Best way to flush engine block?

[1KWIKSIX]

I’ve been running distilled water & RMI25 in my cooling system & decided to change over to ethylene glycol (anti freeze) for the winter.
To my horror I found my upper aluminum radiator pipe coated with a thin layer of surface rust .
I’ve run Evaporust ThermoCure cleaner thru the engine for 3-1/2hrs total & drained
What came out was a black coloured liquid.
Have drained the rad & filled with distilled water & run thru heat cycles several times , but still getting muddy looking water.
Believe the block needs to be flushed .
What’s the best way to do this ?
Any recommendations ?
I’d love to hear from you all as I believe there are several different ways to go about this task.
Thanks in advance

 

[Anthony P]

Dave, need a 9/32 pipe plug socket to remove the factory block drain plugs (109 blocks). got that socket from McMaster.

drain plugs are 1/8-27 NPT. replaced the drain plugs with these valves by Omix-Ada. link below or where ever you can get them. the other end is barbed so can use a short hose to direct the drained glop.

I disconnected a heater core hose at the heater core and fed low volume low pressure garden hose water thru the hard line to flush from the top down. disconnected lower rad hose at rad so that glop would not enter radiator. also used compressed air at about 15psi to blow thru the hard line to evacuate the water around the block drains. did the water flush then compressed air blow down a few times until the water from the drains ran clean.

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[1KWIKSIX]

Thanks Anthony,
I’ve got the 9/32” four point socket on order with McMaster Car.
Just trying to source out locally for a couple
of 1/8-27NPT Angle Brass Bib Drain Cock Valves
Appreciate your help
Have a Merry Christmas & Happy, Healthy New Year

 

[pacecarta]

you don't need a special socket for the drain plugs
just grab a tap handle and tighten it up, its made for square ended taps ..perfect for drain plugs

 

[1KWIKSIX]

Good to know ,
Thank you

 

[6gunn]

Would it be a good idea to use apple cider vinegar or even mix it with water to decrease it's strength? I've used it on ATC gas tanks to get rid of rust and it does a remarkable job. Of course, it's a good idea to use a baking soda/distilled water mix afterwords to neutralize the chemical reaction. Not sure if using vinegar in the cooling system would be harmful to other components(seals, gaskets, ect..) Any input?

 

[Turbo6inKY]

Would it be a good idea to use apple cider vinegar or even mix it with water to decrease it's strength? I've used it on ATC gas tanks to get rid of rust and it does a remarkable job. Of course, it's a good idea to use a baking soda/distilled water mix afterwords to neutralize the chemical reaction. Not sure if using vinegar in the cooling system would be harmful to other components(seals, gaskets, ect..) Any input?

Introducing any acid is going to create a corrosion problem. The OPs mess was created by running straight water with no anti-corrosion additives. Our cooling system has dissimilar metals in contact with each other. That's going to result in some galvanic corrosion, which then contaminates the water and makes it caustic, and the loop starts feeding itself. Let's not make that worse or perpetuate it.

I'd just flush it with hose water until the stuff starts coming out of the block drain clean, then run a few gallons of distilled water through to get rid of the crap from the tap water, and then fill it with 50/50 anti-freeze and distilled water.

And change it annually from here on out. Unless you're racing the car in a series that demands plain water, you shouldn't run plain water. And even if you do race in a series that demands plain water, drain it and fill it with 50/50 for the off-season.

 

[1KWIKSIX]

Decided to run distilled water only a short time since it’s a fresh engine build using ARP head studs. Wanted to be sure the studs were sealed and not leaking antifreeze .
I also used a bottle of RMI25 as I have done in the past when I previously ran glycol / RMI25 mix. Thought this is supposed to also be a corrosion inhibitor?
My initial intention was to run the distilled water for a short time only during engine break in & then change to ethylene glycol however since my garage is heated decided to leave it in. Obviously an error in judgement on my part.
Thanks for your comments & suggestions.

 

[Chuck Leeper]

Sealed studs with a couple GM seal tablets, no issues here.
As for the block drains, I've had some so plugged up I had to run a small drill into the crud, in order to get it loose enough to start digging with the coat hanger.

 

[1KWIKSIX]

Good to know Chuck,
Thanks for the heads up

 

[hensleyt]

I had the same problem with RMI25.Most people like it but it was a fell for me.
I got some Preston radiator flush followed the instructions. Twice. After draining the system
Then I pulled the upper hose off and let it hang down to drain. Then stuff the top radiator inlet with a rage,
I put the garden hose in the radiator and let it run ,started the engine and let it run, it took maybe a hour with the hose and car running to get it clean.