Coolant flush or drain?

thomas04 · **Joined:** Sun Feb 28, 2010 1:57 pm **Posts:** 129

The time has come to replace my coolant. Is a flush much differnet from a drain or will a drain be just as effective as a flush? Mainly, what will keep the Jeep happy and running without problems? Thanks.

Peace.

rob40wilson03 · **Joined:** Sun Jul 10, 2011 9:43 pm **Posts:** 51

If you're doing the work yourself, flush it! All you have to do is drain it, fill it back up with DISTILLED water, run it for a minute, drain again. Repeat until the water comes out nice and clear. Then fill it back up with a 50/50 mix of the proper antifreeze and distilled water.

thomas04 · **Joined:** Sun Feb 28, 2010 1:57 pm **Posts:** 129

Thanks for the help. Is there anything else I should be aware of before I dive into the change? I have read a couple different post and there some seem to say draining from the petcock is enough others recommend the lower hose removal. Will it make a difference? Also, draining then refilling with water, draining and refilling with water 5 more times is all that is really required?
Thanks.

Peace.

papaindigo · **Posted:** Sat Dec 31, 2011 9:26 am

See my post part way down viewtopic.php?f=5&t=64323&p=709785&hilit=flush#p709785 .

Don't even think about trying to remove the lower radiator hose. I've looked and it's simply not worth the trouble.

Some things to remember. The plastic container on the firewall functions as both the top of the radiator and the overflow bottle so only open its cap on a cold or almost cold engine. To drain 1) open that cap; 2) open drain at bottom passenger side of radiator; 3) wait until plastic container drains then crack the vent (FYI it can be removed by turning to 4 o'clock and pulling up) on the top passenger side of the radiator. To fill 1) close lower drain; 2) add fluid to plastic tank until it overflows at that top radiator vent; 3) close that vent; 4) complete fill and reinstall plastic tank cap. For final fill 1) follow fill instructions BUT add unmixed antifreeze first to make sure you get all of about 1.6 gallons into the system and then top off with demineralized water (don't worry about mixing that will happen as you drive); 2) top off plastic tank to about 1/2" above midline; 3) do a couple of drive cycles to full operating temp and full cool down to purge air from the system; 4) check coolant level in plastic tank, it may go down a little bit, top off as needed.

thomas04 · **Joined:** Sun Feb 28, 2010 1:57 pm **Posts:** 129

Completed flush this morning. Took only 4 distilled water flushes to get clear discharge. Everything else went over smoothly. Thanks to all who replied. I will be watching for air over the next couple of days while I drive it around. Unless otherwise noted, all is well! Peace.

CRDMiller · **Posted:** Sun Jan 01, 2012 7:49 pm

I swapped the coolant I my crd from g-05 to elc around 3 years ago (and 60 thousand miles)

I drained and refilled the radiator with distilled water, ran it to operating temp (to open thermostat) and repeated untill samples taken from drain water registered at 1.0 on a refractometer (around 6 refills). Then i added 100% elc untill it was 50/50 on the refractometer.

Was it unnecessary to attempt to get to thermostat opening temp? I know from replacing the t-stat that coolant has a few different options to get around the t-stat, but i wanted to be sure. What do you guys think?

papaindigo · **Posted:** Mon Jan 02, 2012 8:32 am

I'm not sure what you mean by ELC, which normally stands for Extended Life Coolant, since Xerex G-05 is an ELC. The important thing is to use a HOAT ELC such as Xerex G-05, Mopar ELC, or Motorcraft Gold ELC or some such not an OAT or "universal" ELC. Too much chance of clogged coolant passages.

I don't think there is any special need to get up to operating temp doing the fill and drain version of a flush. On a closed or mostly closed CRD tstat the path to the viscous/heater core, degas port, and bypass to water pump and hence the block are all open. On an open tstat the bypass is closed and the path to the radiator and water pump and hence the block is open as are the ones to the viscous/heater core and degass port. Since you drain via the lowest point of the radiator (e.g. the plug at the lower passenger side of the radiator presumably with the vent on the top of the passenger side of the radiator open after the coolant bottle drains the entire system is "open to air". The only difference is on a cold tstat the block may drain mostly backwards (e.g. via the lower radiator hose) as opposed to on a open tstat at least some of the block will drain thru the upper radiator hose. But think about it - in either case gravity controls hence the only way (tstat open or closed) the system can drain is by coolant flowing "down" which means in either case the majority of the flow is 1) down from the radiator core (vented to air by that passenger side vent and 2) down thru the lower radiator hose vented to air via the degass port.

