overheating problem

[rach]

hi guys, my 2003 1.2s apears to be over heating lately. the red temp light comes on, but only after i've been driving at 70mph for a few minutes, in traffic and around town its fine.

the coolant was changed about 9 months ago and the level of it is fine. the heater inside the car works as it should, and a quick blast on this knocks the red light out on the instrument panel.

if i leave it idling and give it some encouragement by revving it, the radiator fan kicks in, but that is without the temp warning light coming on.

all pipes are hot at the top and bottom of the radiator, the radiator isn't obstructed by anything so its a mystery at the moment, is it likely to be the thermostat or water pump?

any help with the investigations much appreciated

 

[kennierobo]

if you take the thermostat out and it still overheats I would then investigate water pump, I would also check the dip stick for contaminants ie water mixing with oil which would point me in the direction of head gasket, if you rule the later out then its a big sigh of relieve..

 

[pollyp]

sounds like the temp gauge sensors faulty if the cooling systems working fine.

 

[rach]

oh, checked the oil filler cap, no sign of mayo in the oil there fortunately, although it's only just done 20k so would be extra-peeved if it was the HG.

are there sany online diagrams for the engine to locate the thermostat, still haven't got around to getting a Haynes manual for it yet, had no need to so far!

 

[frank]

there,s a pdf manual around i think rach :grinning:

 

[Scott]

 

[rach]

Took the temp sensor out today to give it a clean and look to see if there were any obvious signs of problems with it, but it all looks fine. Cleaned the connection between the sensor and the plug too. I ran the engine with the sensor unplugged (but screwed into the engine, just not connected) and the fan came on straight away along with the engine warning light. Have reconnected the temp sensor back up, which knocked the fan off but the engine light is still on. is there a quick way to reset this wihtout any special gizmos?

Might just replace the temp sensor and thermostat and see what happens, rather than take the thermostat out to test it, just whack a new one in :suspect:

 

[Bombardier]

It may be that the radiator has been topped up with tap water at some stage. The minerals in the water clog up the radiator tubes slightly which makes them thicker and so they do not exchange heat as well as they should.

This can be detected by a flow test at the bottom and the top hose separately. There will be a maked difference in the flow if the radiator is clogged.

 

[Shaun]

A new thermostat is pennies anyways
Clicky

Halfords etc. should do them to if your in a rush.

 

[rach]

thermostat and temp sensor swapped at the weekend, but it's still doing it Only other guess is that the coolant has somehow stopped doing its job, so that is getting changed this evening for some fresh stuff.

 

[Grevs]

this happened my 1.0 k11 and I changed my rad and its perfect,my old rad looked perfect but i changed it as I had a spare

 

[slamdunk]

Our 1.2 did it in the summer during a good run on the motorway. It was one of the few times it was run on standard unleaded. 5 minutes on the hardshoulder and it was fine. It has been run on super unleaded ever since and has been fine?????

Slam

 

[Bombardier]

sounds like you need the radiator tubes cleaned out.