mk1 Focus 2.0 rushing/whooshing noise

[Limpet]

I've just bought a snotter Focus 2.0 mk1 which drives really well except for an odd noise.

Under acceleration below about 2,500 RPM, there is a loud "rushing" noise from under the bonnet. The best way I can describe it is the noise you get when you drive through a puddle at a reasonable speed. That sloshing/hissing sound of water moving quickly. It gets louder / more prominent the more you open the throttle, and it disappears past 2,500 RPM (or if you lift off). It also seems louder once the engine has warmed up.

The clutch is quite worn (bites high but doesn't slip), and is on my to-do list, but otherwise it all seems good. Engine is smooth and sounds sweet, idles steadily, and seems to pull OK for what it is. I haven't driven another 2.0 to compare, but performance wise it feels there or thereabouts, and is doing about 30 mpg so far in mixed use.

Car has done 114k with a very good service history (full Ford main dealer to 97k).

Any ideas gratefully received.

[Dr Doofenshmirtz]

Probably a split in the large intake hose or one of the vacuum hoses.

[Dogwatch]

Dr Doofenshmirtz said:

Probably a split in the large intake hose or one of the vacuum hoses.

Could well be. I'll bet not many main dealers get to service cars that old - every service is a potential rebuild by their standards.

[All that jazz]

I would have thought if it's a split hose you'd notice quite a drastic reduction in performance. I had the turbo pipe come adrift on my ST and it made a hell of a "rushing" din when planting the accelerator as the air was being forced out of the gap rather than into the engine, obviously with much reduced performance as a result. Was a 5 min fix to put back on once up on some ramps though.

[IanCress]

Open the bonnet and rev it to see if you can pin point where the noise is coming from. As above chances are it will be a split pipe / hose.

[eybic]

A way to tell if an intake hose has a split is to spray some wd40 on it when the engine is running, if the idle changes then the wd40 is finding a way into the hose.

[Limpet]

Thanks everyone. Will start investigating vacuum pipes. I've had the big plastic inlet pipe off and inspected it carefully, and that's all in good nick. I've also checked it's securely attached both ends. Whatever it is, I think it's very minor as it idles steadily and seems to go OK.

Will post an update once I've had a look.

Cheers again.