Cracked piston ring?

just found out from the garage that i have low compression in cylinder 1, the plugs had been taken out and there was oil in there. This has also caused oil to be dumped into the air filter, the airbox is very full of oil, do i have a cracked piston ring or is it something else? the engine is a TD 19j.

the oil in the air box & filter is nothing to do with the knackered piston ring. that is possibly a blocked breather or there was a thread on here about overfilling the oil level causing this ?

if the breather is blocked will this cause oil to be in the cylinder chamber, and what could be causing the low compression?

no, the breather could be causing the filter etc, the low compression and oil in the cyl is more than likely a ring

Am i putting the engine in any danger if i drive it around with a cracked piston ring? cheers for the help.

no more than already done, it needs stripping down for the new ring to be fitted and you could have scored the liner, its best to get it fixed as soon as you can cos realistically its knackered anyway

could be head gasket,cracked head,cracked block or gubbed valve stem seals..
you need to do more testing before you can say what it is.
a wet and a dry comp test is a good place to start.