Flushing GM 6.2L

Status
Not open for further replies.
Joined
Jun 4, 2014
Messages
6
Location
LA
I have a GM 6.2L with about 107k miles & I'm needed to do all of the 100k mile mark maintenance.I have a few questions.

1. What's the radiator capacity?
2. Is flushing with distilled water ideal?*

*Where I am renting, the water is not suitable to drink (long story) & there's not only high sulfur, but debris. I feel I should just buy water at Walmart to circumvent any issues.

3. I live on the Gulf coast, so I believe any freeze temps are gone until Nov/Dec. Should I just fill half w/ Dex-Cool 50/50 & the rest w/ distilled water or just go 100% 50/50 mix?

This is my first time flushing out the radiator, so I'd rather get it right than to cause damage.
 
Last edited:
If the water is that bad then yes get water from Walmart and use that. Flush it until is runs clear and then go back with the 50/50 mix. You need to keep it at that ratio for protection against freezing as well as to keep corrosion down.

What year GM? I would say it takes 17qts total for the cooling system.
 
Thanks guys.

It's a 2009 H2. I just searched again & found it. 16.7qt. Right on the money, Rat407! The SUT (truck version) holds less, which is weird!

I figured 100% 50/50 would work no matter what.


One other quick question.
To flush the rad, is something like Prestone flush & cleaner a good product or is there something better you guys recommend?
 
I would flush with distilled water following this basic process:

1. Drain the radiator (whether that can be done via petcock or detaching lower radiator hose) and then close it back up
2. Refill with distilled water
3. Run engine for a few minutes
4. Drain the radiator and close it back up
5. Follow steps 2 to 4 until what is draining is clear (probably 3 to 4 drain and fills)
6. Add concentrated (not 50/50) coolant at 50% of the cooling system capacity (so about 8.5 quarts in your case)
7. Top off with distilled water
8. Do whatever you need to do for your vehicle to "burp" the cooling system in order to remove trapped air

It is important that you use 100% coolant in step 6 because you will still have some straight distilled water in the system. If you add 50/50 at that point, your final mix well be more like 30/70 or 40/60 coolant/water.
 
Drain and fill with Distilled water 4-5 times and then add 2 gallons of straight coolant into the system. No reason to buy a third gallon to get the extra quart.
 
Now I have a plan of action, thanks NMBurb02.

901Memphis, that'll be the easiest. A little more water won't hurt (8qt vs 8.5qt).
 
I wouldn't flush it per se. I would drain the radiator, pull the thermostat and drain the block and then refill what you pulled out with a 50/50 mix of whatever coolant the manufacturer recommends and distilled water. The chemical flushes you buy at parts houses can be dangerous, and flushing with tap water can lead to enhanced electrolysis. You could take it to a local BG shop and have the coolant system serviced, but it seems like you want to DIY. No problem with that, Im the same way with most things, but I darn sure wouldn't put that non potable water through the system. Oh and while your there doing the 100k mile maintenance, I would even consider replacing the water pump, belts, hoses, pulleys, fan clutch, spark plugs, coils etc. May as well while your there. Just my
49.gif
thumbsup2.gif
 
Last edited:
I just did a drain and fill with almost 2 gallons of distilled water, drove for a day, drain and fill with one gallon concentrate dexcool, and top off with 50/50 (approx half gallon) to normal level. Now I'm good for the next 3 years at least
 
Originally Posted By: jk_636
I wouldn't flush it per se. I would drain the radiator, pull the thermostat and drain the block and then refill what you pulled out with a 50/50 mix of whatever coolant the manufacturer recommends and distilled water. The chemical flushes you buy at parts houses can be dangerous, and flushing with tap water can lead to enhanced electrolysis. You could take it to a local BG shop and have the coolant system serviced, but it seems like you want to DIY. No problem with that, Im the same way with most things, but I darn sure wouldn't put that non potable water through the system. Oh and while your there doing the 100k mile maintenance, I would even consider replacing the water pump, belts, hoses, pulleys, fan clutch, spark plugs, coils etc. May as well while your there. Just my
49.gif
thumbsup2.gif




Dude, cmon!!!

Wile you're changing the oil and filter, may as well change the drain plug gasket, oil pump, oil cooler lines, fill cap, drain plug and gasket. Sorry!




To the OP, I would (and did) just pull the lower rad hose and let drain, put back on and fill with Dex and distilled at about 50/50. On the Saturn I had, I did as was mentioned and drained, filled with water, then ran engine on full heat until at temp, cool, drain and repeat til clear. The guy at the shop I took the runoff coolant to didnt seem happy, but peeved and a bit confused when I took in several gallons of used dex.
 
I went to Walmart today & picked up 18 gal of distilled for 4 gal per flush (could be up to 4 flushes) + 2 for the diluting the coolant. Not a big deal.


mjoekingz28, you make a good point. Do auto part stores not take coolant flushes like used oil? You have to find a mechanic?

I'll probably do the coolant change while changing the oil anyways as I have to remove a skid plate, so I might as well.


guyonearth, if I spray my vehicles w/ tap water, they become extremely spotty with large white circles. I've never seen this before in any house I've lived in. There's also some kind of black crud in the pipes as well. To give you an idea, my shower has a filter on it. Buying 16 gal of water was no biggie.

I'll be doing this when the weather gets better. It's dropped almost 50° degrees in the past 24 hours (79F to 31F tonight).
 
Last edited:
Some municipalities actually recommend dumping it into any sewer connected drain (sink, toilet,,etc.). No rain collecting drains (street drains) or septic tank systems.
 
Status
Not open for further replies.
Back
Top