Getting ready to replace coolant, radiator is in poor condition (alot of build up).
Wanted to know what is the best method to fully clean a radiator?
Do Prestone flush/cleaners work well in this situation?

 

I've had OK experience with Prestone SuperFlush, but I think it's re-formulated since then. Yeah, it's been awhile since I did that...

I usually take out the thermostat while doing this, just so I can let it circulate without completely warming up. If you haven't already, think about getting a new T-stat.

If the radiator is badly plugged, it may also be corroded. So be prepared to flush it a couple times. Also be prepared (at least emotionally) to replace the radiator. After flushing it, it may start leaking...

After you use that stuff, it's important to get it ALL rinsed out. I forget what year/engine you have, but there's probably a block drain plug in back. Use that & do a few fill/drains. On my '98 F23, I've had to do about 5 fill/drains before it drains out clear without any antifreeze color. If you want to use a garden hose but then use distilled water for the last couple drain/fills.

 

Jim's reply is very good. I always take the thermostat stat to get full flow of coolant thru the radiator. I leave the cleaner in for about 200 miles. You may need to do two cleanings if the system is dirty. If you have bloom around the outlet tubes in the radiator then your system is dirty. A lot of the scale comes from hard water so distilled water or clean rain water is great for the final flush. Distilled water is cheap in the grocery stores. And don't use a cleaner that will attack aluminum!!!

My cooling systems stay pretty clean by replacing the anti-freeze every two years. The bloom won't build up and one cleaner solution will do the job.

 

I also flush and back flush my cooling systems on my cars evey 2 years, this keeps them operating effeciantly all the time.

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