Cooling System Flush

[thomas m]

Is a good idea to flush the cooling system with one of those "cooling system flush" liquids when replacing the coolant?

Is it, or could it be, harmful in any way?

Opinions?

[air-cooled or diesel]

i use the super gunk stuff, have good results, then again i dont have cooling system problems to start with, rinse 2x, i have well water so i use deer park gallons or poland springs. never had a problem with this level of strong flush. i drop water/flush warm.

[Toby]

You can no longer buy the only cooling system flush that actually worked: The Prestone 2 part flush. Luckily you can approximate it with vinegar and washing soda. The old Preston 2 part used tannic acid as a cleaner and washing soda as a neutralizer. But since it actually worked they don't sell it any more. Just the crap that doesn't really do anything.

Put a gallon of white distilled vinegar in the cooling system and top off with water. Run the motor for 30 minutes up to all day.

Drain the vinegar/water flush into a tub. Add about 3/4 to one cup of washing soda to the cooling system and fill with water. Run the motor until it comes up to operating temp. Drain it into the tub. The mix of vinegar and washing soda ends up with a neutral ph so no hazmat. (Other than the heavy metals in the flush) ;<) You can pour it down the drain as long as its not a storm drain.

Flush the cooling system with water several times. A flush T in a heater hose works best.

You will be amazed at how clean this gets a cooling system.

FWIW, a gallon of distilled white vinegar is about $2 a gallon at Costco, so its a cheap flush. Ace Hardware carries washing soda. Works really well on dirty clothes when used as directed (in addition to normal clothes detergent) so its a good thing to have on hand anyway.