2003 Discovery HSE VACUUM noise when start the vehicle

[Rovermike85]

I have a 2003 Land Rover Discovery HSE, every morning or when i have the vehicle turned off for more than 4 hours and then i turn it on it makes this loud weird noise it seems that is coming from the sauganlage vacuum resorvoir or the part that is right next to it, does anybody know what should i do...

[Savannah Buzz]

If your vehicle is equipped with Secondary Air Injection then part of that system is involved. The system waits until engine is cold (or off for a long time), and has an electric pump that blows air into the exhaust manifolds for the first 1/2 to 2 minutes. Can sound like hair dryer. Also have associated vac bottle and vac control valves. Review RAVE workshop pages for you truck under Emission Control.

[Spike555]

All '03's and '04's have SAI.
It works like a blacksmiths bellows to make the fire hotter, only this makes the catalytic converters heat up faster, it reduces emissions.
In the DII write up section there is a write up and how to replace the filter to it, which should be done once a year or so.