Hi there everyone thanks for taking the time to read I have a focus 1.8 tdci on a 06 plate the last couple of weeks while driving I have noticed a hissing noise that has gradually got louder and have noticed a big reduction in fuel consumption. There doesn't seem to be a problem with it boosting but when you power off you get a loud hissing noise also if you put your foot down you can hear it at high boost. There is no white smoke although at high revs I have noticed some black smoke been told off a friend it may be a leaking hose. I have had a look under the bonnet and there are that many hoses I wouldn't no we're start it does seem that the hissing noise is coming from the back end of the engine rather than the inter cooler end... Any advice on which hoses to check or tips to try and diagnose the problem any help would be much appreciated... Thanks

 

On the right hand side (drivers side) the boost pipe is metal with a rubber elbow going into the inlet manifold, this elbow splits underneath. The replacement is a complete pipe with rubber/metal parts.
If you feel underneath it'll be a bit oily and split.

(this is providing it's the 1.8 'lynx' engine, not a French DW4/6)

Hope this helps.

 

Googled a pic.



Can see the right angled elbow pipe underneath the brake fluid reservoir.

 

Thanks for the reply also just noticed oil on the drive only a few drops could this have something to do with it?

 

Could be!

 

Thanks for the pic mate will have a look in the morning and let you no as the Heavens have just opened up here... torrential..

 

I've changed a few of them, worth a look, they usually split underneath as I say.

 

Managed to have a quick look couldn't feel anything. will take pipe off tomorrow and have a good look the pipe was caked in oil though just like you said..