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Radiator Drain Plug


TRB482000

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The radiator drain is low on the driver's side of the rear of the radiator. You should be able to reach it from under the car easily, particularly if you jack it up. Some say that you can reach it from above, and I can -- but I can't turn it because my hand is too cramped. If you use pliers, pad the jaws because the plug is plastic with an O-ring. The tanks are plastic.

If your model year uses Dex-Cool (red antifreeze) be sure and have Texaco Dex-Cool or equivalent red late-model GM certified anti-freeze ready. I think that the 1993 model year used green. If you have ever put green anti-freeze in the car, there isn't much advantage in using red because it will still have to be changed every 30,000 miles or 24 months.

I saw a post here that Wal-Mart sells distilled water for $0.50 a gallon. If you want to refill with anti-freeze and distilled water, have some ready.

The factory service manual (FSM) says to remove the plugs in the engine block to drain the system completely, and to remove the surge tank and clean it out. The dealer uses a power flush instead. The FSM says to flush the system if the coolant is dirty. If the coolant is clean, it's probably sufficient to drain as much as will come out the radiator drain plug with the radiator cap off. Since the thermostat will be closed, this will take awhile.

The FSM says to add three pellets of engine cooling supplement sealant, GM part number 3634621, to the lower radiator hose before refilling. Don't add sealant to the surge tank; most of it will stay there.

Your system holds about 12.5 quarts of coolant (1997 FSM page 0B-8). If you simply drain the system, you might use a pan and pour it back into gallon containers to get a good idea of exactly how much coolant has been drained. This will let you know how much distilled water and how much antifreeze to add. The FSM says that the percentage of antifreeze must be greater than 50% and should be less than 70% so 60% is a good safe target percentage. Of course, if you use 50-50 coolant this is moot.

If you don't flush the system, some coolant will remain. I would reduce the period between coolant replacements to compensate for some stale coolant remaining in the system.

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If your model year uses Dex-Cool (red antifreeze) be sure and have Texaco Dex-Cool or equivalent red late-model GM certified anti-freeze ready. I think that the 1993 model year used green. If you have ever put green anti-freeze in the car, there isn't much advantage in using red because it will still have to be changed every 30,000 miles or 24 months.

That is correct. 1996 and later use Dex-Cool. 1995 and earlier use conventional coolant.

I cannot get to the drain rooster at all on my '97. I usually "drain" out the lower radiator hose. I say "drain" because it's really more like a tidal wave of coolant, but it's the only way I've found to get it out. I've drained the system twice, once for a water pump change, and once again to replace a seal that I should have replaced, but reused, when I first did the water pump change. :P

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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There are no block drains on the Northstar engine despite what the FSM states. I looked all over for them on my '96 the first time I changed the coolant and when I couldn't find them, I talked to our resident guru at the time and he confirmed that they did not exist.

Always premix coolant 50/50 with distilled water. Concentrations higher than 50/50 are not desireable unless you live near the arctic circle. Extra silicates in the green coolant mixed at concentrations higher than 50/50 will abrade the water pump seal and shorten it's useful life. Also, too much silicates can cause the coolant to gel in low flow areas such as the heater core.

The subject car is a '93 which will use green coolant but an additional note: With DexCool, it is even more critical to use a concentration of 50/50 due to the acid based corrosion inhibitor package. Too high of concentration will cause cooling system problems. It should always be pre-mixed with the distilled water before adding it to the system.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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