Urgent help re coolant leak please!

Post by **fairwynds** » 18 Apr 2007, 19:33

Hi all
supposed to be going away in van this Friday for weekend....but....
just got back from the food shop (2 miles each way max) and find water leaking steadily out of bus....

1900 DG 1985

Leaking from what looks like a manufactured set of three little 'holes' in top of coolant top up tank! heres some pics:

The van has had a major rebuild and has done approx 600 miles since that, without a problem. I had been checking coolant regularly and noticed that (from cold, level at 'max' mark) the level would rise up in the top up tank (above the filler cap) - but thought this was normal?

Is it just a case of a new header tank cap (black one with 'valve' looking things inside?)

If it makes any sense, when I cause a vacuum (suck the three little holes) in the tank there is hissing at the cap (which is off the header tank at this point) and also when pressure is in the tank (blow down the three holes) cap hisses also??

Sorry for dumb question....

Post by **tonytech** » 18 Apr 2007, 19:43

I dont think the level of coolant in the top up tank should rise like this.
The expansion tank top should pressurise the coolant system and allow coolant to be sucked from the top up tank into the system if it needs it.

I'd start with a new expansion tank top.

T

Post by **clartsonly** » 18 Apr 2007, 20:15

hello fairwynds, good to here that the rebuild was relatively successful

you are sure the system has been bled correctly aren't you? I still think mine has air in :yikes:

your bleed valve screw hasn't been left open or is broken?

I have replaced my cap, and it no longer leaks from underneath it now when it gets hot, but leaks out of the sensor instead (still need to get new washer form vw). perhaps the trapped air is so large that it pushes all the water out of the expansion tank through the cap and when the top up tank is full escapes through the three holes (maybe emergeny relief)

I would personally rebleed the system, you may find it has been fine for 600 miles until the weather and traffic meant that the trapped air expanded too much, I drove mine to the MOT with no leaks (after changing a gasket and not bleading the system) then after idling for 10 minutes loads of water left the system, just missing the MOT fellow.

good luck

Post by **dave friday** » 18 Apr 2007, 20:29

i just checked in the bentley book and it says "apply a pressure of 0.9 to 1.15 bar(11 to 16 psi) if pressure relief valve opens within this range,cap is ok. the black cap has been replaced by a blue one ,get a cap from vw as some of the patten ones are dodgey(ive heard).so as Tonytech says start with the cap!.you might have to re-bleed the system.

Post by **fairwynds** » 18 Apr 2007, 21:35

.......new cap it is then....hope thats all thats needed! Cheers all.

Post by **Dan Wood** » 19 Apr 2007, 05:39

....I got a brand new blue cap from JK....

It didn't work. Get a genuine VW one if you can!

Post by **toomanytoys** » 19 Apr 2007, 07:54

new VW cap and bleed the system, take it for a run and iff it still fills the topup tank I am afraid it could be a bit more serious...
the 3 holes in the top up tank are vents and are there to stop it being blown apart in these situations...

Oh and can you complete your profile so we know where you are... there maybe a local member that can pop round to assist...