Best way to flush a coolant system

[askoop]

Well, I need to flush my coolant system soon. I did it last summer, kinda, but didn't get all the old out, so I'm gonna do it again and do it right. I have a 2000 grand Cherokee with the 4.0L engine, if that matters... I have 1.5 gallons of 50/50 prestone/distilled water mix left from last summer. If I get supertech or Advance Auto coolant, is that the same as prestone (I have heard those are made by prestone)? Does mixing different brands matter?

I have found many write ups, but of course, all of them are different. So I have a few questions...

If I install the T in the heater hose, and back flush (with the hose through the T), do I need to remove the thermostat? some say yes and some say no.

If I flush by opening the drain cock and pouring distilled water in the top of the radiator, do I need to remove the thermostat? If I just run it and pour, will that flush everything out?

Are there any better ways to do it? If I back flush with the hose, do I have to get all the hose water out before putting in my coolant/water mix?

What is the verdict on those prestone flush additives? good or bad? will they knock stuff loose and plug up my system, or dissolve some of the junk and clean the system? Is there any additive I should add with the coolant/water mix? What would be the benefit to the additive?

Anything else I should know before I start?

Sorry for all the questions, I just want to get it right this time, so I dint have to do it all again. Thanks!

 

[TR3-2001SE]

First off you want to use a good coolant. Toyota and Honda make the best but it is reported the G05 fluid you can buy at auto zone is almost as good. This is what I used in my 2001 miata. It is fairly expensive compared to prestone but it is low in the stuff that damages your system after a long time. It says it is good for 5 years but I trust it for 3. Then use distilled water. You will need lots for the size system you are doing. You have to have enough to load the system twice and bring it to operating temp and then dump it. You also have to have enough to add it too the antifreeze also. So you first drain the system as completely as possible. I use a gallon or so distilled to make sure the radiator is clean. I then fill with distilled water an bring it to operating temp. Then drain it again. I did this twice. This make sure all the old stuff is out of the block. Now you are ready to add the proper amount of antifreeze. You will also want to clean out the overflow bottle. That it you are done for at least 3 years.

 

[JHZR2]

I tried doing my chevy truck once. I just tried to open the radiator, drain, then flush.

It ended up that I couldnt get any fluid out of the block, etc. Only the radiator. Even filling the radiator with pure water, running until hot and draining resulted in mostly clear water!

I dont know what I did wrong. Surely I did something. I think the key is to remove a radiator hose?

Anyway, my point is, make sure youre getting all the fluid, not just whats in the radiator.

JMH

 

[medic]

I took my vehicle to the shop and had them hook it to the machine. It was only $30 plus the coolant. I am not sure how it works, but at one point I saw the upper radiator hose colapse from the vacuum the machine applied. Pretty much, the tech unhooks the upper hose from the radiator and has fitting that hook into the hose and radiator.

This is a link the the machine he used. I was happy, and now that I see the MSRP on a flush is $69, I am real happy to only pay $30. MotorVac CoolantClean II

 

[Kestas]

The procedure I use is as follows:

1. Drain fluid
2. Remove the thermostat
3. Reinstall the t-stat housing and upper radiator hose
4. Disconnect upper radiator hose at radiator
5. Flush system with garden hose through upper radiator hose until water runs clear
6. Disconnect heater hoses, open heat valve
7. Flush heater core
8. Flush overflow tank
9. Drain as much water as possible from cooling system
10. Siphon water from overflow tank
11. Reinstall thermostat
12. Button everything back up
13. Refill cooling system with specified amount of antifreeze, bring up to level with water, preferably distilled
14. Run car, top off coolant
15. Keep adding water as required every morning until system is topped off

I heard it sometimes helps to run the engine a bit while it's flushing. This helps move fluid from any dead spots.

 

[doitmyself]

My 2 cents based on lurking on a few forums:

I have the impression that today's new generation coolants require very pure water to maintain their fussy chemistry. Old formulations said use "quality water". New bottles say to use DI or distilled water only.

Using a garden hose could leave half of the system's capacity full of questionable water - softened water, city water, or very hard well water.