Bottom line is I think the most important thing is to only open the top radiator vent AFTER the coolant tank has drained. Doing so opens the higher parts of the system to air via the degass port and that tank and forces them to fully drain first. Once they are drained opening that vent allows the remainder of the system to drain faster.

LMWatBullRun · **Posted:** Mon Jan 02, 2012 11:18 am

My CRD has yellow coolant in the reservoir, not the red stuff. This did not concern me at first, as all of my (older) vehicles used regular glycol based antifreezes, and I figured I could flush and refill with regular antifreeze as part of my planned complete fluid replacement when the time came. Having done some reading here, now I am concerned that if the PO went to regular antifreeze that I may have a problem changing back to the right stuff. My intention is to use this vehicle for heavy duty use, (Mountain driving, OR, highspeed towing, etc) which is why I got the diesel engine, and I do not want any problems with proper engine cooling, so I want to use the specified coolant. I also do not want to clog the radiator!

Is there any easy way to test this and figure out what is in the cooling system now? I probably should know this but I simply have never used anything other than glycol antifreezes, and I'm a bit taken aback. Advise would be welcomed!

Larry

papaindigo · **Posted:** Mon Jan 02, 2012 12:11 pm

Color doesn't tell you a whole lot about what you have in the system although I'd be inclined to guess just regular old Prestone or something similar. Zerex G-05 HOAT coolant seems to be on the pinkish side of clear, I don't know about the color of Mopar or Motorcraft HOAT coolant.

IMHO your best bet is to clean out the system of all that yellow stuff, see the link in my earlier post as to how. Assuming you get a clean drain (e.g. no solids in the fluid) you should be just fine refilling with one of the above 3 HOAT coolants.

Note at least one member had a fully clogged radiator and another did get a few solids out of his heater core. A few probably don't matter especially if you use racertracer's method and don't see any after the initial flush. FYI a simple drain should produce about 8qts of fluid, if you get a lot less then something may be clogged. Also FYI the drain goes much faster if 1) on cold engine open radiator cap on plastic firewall tank, 2) open bottom radiator drain with the mentioned tool, 3) let plastic tank drain, 4) open vent on top passenger side of radiator to speed up the final drain. Refill is more or less the reverse but also goes faster if you fill from from the firewall tank until fluid comes out of that radiator vent, then close it to complete the fill.

LMWatBullRun · **Posted:** Mon Jan 02, 2012 1:06 pm

papaindigo wrote:

Color doesn't tell you a whole lot about what you have in the system although I'd be inclined to guess just regular old Prestone or something similar. Zerex G-05 HOAT coolant seems to be on the pinkish side of clear, I don't know about the color of Mopar or Motorcraft HOAT coolant.

IMHO your best bet is to clean out the system of all that yellow stuff, see the link in my earlier post as to how. Assuming you get a clean drain (e.g. no solids in the fluid) you should be just fine refilling with one of the above 3 HOAT coolants.

Note at least one member had a fully clogged radiator and another did get a few solids out of his heater core. A few probably don't matter especially if you use racertracer's method and don't see any after the initial flush. FYI a simple drain should produce about 8qts of fluid, if you get a lot less then something may be clogged. Also FYI the drain goes much faster if 1) on cold engine open radiator cap on plastic firewall tank, 2) open bottom radiator drain with the mentioned tool, 3) let plastic tank drain, 4) open vent on top passenger side of radiator to speed up the final drain. Refill is more or less the reverse but also goes faster if you fill from from the firewall tank until fluid comes out of that radiator vent, then close it to complete the fill.

Good tips, PapaIndigo, and I thank you for your response. Anyone have any thoughts on flushing?

Coolant flush or drain?

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