Hiya folks,

Bit of an odd one this, and everyone i know in the trade aint got an answer either.

We have just come back from a 6 day road trip round europe which included a visit to a 2 day RMA trackday at Spa-francochamps and an evening at the Nurburgring, all in all i have done some 2000 miles with 2 x strange coolant issues.

I managed to sneak out for a play on the spa circuit and managed 45 minutes on track in the rain, with no problems. Came to move the car later on and the low coolant warning light was on and the header tank was well down. Topped it up and did the usual driving abaout without incident.

All was well till 2 days later and our second lap of the ring when the low coolant level light came on up the long uphill section. i immediatly stopped, saw that the coolant had been spat out of the overflow pipe from the header tank, waited a few minutes, topped it up and continued as normal.

Since then we travelled all the way back from europe in some major hot (32c) traffic jams, 4 up, loaded like a pick up truck, ive done another 1500 miles since and not lost a single drop of water, temp is fine, no leaks from the water pump area etc etc.

Ive had a "gas test" done on the coolant and theres NO signs of headgasket failure, it just seems to have spat the water out when it was working at its very hardest/under the most load.

Its done 56k miles now, and never missed a beat. The only thing i can think of, is if a couple of blades have fell off the water pump and it just got too much for it to cope with? Does that happen with the waterpumps on the diesel??

The only way i'll find out is when we do the cambelt / water pump at 60k, which will only be 8 weeks away at the current rate of mileage!

Any ideas folks?

Take the return off the header tank, run the engine up and see if you get flow out of the pipe, should be a steady stream at a couple of thousand RPM, put it in a bottle if you want to reuse it. If its not then the impeller has mre than likely started to come loose. I'd advise replacing it along with the cambelt (60k or 4 years if its not been done).

Failing that test the cap is holding pressure.

Good idea!

I suppose i'm not overworried at the moment because under "normal" driving its 110% fine. I was going to change the waterpump at 60k as a matter of course, but i never thought about the cap!!

It did put a bit of a dampner (pardon the pun) on the latter part of the trip because i was worried about it happening again.

Perhaps the race circuits frightened it? LOL

I'm assuing that if the impellor was minus a few blades it would function perfectly normally under "normal" driving?

It doesnt tend to lose blades, it comes loose so dosnt turn as fast as it should. Fine at low speeds etc but at sustained rpm the water doesnt flow quick enough to cool down.

Coming loose dont sound good!!! LOL

I was under the asumption that the pump suffered the same failings as teh vrs ones?

Eitherway, i'll try the return pipe trick to see if its obvious!

Cheers for the advice so far!

I know the symptoms, agree about the water pump, but it could also be the head gasket. The easiest way to try for gasket is to drive the car hard for a while, then leave it to cool down (a few hrs). Then open the coolant cap. If after cooling down you still have pressure in the system (there should be very little over or under-pressure, with leaky gasket the overpressure will be quite high), then the gasket is leaking exhaust into the coolant under load.

Sadly, I am an expert on this - on the Octavia I replaced water pump, thermostat, flushed radiator, removed airlocks, pressure tested the system, you name it, before finally having the gasket replaced. The new gasket cured it.

One of my mates had this happen on a 110, and as Ross says, what had happened was that the splines on the plastic impellor had stripped, so it didn't spin at engine speed any more.

Perhaps the car is telling you that the next mod should be an external electric water pump?

Perhaps the car is telling you that the next mod should be an external electric water pump?

I think your right LOL

Even 4 up round the ring, the first ever lap of 11.30 minutes i thought was impressive!!

At least general concensus is the water pump! fingers crossed, and thanks for the advice guys.

This plastic water water pump issue. Does it affect all octavias? ie, should i be concerned about my 2002 sdi which had a new timing belt kit fitted at 60k last year but no water pump?

Yeah it can effect all Octavia models but far more common on the petrols that diesels.

Headgasket? Only if its overheated i'd say. On the 110 diesel I dont think I have changed one headgasket due to overheating, the multi layer metal headgaskets are pretty good.

>>Headgasket? Only if its overheated i'd say.

Quite possible. But if the engine is chipped (Nurburgring makes me think that :-) then it can overheat while driving hard.

On my Octavia the gasket most likely overheated due to the service not removing airlocks - Vindis Skoda Cambridge did timing belt and water pump, I got the car with low coolant level, and ever since I got a car back it had coolant loss which grew larger over time. My current guess is that they failed to remove airlocks during/after refilling and yes, probably overheated the head/gasket. Since the service was deaf to my calls afterwards, I left Vindis a consistent opinion elsewhere on this site.

Anyway, the failure was gradual, and in the first stages (meaning in practice 1 year+ before it gets serious) you only get minor coolant loss. Even after 2 years whenever my wife was driving there would be little coolant loss, 0.25l/week or so. But if I joined motorway on an uphil, with full throttle in 3rd and 4th, this was good to bring engine to 120deg and lose 1 bottle of coolant....

The point I am making is to check the pressure in the coolant system after engine has cooled down. If there is high pressure, the water pump replacement alone is not going to help, at least not for long, and the preparation for water pump replacement is half of the TB job effort and half of the gasket job effort anyway.

And in this case, change the gasket, water pump and put a new timing belt kit while you are at it, plus possibly a thermostat (stlg6 or so). 4 years of piece of mind afterwards.

On the water pump issue, yes any 1800, 1900 or 2000 VAG (I've never heard of it on the 1600 or smaller capacity units) engine can get it, but it's more common on the petrols, I suspect because they run hotter anyway.

Oh and dieselV6, wasn't Lofty's sig "...Tdi Estate, Remap, 17" TT alloys..." enough of a clue about the car being remapped?