Expansion tank full

My Fronty seems is losing water from the rad and filling the expansion tank until it overflows. The engine temps are fine whist driving, on a run it hovers about 80 and in town it goes upto 100 and the cools down again. The heater works fine so why is it pushing water into the tank. The pipe is connected in the bottle ok.

Thermostat and/or expansion cap would be the first two to investigate/change.

By expansion cap do you mean rad cap or expansion tank cap.

Both if fitted

Check the rubber tube in the expansion tank. Make sure it has no splits or holes and that it is a tight snug fit . if its loose or leaking you will get the same symptoms as yours. If the pipes loose, just pull it off and reconnect the other way around as the bottom end won't be stretched. The pipe I'm referring to is the pipe in the expansion tank on the underside of the expansion tank cap and NOT the pipe from the cap to rad.
What happens is the coolant expands and enters the expansion tank and as it cools it sucks it back into the rad. If the internal pipe is damaged or loose then when the system cools it sucks air in, and so the cycle repeats and the tank fills up. A faulty rad cap can also cause this.

Just as a precaution, get a garage (or if you have one yourself) to so a combustion gas "sniffer" test on the coolant, mine was doing exactly this only was filling the overflow bottle and throwing it out onto the floor, in my case its the head gasket failing causing combustion gases to pressurise the coolant system which forces it out the overflow

i hope it isnt this for you, but a sniffer test will confirm it right away rather than messing about replacing thermostats etc

Have to say that crossed my mind this afternoon when I started it and it spluttered a bit. First thought was could there be water in a cylinder. I looked in the top of the rad when it was still warm and the engine was running and it was blowing bubbles, much like when you are bleeding it.I have fitted a new pipe in the expansion tank and filled the bottle to the max line and will look again tomorrow.

this does sadly sound alot like whats wrong with mine, i get alot of steam out of the exhaust too even when warmed up, temperature stays normal when driving but at a standstill it boils up pretty quick, as a temporary fix i am going to try some k-seal and see how that goes

Again, check if your local garage has a combustion gas tester, only takes a few minutes and will show if it is the head gasket or not

Took a peek under the bonnet tonight and just happened to press down on the rad cap and a fine mist of water came out from under the sticker. Looks like the rad cap could be the problem. Have new one on order which should be here tomorrow so will fit that and then if still got probs, will have a sniff test done.

Good luck.

Would be easier to buy a ton of rocking horse pooh. Discontinued by Vauxhall and none of the motor factors have one. Anyone bought one recently and if so where from.

Quick update, contacted my local radiator specialist, who has them in stock, £5 +vat. Result.

Was going to say .. standard rad cap isn't it .. or do you mean expansion tank cap?

howd you get on with the new rad cap mick ?

All sorted Foggy me ole mate. £5 cash and me a happy chappy. If anyone else buys a cap you need a 16 psi variety.

nice cheap fix then mate :thumbup:

That was lucky ... well done buddy!