How To Bleed the cooling system

Fast Guy

Staff member
This keeps popping up, so I thought I'd put it in here, so there's no excuses for asking this again.

Set heater control to max hot and remove the bleed screw on the thermostat housing. Fill radiator until water starts to run out of the bleed screw. Replace the bleed screw and fill up the radiator and reservoir tank to the max line. Now you need to modify the rad cap by putting a piece of wire or similar between the rubber and the metal centre bit.(it lets the air bleed out into the overflow tank) Fit it to the radiator. Start the engine warm it up and run it a 2500rpm for 10secs, turn off, fill up the radiator. Repeat 3 times.
Remove wire from rad cap and refit it as standard item. Run engine at 4000rpm and move heater control to a few positions between hot and cold , then check level again. (rad will be pressurised this time, so let it cool down or cover the rad cap well)

I always check the level a couple of times over the next few days just to make sure all is OK. Haven't had to top it up again yet.


Gaz gtiR

New Member
when you say set heater controlls to max HOT. do you mean the hot & cold controll or the fan controll aswell??


Staff member
The hot/cold control. - By putting it on max you're fully opening the valve, which allows the coolant (and/or any trapped air) to flow through the matrix.


when filling i pull the top heater hose off and fill put the hose down the rad cap hole and it gets a huge amount of air out of the lines slip the hose on clamp it and remove the bleed topping the rad up till no air passes
slip the wire in the relief of the cap and run it up to temp and fill the overflow and go do something else while it cools again and check after
havent had a problem yet doing it this way