How often do you drain and flush?
Thread Starter
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
How often do you drain and flush?
The radiator. I am long overdue. Been thinking about it for a long time tho, and have accumulated most of what I need.
- antifreeze, check (been in the garage for 2 years)
- distilled water, check - wife picked up 6 gallons today
- thermostat, check - have 2 Stant superstats (180) in the basement for at least a year. Also have a 195 regular one.
- thermostat gasket, check, in a plastic bag but it's so old I may get a new one.
- gasket gunk. what should I use, blue rtv? I have black, maybe I will pick up some blue.
- prestone radiator flush stuff. Have 3 little plastic bottles plus a bottle of zerex sitting in the garage for a couple of years.
- pans and empty bottles... I guess so.
Anything else? Its been so long I forgetted!!!
- antifreeze, check (been in the garage for 2 years)
- distilled water, check - wife picked up 6 gallons today
- thermostat, check - have 2 Stant superstats (180) in the basement for at least a year. Also have a 195 regular one.
- thermostat gasket, check, in a plastic bag but it's so old I may get a new one.
- gasket gunk. what should I use, blue rtv? I have black, maybe I will pick up some blue.
- prestone radiator flush stuff. Have 3 little plastic bottles plus a bottle of zerex sitting in the garage for a couple of years.
- pans and empty bottles... I guess so.
Anything else? Its been so long I forgetted!!!
Melting Slicks
Joined: Jan 2004
Posts: 2,672
Likes: 1
From: New Cumberland PA
Originally Posted by PRNDL
How often do you drain and flush?
The radiator.
The radiator.
As for the radiator, I drain that much less than the recommended interval. Never had a problem.
Melting Slicks
Joined: Jan 2003
Posts: 2,817
Likes: 21
From: Somerset, NJ
I think it really depends on how much you use the car. On my 73' with original 25,000 miles on it I have only changed the antifreeze in it twice since 1982 when I purchased it with 17,000 miles on it. I don't drive it much, less then 500 miles a year because I have other collector cars also. The car still has its original upper and lower radiator hose from the factory. I did change out the heater hoses though years ago. I have been using only Prestone Antifreeze in this car. Basically everything is still original to the car. Original radiator, water pump, carb, a/c compressor etc. The only thing I ended up changing out was the M/C and had the original calipers rebuilt with SS Sleeves. Still have the original M/C on the shelf though. Something I did do years ago that I maybe shouldn't of was I got rid of the original radio for a cassette deck. The other thing I did was to replace the original vinyl seats with leather ones. This I am still glad I did because looks wise you can't beat Leather.
Melting Slicks
Joined: Jan 2003
Posts: 2,817
Likes: 21
From: Somerset, NJ
Originally Posted by rihwoods
The pH of the coolant only lasts so long..but this could be more critical in aluminum rads...anyway,corrosion starts at that point..
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Drifting
Joined: Aug 2005
Posts: 1,430
Likes: 8
From: Hamilton NJ
What is the general flushing (of the radiator) procedure? My heater is completely off line, plugs in the block and manifold. Is it enough to drain the rad and backflush through the cap and out the drainplug. Should I pull one of the plugs and backflush through the block? Which, the manifold, the block, both??
Thoughts and details appreciated...
Many thanks
Thoughts and details appreciated...
Many thanks
Melting Slicks
Joined: Jan 2003
Posts: 2,817
Likes: 21
From: Somerset, NJ
Originally Posted by Wuttin
What is the general flushing (of the radiator) procedure? My heater is completely off line, plugs in the block and manifold. Is it enough to drain the rad and backflush through the cap and out the drainplug. Should I pull one of the plugs and backflush through the block? Which, the manifold, the block, both??
Thoughts and details appreciated...
Many thanks
Thoughts and details appreciated...
Many thanks
CF Community Team
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They say every 2 or 3 years is a good rule of thumb. Generally, it seems one of the following will usually need fixing or replacing within that time frame: Radiator, water pump, thermostat, heater core, hoses etc. so that usually takes car of the anti-freeze change.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Originally Posted by PRNDL
The radiator. I am long overdue. Been thinking about it for a long time tho, and have accumulated most of what I need.
- antifreeze, check (been in the garage for 2 years)
- distilled water, check - wife picked up 6 gallons today
- thermostat, check - have 2 Stant superstats (180) in the basement for at least a year. Also have a 195 regular one.
