Phantom water leak....

[Critical_Mass 10]

Hi all,

 

Well out of no where the temp warning like starts flashing. Luckily i wasnt too far from home so kept an eye on the temp and got home. Popped bonnet and the level was very low. I was confused by the is as there has been no wet patches under or near the car.

 

Topped the water up and it took about a pint and half. Went to the shops and got back home. Didnt check the level, but the light wasnt flashing at me. A few hours later, went out in the car again, no water patches. Got a mile down the road and the light started flashing again. I immediately turned home and left the car.

 

I was on the way to the cinema with the girlfriend, plus it was dark. So i havent had chance to check under the bonnet. But i suspect the level will have dropped again.

 

Where the h3ll is the water going???

 

It must have lost a good pint and a little bit more within a space of about 2-3 hours for the light to come within a mile.

 

Question is where is it going? The first time it came on today i looked under the bonnet and i couldnt see any water leaks nor steam. The rad was changed within the last 4 months.

[OllieVR6 0]

My VR did this once. Water 'disappeared' topped it up, it did it again, topped it up a second time. Hasn't done it since, that was a year ago!

[CorradoVR6-Turbo 0]

get it pressure tested,if you have antifreeze in there you will see a stain from the leak,check your coolant cap seal as they can flip over,other than that start to suspect the headgasket.

[Critical_Mass 10]

I'll check the cap tomorrow, but it was replaced at the same time as the radiator, so wihin the last 4 months.

 

Id be suprised and v pished off if the headgasket has gone as the engine is only 30k miles old. Plus the engine is running fine, no steam, no misfiring, no oil in the water.

[Pat_McCrotch 0]

Check the coolant sensor flange area as well.

[Critical_Mass 10]

Check the coolant sensor flange area as well.

 

The one on the thermostat housing?

[robrado974 1]

Also check the seals on the temp senders and rad sender . There is a chance that it will not leak until under preasure .Leave it running in the drive and look for leaks when she starts to get hot .

[fla 9]

^^^ this is often the nature with coolant leaks. As Mr McCrotch has said check the sensors, check that the clips are all holding the sensors in place. When you get back from a drive, keep the engine running, pop the bonnet and inspect the cooling circuit as far as possible. Also see that the cap for the header tank is ok and that it it not venting it continuously - remove the black G12 cover and have a look around there. Use an inspection lamp if you can or a very pointed beam of light and look at the thermo housing and the ends of the crack pipe. If there is no leakage, it could be hitting a hot surface and evaoprating quickly. In that case, look round the engine for hot areas and then look above it, if that makes sense? Good luck, i hate leaks which you cant find easily!

Edited October 23, 2011 by fla

[CorradoVR6-Turbo 0]

yea all the above,the crack pipe and thermostat area are the places you cant see without getting a mirror and light in there,you can have a leak as you are driving and it will probably evaporate and leave a stain,so look for a stain around those parts mentioned.

[Critical_Mass 10]

Cheers guys ill get it checked out today.

 

Ive got a feeling, if it is leaking from one of the temp sensors, it'll be the rad switch. BUt i'd expect water on the floor if thats the case.

 

---------- Post added at 10:52 AM ---------- Previous post was at 10:50 AM ----------

 

Can anyone tell me how much a new rad switch is and with seal? Can this be replaced without dismantling the front of the car to get to it?

[CorradoVR6-Turbo 0]

cant tell you how much a new one is but its just a rubber o-ring,in most cases it just wants removing,cleaning and refitting. You can do them without removing the front,remove the rad cover screwed to the top of the slam panel for more room,make sure the car is cold,remove the pressure cap to release pressure and then refit it,remove the switch and go from there,the pressure cap staying on will stop the coolant system syphoning its self so the quicker you are the less coolant and bleeding you have to do.

[fla 9]

i think you need a 26 or 28mm socket to get it off, cant remember - Stonejag did his recently he will know the size. Pricewise i think its about £12 or so.

[Critical_Mass 10]

James thanks for the tip. Fla - thanks.

 

I suspect its the seal because when i changed the rad, one think i forgot to note was the rad switch - i should have replaced it. SO when i took it off the seal was more destroyed. So i replaced it with a random O ring i got from B&Q. So i suspect its not been up for hte job and given up the ghost. My fault really but at the time i just needed the car back on the road.

 

I will look here first.

 

Cheers fellas.

[RW1 0]

Rad switch about £26 from VW, Part 1H0959481B for yours. Should come with a seal. If not, part N043 808 3 fits and does the job @ £1.36. The seal is a flat hard card compressible type. Switch is a 29mm size socket.

