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98 sls
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Discussion Starter · #1 ·
I have attempted looking on this site if this question was previously posted. Where is the radiator drain plug, I need to flush my radiator. I am handy, removed the plastic guard, and cannot find a drain plug anywhere. I need help! Thank you.
 

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98 sls
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Discussion Starter · #3 ·
Good, I'm not blind. I'm planning on getting rid if the dexcool and using green prestone, diluted with distilled water. It's never been flushed, so I'd like to flush it as well, or should I just change the fluid?
 

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1989 Sedan DeVille is now just a fond memory ....
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Krashed989 said:
I don't think there is one, and that means that the only way to drain it is to remove the lower radiator hose.
Correct. It is recommended that you not flush but merely drain the old fluid and replace with new 50/50 coolant and distilled water and be sure to add the GM coolant pellets! They can be added to the system through the upper or lower hose, never into the overflow tank.
 

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1989 Sedan DeVille is now just a fond memory ....
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nyremodel said:
Good, I'm not blind. I'm planning on getting rid if the dexcool and using green prestone, diluted with distilled water. It's never been flushed, so I'd like to flush it as well, or should I just change the fluid?
Is there a reason you don't want to stay with the Dexcool? It's supposed to last longer than the silicated coolant. If you do go green you can't go back.
 

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13 Challenger RT, 11 CTS Coupe Premium, 94 Eldorado (RIP)
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There is one under where the bottom hose connects to the radiator. You need a flashlight to see it. It is rather difficult to get to but can be done. Most of us just remove the bottom hose and be done with it.

If you need to flush the radiator, you will need to disconnect the bottom hose anyway. You do not want to flush the engine.
 

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2000 DEVILLE,2001 STS.
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The radiator drain plug is located at the lower right corner of the radiator.It may be partially hidden by a plastic corrugated electrical wireway.When flushing this engine remove the thermostat housing, remove the t-stat and re-install the housing to the engine.This will allow proper flushing of the block and a larger opening for scale/rust to exit.disconnect the upper radiator hose and place garden hose into radiator inlet.Flush until water is clear.re install the t-stat and undo the lower radiator hose.Put three sealant pellets in lower hose and reconnect.Put the heater on high and refill with 50% dex-cool (orange) and 50% distilled water (radiator cap off).Run engine until t-stat opens (upper radiator hose will become hot)turn engine off and let it cool completely.Top it off to the bottom of the filler neck.Squeeze upper hose to purge air and add more antifreeze mixture if needed.Put the cap back on and check for leaks
 

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nyremodel said:
Good, I'm not blind. I'm planning on getting rid if the dexcool and using green prestone, diluted with distilled water. It's never been flushed, so I'd like to flush it as well, or should I just change the fluid?
It's your car, but I'd highly recommend staying with OE Dexcool and GM supplement tabs. If you go to the green stuff, you'll need to drain/refill every two years and will never be able to go back to the Dexcool 5 yr/100K cycle due to the fact that the silicates from the Prestone will have permanently plated your cooling system. Dexcool is a little pricey, but it's time tested, proven, and will last at least 250% longer before risking gasket damage. The last thing you want or need is gasket problems with this engine. Big $$$ to remove/replace most anything gasket related besides the waterpump.

Just my 2 cents.
 

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98 sls
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Discussion Starter · #10 ·
Holy cow, I didnt realize how much I dont know about this car. So, I will now plan on using dexcool, diluted 50/50 with distilled water. Should I flush or not? I'd like to replace the theromostat as well.
 

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13 Challenger RT, 11 CTS Coupe Premium, 94 Eldorado (RIP)
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No flush unless you know there is a pluggage in the system.

Just a tip if you change the thermostat...before installing the new one, put the old stat and the new stat in a pot of water and turn on the heat. If you have a cooking thermometer, that would be great. Make sure the new stat starts to open at approximately the same time as the old one. I had bought a new stat about a year ago and didn't test it first. Put it in and the car started to get close to overheating. Took it out and put both in water, turned on the heat...new one didn't open until minutes after the old one.
 

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Don't flush. Not worth the hassle unless you are certain there are catastrophic contaminants in the cooling system. Just drain, refill with 50/50 mixture (Distilled H2O only) and add the pellets. You can buy them at any GM dealer, they're a few bucks per 6-tablet pack. Crush and put 3/4 tabs in upper or lower hose - not surge tank. I just put all six in when I did mine. I'd replace the awful OEM spring-type hose clamps with a decent set of screw-type ones for down the road.
 

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2010 DTS
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No, it drains everything as it is the lowest point in the system. Now, having said that, there will always be a little residual left but that is not going to hurt anything. You can get some of that out by reversing the flow on a shop vac and inserting the tube in the surge tank. Seal it with your hand and blow out most of the residual.
 

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1989 Sedan DeVille is now just a fond memory ....
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Initial fill at the cap, let it run for a little while so it can "burp" itself. After that you should use the overflow tank to maintain the level.
 

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1999 STS - diamond white
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mramazingman said:
The radiator drain plug is located at the lower right corner of the radiator.It may be partially hidden by a plastic corrugated electrical wireway.
"Right" meaning driver's side. You don't even have to remove the lower apron - there's a cutout in it.
The drain plug is lower than the lower rad hose. You may even get more sediment out with the extra coolant. Then just open the upper hose to add sealant.
 
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