Good afternoon to all

I'm new here and by no means an expert when it comes to cars.

I have a Focus ST225 T3 57 (82K) plate that has started knocking from what seems like the top end behind the manfold. It's very loud on startup when it's cold but soon stops until i'm driving a long then it'll start again when accelorating beyond 3000 rpm, but it's very faint.

i'm told it could be a the turbo compression valve??

my oil pressure is also very low when the car has warmed up. it sits at about 2.5 but when cold it's up to the max 5 bar. i beleive this is due to the auto choke kicking in for a few minutes.

There is also a howelling noise from the bottom end drivers side which i beleive could be the Oil Diaffram? when the car is ticking over, every 30 to 45 seconds, you'll here a clicking noise.

In all honesty the oil was running low when this started but no lights came on the dash. it's now be filled up again and the noises have calmed but there still there and the cars not boosting until about 4000 rpm now. :( can anybody help diagnose this problem please?

Thank you

I've had 2 Focus ST's now and have never heard of a turbo compression valve before, unless it's another name for something but even google doesn't help there.

With the oil pressure I'm certain that's normal behaviour - think you get higher pressure initially from cold as the oil is thicker, then the pressure drops to about halfway once it's warmed up. Once warm it will rise and fall more or less with engine revs.

The oil diaphragm if failed makes a noise like a kettle boiling. Think if it goes away when you pull the dipstick out that's a sign the diaphragm gone. Maybe the same if you unscrew the oil filler cap. How low was the oil when you checked it, and are there any signs of oil leaks? problem with the diaphragm failing is it causes the engine crankcase to become pressurised. If left like this for too long it can cause oil seals to fail, know of 1 case where the camshaft seals went due to this. Could be your oil has run low due to a failed seal, and worst case the engine has suffered some wear due to this. Similar with the boost problem as the system routes turbo boost pressure to the diaphragm unit.

If you need expert advice I'd suggest you speak to Gary Lendon at Collins Performance in Congleton, he's very experienced with ST's and real helpful guy.