And, that one year old Prestone is probably the old silicate formula - not compatible with their new Dexron clone extended life formula.

What ever you do, my vote is to use really good water.

I used the drain and refill method in the past. It is just very time consuming to warm the engine up enough to get the thermostat to open and circulate everything.

 

[Roger]

I'm a believer in using the type of coolant specified by the manufacturer and not experimenting with others available these days, but that's just me. I'm not smart enough to figure out the difference between the confusing array of coolants on the market today to know if a different breed works okay in my vehicle. So if Jeep specified good old ethylene glycol, that's what I'd use. Dexcol? Then use Dexcol and sleep well at night.

Last weekend I changed the coolant in my E150 and used Prestone Cleaner for the very 1st time. It was a pain because it specified removing all the coolant inorder for the cleaner to do its job the best. After draining the radiator and block 3 times and STILL getting a light green color coming out, I gave into removing the heater hoses and flushing the system both ways with a garden hose. I did not bother taking out the thermostat (big PITA anyway) because with the garden hose, clear water came out the block plug when flushing the heater hoses one direction, and clear water eventually came out the radiator drain cock when flushing the heater hose in the opposite direction. Then I loaded the Prestone Cleaner & plain water and drove the van for about 4-5 hours over a couple of days (another PITA) before draining the cleaner. It came out a light pea green/brown color despite all the previous clear water flushes beforehand. No interesting chunks of anything, just a dirty color. I suspect the cleaner "bleached" the inside somewhat, but did not even put a dent in the white-powdery corrosion I could see through the cap inside the top of my radiator. Still, I'm glad I used it.

At that piont I put the garden hose to the van's heater hoses once again, refilled with distilled water, ran the engine till the upper radiator hose got hot so I knew the water was circulating thru the system, and then drained the radiator and block. Did this last step twice more before finally adding the fresh coolant and distilled water.

In my case draining the block and radiator took out about 14 quarts from a 20 quart capacity system. So I figured 3 flushes took out about 95% of the residual liquid. Good enough for me.

Then came the best part...using a couple of Coors Lights to "flush" my primary coolant system!

 

[johnd]

In an automechanics class in H.S. I remember seeing a device that was made to flush out radiators and blocks. It had inputs for water and compressed air. I built one out of PVC pipe. A hose coupling on one side and a Milton air fitting on the other, two valves and a common output. We tried it out on my son's truck. Took the thermostat out and back flushed the radiator and block. Lots more junk came out once I turned on the compressed air along with the water. It does require that you have a compressed air source but it did seem to work.

JohnD.

 

[Bob The Builder]

Hi kids. I wanted to make a suggestion. I remove the thermostat and reconnect the housing, then I remove the radiator cap and run my wet/dry shop vac through the upper hose as I am refilling the rad with fresh distilled water. It sucks everything out. Works pretty good. Do I get a prize for the most innovative tech tip?

BtB

 

[JohnBrowning]

Prestone reverse flush kit is my pick they have been around since at least 1986 maybe longer. I like Toyota Red Long Life the best but would not be afraid of G05 if that is all that is available. You have to make sure you get all of the old coolant out though when switching from one type to another. Even though G05 is tolerant of hard water it is still best to use distilled water. If you just can not afford $.89 to $1 a gallon for distilled water at the super market at I would at the least use a water filter to remove as much as possable from the water. I will use my pure filtered water to top off the resovoir but not for a complete refill!

Even with long life coolants I like to drain the radiator by opening the petcock valve and just refilling the radiator with distilled water and coolant once a year. This almost illimanates the need to ever do a formal flush on the system. This only works though if you are useing the OEM coolant. I would never recomend Dex-Cool in any system that passes coolant through anytype of plastic polymer. Ford,Chrysler and Honda all agree that Dex-Cool and plastic parts do not agree. Toyota has not said anything one way or the other on the Dex-Cool issue. My Dad has been useing Dex-Cool in his 1995 Toyota Tacoma for at least 5 year now and not problem. His 2.7 I4 does not pass coolant through anything plastic though either!

 

[Winston]

John,

Don't you need to hook up your hose to use the "prestone reverse flush kit"? That seems like a bad idea to me.

