Ford galaxy - Pressurising

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Sun 17 Jan 2016 15:58
Ford galaxy - Pressurising - Amac

I have a Ford galaxy that is pressuring the water jacket and blowing pipes off, now the usual suspect would be the head but it's had another cylinder head which was crack tested and checked for level and came back all ok, as it is now it has no increase in temperature and stays solid in the middle of the gauge, and there is no evidence of water in the oil, so any advice on things to check and eliminate would be greatly appreciated.

Regards

A Mac

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Sun 17 Jan 2016 16:15
Ford galaxy - Pressurising - Bromptonaut

Are you saying it's done it with two different cylinder heads?

Presumably ch gasket was replaced with new and properly specified item, any recomendation for new studs was followed and correct tightening sequence used?

Are you sure it's not the block that's a problem?

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Sun 17 Jan 2016 20:28
Ford galaxy - Pressurising - Railroad.
If pressure is building up in the cooling system very quickly when the engine is cold then the cooling system is being pressurised by the by compressed air in a cylinder, which has a leak across the cylinder head or block due to a crack, or the cylinder head gasket. There really isn't much else it can be.
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Mon 18 Jan 2016 15:01
Ford galaxy - Pressurising - Peter D

Have a sample of the coolant header tank taken and get them to check for combustion gases. Regards Peter

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Mon 18 Jan 2016 19:57
Ford galaxy - Pressurising - Amac

Yeh Peter I'm on it, gonna borrow one from work

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Mon 18 Jan 2016 19:56
Ford galaxy - Pressurising - Amac

Thanks for your input railroad, but would that not produce an increase in temperature?

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Tue 19 Jan 2016 13:28
Ford galaxy - Pressurising - Railroad.
Unlikely I would've thought, as any increase in temperature resulting from the pressure increase in the cooling system caused by a crack in the cylinder head/block would be absorbed by the coolant.

The pressure in the cooling system is directly related to the temperature, and will increase in line with the temperature increase as the engine warms up. The pressure is therefore regulated by the temperature. The pressure cap is an overall safety valve which should lift to let off the excess if the pressure exceeds the rating of the cap. In theory this should never happen because the engine should never get that hot, but it could do if the engine is not correctly dissipating heat due to a thermostat or radiator fault. In any case split hoses and rapid excessive pressure build up should never happen. If they do then a compression leak from one or more cylinders almost certainly the cause.

Excessive pressure on a cold engine indicates a clear problem.
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