ok, so a friend of mine told me that he read somewhere/someone told him that when water spits out your exhaust when you rev, that your engine is healthy. now, today i revved my car up and dust came out, kinda brownish. is this because its old (72)? or is this indicative of a certain condition?

Usually that brown stuff is pieces of rust coming off your exhaust pipe and muffler. Water usually comes out a tailpipe on a car with a catalytic converter.

Hope it helps

Dave

Water will spit from the exhaust after you first start it. This is built up condensation from the atmosphere (kind of like a cold drink sweats). This will usually evaporate after the car warms up. Chances of water getting from the engine to the back of your tail pipe are pretty slim. When a head gasket goes you will usually get steam coming out of your pipe, which is not good.

When you revvvedd your engine are you sure it was dust. Maybe it was a little blue smoke which is normal for an old car.

no, it definitely wasn't blue smoke. doesn't excess blue smoke signify a bad head gasket? its burnt coolant or something right? its dust, or some other dust-like substance. its brown. doesn't show when i start it up, though that's what i meant with the water. the dust came after revving pretty high (not *too* high though, hehe). kinda freaked me out, not sure what to make of it. maybe the piping's dirty? or rusted like 59 said...

The dust could be carbon being blown/burnt off of the top of the piston or the combustion chamber, It could also be corrosion from the inside of the exhaust manifold and/or exhaust system.

Blue smoke is usually indicative of valve stem seals leaking and/or oil rings allowing oil into the combustion chamber. It shouldn't be anything to do with coolant.

Blue smoke would be oil, wether blow by or stem seals etc, there are ways to test for this of course.

The water thing was explained above, for every gallon of gas you burn a healthy cat will turn out 1 gallon of water. There are 3 and 4 way CATs though and I dont know if it varies between the two.

be vary careful of high revs when an engine is not under load! you could easily damage the engine, when not under load you are putting stresses on the engine that it was not designed for. As was stated water in the exhost is usually from condensation . If there is water coming out of the tail pipe after driving 10 miles or so ,you may have a head gasket problem . Most often water will be found in the oil and or oil found in the coolent when a head gasket is blown. If you are seeing "brown dust " exiting the tailpipe , you are most likely reving the engine to extreems, unless you lugg the engine in normal driving and rarely are driving at hi way speeds. There is no reason to rev a engine higher than 2500 RPM with out being under load.:disappoin

Yes, water spits out when the engine is healthy, because water is a natural by-product of combustion. Water is streaming out of teh tailpipe the ENTIRE time the engine is running. You can only "see" all that water when the tailpipe is cold and acts like a long condenser and drops the temp so the water drops out of the exhaust gas. When the tailpipe gets hot after running the car for a while, the tailpipe does not condense the water out and it goes "invisibly" into the air.

So yes, all healthy engines, by definition, are streaming out water through the tailpipe. You only see it when it's cold....