Coolant flush questions

tutz724 · Jun 21, 2014

I have a question about getting the proper 50/50 mix when flushing my coolant system.

I've never done this task, but it seems easy enough. The question I have is about getting the proper 50/50 mix of coolant to water. While flushing the system I should continue to add water while the engine is running until clear water comes out of the top radiator hose, correct? This would mean that the system has only clean water and no coolant in it. Now the question I have is how much coolant can I expect to add to the water? Seems to me that if the owners manual states a 16.8qt capacity, 8.4 of those qts need to be coolant and 8.4 of those qts need to be water.

If I flish the system until clean water comes out, can is it safe to assume I can add 8.4 qts of coolant to the system and then top of with water until it's full? That should get me the proper mixture in my mind. The other question is: what do I do if I go to add coolant and it won't take the 8.4 qts? That would lead me to believe that the ratio is off, thus I did something wrong.

Just a math check, 8.4 qts would be 2.5gal of coolant, so buying 3 gal of coolant and having half a gal left over should mean I have the correct amount of coolant in the system.

Sorry if this is a stupid question, but I want to be sure I'm not overlooking anything.

Thank you.

Onlyina_Chevy · Jun 21, 2014

Not a stupid question. Questions like this are great. While it seems to most people that this is an elementary question with a simple answer that anyone should know, we must always try to remember that we were not "born" with the knowledge of how to fix or maintain a vehicle; it is learned over time through experience and research.

Anyone can research an answer, but it isn't till that first answer is thrown out there that the debate begins. You also asked your question in Shop Talk and a decent conversation started there via different people's ideas of how to complete your issue.

Don't EVER be afraid to ask a question, we all had to start somewhere (just don't ask "Hey, what's the biggest tire I can put under my truck w/o a level?"; then I'd have to kill you).

SierraHarley · Jun 21, 2014

I agree, don't be afraid to ask questions. Having said that I was wondering something myself...
Hey, what's the biggest tire I can put under my truck w/o a level?

Z15 · Jun 21, 2014

Waste antifreeze contains heavy metals such as lead, cadmium, and chromium in high enough levels to potentially make it a regulated hazardous waste, so most states strictly regulate antifreeze disposal. Antifreeze generators and state and local programs should not dump spent antifreeze on land or discharge it into a sanitary sewer, storm drain, ditch, dry well, or septic system; dumping antifreeze can cause serious water quality problems and might harm people, pets, or wildlife.

Its sometime less of a problem if you have a professional shop do it.

Cornfed · Jun 21, 2014

First let's clear up some of your concerns. Your manual calls for a 50-50 mix of coolant and water. If you end up with 49-51 mix or even a 60-40 mix, the engine will not blow up and your warranty (if any) will not be voided.

Flush the system until the fluid runs clear. Turn off water and let run a minute or so to drain system down. Fill with radiator fluid. Do not be worried about is it .4 qt or .8 qt. Put in 8 qt or put in 9 qt. What you going to do with the extra .6 qt? The EPA regulations and fines for improper disposal is probably higher than price of a new engine. With the coolant in, add water until full.

Your on the right track with what you are trying to do. There are situations were .1 of a inch or 1 cm makes a big difference. This is not one of them.

Cf

tutz724 · Jun 21, 2014

Well, the job is done. It wasn't as easy as I had imagined, but it wasn't terrible. I caught some snags along the way that slowed me down:

First off, that factory clamp on the radiator hoses that requires pushing the tabs together to remove is a pain in the ass! I ended up switching it with a regular radiator hose clamp, made it a heck of a lot easier.

Then, completely unrelated, my battery died before I got to do the flush run, so I had to wait for someone to give me a jump to continue. I pretty much ran it until it was clear. There was a little red tint to it, but I ran 4 gallons of distilled water through it and ran out so I figured it was best to cut the engine at that point. I hooked the top radiator hose back up and proceeded to put 100% dexcool in. I'm a little confused why it didnt take a full two gallons of dexcool, though. I drained the radiator before putting the dexcool in, and had it running while adding it. Any thoughts?

