My '02 Octavia 1.8T has overheated in heavy traffic three times now.

It only happens when it is a warm day (22+) and I am stuck in traffic for a long time (1 - 2 hours).

Symptoms in order:

Air con stops blowing cold.

Temperature needle starts going towards the red.

I lose power.

If I turn the heating up to HI, the needle returns to normal.

If I turn the air con off, the needle indicates overheating.

I have looked inside the engine bay and there s no obvious signs of boiling, but I have never seen the fans spin up. The radiator matrix is cool to the touch, but the top pipe is too hot to touch.

I have taken it to my independant garage and to a local Skoda dealer, both who cannot replicate the problem and say there were no error codes showing. They gave me the car back saying nothing to fix.

Am I missing something or are they both wrong?/

Is there another local garage to me anyone can recommend? (Kingston Upon Thames area)

Ideas please people!

Could this be a faulty thermostat?

Surely if this was a thermostat, it should be reasonably easy to diagnose? Would it not show up as an error or is this not something that is monitored?

Err i don't think it is monitored by ECU. How many miles has it done? and how old? when was water pump and timing belt last changed?

I am just woundering if the water pump impellor has shattered and one fin got lodged in the thermostat.

This is not unheard of but i don't want to worry you i'm just thinking aloud.

Also is the radiator nice and clear with no muck in the fins?

The car has done 70,090 miles and is booked to have the timing belt and water pump done in 2 weeks time. It is still on the original.........

If it is the thermostat, then why no fans?

The radiator fins are clean.

Don't know about the fans but i have a bill upstairs from the previous owner for £4341 for a snapped timing belt at 77576miles and 3yrs.

Skoda have revised the age/milage to 60000miles or 4yrs.I think this is due to water pump and belt faliure.

sounds like may have a blockage and the water isnt getting around.

Check the fan fuse

See this link for location

http://www.briskoda.net/forums/octavia/two-questions-re-fuses-relays/81889/?highlight=fan+fuse

if you have never seen the fan spin as you say, start the engine and turn on the aircon (not in econ mode) both fans should spin.

On mine the small fan spins only so there is a fault somewhere- this was found when i had my aircon regassd, they said i wouldnt notice any issues fom the main one not working and its never overheated, the small fan has come on for a short while after a drive on hot days but ive never been stuck in taffic for it to be put to the test.

If your radiator is cool this indicates poor circulation. Probably thermostat, possible water pump vanes gone.

Sounds like a waterpump issue maybe the plastic impellor has started to break up and caused a blockage somewhere personally i would not drive it anymore till you get the belt and pump sorted you could end up with a hefty repair bill otherwise as this is all overdue. Be carefull as pumps have been known to break up and jam the pump resulting in a broken cam belt i certainly would not chance it.

Thank you everybody for your responses.

Due to the tone of much of the advice, I have persuaded the garage to move the cambelt change to tomorrow, where the water pump will be replaced and cooling system checked. I have learnt so much recently from here and wish to thank all concerned.

Due to owning a Skoda, I haven't laid a spanner on a car for over 5 years and am very rusty (and older!). With todays engines being so much more complicated than my old MGB (the last car I needed to spanner), I now realistically know nothing! I have relied on the garages for advice, but from this have needed to get my knowledge up to speed.

Hey as long as you get it sorted thats the main thing.

Best of luck with it and let us know what it was

So, I now have a new cam belt, tensioners and water pump with metal impellers.

The old water pump was shot, the impeller had the structural integrity of a potatoe crisp. All bits were recovered. The water flows round the engine, but is still overheating.

Time ran out (I did ask for the job to be brought forward), but there is no power at the fans. The fuses on top of the battery are all intact and have power.

Tomorrow is another day. Maybe a solution will be found then.

Do you think it could be the fan motor then?

Best thing to do would be to check the power at the fan connections.

Following a discussion between the garage and Skoda, the suggestion is that the fan control unit might need replacing. This £77 part is currently on order. Does anyone know if this unit controls the air con fan as well as the engine cooling fan?

This problem has now been resolved after all this time, one trip to a dealer and four trips to an independant.

The fuse on top of the battery had burnt out one leg, but not blown.

Now I have checked this fuse in the past and so had the garage, but it turned out to be the fuse holder that has burned out and presumably has been arcing all this time, finally burning the fuse leg. The circuit was tested as complete with a meter before, but clearly there was not enough juice to power the fans, only my meter.

SWMBO now has cooling and air con. Groovy.

Glad to hear that you finally got it all sorted mate