- thermostat gasket, check, in a plastic bag but it's so old I may get a new one.
- gasket gunk. what should I use, blue rtv? I have black, maybe I will pick up some blue.
- prestone radiator flush stuff. Have 3 little plastic bottles plus a bottle of zerex sitting in the garage for a couple of years. pans and empty bottles... I guess so. Anything else? Its been so long I forgetted!!!
- antifreeze, check (been in the garage for 2 years)
- distilled water, check - wife picked up 6 gallons today
- thermostat, check - have 2 Stant superstats (180) in the basement for at least a year. Also have a 195 regular one.
- thermostat gasket, check, in a plastic bag but it's so old I may get a new one.
- gasket gunk. what should I use, blue rtv? I have black, maybe I will pick up some blue.
- prestone radiator flush stuff. Have 3 little plastic bottles plus a bottle of zerex sitting in the garage for a couple of years. pans and empty bottles... I guess so. Anything else? Its been so long I forgetted!!!
I'd suggest a real good coolant system CLEANING ... not just a flush but a real cleanout. Best stuff out there is at GM parts dept ... GM P/N 12346500 it's actually Prestone P/N AS100 Heavy Duty Cooling System Cleaner ... but you'll rarely find it anywhere but dealer ... under $10 ... strong powdered stuff, not those wimpy liquid flushes you'll find at WallyWorld or Advance ... wear eye protection. Get a free DexCool plugged radiator service bulletin (#99-06-02-012D) printout at GM dealer Svc Dept ... it'll walk you through a cleaning procedure that REALLY works. BTW ... proper procedure w/ AS100 takes about 4 hours at high-idle. Use the GM procedure as a guideline ... do it right and this stuff REALLY WORKS WELL!!!!!! Also get a new rad cap.
And YES ... AS100 safe for aluminum if you use as directed or as in the GM tsb.
Race Director
Joined: Feb 2005
Posts: 16,100
Likes: 17
Originally Posted by ffas23
If this is really true and myself being in the business I have heard the same plenty of times. You would think that the original radiator in my 73' should of been replaced already whether it be an original 25,000 mile car or not since I have only changed the antifreeze twice in 24 years. But the fact is I am still driving around with the original radiator, no leaks and it runs cool in this hot weather.
My first rad lasted 24 years..but not without decreased efficiency with crud at bottom of rad/etc..hard to get that crap out of there....looks as though Jackson has posted a good procedure...can't wait to try that and see how much more crud comes out as I just flushed mine last month..
Last edited by rihwoods; Aug 4, 2006 at 01:45 AM.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Originally Posted by rihwoods
looks as though Jackson has posted a good procedure...can't wait to try that and see how much more crud comes out as I just flushed mine last month..
BTW ... if it's running good & cool ... I wouldn't tempt fate.
Race Director
Joined: Feb 2005
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Originally Posted by jackson
BTW ... if it's running good & cool ... I wouldn't tempt fate.
Thread Starter
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
OK, I done did it. Not going to get too too fancy this time. I drained about 3 or 4 gallons of coolant. The bigblock cooling capacity is supposed to be 21 qts = 5+ gallons. I jacked up the rear to get out a little more from the radiator petclock (sic, it won't let me spell it the right way).
I only put in one gallon of antifreeze. (That will be around 20%).
The first stuff I take out I save and take to a special disposal facility they have here in the county.(It is only 20% antifreeze) The second time I fill and drain I save the stuff and flush it down the toilet. It is very diluted. After that, when I am flushing using the prestone backflush kit I run it down the driveway. Most city sewage treatment plants can handle small amounts of antifreeze even if they don't permit you to flush it down the toilet. You definitely don't want to dump it down a storm sewer or on the ground. It is very poisonous.
I only put in one gallon of antifreeze. (That will be around 20%).
The first stuff I take out I save and take to a special disposal facility they have here in the county.(It is only 20% antifreeze) The second time I fill and drain I save the stuff and flush it down the toilet. It is very diluted. After that, when I am flushing using the prestone backflush kit I run it down the driveway. Most city sewage treatment plants can handle small amounts of antifreeze even if they don't permit you to flush it down the toilet. You definitely don't want to dump it down a storm sewer or on the ground. It is very poisonous.
Race Director
Joined: Feb 1999
Posts: 19,659
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From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
I have wound up draining and flushing mine about every 2 years because of different work I have done on the engine. Intake manifold change is a good time to do the antifreeze change. 
