High Pressure

[Tony5496]

Hi can someone help me out please my expansion bottle has got very high pressure so can't get a true reading when cold it's on the minimum mark and I undo the lid and it rises above the max so can't get a proper reading very high pressure any help would be great

[chrispb123456]

If your constantly having pressure still in the system when cold you have early stages of head gasket failure

[Tony5496]

Thanks very much a reply. What would be the best way to check the head gasket i have no slime in the expansion bottle or on the dipstick: or oil cap many thanks.

[chrispb123456]

You very rarely get oil in water or vice versa on these engines later stages of HGF are loss of water especially after driving under load or motorway driving, a failed water pump in the past could have brought on the problem there is also an electric coolant pump to help with circulation through rear heater and booster heater.

You may also suffer from the front heater blowing cold caused by air constantly being introduced into the system, bleeding the system will not cure the problem but might appear to give a temporary fix

[Tony5496]

Yes thanks again do you know what causes so much pressure in the expansion bottle when cold won't even let me put water in when cold as rises over the max line ?

[insanitybeard]

If it's head gasket failure, the gas in the combustion chamber (cylinders) which is under pressure as it is compressed by the piston as it moves upwards on the compression stroke seeps past the head gasket and into the coolant passageways of the engine (which also run through the head gasket into the cylinder head), thereby adding extra pressure to the coolant system.

[Blevins]

Also, i'd suggest checking the little plastic valve in the return hose of the expansion bottle. Mine was almost totally blocked, causing lack of circulation, cold heater, and lots of expansion bottle pressure. I cleared mine and its made a big difference although i suspect i might still have head problems!