I have a 54 plate golf tdi it wont start but when you take the oil filler cap off it starts but you have exhaust smoke comeing out the filler cap hole ive already stripped the egr valve and cleaned it any ideas please

You didn't say what colour the smoke is. I assume it is from the exhaust and is darkgrey/black sooty sort of smoke which along with the engine misfire would indicate faulty diesel injector(s).

If only at start up it'l be moisture condensation in exhaust if all the time your head gasket is on it's way out check condition of oil if milky on dip stick or on underside of oil filler cap defo head gasket

smoke when opening the filler is usually normal -smoke from exhaust is problem --and as to oil leak possible valve gasket --if oil level is normal dont add oil {over filling is bad for engine ]

sounds like blown head gasket (through exhaust port) fill with water and start up, look under car, and see if water is coming out of the exhaust pipe)note: if head gasket is blown thru exhaust port you won't have water in the oil. it will come out of the exhaust. if this is the case then possibly can fix with (k&w block sealer or comparable block sealer) since no water in oil engine should be fine.) but follow directions to a T on block sealer if you don't it could stop up the radiator and you'd be back in the same position. also make sure you fix problem that caused it, probably bad thermostat or water pump.

"smoke"?? you sure it's smoke & not water vapour/condensation?
the gunk in the oil cap tells you nothing really, you can check the coolant reservoir for contamination.
so, to sum up, i don't think you have a problem.

turbo might of started to **** oil pull off the air hoe to the turbo and see if it is full of oil that will give oyu a place to start looking

Check your radiator and see if you have oil in it by what you are describing it sounds like you got it to hot and possibly blew a head gasket.....this vehicle has a low indicator oil switch if your lucky and havent blown gasket try adding oil to required level and then start this will also confirm if head gasket is blown by the presence of the oil lookin like coffee with alot of cream....Good Luck...Please rate so it helps with future diagnostics .....Thank you

not starter motor, if car starts but is slowly smoking like that you are probably burning oil...