si tu es ok en anglais voici en details la procedure que j'ai copier sur un site. La procedure est aussi exprimer de maniere differente dans le shop manual et dans le manuel d'entretien du proprietaire , mais dans tout les cas ca veut dire la meme affaire. Il faut s'assurer de pas avoir de poches d'air dans le systeme.
voici le lien tres utile
http://home.comcast.net/~fierocave/How do I drain the system?
You'll need a catch pan and a 5 gallon pail. One of those pumps you can run with a power drill is really nice. With that you can pump the coolant to the pail and not spill it all over. Even with a pump, you'll need the pan to drain the under car pipes. (The drill pump works really great if you have to use old jugs to collect the waste coolant. Beats the hell out of a funnel.)
Remove the filling cap on the engine. Leave the cap on the Radiator. If you take both off at the same time, you'll dump around a gallon of coolant all over the place. (The check valve on the radiator cap will open when the radiator starts draining. It should also siphon out most of the recovery tank this way.)
There is a petcock in the radiator that you open to drain most of the system. Once coolant has stopped draining from the radiator remove the plug from the rear of each coolant pipe under the car. The plugs are just behind the doors.
There are drain plugs in most engines but they are giant pains to get out. Even with the plugs out you often can't drain it dry. Flush the old coolant out until the water drains clear.
Don't forget to empty and clean the recovery tank! That thing gets amazingly filthy.
How do I fill my cooling system?
Important Update...
This document was originally written as if you would be filling a dry system. (Like you just changed an engine or something...) If you are filling a system that has been flushed, you now have plain water trapped in the engine and heater core. If you add premixed coolant to the system the trapped water will dilute and weaken the antifreeze.
This update was added because I was reminded by the IMCOOL.com article linked above that allot of people, including people who should know better, forget to consider flush water when refilling the system. This apparently has been a large problem with DEX-COOL but it's a problem with any coolant. None of them will work properly if they are weak.
The whole point of flushing was to eliminate weak coolant and dirt. We certainly do not want to install new coolant only to dilute it below spec. That would leave the coolant too weak to properly protect the system, defeating the large amount of work you just did.
To account for the trapped water:
Drain the under car pipes and radiator after flushing.
Find the total system fluid capacity. (Approximately 14 quarts for all Fiero models.)
Divide system capacity in half and pour this amount of antifreeze into the system. (Approximately 7 quarts of new antifreeze for all Fiero models.)
Fill the rest with water. (De-ionized or Distilled water is preferred.)
This will eliminate the problem of trying to figure out how much water was trapped in the system after flushing. The rest of the filling procedures do not change! Don't forget to fill the recovery tank with 50/50 premixed coolant.
Moving on...
My method is longer than the ones most people use. I've developed this based on filling many other systems and the special needs of Fiero. It takes longer to do this way but it solves several issues all at once. While it can be used during any fill, this procedure was developed for filling dry systems or systems where the heater core has been worked on.
Remove the front and rear filling caps. Pull the thermostat out.
Pour premixed coolant into the rear cap until the radiator is full. ((Filling from the back helps push air bubbles out of the coolant pipes under the car.))
Cap the radiator when it is full.
Fill the coolant thank to the "add" mark with the same mix you are using in the rest of the system. Remember the tank says check hot... We want to leave room in there for coolant to expand out of the radiator.
Here's where most procedures being used leave out an important item. Air bleeding the heater core. If this isn't done you might never get all the air out of it and that will reduce its heating capacity considerably. It's also a likely cause of people having a hard time getting all the air out the thermostat cap. The heater core and hoses can trap allot of air.
This part is allot easier with 2 people. If you're by yourself fill the back then vent the heater. If you are starting from dry then you may need to go back and forth a couple times.
Carefully move the top hose clamp out of your way and loosen the hose. Don't pull on the hose. If it is stuck make a hook from some thin rod or bar stock and work it under the hose to loosen it. Pulling or twisting on the hose can crack the solder joints at the heater core tank.
Once the hose is loose work it slowly off the core tubing to let the air out of the system. If need be add coolant to the back until the heater fills. Try to hold the hose as shown below. You want to keep the opening as small as you can to eliminate as much air as possible without spilling coolant all over the place.
When the air is gone put the hose back and clamp it in place.
This will eliminate the vast majority of air from the heater core and its plumbing. It should make heater core replacement and filling the system from dry allot less of a headache.
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Now we're back to filling in the rear. This varies a bit from person to person just what the best method is. Here's what I do on mine. Don't forget to keep checking the recovery tank. If you let it run low air will be pulled into the radiator when the system cools.
Fill the engine until you reach the top of the hose connected to the thermostat housing.
Start the car and let it run with the thermostat cap off. This will burp out the big air bubbles. Leave the car running until step 14. (Some cars hate having the cap off. I don't know why. If yours is like that then just put it on. Just don't let the thing warm up and build pressure. You only need it to run a minute or two. You may have to stop and check it several times. read on for more notes on this step.)
Pour in more coolant mix if the level drops below the top of the hose.
Once the engine stops spitting up air put the cap on.
Run the car to normal operating temp. This will happen fairly quickly unless the fan is on.
Let it run a few minutes. Keep an eye on the temperature to make sure you don't over heat. If you have an ECM scanner hook it up for this. Watch the coolant sensor. If it warms up then drops, or fails to warm up, shut off the car. You likely have a big air bubble in the thermostat neck. (This shouldn't happen but it's something to watch out for. Gives you one more thing to use your scanner for.)
Shut it off and let it cool.
Open only the rear cap to check the system and top it off.
Install the thermostat now and cap the system.
Run the car to operating temp
Check the overflow tank. Fill it to the full line.
Shut off and let it cool.
Check the level in the engine again. It should not need more than a little bit if any.
Some air will always be trapped in the radiator. This is normal for side tank radiators. Most of it will work itself out through the coolant recovery tank. It is critical the recovery tank is never allowed to run low on coolant. If it gets too low air can be pulled into the radiator. Not a good thing.
Some people claim that it helps to have the car parked on an incline or jack it while filling. I've never found that necessary myself but it's one more thing to try if you have trouble.
More on Step 9...
The trick with opening the cap with the engine running is that the Tstat has to be out and you don't start the car with the cap off. (DO NOT even think about this on a hot engine!)
With the engine running at idle for a few seconds to get the water all moving, you can often open the Tstat cap and watch the water flow by. It may only work on the L4. It also won't work if there are any problems in the plumbing like a partly blocked radiator or a crushed pipe under the car.
If you try to start the car or hit the throttle then water will go all over because of simple inertia. The sudden change in pump speed creates a spike in one part of the system. It takes the coolant some time to catch up thru the whole system.
The nice thing is when the cap off trick works you can just add coolant as the level changes. If the cap off trick doesn't work then just run the engine 20-30 seconds to kick the air bubbles out of places and check the level. Once most of the air is out then run the engine to full heat and let it cool. Check the level in the back only. Do NOT open the front cap after this or you'll let air into the radiator.
