Coolant Leak - Head gasket?

My car is a V-reg ('99) V5 with 120K miles. Mostly trouble free, with the occasional small problem that ends up in a not-so-small VW bill :(

The latest problem however has got me tied in knots: I'm losing heaps of coolant. With normal use I need to replenish about 1 - 1.5 litres per journey. However...

• It only leaks when driven
• In spite of the volume lost, I cannot see anything leaking from anywhere
• The volume of loss seems to be unrelated to the length of the journey (300m or 50m)
• The volume of loss goes down *significantly* if I switch the heating from ECON to OFF (about 3/4 less!)
• Even with a virtually empty reservoir, there is very high pressure in the cooling system when it's hot.
• Any attempt to de-compress the reservoire, brings water rushing back from the engine. Running the engine on idle just draws it slowly away again.
• No water loss inside the car or steaming.
• No white clouds from the exhaust (that I can see...)

I went to my local garage and they also can't see anything. However they tested it with some liquid (block test???) and they think that there are exhaust fumes in the coolant. They suggested head-gasket as a possibe problem, but they're not touching it!

I have now booked the car with a VW specialist (independent) for a full compression test to test if it's a gasket problem.

:confused: Here's where I need your help:

1. Do these symptoms seems familiar to anyone? What else could be the cause?
2. If it turns out to be a gasket and the head(s) (2 or 1 head on the V5?) need to come off, what else should I be fixing/changing at the same time? Hydraulic tappets? Thermostat? what else?
3. I assume that a head-gasket change will have a £££ bill. probably 1/3 of what the car can fetch today. Is it worth it?

I really love my V5 and I'd hate to end its life here...

I look forward to your collective wisdom! Many thanks.

hi there sorry to here of your trouble......if the garrage has done a liquid block test they are usually pretty acurate......can you smell hot coolant when you have parked up??????

I can't really tell. The engine smells "hot" but I can't really tell if there is coolant or not. I have seen water puddles shortly after parking after a long drive, and I've seen radiator water sitting in the undertray when I took it off, but very little. Still, I can't see any water leaking from anywhere.

Another thing that puzzles me is: The car does not seem to have lost power - the 2.3 accelerates smoothly and does get a kick when you put your foot down, even at high speed/revs. If this was a gasket, shouldn't I be losing power somewhere? Also, if exhaust fumes are leaking into the coolant, where is the coolant going? If it was going to the cylinders I'd be seeing white smoke - no? The enging pressure is much higher than the cooling circuit, so why would the coolant flow the other way? Also - the car is not overhearting, as far as I can tell...
:confused:

Maybe irrelevant: The enging has been "knocking" a lot more recently, when accelerating in low revs, especially when cold.

Any thoughts? Thanks

R u sure its not the rad, they fail in the bottom left corner( looking at the car). Look thru the grill near where the fog light is. Would not expect it to be the head gasket unless the engine gad over heated at some point earlier.

Thanks for your response. Update: The VW specialist (indie-tech) has done a coolant pressure test and found out that at least two of the pipes leading into the thermostat housing are leaking profusely. He also assured me that they checked the head gaskets and they are fine. That's a relief...! :approve:

But the euphoria didn't last long... Parts (housing, pipes, thermostat, etc.) are on back order for 7-10 days and on the V5, changing the thermostat housing means taking the gearbox off...£360 bill to £55 parts :(

I still don't understand all the symptoms, or why the previous garage found gas in the coolant, but I'll refer judgement until this problem is solved first.

Keep you posted!