I let it idle for a while so it got to temp and it never overheated. The reservoir shows coolant in it while it idles at operating temperature. Is this a problem. Right now I'm letting it cool to see where the cold level is. If it doesnt come up when cool I'll add the remaining dexcool.

Any suggestions? Concerns with what I did? Anybody see any gaping holes in my work? Thanks.

tutz724 · Jun 21, 2014

Oh, and also! This job is very messy! I do not like the way the system is set up for maintenance purposes. In a shop I'm sure it's cake, but backyard the backyard mechanic will be hard pressed to not let at least a drop or two (or more) hit the ground without the use of a large catch container. Just an observation of mine.

bryn0727 · Sep 25, 2017

bryn0727 said:
First let me say thank y'all for this thread the detail and the pictures were incredibly useful. Here is my experience and some additional useful links. Coolant Flush types, advice & opinions

bryn0727 said:

For any of those following along or considering attempting this here is my update after fighting through this..

Also these posts helped me the most and answered questions that I didn't think of on the front end so I highly suggest reading them prior to starting. Most useful in order...

2009 Silverado 100k Coolant Flush
Coolant flush questions
coolant flush

What I did right...

1) Bought CONCENTRATED Prestone dex-cool and plenty of distilled water (like 7 gallons of water)

2) Unhooked the engine side of the lower radiator hose instead of the radiator side. (reason being I had better control of where the fluid drained to and the hose clamp on that side is MUCH easier to handle.)

3) After I felt that I had flushed enough I drained again from the lower hose with the engine off, and started the refill with straight concentrated dex cool instead of water or mix. (I knew I wasn't able to completely drain ALL of the 'flushing' water from the system so it made sense that if I was going to try to get the 50/50 mixture I needed to start with straight coolant. Low and behold it didn't even take a full gallon of coolant when filling up the reservoir tank.)

It didn't seem like it would be an issue to get the 50/50 mixture before getting started. 16.9qt capacity so 8.45 coolant 8.45 distilled water right?? NO!! the problem I didn't realize is that the system wouldn't be able to be drained completely so the leaves an undetermined amount of water that you have to kind of guess how much coolant you need to offset. See links for posts 2 & 3 above.

What I did wrong...

1) Bought that $40 hose clamp plier from auto store xxxx. ( The tool is and would be very useful and convenient to have so I suggest getting a GOOD one online if you have the time to wait for it to come in. BUT the one from AZ, AAP & O'R are all cheaply made and don't depress the clamps enough to use for this job. The one I bought broke on the second try on the top hose clamp. Take this advice for what it's worth to you.)

2) Didn't keep track of how much fluids I was draining each time. (This is important in two ways... First it helps to know so you know how much coolant and/or water you need to re-add each time. Second, my 4 gallon drain pan got too full before I realized I needed to drain to some empty containers and I had a mess to deal with because of it.)

3) I didn't run the engine the full 10 minute (or to normal 210 degree temp) between draining's while flushing. I ran it until the fans kicked on and this may end up not being that big of a deal, but I tend to over analyze and over do things so me being me I didn't feel confident in the end because of it. I did do the flush 4 times so I feel confident that I circulated the system enough, but IMO I'd suggest going the full 10 minutes each time.

At the moment I only have one full gallon of dex-cool in the system. It's running fine and have had no issue getting hot yet, but I'm not going to sleep right until I know there's 2 gallons of coolant in there. Highly likely I start this process all over again and do it right. Anyone that has suggestions/feedback/comments please feel free.

Click to expand...

TRICK1 · Nov 9, 2017

At the end of the day it all boils down to proper protection, This is done by checking the fluid with a antifreeze gauge.
On the back of the jug there is usually a table showing mix to protection and the gauge will show you where you stand.
If needed drain some fluid, add water or coolant accordingly.

sobieski · Nov 9, 2017

Where are the drain plugs on the block.
A 1998 5.7L v8 ?
I need to really drain the block thoroughly.

