Coolant flush

DEEZUZ

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Nov 20, 2008
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Starting to see the sludge from the Dexcool breaking down... What is your gheys normal flushing procedure?

IMO, taking this from the diesel world, Id remove the T-stat, drain everything thats in raditor, hopefully there is a block drain also(if so, where abouts?). fill up with a flushing agent(we use stuff from Cummins), let her get hot as possible, usually an hour run time, than just continually keep vacuum filling with distilled water til your last drain is pretty clear... usually 3-6 hours on a truck...


Do the 3.8's like the vacuum fill system? I know some trucks we cant use it cause it tends to suck in gaskets and then they leak....

thanks
 

RICH17

Dr. Pussy Slayer, MD
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Nov 14, 2008
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I wouldnt use the vacuum pump system. I'd take the tstat out and drain the coolant, the petcock is on the drivers side and will drain out from the rad mount. Then I'd just throw straight water in it for a while with a cleaning agent and then refill with a new tstat and just ethelglycol
 
If you really want to do justice drive around with it for a day or two with a cleaning agent in it. It's not going to hurt and it does do justice. I only let mine run for an hour the first time I flushed out my dexcool with a cleaning agent and it didn't do much. I just did LIM gaskets on my buddies Buick tho and drove it around for a day with the cleaning agent in it and maaaannn did that shit smell nasty when it came out. Definitely did some justice, his system was pretty gunked up too.
 

DEEZUZ

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well id run it with a throttle stick and heat on, so probably 2500 RPM for 45 minutes or so... Im going to just use the recycled 50/50 we got at work, but ima flush with distilled... trust me, $1/gal is worth this shit not happening again...
 

RICH17

Dr. Pussy Slayer, MD
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I wouldnt run it like that. Seems like a waste. Its not a diesel. When I switched mine out with the new motor I drain as much as a could and used an all makes coolant and just filled it back up. It diluted whatever was left of the Dexcool and the all makes seems to let the engine run cooler.
 

Turbocharged400sbc

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Jun 16, 2007
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There is a block drain but it's practically pointless...
both of the knock sensors are the front and rear water jacket plugs but the rear is a pain in the ass to get to as well as they have to be properly tq'd.
there is an additional block dream on the front of the motor underneath the supercharger idler pulley stand.... but it only drains the front Bank
 

Alacran

GM fanatic
Jan 18, 2009
1,152
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Chicago
Block drain = knock sensor. use thread sealant to reinstall the knock sensor.

How bad is it? I wouldnt want the radiator to get plugged.

Vaccum fill is overkill for these engines. I never trapped any air the system that the vent on the thermostat housing could not remove.

I say while you are at it get a new thermostat, radiator cap, and switch to Zerex G02.
 

DOC-Z

Chickun maka LOUSY housspaat!
Oct 13, 2008
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From my TCG thread started on 10-15-12:

http://www.thechicagogarage.com/forum/3800-discussion/125136-low-coolant-no-heat-c-feels-like-its-all-time.html

After a few weeks and 4 cooling system flushes, I resolved the problem. I've done some research and found that that orange DEX-COOL coolant is SHIT! If you get a leak and don't notice it for a while, the coolant WILL degrade and turn into what looks like puree'd coffee grounds or basically mud!

Here's a link to what I found out about DEX-COOL and it's many PROBLEMS. (link --->)
Dex-cool Contamination

Apparently, this stuff will break down after 5 years OR 100,000 miles. In order to NOT void any current vehicle warranties, they recommend you replace your coolant every 2 years!

Direct Quote from link above:
General Motors introduced Dex-Cool to certain lines of vehicles in 1996. Since it was formulated without the addition of silicates (the corrosion inhibitors in green antifreeze) a different corrosion inhibitor strategy was needed. Organic Acid Technology or OAT is the inhibitor part of DEX-COOL. Unfortunately, the DEX-COOL is capable a rather nasty breakdown. The residue it leaves behind is very sticky, and likes to find areas in the engine and other areas to "drop out" or "fall out " of solution and stick to the wall surface of engine and radiator. If the residue is in the radiator, hoses, or recovery bottle, it's relatively easy to clean and remove the debris. When the residue is in the heads and block, only a chemical flush will remove this orange mud. In some cases, the orange mud hardens, and seems to expand or push the gasketed surfaces out of position, causing leaks.

As a side note, I also read that DEX-COOL doesn't play well with tap water. Instead, you need to dilute it with DISTILLED WATER ONLY.

To clean out the "MUD", I looked online to see what other people did. What you need to do is use a very weak acid, to break up the solid contaminants in your cooling system. I read that OXALIC ACID works really well. OXALIC ACID is commonly found as WOOD BLEACH. I called around and found some WOOD BLEACH at my local Ace Hardware. Neither the local Sherman-Williams or Home Depot had WOOD BLEACH in stock. Another thing you could use is VINEGAR. The WOOD BLEACH was $9.99 at Ace Hardware in McHenry, IL.. 2 gallons of VINEGAR was under 7.00 at the local IGA, Jewel and Meijer.

