I have a 98 A4 B5 1.8t. Recently it has developed what seemed like an intermittent coolant leak. I have looked all over and haven't found anything too obvious (no pools of water under the radiator or anything), but the coolant light kept popping on--

The other day I had to drive into town and the leak seemed to be worse, the coolant warning light was coming on and the water temp gauge kept spiking. I turned round for home and was making regular stops to top off the coolant, but halfway home the engine started to lose power and then died.

I looked at the oil and the plugs and didn't see any site sign of coolant, but I could be mistaken.

I'm trying to get some pre-diagnoses before I start tearing the ngine down, so does anyone have any suggestions of what it could be?

Thanks

 

2.8 or 1.8t?

 

Should have said, sorry

 

Common places for coolant leaks on the 1.8T are the coolant flange at the back of the cylinder head where your temp sensor plugs in, the t-stat housing which is bolted to the block just to the rear of the alternator, and the expansion tank. I've personally also had leaks from the coolant lines running to and from the turbo and in/out of the radiator. I've read about people having coolant leaking out of the heater core, but haven't experienced this myself. Coolant leaks often only happen when the motor is up to temp, in which case they won't leave puddles after you park. Instead they'll leave a pink/white crust around the leak.

How much coolant are we talking about here? How long was the drive into town you mentioned? If you don't see coolant in the oil or vice versa, I very much doubt your head gasket is the culprit.

 

The drive into town is 60km. I got into town and the water temp was way up and the coolant light was on. I added about 1.5l of coolant, which was gone by the time I'd done 20km of the trip home.

 

Jeez, that's a pretty huge leak. Did you look for the pink/white crust I mentioned in my other post?

 

Looking over it now. Will report back

 

and the only white crust I could find was around where the oil filter mounts.

Now the other thing is that now the car wont start at all. It turns over and *almost* catches, but after flattening the battery I got nowhere.

Even with coolant leak that shouldn't be a problem.

I was reading an article about this and was reminded that when I went to top up the coolant I did see it boiling out of the reservoir. As I understand it the cause of that could be hot gasses from a head gasket leak, which in turn would mean no compression and the car not starting.

What do you think?

 

Possible I suppose, I'm just confused about why there's no coolant in the engine oil or oil in the coolant. I've never seen a head gasket give out without one leaking into the other. The coolant boiling out of the reservoir would happen if you opened the cap while the coolant was hot. It burns real bad. AMHIK

 

Yea I'm like CCA4 on that one. When the cooling system is pressurized the boiling point goes up. As soon as you release the pressure, the boiling point drops like a rock and the coolant boils.

That motor is not known for head gasket problems. But if that was the problem, typically the exhaust gases would pressurize the coolant and blow it out the bottom of the reservoir where all excess pressure goes. If so, you'd see lots and lots (1.5l in 20 km is a lot) of white powerdery residue under the tank.

Two thoughts:

1. Your starting problem may, or may not, be connected to the coolant loss.
2. The coolant is going somewhere. Losing coolant at the rate, there is either going to be some residue somewhere, or you'll see white smoke/steam out the exhaust. Find where the coolant is going before you read more head gasket stuff.