Nissan Micra 2002 - Coolant temperature

After a 60-mile journey yesterday I noticed that the radiator fan had
come on. I thought it was strange since I'd had a long motorway
journey, and the cool air should have cooled down the engine.
This morning I looked under the bonnet - and noticed the pressure cap
was off, although the coolant reservoir was still saying coolant was
at max, and there was coolant that had clearly come out.
I put the cap back on and took it 2 miles this morning and noticed
that the temp gauge on the dash board was heading steadily towards the
danger zone. Usually the temp guage stays halfway.
Any ideas folks?

"Colin" > wrote in message
om...
> After a 60-mile journey yesterday I noticed that the radiator fan had
> come on. I thought it was strange since I'd had a long motorway
> journey, and the cool air should have cooled down the engine.
> This morning I looked under the bonnet - and noticed the pressure cap
> was off, although the coolant reservoir was still saying coolant was
> at max, and there was coolant that had clearly come out.
> I put the cap back on and took it 2 miles this morning and noticed
> that the temp gauge on the dash board was heading steadily towards the
> danger zone. Usually the temp guage stays halfway.
> Any ideas folks?

Ive never seen the pressure caps on radiators just come off unless the cap
or radiator neck were damaged, or unless someone had taken them off and
failed to replace them properly. I suspect the latter in your case.

Drivers have been known to remove the pressure cap so that they can limp
home
if there is a hose leak, a waterpump failure, or maybe a welch plug leak.

You need to be sure the system is properly filled with coolant and air is
bled from the system. Then reattach the pressure cap correctly.

If it still overheats, look for things like a sticking thermostat,
obstructed radiator,
or internal engine problems such as a blown head gasket or cracked head or
block.