It's the rings/pistons isn't it? :(

[StanTheMan]

It would be worth it just for shitz & giggles.

If you remove the head. surely you'd be able to tell if a valve is burned or not?

pour some petrol or turps into the tunnels, then turn the cams & check if you have leakage in valves. should run like Niagara falls if its burnt out right?

[manga_blue]

Short of another compression test is there any other way to know if it's valves or head? Would escaped soot/markings be visible with the camshaft moved out of the way?

If you've got a major compression leak around a piston (broken ring, scored bore, holed piston, seized piston damage, etc) the you tend to get a lot of blow-by past the piston. That gas has to go somewhere. If you just take the oul filler cap off you can often hear it choofing or put your hand over it and feel fairly big pressure pulses. There is usually some other damage from so much gas going into the crankcase: blown PCV valve, oil particles and fumes going into the inlet manfold and back up through the hole in the piston/bore, oil leaks from the front and rear seals and often a few other places, ...

You can just take the cam cover off to check for a broken valve spring, then take the cams and HLAs off to find a stuck valve. If the valve failure is deeper then the head needs to come off. Such a large compression loss would mean a cracked valve or a chunk burnt or ripped out of it and/or the valve seat . You'd spot it straight away.

[XMX]

Something to do over the weekend...

I've bought a new water temp sensor ($16, why not?) on the offchance that there one problem is masking another.

It's good to know you can check under the cam cover for the valves, sounds like it might be a good time to pull apart the lifters and clean the gunk out, even if I don't find the big problem I won't go crazy from the ticking!

Thanks again for all your help, it's rare to find a good forum these days!