Cooling System Flush...I just know I can get a simple answer!

[Vince]

After reading about 200 posts on several sites, I'm returning to the most knowledgeable group I have found. I'm getting ready to do an engine flush on a couple 8-92 Detroits that are starting to run warm. Impeller is new and intakes are clean. I've read so many opinions from so many sources, but I have decided on Ospho. Phosphoric Acid seems to be the most effective, while being gentle on the metal parts. It's what Barnacle Buster is comprised of.
So, my question is this.....How much Ospho to How much water. Everyone states 2:1, 3:1, etc, without stating water vs. Ospho in their ratio statements. I'd just like to know how much water to each gallon of Ospho. I've got the rest all sussed out.
Thanks a bunch,
Vince

 

[cww]

If you are 100% sure you have a good baseline then sure do an acid flush, but if the boat is new-to-you, the first time I would always take the heat exchanger bundles out and clean them manually. That way you know you don't have impeller blades, plastic bags, or other crap in there that won't be dissolved by the acid flush. Once you've done it and you know firsthand that it's clean, after that acid flushing is fine.

 

[sgharford]

Don’t want to derail your original question regarding mixture ratio, but thought I would add to above. I use an inexpensive Amazon boroscope to check my heat exchangers. I have Cummins 903’s and go trough pencil zinc fittings, imagine easy way in on DD too. Use to check after acid flush results too. Make sure you keep return hose to acid bucket few feet above highest point on engine to really get top section of heat exchanger, I have to go about 5’ above to fully get top. Now, somebody answer the good man’s original question

 

[whoover]

Mr. Clarkson had a thread on flushing his 12v71's. He is very thorough and might have his mix ratios. He had it down to a science, he also fresh water flushed after each use.

Walt Hoover