if a valve is gone yes it does run like ####. it also runs like #### if the bolts come loose on the rocker assembly that happened to me it sounds cool though

However if its still running smooth wouldnt that lean more towards the the rings gone. When the valves go doesnt it usually run like ####.

Yeah that is the easiest way -- forgot it even though I did the same test last month on a car. If the head gasket is blown, the test won't tell, you might think it's valves and get discouraged. But then you can check adjacent cylinders -- if one is low also chances are it's a blown gasket leaking between the two adjacent cylinders. That still leaves blown gasket leaking into water or oil passages, but that has its own symptoms, like water in the oil, unusual (non-black, non-disappearing) smoke out the tailpipe, or oil in the water. Keep in mind that it's normal for cars when first started, until warmed up a bit, dribble some water out the tailpipe possibly with black soot in it or some water smoke that quickly dissipates into the air. It's the bluish-white smoke that blows away but doesn't evaporate that indicates oil burning from the rings or valve stems.

Going off topic a little, valves are easy to change (don't know about the CA18, but easy on an A12/A14) and head gasket even easier. To replace a burnt valve, usually you can just lap the seat (inexpensive tool is just a suction cup on a stick) with lapping compound, wash the compound off and put the new valve in. Unless you are racing there's often no need to do the 3-angle grinding job again -- the valve burns but the seat usually doesn't, even when the valve is badly burned. To compress the valve sping you can rent a special spring compressor from the rental store.

I think the easiest way to determine if it is valve related or piston ring related cylinder pressure loss is to do the compression check again. On the cylinder that is low check the compression, then remove the tester, add some oil into the spark plug hole (not too much!), and retest. If the pressure goes up, the rings are shot. If the pressure stays the same, it is valve/head related. Good luck!

-Andy

will let ya in on a lil trick when ya do a compression test do it once on all cylinders then do it again but ad a few squrts of oil from an oil can then check the compression if the reading goes up its rings and if it stays the same its valves/head gasket

Yep, Matt's exactly right. You can even buy an air hose adapter for the spark plug threads. Put the bad cylinder on TDC and prevent the engine from turning somehow. Use an air-compressor, you should hear hissing. To narrow it down listen with a length of heater hose -- stick the hose in the exhaust manifold and intake manifold to see if a valve is leaking. If the hissing only comes out the oil cap, but not the manifolds, it's likely the rings, possibly head gasket. If hissing comes out the thermostat hole, think blown head gasket.

The engine doesn't need to be in the car to perform a leak down test, just complete.

What you do is get an old spark plug break/drill the insulator out and weld in an air hose fitting, then screw in the in place of a spark plug, pressurise the cylinder and check the exhaust, inlet, breathers, water jacket entry, and spark plug fitting of neighbouring cylinders, this will tell you where the leak is!

could be head gasket if it is blowin alot out of the arse

it was splutterring black water substance on my driveway mainly in the mornings there was a fair bit it wasnt just a little bit of dew the engine was running smooth too im hoping the valves have gone that would give me a lifeline with regards to the warranty mini-series im in at the moment

what do you mean by water out of the exhaust, was it still running @ that time, or do you start the engine outside of your cabbie