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Discussion Starter #1
Recently bought a 56 plate mini one had an issue with the expansion tank blowing off , garage replaced radiator and fluids but again 3 days later is doing the same thing ??? Arghhhh please any help heard things saying it the thermostat
 

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would do a sniff test first of link below you need bt3 as per link works with all antifreezes etc that will show if got exhaust fumes in water jacket if have then gasket or head issue post likely, if passes that test then thermostat housings are common as its a mapped thermostat ie has its own heater core and opens and closes via ecu map controlled, also there is a upgraded housing with 4 wire plug and wiring update available, do a code read on it might show short to positive code when heater plays up its also switched earth to ecu, the heater is 12v and the sensor is max 5v typical voltage at 20 degrees 3,2volts more heat less voltage,, also when changing the housing worth changing the link pipe that runs at rear of engine these crack with age need to remove water pump at same time, water pumps have plastic impeller and this cracks and spins or breaks up this also causes over heating issues, would not bother fitting cheap thermostat housing as they tend to be very hit and miss and can make car run wrongly, there is a bleed screw on top of thermostat housing ie add water to header tank with this bleed open until all air comes out also one the the top hose from heater matrix same thing, the rad flows hot water to top of rad should have arrows on housing if wrong way round car will over heat
 

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Discussion Starter #4
would do a sniff test first of link below you need bt3 as per link works with all antifreezes etc that will show if got exhaust fumes in water jacket if have then gasket or head issue post likely, if passes that test then thermostat housings are common as its a mapped thermostat ie has its own heater core and opens and closes via ecu map controlled, also there is a upgraded housing with 4 wire plug and wiring update available, do a code read on it might show short to positive code when heater plays up its also switched earth to ecu, the heater is 12v and the sensor is max 5v typical voltage at 20 degrees 3,2volts more heat less voltage,, also when changing the housing worth changing the link pipe that runs at rear of engine these crack with age need to remove water pump at same time, water pumps have plastic impeller and this cracks and spins or breaks up this also causes over heating issues, would not bother fitting cheap thermostat housing as they tend to be very hit and miss and can make car run wrongly, there is a bleed screw on top of thermostat housing ie add water to header tank with this bleed open until all air comes out also one the the top hose from heater matrix same thing, the rad flows hot water to top of rad should have arrows on housing if wrong way round car will over heat
Pressure tested and found to head head gasket and replaced thermostat aswell
 

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