Safe cooling system flush procedure

[4onthefloor]

Guys, been going thru the whole car with all this down time. Rebuilt master cyl, working on distributor and timing issuesetc. While doing the checkovers I found some pretty rusty and cloudy antifreeze in the system. One of those things I didnt really need to check over the years. I want to flush it and get some fresh coolant in it and maybe a water wetter product. I used to use the old Prestone flush kits whit included a T for the heater hose to run garden hose thru it. Well I dont have heater hoses so just going to run it with a hose in the radiator. What flush has anyone used and should I even bother putting a chemical flush thru it ? Pretty filthy stuff in there now.

 

[Tim]

There’s a drain plug on the bottom of the block in the middle right above the oil pan. Drivers side I think. That will completely get most all out of the block. I took the thermostat housing off and flushed from the top with water every year in my boat that had a 350 in it. (Raw water cooled) W motors have the same plug.if it’s that cruddy you may need a piece of wire to poke out the crap as it drains. Rad is easy just take hoses off.

 

[Don Jacks]

Do that on BOTH sides of the block,that's where your rust will settle to.

 

[409gang]

Yes like Don said there are drain plugs on both sides of the block on all chevy V8's. On my Nova I put MerCruiser brass block drains in place of the drain plugs as race cars need to be drained down every fall, you don't run anti-freeze at the track.

 

[Tim]

Forgot they are on both sides....I had to go look! lol

 

[Junky]

What I used to do was to loosen the lower radiator hose at the radiator, and remove the thermostat once the radiator and block were drained. Then I would put 2 cups of Arm and Hammer washing soda into a bucket, and dissolve it with hot water. With the lower radiator hose on the radiator, loosely, I would fill the rest of the radiator with water. Leaving the cap off, I would start the car, and run the engine at 1200/1500 RPM till the engine was hot, and the solution turned the radiator coolant rust colored. Shut the engine down, and pull the lower radiator hose off and let it drain, until the engine was cool enough to do this again. Usually it took between 2 and 4 treatments until the solution came out white like the way it went in. Then I would give it a final 2 rinses with plain water, and a box of Arm & Hammer baking soda to neutralize everything. If I thought that the heater core needed cleaning, it was done in the last washing soda treatment. The nice thing about this method, it isn't harsh on the radiator, but it does sometimes cause a freeze plug to fail, but that would have happened anyway. This is how it was done back in the old days (1920's/1930's).

 

[4onthefloor]

Thats about what I wound up doing Junk. I didnt use baking soda though. Just rinse and flush about 5 times until water was clear.

 

[Cayneman]

A properly designed cooling system doesn't need Snake Oil like water wetter which is a waste of money.

 

[quik9r]

Royal Purple makes Purple Ice and it will lower under temps by 10 degrees. Corvette guys like it.

 

[IMBVSUR?]

A properly designed cooling system doesn't need Snake Oil like water wetter which is a waste of money.

This reminds me of when I was working with transmissions. An old timer once told me that the only thing you should put in a transmission is transmission fluid if the transmission was built right.

 

[Junky]

My transmission guy who is normally against using any additives in transmissions, suggests using Sea Foam transmission additive prior to giving up on a automatic transmission. He said that it will sometimes help, but it doesn't do any harm like other additives, when he dismantles the transmission for rebuilding. He also said that the worse thing to do is use a "sealer" to fix a leak. Said that it will gum up the works, and make it worse, and more difficult to clean for rebuilding. He has been doing transmissions for over 45 years, and can recognize a wrong part that was previously installed by a former rebuild. He found the problem with my 1962 not shifting correctly, because the previous rebuild, they left out a wave washer. He had to machine the drum, and add an additional clutch to fix the problem, since he couldn't find the correct washer. Now, it shifts perfectly.

 

[409gang]

My dad was a transmission guy had his own business, he would always put a can of TranSeal in when changing transmission oil. He said it keeps the lip seals and O rings plyable, hard seals are caused by excessive heat and lead to a lot of transmission failures.