Hi, I’ve just recently bought a 2023 Ford focus mhev and I’ve noticed that when the car is accelerating there is a loud rattle noise which is also present when the revs drop, I’ve taken it to 2 different garages but can’t seem to find any issues, it’s driving me insane and sounds horrendous when driving low speeds any idea what it could be?

I’ve been told that it’s normal wastegate rattle but it’s much louder than another focus same year I had at courtesy car

A slight wastegate rattle when the wastegate valve is open or partially open is completely normal.

The wastegate mechanism has a little bit of intentional play between the valve plate and the shaft assembly. This allows the valve plate to close properly. This intentional play also allows the valve plate to vibrate/rattle when the valve is not fully closed.

However, during acceleration the wastegate should be fully closed, otherwise there will be little to no boost. When fully closed the wastegate valve plate is pushed firmly against the valve seat which prevents it from rattling.


The fact that in your situation the rattling also occurs during acceleration can indicate 2 things:

1: There is a different problem that causes the rattle (unrelated to the wastegate mechanism).
2: There is something seriously wrong with the wastegate mechanism or its adjustment.

Ford does not consider the turbocharger or wastegate mechanism to be a serviceable item. Separate parts or service information are not available from Ford. Any problem related to the turbocharger or its adjustment usually result in replacement of the turbocharger.

7 hours ago, JW1982 said:

A slight wastegate rattle when the wastegate valve is open or partially open is completely normal.

The wastegate mechanism has a little bit of intentional play between the valve plate and the shaft assembly. This allows the valve plate to close properly. This intentional play also allows the valve plate to vibrate/rattle when the valve is not fully closed.

However, during acceleration the wastegate should be fully closed, otherwise there will be little to no boost. When fully closed the wastegate valve plate is pushed firmly against the valve seat which prevents it from rattling.


The fact that in your situation the rattling also occurs during acceleration can indicate 2 things:

1: There is a different problem that causes the rattle (unrelated to the wastegate mechanism).
2: There is something seriously wrong with the wastegate mechanism or its adjustment.

Ford does not consider the turbocharger or wastegate mechanism to be a serviceable item. Separate parts or service information are not available from Ford. Any problem related to the turbocharger or its adjustment usually result in replacement of the turbocharger.

I took it out today and notice that there is rattle when starting the car as it was idling aroun1.2k then dropped. No rattle when pulling off but a lot of rattling when in second and the deceleration happens coming to a stop. I noticed that it is normal but this sounds like more than normal but had car at dealership garage and said they couldn’t find anything wrong. It’s driving me insance

On a modern turbocharged engine with a vacuum controlled wastegate like the 1.0 EcoBoost a bit of wastegate rattle is completely normal.

Traditional old fashioned turbocharged engines use boost to open the wastegate. The valve is normally closed and when the boost is higher as the spring tension of the wastegate actuator the wastegate opens and releases the excessive boost pressure. On this system the amount of boost and wastegate spring selection determine when the wastegate opens.

Modern turbocharged engines like the 1.0 EcoBoost have a vacuum controlled wastegate system. The valve is normally open and controlled by the PCM. In other words: The PCM determines completely when the wastegate is open or closed. By continuously regulating the amount of vacuum the PCM is also able to partially close the wastegate.

It is a fact that some turbochargers seem to suffer from wastegate rattle more than others. I suspect that this is caused by 2 different things:

1: The amount of play between the shaft and the valve plate.
2: How far the PCM opens the wastegate. Opening the valve just a little bit, allows the valve plate to rattle against the seat.


Replacement of the turbocharger can solve (or more likely reduce) the problem but is not guaranteed at all. Wastegate rattle is annoying but since a bit of play between the shaft and the valve plate is intentional, from a technical perspective it is not a problem. Wastegate rattle on these engines is discussed quite often on multiple forums, but I have never seen or heard of turbochargers being replaced under warranty just because of the rattle.