TRICK1 · Nov 9, 2017

Never heard of a drain plug, I can only suggest removing the pump running a small hose in and pumping it out.

jake2250 · Nov 9, 2017

Here's what has helped me,, The wifes cat passed away a few years ago, thus leaving behind I was willed the cats liter box! Very thoughtful of a cat that I never got along with!
Litter box has a rather large plastic bottom, the top was useless to me so I recycled it!
I use this cat pan for fluid retrieval in the shop,, kinda like the cat did but on a larger scale (unless your the one that has to clean the liter box)!
I find it helpful when doing a coolant change, it catches 98% of the old coolant!
I also learned a few years back that it is best to use Distilled Water when mixing it with coolant. Where I live we have hard water (lots of metals and other crap). A gallon of distilled water at the grocery store is $.99, so I always have a few gallons on hand!
The other benefit of that is,,I have a few empty gallon jugs. I buy non mixed coolant and just mix it 50/50 in a gallon jug. Now I know I have good water with good coolant! Also makes it easy to Pre-test the coolant with a coolant gauge or meter (a must have tool).

silentbravo · Nov 10, 2017

tutz724 said:
Well, the job is done. It wasn't as easy as I had imagined, but it wasn't terrible. I caught some snags along the way that slowed me down:

First off, that factory clamp on the radiator hoses that requires pushing the tabs together to remove is a pain in the ass! I ended up switching it with a regular radiator hose clamp, made it a heck of a lot easier.

Then, completely unrelated, my battery died before I got to do the flush run, so I had to wait for someone to give me a jump to continue. I pretty much ran it until it was clear. There was a little red tint to it, but I ran 4 gallons of distilled water through it and ran out so I figured it was best to cut the engine at that point. I hooked the top radiator hose back up and proceeded to put 100% dexcool in. I'm a little confused why it didnt take a full two gallons of dexcool, though. I drained the radiator before putting the dexcool in, and had it running while adding it. Any thoughts?

I let it idle for a while so it got to temp and it never overheated. The reservoir shows coolant in it while it idles at operating temperature. Is this a problem. Right now I'm letting it cool to see where the cold level is. If it doesnt come up when cool I'll add the remaining dexcool.

Any suggestions? Concerns with what I did? Anybody see any gaping holes in my work? Thanks.

I found the same thing as you when I changed my coolant. The block and hoses hold more than half of the water you used to flush with, so adding back the 2 gallons of dexcool doesn't quite fit back in there. I fit like 1.5 gallons of dex back into my truck and then it was "full" so I ended up draining out a bit of the mix and adding the rest of the concentrated dexcool back in. It worked out alright the coolant mix gauge I used said it was good to like -40 F or colder so I think it was mixed well enough.

The expansion reservoir on the fender is supposed to be about halfway filled up at cold, it has a mark or something that says on it but its basically halfway down. It may take some time to get get air out of the system if you introduced any (it likes to get stuck in the heater core) so if you hear some running water sounds while driving that is probably air in the system and it should eventually work its way back to the expansion tank, and you may have to top off the coolant from there.

Sounds like you did it right, I agree with that lower radiator hose clamp being a pain though. Probably the worst part of the job lol

crbws6 · Nov 24, 2017

bryn0727,
I assume you figured it out, but for the sake of others, to get 2 gallons of concentrated coolant back in, you need to get that much out with each drain.

I found that removing the entire thermostat housing instead of just the lower hose allowed 2 galllons to drain out. About half from the engine and half from the radiator.

The nice thing about this approach is nothing else needs removed. Just reach under the intake tube with a standard 10mm socket and a short extension on the 2 housing bolts. No RTV or threadlocker necessary. The bolts are only 11 ft-#, so be sure not to overtighten. I placed aluminum foil over the compressor and belts to keep things tidy. I did 3 drains and added back distilled water. On the final drain, I filled back with Prestone Dex concentrate.

Coolant flush questions

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