I want to do a thorough cooling system flush on my motor to get all the rust and acumulated crap out of the engine cooling system. The motor is fully assembled SBC sitting in an engine cradle on the floor on casters. It is much easier and far less messy to do it before I put it into the car for sure. Don't want to put it in the car and have all the cooling system crap wind up in the radiator when I flush it.Want to hear from people that have done it, what they used to do it, and how good it worked. Been reading up on it on the internet and there are a number of products that have been used from Evapo Rust for Cooling Systems to 420 CF to Citric Acid solution and others. My I plan is to take out the thermostat, drain the antifreeze flush it with water and fill the cooling system with the cleaner/derusting solution, join the upper and lower rad hoses together with plastic PVC pipe or muffler tubing and hook up a small electric motor with a belt to the water pump to circulate the solution through the motor for a a day or two. Then drain the system of the flush solution and flush it clean with water before I put in clean antifreeze.
I had quickly drained my coolant last year after I re-wired the truck. I can't believe the crap that came out! wood chips and pine needles...... Leads me to believe the previous owner who owned the truck for 10 years had never flushed it out...
I've used Evapo Rust and it works well for removing rust. I don't think it will work as well on scale. I've used citric acid for cleaning my cooling system and ran an acid solution for a few days. My engine's interior looks freshly cast. I wrote this article up after some guys in my old car car club were having overheating issues: Cooling System.
Take out the drain plugs in the block,when you take those out,you will find that the holes will be plugged up,gently clean out with a screw driver and watch the crud come out,also good to get all the water out if engine will be sitting in the cold.
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If it has Tits,Tires or a Track,your gonna have a problem with it.
I drained the system, removed the thermostat, pulled the bottom hose from the water pump and connected it to small electric re-circulating pump which sat in a bucket under the motor.
I installed a length of vinyl hose to the water pump and ran it to the bucket.
I filler the bucket with white vinegar and started the pump. I continued to add vinegar to the bucket until it had ehough to re-circulate without over flowing or sucking air.
Once finished I flushed the system well with plain water. Worked well, clean as a whistle and no damage. I ran the vinegar through a couple paint filters and put it away for further use........in the shop, not for pickling.
Used to be a product available years ago at Crappy tire, but probably not available anymore because of all the environmental laws. It was powdered oxalic acid which worked great. The kit also came with with a small amount of neutralizing powder to run through the block after the acid was drained. Good old days.....
I originally used vinegar to clean my cooling system but I found that it did not remove all of the scale (ie, white deposits) and didn't seem to have much effect on rust. Acid has more activity when it's hot so I even ran it for a few days.
I also looked for oxalic acid but couldn't find any locally at a reasonable price.