water leak

[hamster]

hi all i have a intermitent water leak i think its leaking from the bottom right of the radiator as you would look in the bay is there a temp sensor down there as it looks like thats the leak strange thing is that the water will not leak for weeks then suddenly dissapear when i fill her up no leak  any ideas would be good cheers mark

[BIG Matt]

When it does leak it could be worth poking your head under the bonnet (and under the engine) and see if you can see if there is any evidence of where the leak is coming from.

If it is leaking from a temp sensor then you should just simply be able to replace the seal ring which sits between the sensor and the rad (if there is one?).

If not just run a small tub of redweld through, this seals most things (even small cracks in the block!) and lasts for ages.  £2.50 well spent 

[Gambit]

aye radweld is good for making your heater matrix explode!!

you'll probably find the leak only happens when the car is really hot. i.e. expansion. as said just replace the wee rubber seal on the sensor

[Judderi]

DONT USE RAD WELD!

[rubjonny]

Agreed, dont use radweld unless you fancy replacing your heater matrix

First thing I'd do is replace both plastic flanges on the front & right side of the head, these warp and start leaking.  Dirt cheap from VW   Once you remove the old ones, plug the holes with some tissue and rub down the mounting surface with some sandpaper to allow the o'ring to make a good seal.

Next take a close look at the radiator, especialy along the plastic end caps.  Its worth taking the grill and radiator fan shroud off so you can get a good look at it

[BIG Matt]

Awesome stuff Radweld, I can't recommend it enough.  I used it on my old Nova SR and it lasted 18 months (probably lasted longer but sold car).  Never had any heater matrix probs on that, unless its just a VW thing?

Obviously its worth doing the job properly, I just suggested Radweld as a cheap fix so to speack.

[AudiA8Quattro]

Agreed with above, nothing wrong with radweld, people just can't read the instructions 

[jezza16v]

I agree, never had any probs with radweld, used in previous 16v to cure the leak in the heater matrix and it worked well but....... Don't put it in cooling the system through the header tank. Warm the engine up to about 1/4 on the temp guage & release the pressure in the header tank. Disconnect the top hose from the rad and drain some coolant off then tip the radweld (small tin) straight down the hose and then reconnect it to the radiator. Top up the header tank and run the engine up to full temp.  If you put the radweld in the header tank it makes a real mess and takes ages to get into the engine also it mixes with the air in the tank and makes a real mucky mess  It won't last forever though, if ever you flush out the coolant and refill with antifreeze it will find the leak again. 

[Veedubgt18v]

Agreed with above, nothing wrong with radweld, people just can't read the instructions

yeah you absolutely do have to shake it up like a mofo cos you get lumps that gum up your system if you dont i used it on a peugeot once when my rad blew a hole. got me home from work!

brought a new car then and drovfe the sh!te peugeout without any coolant in it for a laugh to see how far i could go, got from witney in oxfordshire to abingdon (prob about 15miles) before it dropped a piston and blew up was a giggle. this was in the days when scrappies paid you for your crud car so i got a tenner, a ride home and a beer!! best thing about that car that was!!

[VeeDubGTI16v]

i think it was radweld that gunked up my bypass valve, but it was starting to stick anyway it did the job on my rad though