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#1 4.2 cooling bleed valve

Posted: Mon Aug 25, 2008 9:47 am
by attwood
In the thermostat housing of the Series 2 4.2 engine is a bleed valve consisting of a white nylon ball held loosely captive against a brass seat.

You can see the valve lying on top of the radiator top hose in the photo below. It fits in the hole you can see at the top left of the thermostat housing. Water flow to or from it is via the smaller hose you can see towards the bottom left of the picture. This hose just runs parallel to the top hose from the radiator to the thermostat housing.

Image

There is a similar smaller valve built into the thermostat itself in the metal surround at the 12 o'clock position.

The question is, which way round should the bleed valve be fitted? It fits physically in both directions.

Should it be the same way round as the valve which is built into the thermostat?

Or is it's purpose to handle certain conditions where the water flow is in the opposite direction to normal for some obscure reason?

Thanks in advance for any advice.

Dave.

#2

Posted: Mon Aug 25, 2008 11:18 am
by Heuer
Dave

Never had an S2 which has a different cooling system from the S1 and the only pictorial reference I can find is in th SC (Limora) catalogue. This has a picture of the valve which I think suggests the valve should be with the white nylon ball towards the inside of the housing. What do you think?: http://www.limora.com/index/lang-2/lkz- ... pl,x-a.htm

#3

Posted: Mon Aug 25, 2008 12:34 pm
by Heuer
Dave

Made some enquiries and the additional valve is to help bleed the system. Goes into the housing 'bobble' first. Some S2 cars do not have it as they reckon it did not work anyway - many just leave it out - but worth putting it back they way it was in my view. More important is to ensure the little bleed valve on the thermostat is at 12 o'clock (as in your picture) otherwise air can get trapped above it.

#4

Posted: Mon Aug 25, 2008 2:52 pm
by attwood
David, many thanks for the effort and the quick reply.

Regards, Dave.