1.9TDi (AFN) coolant loss - poss head gasket failure, opinions required
My A4 is losing coolant and I'm not sure why. I've searched this and the other forums exhaustively and read plenty of similar stories, but none are quite the same and it seems that people seldom update their threads once they've got sorted. So, I'm asking for help!
Car is a '98 1.9TDi quattro Sport saloon with 185k miles, AFN engine. I'm doing between 350 and 450 miles a week and I'm having to top up the coolant once a fortnight or so; it's usually one or two centimetres below the 'min' level so the loss isn't great but it's consistent. It appears to be venting from the bottom of the expansion tank as there are telltale splash marks below. When the engine has cooled there is still pressure in the tank and when I release it the coolant level rises slightly. The car is running perfectly normally, there's no white smoke on startup and there are no signs of contamination, i.e. no sludge in the tank and no mayo on the filler cap or dip stick. The radiator itself was replaced last August after it began leaking through corrosion.
The independent I use took a look at the car and this is what they found (taken from the invoice):
As well as the thermostat they replaced the tank cap which made no difference either. I'm not convinced they really know what the problem is so I thought I should run these symptoms past the experts on here before I shell out on a head gasket replacement.
CHECK FOR COOLANT LEAK, NO EXTERNAL LEAKS FOUND BUT COOLANT BLOWN OUT OF HEADER TANK AFTER ROADTEST. BOTTOM RADIATOR HOSE COLD, SUSPECT THERMOSTAT. REPLACE THERMOSTAT & RUN UP TO TEMP, OK. ROADTEST AGAIN COOLING SYSTEM STILL PRESSURISING UP UNDER LOAD. SUSPECT HEADGASKET/INTERNAL LEAK.
Just to confuse matters further, shortly after I started losing coolant I started finding it difficult to demist my windows. After researching this I discovered that a leaking heater matrix is the likely culprit, which could itself be brought on by pressure and/or air locks in the cooling system. My carpets are bone dry and there's no sign of there ever having been any water in the plenum chamber so I don't think the drain holes are blocked.
I'm not particularly mechanically minded when it comes to the business end of things but I'm willing to learn, so any opinions and/or suggestions from the experts on here would be most welcome. I assume I need to do a compression test next?
Thanks in advance.
Audi A6, 1.9TDI AFN. Coolant leaks
Hi, first of all I hope that this thread isn't dead yet, although it's 2 years old... :D So I have a similar problem. (Might be, that the answer lais in this thread, but since I'm not a good english spoken man, I might haven't understood it.)
Originally Posted by JohnC
Things I have done:
1. Bought a car with a defective engine. (Head or gasket failure - spitting out oil from one of the air intake 'holes')
2. Bought used head (made a huge mistake and heavent checked it for cracks, before mounting it :/ )
3. New head gasket, oil - fuel filters, new timing belt, tensioners.
First start was a success! Everything seemed to be ok, only a little bit bad timing :)
But after 3 or 4 months car started to loose the coolant, and the main top hose that goes to the head from the radiator becomes very hard, I mean the pressure inside becomes very high. Now I have to refill and let out the pressure from the coolant container every 60KM! Actually I should do that more often, but since I have to go to work with my car I dont have time to stop every 100meters to do that. If I press accelerator in my rear window mirror I see a lot of white smoke (Road becomes like a disco with all that smoke/fog.. :/ ) So recently, actually yesterday I have changed thermostate (used one, but the man whom I got it from claimed that it's fine). Nothing changed, only the fact that before doing that, car temperature was 90 degrees or even in some moments after heating up the throttle, the temperatures was rising up to 95 - 100 and day before changing the thermostate it even was at the peak of 105 degrees!! :/ After the change of thermostate the temperatures became different, now after heating up the throttle it's even very hard to reach 87 (to open the thermostate atleast) :/ At idle it drops from it's now usual 70 - 75 to 60 or even below, since the gauge doesn't show less. But I get hot air blown out of a heater anyways...
Question is: What's the problem, what might be wrong..?
So after visiting some forums and threads I have decided, that I'm going to buy and replace the folloving (after about one week or so):
Water pump, brand new thermostate, temperature sensor, coolant ofcourse, head gasket (not sure if I have to change it), timing belts, tensioners (if I would have to change the gasket anyways).. So, if You understand what's my problem, please answer me as soon as possible..