To dissolve the WOOD BLEACH, you need to add it to hot or very warm water. If you buy VINEGAR, you just add it into your radiator when it is cooled off.

However, my heater core was completely blocked and I had NO HEAT in my 2000 V6 Firebird. When I looked into the heater hoses, both the outgoing and return hoses were caked with mud. Figured it would work, I used a garden hose to try to push all the gunk out. It sort of worked, but not really well. I managed to bet a semi-solid, worm-like plug to ooze out of the heater core return hose. However, I was squirting water all over creation and when the hose slipped, water shot back out of the hose I was trying to pump it into. When I went against the normal flow, a brownish, chunky liquid started to come out of the other end.

I thought that was kind of odd, but at least some crud was coming out. As a result of the first flush, it looked like someone from Starbuck's had a full garbage can of coffee grounds and spilled them under my car. After the car was cooled down for several hours, I removed every hose and flushed out the entire system with water...reservoir and all.

I did the WOOD BLEACH flush and drove the car for a few driving hours. When I went to remove the hoses again and do another thorough flush, I was amazed that the rubber hoses looked really clean inside and the radiator was cleaner looking. I repeated the flush and draining of the system 2 more times...each time the system was looking cleaner and cleaner. The heat was still marginal at best, but every time I hooked the garden hose up to it, more gunk would flow out.

Yesterday, I did another flush. The radiator was immaculate inside.

I wound up running out of Oxalic Acid (a.k.a. WOOD BLEACH), but was told VINEGAR works just as well. It did work, but I think the WOOD BLEACH dissolved the gunk up better. The VINEGAR only emulsified it a little bit and caused it to come off the inside of the engine bits and want to float on top of the fluid. If you only have VINEGAR, then that will work, but the WOOD BLEACH worked better and quicker.

Moral of the story:

1). CHECK YOUR ANTIFREEZE!
2). If you have DEX-COOL in your vehicle...CHANGE IT!
3). If you have what looks like brown mud inside of your radiator, OXALIC ACID will work well to clean it out.*

* = I read you should drive the car for about 3 hours and then flush it out. I did this seven times over the course of a few weeks. My heater blows warm, so I know there is still more "mud" floating around inside of the engine. Still, a little heat is better than NO heat!



.
 

DOC-Z

Chickun maka LOUSY housspaat!
Oct 13, 2008
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Johnsburg, IL.
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Being it's warm out, what you could do to flush that F*CKIN' Dex-Cool out of the block is:

1). With the car completely cooled down and not even remotely warm, remove both, the upper and lower radiator hoses. DO NOT DO THIS WHILE THE CAR IS HOT!!!

2). Get a garden hose with an attachment, where you can easily control the flow of water that comes out.

3). From the water neck, spray water into the engine to flush out the remaining Dex-Cool. You can also do this to the Heater hoses in order to flush them out better.

4). Flush out the radiator with the garden hose to flush out remaining Dex-cool. This should get 99.999% of the coolant out of the radiator.

5). Remove the coolant reservoir and flush it out completely.

6). Reinstall the radiator hoses, coolant overflow bottle, and make certain the radiator spigot is closed (bottom of the radiator).

At this point, you should be good to use which ever radiator flush you want. The vast majority of the Dex-Cool should be gone and after you do 1 or 2 flushes, the system should be cleaned of Dex-Cool brand coolant. You may still have some mud in various areas, but that shouldn't do much in the way to harm your engine.
 

Qball

Yes, I would like fries with that.
Sep 26, 2010
69
64
Plainfield, IL
If you really want to do justice drive around with it for a day or two with a cleaning agent in it. It's not going to hurt and it does do justice. I only let mine run for an hour the first time I flushed out my dexcool with a cleaning agent and it didn't do much. I just did LIM gaskets on my buddies Buick tho and drove it around for a day with the cleaning agent in it and maaaannn did that shit smell nasty when it came out. Definitely did some justice, his system was pretty gunked up too.

Was the cleaning agent you used wood bleach like what was mentioned above? Also, I need to change my intake gaskets. Does it matter if I use a cleaning agent to flush my cooling system before or after gasket replacement?
 

Qball

Yes, I would like fries with that.
Sep 26, 2010
69
64
Plainfield, IL
I would also HIGHLY recommend changing the coolant elbows too. Those things suck I've had them burst on me twice and it's never fun.

I changed the elbows, already. Used those baller aluminum ones :werd: Changed the water pump and got a new radiator cap. Still losing coolant somewhere. Oil looks great, no dripping anywhere. The car has 163k miles and still has the original gaskets. It's time.
 
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