[brando93]

Hey guys, g16b vit been running rough, turned out not to be firing on cyl 2 (second from front). Just did dry compression test as follows:
Cyl 1: ~120psi
Cyl 2: 0psi, no movement on guage, tried 3 different times.
Cyl 3: ~122-125psi
Cyl 4: ~130psi

Now i found a thread stating compression should be 199psi, as low as 170psi, and a difference of up to 14.2psi, so it would seem that myne are all a bit low, tester is old though and could be a little inaccurate. But zero psi is really worrying, it didnt even budge. Could the cause of that be valves orrrr...
Next step is pulling rocker cover off but would be nice to know what im looking for.
Any input or info would be great

[Paulw]

Only time I've seen a cylinder have that low compression is when the piston had melted a large hole in it. Try taking the oil cap off while the engine is running( will get a bit of oil flicking out from the rockers) if there is puffs of smoke coming out it might indicate a hole in the piston. Best way to check is really to take the head off to inspect everything.

Also have u noticed any noise coming from the motor?

[sideways]

Pull the rocker cover off and check for stuck valves.

[brando93]

How do you check for stuck valves exactly?
Hopefully not a piston haha, well theres a sort of ticking noise.
Runs rough but still has been driving for ages with problem and is bearable but obviously needs to be fixed.

[droverdave]

If you take the rocker cover off, and you turn the engine over by hand you might be able to see the valve not returning to the closed position.

[fordem]

A leak down test would be the next step - or - disconnect the compression test gauge and connect an air compressor in place and supply low pressure (no more than 15~20 psi) to the #2 plug hole and listen to the intake, exhaust & oil filler to see where you hear the air escaping.

If you hear the hiss from the intake or exhaust it'll either be an incorrectly adjusted or possibly a burned valve - and incorrect adjustment, can over time lead to a burned valve, especially if it's the exhaust valve.

[ajcmbrown]

Valve clearance will be excessive if the valve is not returning or bent.

A Burnt valve will normally show some compression unless its REALLY bad.

I agree with the leakdown test to see where the air is escaping, that will give you a good indication of the cause.

[Rhinoman]

I recently bought a cheap USB camera with an 8mm head, its not the best quality but it fits nicely down a plug hole.:

http://www.banggood.com/2M-7mm-USB-LED- ... 29698.html