange rust and flecks of rust and dirt came out.
4. Repeated the procedure, 2 more times. and gave the block a final flush with a hose. The amount of rust never changed, I'm convinced that if I'd done the procedure 20 times, I'd still had rust coming out.
Warning: The flush water and CLR killed the grass all along my driveway, and my wife was seriously miffed!
5. Now here comes the weird part. :lol: I took a couple of 2 liter Diet Cokes and filled the block up again with the Coke. I let it set overnight and drained and flushed it again the next afternoon. The Coke contains Phosphoric Acid, which is supposed to remove rust or convert it to Iron Phosphate (or Phosphite)
6. After all this I had to replace the rest of the freeze plugs because apparently the only thing holding them together was rust, they were steel and not brass. I don't know how CLR would effect brass freeze plugs, read the bottle and see if it is corrosive to brass or copper before you use it.
When I replaced the freeze plugs I saw that the block was pretty darned clean (compared to what it had been before) and most of the lumps of carbonate and rust were gone or greatly reduced. I'm sure your engine isn't anywhere near this bad, so you shouldn't have to go to these extremes.
Good Luck!