 

[Bob The Builder]

quote:

---

Originally posted by Bob The Builder:
Hi kids. I wanted to make a suggestion. I remove the thermostat and reconnect the housing, then I remove the radiator cap and run my wet/dry shop vac through the upper hose as I am refilling the rad with fresh distilled water. It sucks everything out. Works pretty good. Do I get a prize for the most innovative tech tip?

BtB

---

As I was saying..........

BtB

PS. That way you can use distilled water.

 

[Winston]

OK you get a prize.

 

[kenw]

no it doesn't suck everything out. It sucks the water or whatever until the level drops enough to allow air to bypass it. The low spots will still have water in them.

prize revoked. although you now qualify for the BITOG overkill award of the year. Which considering the propensity for irrational, psuedo-scientific behavior here, is in itself quite an accomplishment....

 

[Bob The Builder]

quote:

---

Originally posted by kenw:
no it doesn't suck everything out. It sucks the water or whatever until the level drops enough to allow air to bypass it. The low spots will still have water in them.

prize revoked. although you now qualify for the BITOG overkill award of the year. Which considering the propensity for irrational, psuedo-scientific behavior here, is in itself quite an accomplishment....

---

Hello. Well, what if you don't ever let the radiator empty itself of water. In other words, make sure that the radiator is constantly filled with clean distilled water. and eventually, the bad stuff will get sucked out do to suction and dilution.

Can't you see how this would work? I have done it, and it eventually comes out clean.

Can I have my prize back now?...

BtB

 

[LarryL]

Until I moved into the new house I had a hand pump that I used to pump distilled water through the cooling system with the thermostat removed and the heater on hot. Now, I'm looking for a new hand pump, any ideas?

 

[johnd]

quote:

---

John,
Don't you need to hook up your hose to use the "prestone reverse flush kit"? That seems like a bad idea to me.

---

I would have responded sooner but I just noticed your post.

If your concern is tap water in the block, yes I'd say so unless you run some distilled or de-ionized through later. Used to be nobody much cared what kind of water went in a radiator but that thinking has changed of late.

 

[y_p_w]

My general opinion is that I'd rather not flush the coolant unless there's some sort of problem with scale or corrosion buildup. The vast majority of coolants these days (even the so-called "conventional" ones) contain some sort of organic acid corrosion inhbitor, which forms a protective coating over a period of time. Anything really vigorous (esp a chemical flush) might partially or fully strip this coating. I prefer to do a drain and fill.

 

[1sttruck]

I just changed the coolant in our older Taurus using some Prestone extended life (?). I wanted to use new coolant mixed 50% with water as a flush as you can't drain all of the fluid out and I didn't want to dilute the new stuff with left over whatever else would be used as a flush. Since the coolant being changed was in decent shape, two years old, I also didn't need to use some sort of scale or rust remover.

I drained out what I could, closed the drain, poured half a container of new coolant and half a container of water in the engine, mixed the remaining water and coolant in one container, put the radioator cap part way on, started the engine, took the cap off, and let it run for awhile to get mixed and 'flushed', pouring in more 50% water/coolant until it was pretty full. After running awhile and before it started overflowing I turned off the engine. While it was and cooling I siphoned out the coolant overflow, cleaned and flushed it too, and added new coolant/water to the cold line. Once it was cool enough I drained it again, and added more new coolant mixed 50% with water. This time when I started the engine I added coolant and let it run until it started overflowing, I put the cap on, did a short test drive, topped off the overflow, and then did a longer test drive.

It runs cooler, I guess because not only did I change the thermostat, but because I added coolant :^)

 

[rocketman]

I did the exact same thing with our 2 vehicles 1997 3.1 Lumina and a 1999 4.8 Silverado. The only thing I did different was doing the second drain a few days later after abit of driving. I plan on doing one more to each vehicle at summer's end then every 2 years. Was told to run the heater now and then in the summer (?) to keep the coolant in the heater core circulating. Both use the "dreaded Dexcool". No problems as of yet. I keep a close eye on it. How does 1sttruck's method and mine sound if there has been no history of coolant problem's