I recently had a scare with my Gallardo when I installed a set of QuickSilver super sports mufflers in the car. This muffler is essentially a straight tube exhaust. When I started the car I saw a lot of water coming out of the exhaust initially. When it warmed up it stopped. There was no white smoke -- a sure sign of a leaking head gasket, but nevertheless I was worried that overnight somehow water was leaking into one or more cylinders via the head gasket seal. I looked at the coolant expansion reservoir and it was down to 1/4 full. However I could not remember when was the last time I filled it. I wanted to be sure no water was overnight leaking into the cylinders. Needless to say that would not be good. The fact that both exhausts were putting out water made it highly unlikely I had a water leak on a new car with less that 10,000 miles on it.
How can one check for leaks. One way is to remove the plugs see if they are wet. Smaller water leaks can be seen by sticking an optic fiber probe down into each cylinder through the plug hole and checking for water on the piston surface. This is not difficult to do but does take time.
The SolutionA better way is to pressurize the coolant reservoir and check to be sure it holds pressure. Most auto parts dealers supply the test equipment. The one I used is put out by Stant Manufacturing of Connersville, Indiana. Figure 2 shows the setup. It's nothing more than an air pump and gage. You attach the pump to the coolant reservoir and pump air into it. Pump up to at least 15PSI. Read the reading on the gage. The next morning the pressure should be the same. If it is not you have a water leak somewhere in your system. Look for water on the ground. If none and you suspect a head gasket. Start the car and let it turn over slowly. It the pressure oscillates with engine RPM's then suspect a head gasket leak. This is standard procedure even for American cars. The only complication is that as you might expect the treads on the coolant reservoir of the Gallardo are non standard. Fortunately Stant supplies adaptors. At first I tried an Audi adaptor. Was far too big. I finally found out that the adaptor they have for BMW cars works (Fig 3). Its treaded specification is M52 X 3. The part number is 46823. The figures below show the pressure gage in action.
I was delighted to find I did not have a problem. I guess because most mufflers have a box. The water first collects there after combustion when the exhaust pipes are cold. When the box gets hot it turns to steam. In the above case the condensed water simply blown straight out.