Really weird issue. Car (Mk 1 Octavia vRS 1.8 20v Turbo) has never done it before tonight. I didn't drive it any differently to how I would usually.

Basically I was going down a country lane at 60, and suddenly the temperature light starts flashing and beeping at me. Slowed down to 50 and it disappeared, back up to 60 and the temperature crept up again.

After having a few cars in my illustrious car-owning history that regularly overheated the temp gauge is one of those things I regularly keep my eye on. It has never gone above 90 before - the needle always exactly splitting the 9 and the 0. This happened so suddenly it's surprising.

All the way home if I went at 60 or above the temp would slowly creep up to around 120, then if I slowed to 50 it would fall again. Really weird thing is that I pulled into some services and a couple of laybys, and as soon as we stopped, the temp went straight back to 90. Literally as fast as the dial could move. When I got back into town I drove slowly, then aggressively, leaving it in 2nd to cruise at 40 mph, and still the temp wouldn't budge above 90. It is only when going at speed. Revs have no effect - only the overall speed. Never seen this before on any car!

I've checked for obvious loose pipes, coolant level is fine (and only 3 months old), all hoses feel warm and I'm getting warm air in the cabin. The radiator doesn't feel hot, but then I guess it shouldn't. (Which is which btw - I presume intercooler is the one in front of the rad?) It's not leaking any coolant, oil level is fine, but I haven't been able to check for mayonnaise in the filler as it's still warm.

Please help! I have to get to work tomorrow in it (which is 27 miles away, all motorway!)

Just to add - I have a Shark STS unit which can read fault codes. Will I be able to work anything out from one, if there is one there? (Haven't applied Shark map yet as car is still getting some warranty work done - alas now out of warranty by 2 weeks!)

Edited 22 November, 201015 yr by Nothing_Less_Than_A_vRS

At a guess sounds like water pump impeller knackered, mine did that any sort of fast driving temp crept up, soon as i slowed down temp dropped. Common fault new pumps have metal impellers, replaced mine same time as cam belt and tensioners.

+ 1 for water pump impellor failure!

Sounds like waterpump to me as well.

Bugger.

Is it ok to drive around as long as I keep under 50, or is it just going to get worse?

Looks like I'll be commuting in the half-finished project MX-5!

Depends on if the shaft has detached from the impeller blades or if the plastic work has broken up (bits then floating around in the coolant system and could jammed in all sorts of places (thermostat, in the engine, etc).

Depends on if the shaft has detached from the impeller blades or if the plastic work has broken up (bits then floating around in the coolant system and could jammed in all sorts of places (thermostat, in the engine, etc).

+1. When mine went impeller had detached itself, it's if they break up you should be worried

Sounds like it's best not to risk it. Thanks for all the replies.

Off to the post office to get tax for the MX-5 then!