plug no 6 is getting wet of oil
 

Hi,I've changed the rings.but still you put new plugs but after few minutes no 6 is not firing.take it out is wet.the car does not have power.anybody with help pls

Could be that the valve cover gasket needs replacing. What to you mean by "changed the rings"?

plug no 6 getting wet
 

I've changed pistons rings.change valve cover gasket,as well as plugs gasket.the thing is it's getting wet from the bottom.could it be valve stem seals?& power is not there

Valve stem seals would be my next guess (and I do mean "guess"), but the M52 is a rather durable and reliable engine. How many miles on the car?

no power
 

It's got 194000km.the other thing it does'nt have the power it use to have before

Probably time to start from square one: air and fuel filters, fluid changes, checking for vacuum leaks, etc.

When you put in new pistons and rings, how, why, and did you line up the ring gaps or stagger them?

same problem happened to my 520i before, had it completely overhauled - changed piston rings at the top and oil rings at the bottom of the piston itself (the mechanic called it oil rings) then sent it to a machine shop for fitting, there shouldn't be any clearance of the piston through the block - maybe valve seals are worn out

Did you measure compression before and/or after changing the rings?

cooling system
 

heppy new year,to everybody.firtly I replaced valve stem seals.then put new water pump,thermostat,head gasket.but now the car is building up preasure in the cooling system.any suggestion pls.

Head gasket is leaking that is why you getting pressure in the cooling system. the oil on the plug could be from stacking the ring gaps or bad valve seals. Did you have the cylinder honed and cross hatched this is necessary for proper ring seating. good luck and Happy new year!