Passat 1.9TDi Diesel drinking water!

**thegriffin** · 21-02-2010,02:36 PM

I have a 2001 Passat 1.9Tdi S 100ps (Engine Code AVB) manual gear box with 135k miles on the clock. It recently began to lose coolant. Local garage replaced radiator and oil cooler but it still uses water like an old steam engine. Amazingly, car still starts and runs smoothly! No sign of leaking on the ground or inside car - and not in sump either! Suspect head gasket has now blown but how likely is this and what are the chances that it might be the head itself? Thanks!

**tullyjoe** · 21-02-2010,05:43 PM

Has the water pump been replaced although if this was leaking outwardly you would see a trail of coolant from around the timing belt cover. Sorry to say but it sounds like head gasket is flunked. Open the expansion cap on the coolant reservoir to see if system has been pressurised, be careful in case you get burnt or some steam blasts out. Had similar conditions on a 115bhp bora, check coolant light kept coming on, top up and run. Car ran perfectly well but then check coolant came back on. Even did a cooling system pressure check which passed! However, eventually went for it, head off and you could clearly see the head gasket had blown between 2 & 3. Not good news, but it may help you. New water pump and belts if you go for it.

Joe

**thegriffin** · 21-02-2010,06:43 PM

Thanks Joe! Water pump was checked when radiator was changed and, as mentioned, there are no other outward signs of leaks/stains etc. So your post has confirmed my suspicions as my 'symptoms' are almost identical to yours. 'STOP! check coolant' warning light keeps coming on but temp. gauge remains rock steady at 90°C. Have tried removing expansion chamber top immediately after running but get very little 'blow-back'. So no danger of scalding here! Seems like it is the gasket then. But before spending another £500 or so, I just wanted to sound out whether the cylinder might be cracked as well! From your experience, it seems that might be unlikely. So in for a penny, in for a few hundred more pounds...Thanks again.

**cazyp** · 21-02-2010,07:15 PM

Was the radiator changed for a new one or re-cored?
Are the engine undertrays off at the moment?
Is there any sign of oil/water mixing - mayo type sludge in the oil?
Have you visually checked the heater matrix for leaks especially the joins on entry and exit?
Does the interior/car smell of coolant?
How was the water pump 'inspected...?'
If you start the engine and watch the coolant expansion tank does it 'boil' in a few minutes?

Sorry for all the questions but with little to no pressurising of the cooling system and (depending on your answer..) no signs of mixing then i'd suspect it wasn't the head gasket at this stage.

**thegriffin** · 21-02-2010,07:48 PM

Oh dear! Just when I thought the water was clearing...! Anyway, here are the answers to your questions...
A new radiator was fitted.
The undertray is back-on.
There was evidence of oil/water 'mayo type' sludge in the expansion reservoir but this cleared after new oil cooler was fitted and system flushed. Water inside reservoir now looks completely clear!
No evidence of leaks etc around heater matrix inside the car.
No unpleasant smells inside car!
Water pump was removed and inspected when radiator was changed. Cam belt was also changed at the same time.
No sign of water boiling when reservoir cap is removed.

What d'you think? Gasket? Or head?!

**cazyp** · 21-02-2010,07:58 PM

Did the problem of water loss start after the flush/cam belt change/water pump change (i'm assuming a new one was fitted as they are very cheap?)

Personally i'd remove both undertrays, park over some clean paper (chip shop paper is always good) and sit in there for a few hours.
If dry I'd try the same with the engine running and under a small amount of stress as if you're pulling away gently but keep the handbrake on) a couple of times. Those undertrays can hide a multitude of sins.

I'd have inspected the heater matrix where it joins the cooling system. Esp' if the coolant system was flushed under pressure. Common leak spot. But seems like this is dry..

If it started after the new rad/water pump etc etc was fitted i'm wondering if somethings not be refitted correctly..

**thegriffin** · 21-02-2010,08:32 PM

Thanks...the mystery is that the coolant loss at the moment is quite significant . I did a 35 mile journey the other day and had to top up with approx. 2 litres of water - I was in a bit of a hurry mind! I now drive around with a 5l bottle of water in the boot and top-up frequently. With losses like that, I would have thought you might see coolant all over the place if there was any kind of external leak. But the water must be going somwhere and if it's not on the ground, inside the saloon or in the sump, I guess the water must be going up the exhaust! Does it still sound like the gasket?

**martin1810** · 21-02-2010,09:06 PM

To lose that much water down the exhaust you would have a large cloud of steam behind you. When it is warm and ticking over, do you have water or steam coming out of the exhaust.

**cazyp** · 21-02-2010,09:20 PM

Originally Posted by martin1810

To lose that much water down the exhaust you would have a large cloud of steam behind you. When it is warm and ticking over, do you have water or steam coming out of the exhaust.

Agreed. 2L of water in 35 miles is a vast amount for a head gasket failure.
(Mine has a bit of steam in this freezing weather even when warm BTW.)

**thegriffin** · 21-02-2010,10:33 PM

Haven't seen any steam (and the weather has certainly been cold enough!) But can't say that I've seen much water dripping from the exhaust either! If leak was around the heater matrix (and I can't be absolutely certain that the garage have thoroughly inspected the pipes/fittings etc) where might the water emerge? Would leak only occur when engine is running? Is this perhaps the reason why I'm not seeing small lakes underneath the car when it's parked?