coolant change!!!!

[Slim m]

I have changed the coolant in my s2 3b and just want to know how I can make sure that their is no air in the system?? am I ment to bleed the air outand if so where is the bleed screw? is it the one on top of the rad? Liam.

[MidnightBlueS2]

Quite easy actually...

Just fill up the header tank till half way up, start engine and get it hot till the fan starts kicking in from time to time.
Keep on eye on the level in the header tank and keep the cap off it and as the level fluctuates, add if necessary.
Then turn the heater on at max temperature and with the fan blowing as well. This will get rid of air bubbles trapped in the heater core and the thermostat should be triggering the coolant to circulate all around the engine and the hose that connects to the top of the header tank will spurt out coolant and any air trapped air out into the header tank. Keep doing this for 10 min or so and that should do it.
You'll find that you'll might have to repeat this operation 2-3 times in between driving sessions as the air bubbles in the heater core are notoriously hard to get rid of... Just keep a bottle of pre-mixed coolant with you if topping up is needed while driving if you get the "low level" warning light flashing.

Also, make sure to use G12 coolant mix !

Be extra careful if you choose to bleed the rad ( it's not absolutely necessary ) with that little top screw as if you overtighten it, you WILL crack the rad housing so be extra gentle

HTH,

David

[BrianSmith_S2]

I have changed the coolant in my s2 3b and just want to know how I can make sure that their is no air in the system?? am I ment to bleed the air outand if so where is the bleed screw? is it the one on top of the rad? Liam.

When draining the system make sure the heater control is set to hot position.

then i usually the pour coolant through into reservoir near full then run the engine. when the rad starts to run hot screw on the reservoir cap then check the fan cuts in when it should.

once cool recheck the coolant level. it may have dropped a bit, but should be near correct level.

i do this each time i change coolant/rad and never had need to bleed the system.

Brian

[CHEN]

I always undo the top hose and back fill the engine. I can't see what difference having the heater on or off would make as it doesn't affect water to the heater matrix, but it is useful to tell if the system is circulating well. There sould be a bleed screw on the hose to the heater matrix. A word of caution though, there is a tendancy for them to sheer off when you undo them.

[Slim m]

Thanks guy's!

just a few more questions though! is the rad ment to be cold at the bottom when the car is up to running temp? and what temp is the thermostat ment to open? Liam.

[MidnightBlueS2]

just a few more questions though! is the rad ment to be cold at the bottom when the car is up to running temp? and what temp is the thermostat ment to open? Liam.

Nope, RAD should be hot. Not scolding but definetly more than warm.

Thermostat should start operating above 90degrees Celsius.

[Jas11n]

Just a query guys, always wondered about this.
Why set the heater control to hot ? there is no valve system to shut water off to Matrix, it flows through regardless of whether it's set to hot or cold.

Jas..

[iain1067]

good question

[Greg_S]

I think it is probably a historical thing from days gone by, and I guess that way you get to find out if there is an air lock stopping it flowing through

[iain1067]

or is it because haynes always says so!!!! lol

[Slim m]

Nope, RAD should be hot. Not scolding but definetly more than warm.

Thermostat should start operating above 90degrees Celsius.

so in theory the thermostat wont even start to open until the temp gage shows 90 deg c !? also dose anyone know what temp the first speed fan is ment to come on? Liam.

[Slim m]

another question or three!! what controls the after run pump? is it on the system as the first speed fan?? are robert bently workshop manuels from the u.s any good for electrical system on s2 3b 1992? Liam.

[Corey]

It is a self bleeding system, the best way of bleeding them is to raise the expansion bottle above the level of the radiator, as you fill the expansion bottle ensure you don't over fill it so that you block the small breather pipe from the top of the rad as this can create an air lock.

[MidnightBlueS2]

another question or three!! what controls the after run pump? is it on the system as the first speed fan?? are robert bently workshop manuels from the u.s any good for electrical system on s2 3b 1992? Liam.

The after run pump is controlled, AFAIK, by a temp.sensor that triggers it if the coolant gets too hot whilst the engine is switched off.

The first speed fan turns on when I turn on my auto A/C heater control. Don't ask me why, coz I really don't have a clue

I'm not sure about the Bentley manual...

And last but not least, the thermostat will limit the cooling capacity of the coolant system so that our engines warm up as quickly as possible on cold start.

[Greg_S]

Im pretty sure the fan kicks in at 90 degree's. The after run pump kicks in from the MFTS signal on the side of the block. You can frig it so that the after run pump will always run.