Using tap water to dilute coolant

[Falcon_LS]

A bit of background - the previous owner never replaced the coolant in my Grand Marquis, so it was a total disaster when I got the car. Also, when he had the coolant pump replaced at one point, it was refilled with Dexcool.

Anyhow, I've lost count of how many times I've flushed the cooling system using various methods. I always use Motorcraft G-05 at a 50/50 ratio, but it always turns dark orange with a brownish tint to it without fail. I also use Liqui-Moly's radiator cleaner, which I add 2 cans of to the cooling system and let the engine idle for 30 minutes as instructed. I use distilled water to flush and refill as well.

As far as how I flush the system is concerned, I first remove the thermostat and the upper radiator hose. I block the upper radiator orifice with a radiator hose I've attached a radiator cap to, to prevent coolant from spilling out as I flush out the system. Next, I start the engine and keep feeding relatively warm distilled water until it runs clean.

Now I don't know what's turning the coolant brownish orange, but I'm thinking about continuing to flush the system another couple of times. Now the problem with this is distilled water is only available in 1 liter bottles, so I end up filling 3 10 liter containers to flush the system. But this isn't doing my back any good.

I was wondering if I could use regular tap water from a running hose to flush the system and make things easier, but dilute the coolant with distilled water. Or on another note, dilute the coolant with tap water but shorten my coolant replacement intervals. Currently that stands at 25,000 miles or 2 years, but I'm really flushing out the system every 6,000 miles because of the color change! Thanks for any input!

 

[eljefino]

You sure could! Can you get some "somewhat filtered" water for 25c a gallon at a supermarket or something? I have to imagine in your desert climate the tap water is somewhat nasty.

I would put tap in, run it for a day (with thermostat), dump it, repeat a few times, then run distilled, then dump that, then make a 50/50 mix.

But there are lots of ways to do it.

 

[Falcon_LS]

Thanks for the input!

Our tap water is actually desalinated sea water with a pH of 7. Would this be alright?

 

[mongo161]

Sounds like you may have some rust in the system. I would use a hose to flush the system as clean as you can get it. I would then open up the plugs on the engine block to empty the engine of water. Once I was satisfied that most of the rust and dark color has been removed, I would then use a couple of runs and flushes of Distilled Water to make sure that any remaining "tap water" has been removed. Then add your coolant mix.

A few years back...I had a Mercury Grand Marquis that had a similar problem. I could not get the water clean after repeated flushes. I finally decided to remove both hoses and run the garden hose full blast through the top and then the bottom of the engine block. I then used a a long narrow brush to see what I could pull out of the bottom of the engine block. After repeated "dragging and pulling" I removed flat pieces of metal and rust.

This led me to believe that they never cleaned out the engine block on the assembly line. It sure appeared that the workers left any scrap metal that fell inside there and it continued to rust in the bottom of the block.

Anyway after getting out all the debris from the engine block the water ran clean. The cause of the rusty, discolored water was the scraps of iron and steel wedged in the bottom of the bock. So much for quality control.....that was the last American made car that I had before getting my Toyota.

 

[eljefino]

Originally Posted By: Falcon_LS
Thanks for the input!

Our tap water is actually desalinated sea water with a pH of 7. Would this be alright?


Depends on the process. If they run it through an osmosis filter that only gets 99% of the salt, I'd be wary. Does it taste alright? Do people regularly drink it without further filtration at the faucet?

I have to imagine there are shortcuts taken to make it economical for the Water Authority.

 

[JHZR2]

I wouldnt use RO water, as it can have 500+PPM of TDS.

 

[SLCraig]

I always use tap water to dilute my coolant when I do a coolant replacement. Have never had problem. Just have to have the right mix.

 

[Brons2]

Originally Posted By: SLCraig
I always use tap water to dilute my coolant when I do a coolant replacement. Have never had problem. Just have to have the right mix.


You must have very high quality tapwater. Many locales have hard water that will clog your radiator. San Antonio's tap water is a nearby (to me) example of a large city water supply that is full of sediment. Tastes like drinking gravel. As for our water here in Austin, it tastes like fish excrement. IMHO. I would not put either in my car.

 

[Boomer]

Also, a flush with oxalic acid dissolved in water is an excellent way of purging rust from the system. There are various oxalic acid flushes available on the market. The acid (a solid found naturally in rhubarb) complexes with iron ions and this is what makes it a godd "rust flush."

 

[mongo161]

I use good old NYC hose water to flush the system....then a few rinses of Distilled Water to get all of the tap water out. I mix my coolant with Distilled Water and not tap water.

 

[Provi]

Originally Posted By: Brons2
Originally Posted By: SLCraig
I always use tap water to dilute my coolant when I do a coolant replacement. Have never had problem. Just have to have the right mix.


You must have very high quality tapwater. Many locales have hard water that will clog your radiator. San Antonio's tap water is a nearby (to me) example of a large city water supply that is full of sediment. Tastes like drinking gravel. As for our water here in Austin, it tastes like fish excrement. IMHO. I would not put either in my car.


Yeah that water is nasty, had to drink it for 6.5 weeks for Air Force Basic Training in 2004

 

[nleksan]

Here in the Cincinnati 'burbs, at least on the east side, the tap water ranges from "better than bottled" to "one step away from being brown sludge", with my house getting a bit better than "the middleground". I have a water particulate meter and just did a few comparisons:
Tap = 258TDS (total dissolved solids)
Brita-Filtered Tap = 188TDS ph7.13
Smartwater GE Fridge Filter = 122TDS ph7.05
Aquafina Bottled = 45TDS ph7.05
PUR-Filtered Tap = 39TDS ph7.07
ZeroWater-Filtered Tap = 0TDS ph7.02
Store-Bought 5L Distilled = 11TDS ph7.00
Reverse-Osmosis Full House Filter = 2TDS ph7.02

I always use store-bought distilled water and run it through the ZeroWater filter to end up with pH-neutral 0tds water and it is the cheapest way I have found to get "perfect" water to use in cooling systems.
I run this in a 60:40 H2O:Coolant ratio in most cars, 70:30 in my 328, all with a bottle of RL WW, and it works wonderfully.
I did a radiator flush and there was no limescale or rust buildup, so now I use this method on all my cars.

I may be overly-anal, but I don't want my cooling system to lose efficiency. Plus, it is way cheaper than a new radiator!

 

[Falcon_LS]

Thanks for all the input. Right, the pH of tap water is 7, but the TDS content is 300-400 with a high level of chlorine. I don't think this is ideal for the cooling system, so I will just continue using distilled to flush.