Popping noise coming from top of engine

[stockportdubfan]

Bear with me. There's an unusual noise coming from the engine. It's on the top circular cutout on the engine cover with a black pipe going to it, something to do with the oil I think. Occasionally it makes a popping noise. It only started doing this after I had it serviced with Nationwide Car Care. What do you think it could be?
thank you.

[eugene walsh]

Hello souds like it is just your EGR valve opening and closeing

[stockportdubfan]

whats a egr valve thanks

[tyreman1]

exhaust gas recuirclation valve,theyre a pain in the **** but i`ve never heard of one popping,perhaps they`ve just dislodged a breather pipe,take it back to nationwide for them to have a look,you`ve paid you`re money

[stockportdubfan]

thanks will do that