Coolant change procedure - C5
The sludge problem results from a leaking (not air tight) system or mixing of the two types. You'll never get 100% of the Dexcool out, so you'll be asking for problems if you go green. If the car is 6 yrs old and you suspect it is the original coolant, and it still looks good - I cannot imagine a better indication that Dexcool is good stuff!
The new petcock installs with a "click" when you get it all the way in.
I'll chalk this "coolant change from hell" up to a leaning experience.
Next time will be a piece of cake.......
Another thing I've learned is don't use the low profile ramps I have seen mentioned on a few web sites. I'll start another thread on that issue.
Use distilled water to mix with dexicool.


Originally Posted by 01QuickSilver
I used 6 1/2 qts. of Dex-Cool (manual says system holds 13 qts.) & my garden hose.
The difference between FLUSHING and REFILLING is:
Flushing uses water under pressure to rinse all of the old coolant and corrosion, sediment, etc. out. Refilling is
just that - refilling.
Also, if all you do is drain the radiator & refill it you will be leaving the block and heater core full of old coolant!!
I'm sure there are many who could provide a more technical sounding description, but here's how I FLUSHED
mine BOTH WAYS:
1.Set heater temp to full hot (90)
2.Open radiator drain
3.Remove both radiator hoses @ water pump
4.Remove both heater hoses @ water pump
5.Remove water pump inlet housing (thermostat is part of the inlet).
6.Flush water through both heater hoses - this does the core both ways.
7.Plug the heater hose fittings on the water pump (I stuffed shop towels in) and flush water through the water
pump where each
rad. hose goes - this does the block both ways
8.Flush the resevoir tank
9.Flush water through top & bottom rad. hoses - this does the radiator both ways
10.Close radiator drain, connect all hoses. Leave the inlet hsg. off the pump for now
11.Pour Dex-Cool in resevoir very slowly until it gets up to the bottom of the hole where the inlet/therm hsg goes
(much like filling a manual trans) - this eliminates much trapped air
12.Install inlet/therm hsg, lower rad. hose & finish filling - total of 6 1/2 qts. Dex-Cool first, then finish with water
13.Run engine to operating temp with cap off resevoir while checking for leaks, shut off engine and let it cool down
14.After engine is cool add water as needed & install cap
15.Check level & top off after the next few times you drive until it stabilizes
Smile as you think about how much $$$ you saved
Another added bit of info
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 drain fowl.
5) Open the radiator drain fowl.
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 drain fowl. Tighten.
Tighten the radiator drain fowl 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.
The stream was very small, so I just put a big pan under it and did something else for a while. My experience with the Saab was that when I turned it too far (more than a 1/4 turn), it just breaks the plug. So I'm being patient.
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I bought a new plug at an auto parts store, and all it had was a tab to turn with your fingers. I fiddled around trying to get the old plug out, and didn't find the trick that allowed it to be removed.
So with the original plug in, I took the 1/4 in drive, opened the plug a 1/4 turn, then moved it back to the closed position. When it reached that position, I could feel a detent that was obviously there to keep the plug closed in that position. (Keep in mind that the torque is not sealing the radiator, rather it is an o-ring on the plug that seals by moving it into the closed position.
I will report back later if this doesn't play out well, but right now I am of the opinion that leaving the OEM plug in the closed position (by feel), is better than trying to get to 18 in-lb torque.
If anyone disagrees because of prior experience, let me know ASAP.
Last edited by tquinn; Jun 1, 2018 at 10:52 AM.





The stream was very small, so I just put a big pan under it and did something else for a while. My experience with the Saab was that when I turned it too far (more than a 1/4 turn), it just breaks the plug. So I'm being patient.
and 18" lbs is like way less then finger tight....maybe one pinky tight
Last edited by bobs77vet; Jun 1, 2018 at 11:03 AM.
But the tab of the replacement drain plug is 20 mm across, so assuming you could apply all the finger force all the way at the very tips of the two ends of that tab, with your index finger and thumb, the force for each of those would be 11 1/2 lbs.
If you push at the more likely middle of each tab end with the pads of your thumb and index finger, the force goes up to over 16 lbs. each.
Try that with your finger alone (not pushing down with your arm) and you're a pretty good strongman if you can do that with your pinky. (I can do about 6 lb).
I did check my clicker torque wrench against another in-lb beam torque wrench, and the 18 lbs on the clicker was a little over 20 in-lbs on the beam wrench. But even if I used the beam wrench, I'm sure that it would still have run right through the 1/4 inch nylon socket on the factory plug.
The key is that as long as you get the plug back to the full closed position, any additional torque doesn't do any good for sealing the radiator.





7" 3/8 ratchet up to 30 ft lbs
stubby 3/8 ratchet was an easy 20ft lbs













