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Engine overheated; head gasket blown; head sent to machine shop for inspection and repair--now excessive pressure in cooling system
What causes excessive pressure in the cooling system?
Is this a serious problem?
What are the causes of this problem?
Can this be a dirty radiator? Bad thermostat valve?
My Volvo mechanic says there is too much pressure in the cooling system. He says this is proved by the lack of squeeze in a newly replaced upper radiator hose...lack of squeeze as in too fat with excessively presurized coolant.
>>He says the cause is a badly done head job I just had done. He thinks compressed air is leaking from the cylinder(s) into the water cavities inside the head. Mechanic: "The machine shop missed something or they said they refurbished it and only shaved it."
History of this problem:
*1989 740 GL with +250,000 miles (oil change every 4,000 miles)
*Radiator replaced 4 years ago--not with OEM radiator.
Incident or event leading to this problem:
*Engine overheated due to cracked/broken heater valve.
*Head gasket blown. Water was found in number 1 cylinder.
*Compression dropped. Engine would not start.
*Head taken off and sent to machine shop.
*New head gasket
*Compression restored and engine now runs fine.
*Had some other issues resolved at the Volvo shop (Miami Volvo Tech) --new temperature sensor, connector and wiring installed, thermostat checked to make sure it was not sticking, some Codes resolved to remove check engine light. ( Dirty throttle and a bad ECT sensor-fuel temperature sensor and fuel throttle housing sticking), replaced valve cover gasket to stop oil leak, shifter bushings replaced, upper radiator hose replaced)
*Volvo mechanic said I have compression leaking into cooling chambers in the head.
What else could be the cause of this problem besides a bad head job?
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