Overnight my S-max has turned in to a futuristic hover skateboard/ufo! It is making a high pitched whistling noise like a kettle (not a fan belt screech). Checked the coolant system and all seems ok. Temperature gauge is ok too.

Took the oil dipstick out and a lot of air rushed in to the vacuum and the whistling stopped. Put dipstick back in and it was sucked out of my hand back in to place by the engine drawing in massive amount of air. As soon as dipstick was in place the engine started whistling again trying to suck in air from somewhere else. Same for the oil filler cap. With it removed if I put my hand over it my palm was sucked tightly on to make a seal- i.e. the opposite of an engine breather problem where air is being expelled.

Any ideas gratefully received.

Its a petrol 2.5T engine 56 reg.

Apparently it was the oil filter housing assembly that has some sort of built in valve that was blocked. Split a few pipes too.

£250 for parts only.

The interesting bit was that when the parts were ordered from the local Ford dealer, they said that they had ordered around 60 in the local branch in the last 2 months!

To me that sounds like a dodgy design but I am not privvy to tech service bulletins so wouldn't know.

The TSBs are all available for download from www.smaxownersclub.com

Only if you pay £10 membership though!

A small price to pay for the info provided....