Thread: No compression!!!

When you say the valves a them for leaks?

I know from past experience a visual check with the valves still in the head won't reveal a burnt exhaust valve. You need to see if they leak by putting petrol or similar behind the valve with it closed.

I have a limited knowledge in mechanics (still learning) but could it possibly be the piston rings? If you put a little oil into the combustion chamber and then crank it again, is the compression higher?

I did lap the valves in, sorry forgot to mention that, I just put a thin wire down the bore just now and it seems that the piston is going up and down when I turn the engine over by hand, and the valve gear is definately working, I'm now wondering if the collets are seated incorrectly and not allowing the valves to shut.

Thanks for the replies guys,
Jack

Try putting a bit of oil down the spark plug hole and see if you get some compression build up if so your rings maybe gone

Adam

check your valve clearances?

0 compression pretty much rules out rings but you might have a holed piston

pull the plug and get a good flow of compressed air going into the plug hole

if it comes out the dipstic breather at a great rate of knots its the piston

if its got some out of the dipstick its rings

IF you hear it in the exhaust pipe its the exhaust valve

if it comes back through the carby its the inlet valve

if it comes up the radiator its head gasket.

also using pot 2 as a reference work out the max height by pokeing a screwdriver down the plug hole. see if pot 3 is at the same height.

Thanks for all the very helpful advice Guys, the compressed air trick is one I shall remember.

My problem was my doing, I had incorrectly set the valve clearance and the inlet valve was partially open. What a relief! I quickly set them and didn't check them afterwards. Lesson learnt! I really filled the garage up with smoke tho from the oil in the bore.

I have fitted a composit head gasket, which is the one the manual says to fit on the 5 bearing engine, do you think it will be necessary to re-torque the head down once its been run?

Thanks, Jack