Hoping some of you knowledgeable guys can help.
Recently had the head gaskets replaced along with machining of head and valve seats, however I am now getting oil in the coolant header tank, knocking from the front of the engine and a misfire on cylinder 5 leading to reduced engine performance warning.
Other than the obvious question of whether the heads were done properly, which I would never know unless I give it them back (fear of more charges) any ideas as what could be the causes???

For info
I've changed the ignitors and plugs around and it still misfires on #5
The knocking sounds like it could be around the front middle of the engine near the supercharger

Thanks

Surely take it back to whoever did the work.

Or am I missing something?

Just about to, but wanted to have some idea as to Help enforce the fixing of the fault under warranty

Well if it only started knocking after they did the head gaskets it's down to them unless you've put a load of miles on it since then?

But be prepared for a fight ime.

I had to go to trading standards and small claims court against a BMW independent in the past and won the case but it took a while to get sorted...

If you have a knocking with a misfire it could be causing the coupler to be noisey in the snout of the Supercharger. Sort the misfire and it should sort the knock ur hearing. Range Rover Vogue SE 2007 L322 4.2 Supercharged 121k. Engine rebuilt @ 120666 Miles