While examining this RV's engine (1989 Fleetwood Southwind 33'), I noticed what appears to be a belt-driven component, which lacks a drive belt. I'm trying to decide how important it is to replace the belt, but I need to know what this device is!

The RV seems to drive without it. It looks like there are air hoses coming out of this unit, one of which goes to the carburetor.

(click for full-size)


1 Answer 1


It's commonly called the smog pump although I am not sure that's the technical name for it. It is a simple vain air pump that puts fresh air into the exhaust manifold to help burn off any unburned fuel and reduce emissions.

It only affects emissions and is not critical to engine operation. It may however require a belt to pass inspection.

See Wikipedia for more information.

  • 2
    Agree with the "it's a smog pump" assessment. The belt was probably removed because these things have a habit of seizing over time and disabling them tends to be a little cheaper than replacing them... Commented Sep 29, 2011 at 19:20

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