Need coolant flush? or not?

stoutdog · **Posted:** Sat Jan 01, 2011 3:56 pm

It appears that a mechanic filled my CRD with Dex-Cool (not HOAT) coolant when I purchased the vehicle over a year ago and had all the fluids changed. Needless to say, I'd like to change that out now and replace it with some Zerex G-05.

So question: Should I just drain the coolant reservoir and radiator through the drain plug in the bottom or should I be more thorough with it and actually flush the system with a T-joint and a hose?

Thanks for the input...

racertracer · **Posted:** Sat Jan 01, 2011 5:30 pm

Here you go S.Dog

viewtopic.php?f=5&t=52315&p=583311&hilit=coolant+bottle#p583311

And here is the part I don't like:

"CAUTION: Failure to purge air from the cooling system can result in an overheating condition and severe engine damage."

Considering the issues some CRD's are having with leaky head gaskets and cracked heads, I would be careful doing it or having someone else do it.

CATCRD · **Posted:** Sat Jan 01, 2011 7:05 pm

I would do a complete flush to get that crap out of there. The refill procedure on these couldn't be simpler. I didn't have a problem with air when I flushed both of my CRDs. Make sure you pull the lower radiator hose at the radiator to get more out. Replace that stupid spring clamp there with a traditional hose clamp.

stoutdog · **Posted:** Sat Jan 01, 2011 7:58 pm

CATCRD wrote:

I would do a complete flush to get that crap out of there. The refill procedure on these couldn't be simpler. I didn't have a problem with air when I flushed both of my CRDs. Make sure you pull the lower radiator hose at the radiator to get more out. Replace that stupid spring clamp there with a traditional hose clamp.

Thanks. Seeing as how I don't have a flushing gun (as the FSM calls for...) what procedure would you recommend for flushing the system?

We just refilled my father's CRD today... Very simple, but he opted not to do a full flush.

CATCRD · **Posted:** Sat Jan 01, 2011 8:11 pm

Well as you know, we don't have a removable thermostat to make the garden hose method easy. I drained all I could, refilled with distilled water, drained that, and refilled until I measured a 50/50 mix. Granted it's not a 100% fluid change, but you could repeat until you're happy what comes out is clear. I think Squeeto came up with a pretty novel method involving the valve at the top of the radiator.

stoutdog · **Posted:** Sat Jan 01, 2011 9:15 pm

Ahh okay, so there is a little tool you can use to measure coolant mix. Any recommendations on what to get for that? I've seen some around $10 online...

Forgot that the garden hose won't work until I get Kap's tstat... doh! How's this sound: Drain as much as possible, refill with distilled water, crank engine (should I drive it around the block with the heater on until it warms up a bit or just let it idle with the heater on for x minutes in the driveway?), check mix with gauge, repeat until cleared enough (maybe 2-3 times). Then fill with the 50/50 mix of fresh coolant.

Squeeto's method is pretty neat, but a little more than I think I need to do... I just need to get the old, incorrect coolant out, not deep clean the system.

Thanks for the help.

racertracer · **Posted:** Sat Jan 01, 2011 11:37 pm

Now that you're at it, I would deep clean the system.

How does one go about deep cleaning our cooling system?

warp2diesel · **Posted:** Sun Jan 02, 2011 1:00 am

The small hose that goes from the top of the radiator to the expansion tank to get rid of any trapped air can be a problem, but not a hard one to fix. As long as the fittings on the radiator and tank are open, you are good to go.
VWs used to get their small hose plugged up from using stop leak. Guess it stopped the air from leaking out of radiator to the expansion tank. :-)r

Need coolant flush? or not?

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