Mk1 GTi Golf Cabrio Coolant Pressure! - EddyG
Having probs with a MK1 GTi 1.8 Cabrio. Coolant pressurises
Have had head gasket and skim, still the same.
Checked Thermostat and changed.
Flushed radiator.

Is there anything else left it can be or am I to assume cracked head?

No oil in coolant or water (mayo) in oil.


Mk1 GTi Golf Cabrio Coolant Pressure! - leeboy
Sounds like a cracked head, also had same type of problem in mk2 Gti 16v. I replaced thermostat, radiator and hoses, no milky oil. Still having same problem. Next stage is pressure test for head. Sorry can't be any more help.
Mk1 GTi Golf Cabrio Coolant Pressure! - sean
What is the problem, please?

The coolant pressurises?

Don't you want it to? All coolant pressurises, otherwise it would boil. Please tell me more.
Mk1 GTi Golf Cabrio Coolant Pressure! - Aprilia

Cooling systems slowly pressurise due to the water expanding and vapourisation. Typically the cooling system should pressurise to 0.9 - 1.0 bar (as determined by pressure cap); this raises boiling point to 113-120 deg. C.

However, if pressurisation begins immediately on starting a cold engine then this is indicative that high pressure combustion gasses are getting into the cooling system. After a few minutes the hoses will be 'rock hard', even though the engine is still below operating temperature.

If you are sure the head gasket is OK, then drive to local garage and get them to waft their 4-gas analyser probe over the header tank (with cap off, of course). If the gas analyser detects hydrocarbons then you have combustion gasses in the coolant - must be a crack....
Mk1 GTi Golf Cabrio Coolant Pressure! - EddyG
Hi thanks for the reply.

The coolant would seem to pressurise more than necessary. It has split 2 hoses and caused one to expand (top rad hose, split hoses from water pump to oil cooler).

When the coolant is pressurised the pipes are rock hard. It can be left for several days and the pipes are still hard and if the cap is released on the pressure tank, you can hear the gas escaping. If it pressurised when hot and then lost pressure when cold I could understand.

The garage did the head gasket and said it had been leaking, but they did not pressure test the head. Since the head gasket was changed and head skimmed, it does not seem to pressurise as much (ie split hoses etc before head gasket changed)

I guess it can only be a cracked head now?




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