bjohnston

Absolutely random question here...I've noticed on several engines a little thing that looks like a miniature air cleaner sitting on top of the valve/cam cover. I think the last time I saw one was in a photo of the Dodge Razor (I think that's what it was called...it's an ugly orange thing with the motor from the 2003 Neon RT4) in the latest Automobile magazine. Anyway, I was just wondering what these things are.

Anyone know???

Thanks

xviper

I think it's to capture oil vapour that escapes from a pressure relief vent. The area under the valve cover usually gets pressurized (from "blow by" and such) so to prevent excessive pressure build up, a vent (hole) has to be made but you can't just let this vent into the engine bay (what a mess that would make). Usually, this pressure is vented back into the air cleaner and re-introduced back into the engine and burned (sorta like what a PCV valve does with the pressure built up at the bottom of an engine). I had one of these in an old VW but when I put on a new carb and airbox there was no place to "plug" the vent back in so I wrapped the end of the tube with a foam sponge so the engine bay wouldn't get filthy with all the oil vapour. That's what the little "air filter" looking thing does. The oil collects in the filter. In time, this thing gets pretty dirty.