 

Genuine Rad switches NOS-OEM can be picked up off Ebay. I've just picked up two recently for £25. They didn't come with sealing washers though.

 

TBH if its 1.5 pints ie. nearly a litre out of 7 that you typically fill a well drained system, you have a major leak and sensors/thermostat housing areas should be awash.

 

The first two places to really examine are the back of the header tank bottle and over the are adjacent to the ABS valve block by the nearside inner wing. Suspect a header cap or crack header tank.

 

The second is the water pump gland drain on the water pump body, a little round hole in the body of the pump.

 

In either case, run the engine to stage 1 fan and take a good look to see whats coming out under pressure.

 

The other is a split hose and that will also show with the system hot and pressured.

 

.

Edited October 23, 2011 by RW1

[Critical_Mass 10]

From when i looked yesterday there was no traces of a leak around the thermo housing, or anywhere else for that matter. There was no signs of any steam either, not even a slight trace.

 

Which is hte second water pump, is that the one that sits on the top right of hte engine near the header bottle?

[RW1 0]

I was referring to the main belt driven pump in the right side of the engine. Second or Auxiliary pump is on the same level immediately behind the coil pack. If leaking same as the thermostat housing area, top of the gearbox should be awash.

 

BTW didn't see the last post about the O ring on the rad switch ........ 1st call definitely as its the wrong type of seal to do the job, let alone it being B&Q. If you can find a red coloured fibre flat seal in B&Q that fits, that is loads better to use as there's no containment for the O ring to stop is being forced out sideways, hence why its a flat firbre washer in there or compressible metal ring type.

 

.

[Critical_Mass 10]

Right, i think its a cracked header tank. The water only seems to drop down below a certain level, but low enough for the light to flash on the dash. I also only think it leaks when hot, as im guessing the head tank being under pressure will expand a little and then the crack is opened opened up allowing water to come out.

 

So, once the car cools down i'll take the header tank off and have a look. Is there anything i can do to temporarily fix it, until i can get a new one hopefully monday.

 

---------- Post added at 01:40 PM ---------- Previous post was at 01:38 PM ----------

 

By the way is the head tank just attached to a bracket and 2 hoses? The hoses are fine, but can see how to remove it from the bracket?

[owen g60 10]

I repaired a header tank not too long ago.

I took the tank off and sealed all the pipe outlets.

Then filled it with boiling water to find the crack.

 

Empty the water out.

 

Heat up a scalpel till its red hot and run it down the crack... Try to push it all the way through if the crack is wide enough, then pull the knife out and it should bond to itself.

 

If that fails there should be some kind of plastic cement that you can apply to it to bond the two surfaces together

[Critical_Mass 10]

Cheers Owen! Can you tell how i remove the bl00dy thing? cant seem to get to the nuts thats holding to the bracket.

 

Ive tried removing the fan control unit to allow access, but even of its nuts is near impossible to get a spanner on???

 

---------- Post added at 04:41 PM ---------- Previous post was at 02:52 PM ----------

 

Well ignore that. I got the expansion tank off, sealed the bottom pipe outlet and filled with boiling water.... no leaks.

 

Anyway, the short story. Turns out the top rad hose has a 5mm long split in it just before it meets the thermostate housing.

 

So as a temp measure ive wrapped it in the coolant hose tape i bought when another hose spit awhile ago.. nothing to say it will hold it. But if it stems it a bit until i can get a hose.

 

Im not after a top rad hose.

 

---------- Post added at 05:51 PM ---------- Previous post was at 04:41 PM ----------

 

Had a eureaka moment after id put everything back together. I could have just cut a bit off the end. But thinking about it are these pipes shaped/flared on the end to allow them to slide over the thermostat housing or could i cut an inch off the end of the pipe to completely rid the pipe of the split, then see about getting a replacement?

[dragon green 4]

If there is enough slack in the pipe,just cut the split out !

its not flared,the pipes swell up with age/use, i would still get another one,....just in case

[Critical_Mass 10]

Cheers Dragon, thats good to hear. i'll cut the end of the pipe off tomorrow. Prob the best temp solution.

 

 

I really should change the thread title to "well hidden water leak" as opposed to "phantom"... it was only buy luck that i spotted the small dribble of water. There was no steam at all.

[moxi2001 10]

I had this problem and found a hidden leak on the bottom of the water pump. It was around the hose itself.

[Critical_Mass 10]

Yeah i should be grateful really that it wasnt gushing out. BUt was a bit of a mystery when i was losing water but there was no signs of steam or water on the floor. Still only took about 30 mins to remove, refit and bleed the system of air. Job done.