C5 Coolant drain and Fill

[pewter99]

Draining and Filling Cooling System

Caution
With a pressurized cooling system, the coolant temperature in the radiator can be considerably higher than the boiling point of the solution at atmospheric pressure. Removal of the surge tank cap, while the cooling system is hot and under high pressure, causes the solution to boil instantaneously with explosive force. This will cause the solution to spew out over the engine, the fenders, and the person removing the cap. Serious bodily injury may result.



Important
If the procedure below is not followed a low or high coolant level condition and/or vehicle damage could result.


1) Park the vehicle on a level surface.
2) Remove the surge tank cap:
3) Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
4) Place a drain pan under the draincock.
5) Open the radiator draincock.
6) Allow the cooling system to drain completely.
7) Inspect the engine coolant for the following:
Discolored -- follow the flush procedure below.
Normal in appearance -- continue with the next step.

Notice
When adding coolant, use DEX-COOL® coolant. If silicated coolant is added to the system, premature engine, heater core or radiator corrosion may result. In addition, the engine coolant will require change sooner-at 50 000 km (30,000 mi) or 24 months.

Notice
Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

8) Close the radiator draincock. Tighten.
Tighten the radiator draincock to 2 N·m (18 lb in).
9) Fill the cooling system through the surge tank.
10) Fill the cooling system with a 50/50 mixture of DEX-COOL® coolant and deionized water.
11) Start the engine.
12) Allow the engine to idle for 1 minute.
13) Install surge tank cap.
14) Cycle the engine RPMs from idle to 3000 in 30 second intervals until the coolant temperature reaches 99°C (210°F).
15)Shut off the engine.
16) Remove the surge tank cap.
17) Start the engine.
18) Allow the engine to Idle for 1 minute. Fill the surge tank to 12.7 mm (0.5 in) above the COLD FULL mark on the surge tank.
19) Install the surge tank cap.
20) Cycle the engine RPMs from idle to 3000 in 30 second intervals until the coolant reaches 99°C (210°F).
21) Shut off the engine.
22) Remove the surge tank cap.
23) Top off the coolant as necessary, 12.7 mm (0.5 in) above FULL COLD mark on the surge tank.
24) Rinse away any excess coolant from the engine and the engine compartment.
25) Inspect the concentration of the engine coolant.
26) Install the surge tank cap.

[MADN3SS]

Good info. I had a check engine light a while back, turned out to be the exhaust. The dealer had to remove the radiator and fluid to fix the problem. I sure hope they just didn't put the old fluid back in! Never thought to find out.

[Melsy]

Great writeup. If I'm not mistaken, the Shop Manual says to not remove the surge tank cap and then when you do drain the radiator as you describe, the surge tank will also drain.

[exile]

Is deionized water just another name for distilled water? After raising the car to open drain cock, do you lower the car while draining the radiator?Other than those two questions, it's a great write-up. Thanks.........Tom

[pewter99]

Originally Posted by Melsy

Great writeup. If I'm not mistaken, the Shop Manual says to not remove the surge tank cap and then when you do drain the radiator as you describe, the surge tank will also drain.

that write up is pretty much right out of the manual from what I recall...

[pewter99]

Originally Posted by exile

Is deionized water just another name for distilled water? After raising the car to open drain cock, do you lower the car while draining the radiator?Other than those two questions, it's a great write-up. Thanks.........Tom

as for lowering the vehicle thats up to you...I seem to recall only lifting mine from the passenger side enough to loosen the drain cock then lowered it while it drained...that being said if your car is lowered there ain't no way in hell you will get anything under the car to catch the coolant so........I would say do what I do when I change the oil....lift the whole damn car

[Charlie_MA]

Where's the draincock ?

Does the Z51 option elimiate this ?
There's nothing that looks like a drain on the passenger side of my 2000.

Is it on the bottom of the surge tank ?

[Guro305]

Dex-cool? I'm almost certain the manual had said to use 50/50 fluid.

Is Dex-cool good stuff?