hi my girlfriends 96 punto 55 is over heating
if i turn the heater on hot it blows hot then goes cold then hot again
when its changing from hot to cold there is a harrid grinding sound
the fan works
there is no gunk on the oil cap or dip stick
water leavel is fine so is oil and coolant
any ideas
thanks

ps my ideas are thermosat or heating matrix

well the heater matrix is under the dash, so if its leaking there would be coolant in the foot wells etc.

my alfa heater used to run hot and cold bleeding cooling system cured the problem, think it was an airlock

yeah try bleeding the system and see if that makes a difference.

i had similar problem with 00 punto
it turned out it was the head gasket was gone
mine would get hot air untill the water leaked out thru the blown gasket
i think its possible you might have head gasket gone also ,
but hopefully for your sake its not

right i removed the thermostat and tested it and it was not working
i got a new one and now the bolts will not go back in i think the thread has gone on the hole how do i fix this and what it going to cost cheers

Did you get it sorted ? How did you manage to strip the threads i replaced my thermostat and i have to admit it was a bit fiddly, well more awkward i guess