Lots of air in the cooling system

billy_bob · Post by **billy_bob** » 18 Aug 2004, 16:37

Hi All,
Recently completed a head gasket change due to suspected blown gasket. Everything machined and put back together with new gaskets (although no gasket seal / gunk) and the problem is just as bad:
When bleeding the cooling system the coolant level in improvised header tank (3 ltr sqaush bottle) rises <i>really</i> fast. Unscrewing the bleed valve nearest the fuel filter housing whilst the engine is running releases <i>lots</i> of gas and the level in the header tank drops again.
Could this be due to a block elsewhere in the cooling system [hopefully [8)]] or is this gas coming directly from the cylinder head again?
Thanks, bb

billy_bob · Post by **billy_bob** » 18 Aug 2004, 17:04

Sorry, should have said it's a ZX 1.9D '96

gjb02 · Post by **gjb02** » 18 Aug 2004, 17:16

Are you bleeding from all three bleed points, in sequence? May be teaching you to suck eggs, but, radiator , the one near filter and then heater bulkhead bleed pipe.(the one that comes off the connector at the bulkhead, normally a plastic cap or screw)

billy_bob · Post by **billy_bob** » 18 Aug 2004, 17:50

Normally I bleed the each of the 3 bleed points you suggested using the system you suggested, and would not expect to need to release any of the bleed valves whilst the engine is running, i.e.:
1, Bleed the system from cold
2, Run the engine till thermostat opens
3, Stop the engine and bleed again
However, so much coolant seems to enter the header tank that it seems that something is wrong - the header tank coolant level rises by about 1cm per second as soon as the engine is started. Could this rapid rise be due to a blockage in the system or is this normal? I don't remember it being quite so vigorous before ...

billy_bob · Post by **billy_bob** » 18 Aug 2004, 17:54

Also, once the thermostat has opened lot of bubbles appear in the header tank. I think this is normal but after a while the bubbles don't go away. I guess this could be to the water boiling but is it more likely to be air getting into the system? Perhaps from the cylinder head? And if not from the cylinder head then where else?

billy_bob · Post by **billy_bob** » 18 Aug 2004, 20:07

Any more ideas?
Otherwise I'm going to try an re-fit the head and gasket ... [:(]

tomsheppard · Post by **tomsheppard** » 18 Aug 2004, 20:14

Fill the system with the heater on full and bleed as best your able. Let the engine cool down to cold. Start engine and run for 30 seconds. Switch off. Remove rad cap. Fountain? yes=Head gasket duff for sure.