I am in need of some assistance.
I am having a coolant pressure on my 1.8 16v clio. (Renault), coolant, cooling-system, overheating (car maintenance) In that when left to idle and engine gets up to temp and when revved the car will hold a lot of pressure in the main rad pipe.
I have replaced the thermostat, new rad, new header tank cap, new water pump, re-bleed numerous times the coolant system, bypassed the turbo and heater matrix. I have no mixing of water in the oil and no mixing of oil in the coolant, I have not lost any coolant other than when I open the cap to relieve some pressure I loose a little. I have also replaced the head gasket and had the head skimmed. And torqued all down in accordance with the manual.
I am still having the same coolant pressure issue and am rather stumped as to what the cause could be as clearly combustion gases are getting into the coolant system somehow. I have done a compression test also on all 4 cylinders and have a range of 148-150psi across all 4 which again I am happy with.
Now from cold the car is fine the pressure seems to only build up once warm? If I was to leave the car running for an hour or the fan will kick in and out nicely but the top rad hose is overly hard. If I was to hold the revs say at 2500 rpm for a few minutes the top rad pipe looks like it will explode and thus unable to use the car until sorted. Any thoughts?