/6 Cooling System: Multiple Cleanings

nm9stheham said
Yes, G05 has plenty of inhibitors. It is the coolant used in a lot of modern Mopar stuff. Look up HOAT coolants.

The heater core and rad were well cleaned and flushed multiple times by me before this. Rad was not rodded, but was removed and backflushed 3 times. There was indeed still rust/crud left in the block and head even after the acid tanking.

That is it point here: that all was a very thorough cleaning, much more than any good driveway flush job. So for those cleaning out an older engine, a good flush is likely not going to complete the job in one pass. It will take several flushes and cleanings, with some running in between, to make up for decades of neglect.

When rebuilding an old engine I really think you need to physically inspect the coolant passages in the bare block with all the freeze plugs out. And you need to physically pick the inside of the block clean. the passage between the cylinder bores and area along the bottom off the bores at the bottom of the freeze plug holes seems where must of the rust and debris are.

I did this to my old 340 block in 1993 and never had heating issues. I have baby jars full of debris we got out of it. And I did it again in 2011 with my new stroker motor... and never had heating issues.

You can hot tanks, soak, ultrasonic, burn oven, whatever... putting in the elbow grease and effort to physically make sure it is clean will reap the benefits over years and tens of thousands of miles of driving.

This is between the outside wall of the block and the cylinder bores. The light hole in the background is a freeze plug hole. In this picture the block is upside down, so the top of this picture is actually the bottom of the water passages.

Be careful not to pick to hard. There is a crater in the bottom left quarter of this picture I don't really like. Thats one step past the line too far. But in the last 8K miles everything has been fine.

Between the cylinder bores.