/6 Cooling System: Multiple Cleanings

[nm9stheham]

FWIW.... the photo here is of the coolant in a /6 that was just rebuilt 700 miles ago. Nothing wrong, just that it has dirtied up pretty quickly. This engine had a ton of sludge in it from setting with little driving for years with no real work to keep the cooling system clean. During the rebuild, the block was not only hot tanked but also acid tanked to help clean out the cooling passages. Yet 'stuff' is still being cleaned out from it.

So, if you have an old /6 that has not been run much, you may want to do several cooling system cleanings and coolant renewals over the course of many months or a year; one 'treatment' will not likely do it.

BTW this coolant is the G05 stuff, which is nearly clear when new. Hence, the lack of green tint.

 

[autoxcuda]

Did you take the radiator and heater core to a radiator shop to have them rodded out and cleaned when you have the motor rebuilt?

When the block was bare and you had the freeze plug out did you look for and pick out any flakes and debris in the cooling passages around the cylinder bores through the freeze plug holes?

 

[RedFish]

heater core is a player also. Drape the heater hoses over the fender and flush with a garden hose until water comes out clear. Reverse direction of water flow and more dirty comes out. By the way... Does a clear coolant include rust inhibitor ? If its designed for the modern all aluminum systems.... just curious.

 

[nm9stheham]

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.

 

[BillGrissom]

After much reading, I started using citric acid to flush while driving. I bought on ebay. Prestone used to use that, but their products seem wimpier today. I put a screen in the upper radiator hose to catch any debris. Seems to remove rust well. Did several in my fleet so far, when switching them to waterless coolant. I hate rust so much the cost is worth it to me.

 

[autoxcuda]

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.