How little unfiltered air does it take to prematurely ruin an engine, assuming that it's not being run in the desert or other super dusty regions?

While changing spark plug wires on my '85 (which I've had for month), I noticed that the hose from the charcoal canister to the airbox was missing. Obviously letting unfiltered air into the engine isn't good, but that's a pretty small hole compared to the surface area of the filter, right? I've got no idea how long this has been the case, I'm hoping it just got knocked off (or not reattached) during the PPI compression test.

 

You seriously want a quantified answer?



Bottom line is that any unfiltered air is not good.

 

I know it can't be quantified, but I guess I was hoping for a chorus of "I had that same problem for years, and it's still going strong"

The danger is worn rings and scoured cylinder walls, right? If the compression was good during the PPI, then an oil change to clear out whatever dust got into the intake should suffice to stop continuing wear?

 

3952 cuft of city air, 4925 cuft of country or dairy air.

Local street racers, on the show Street Outlaws, don't use air filters at all. Then again it seems like they are rebuilding their motors every seven to ten quarter mile runs.

 

You sure its unfiltered? On later cars the charcoal filter goes to the intake via a solenoid to a vacuum port.

Are you talking about the cat air pump? I don't have an '85 but the config. you describe sounds odd to me.

Alan

 

no problem! unless you are racing at laguna seca without a filter.... then, better plan on a rebuild every year. a hand full of sand in the engine every 30mins, probably isnt that good!

 

Jeremy,

I would not worry about it. Tape it closed or reconnect.

It's a very small opening and it was probably not used off road all that much.

It looks very nice btw,

good luck with it.

Matt

 

Welcome to the tank! I would not be tooo worried unless the car is running like crap. How does the oil look?

 

i had that port on the air box open for like, 2 years. i had no idea it was there! no dirt in the throttle body and cylinder walls looked fine when i took that motor out.

 

Hmm. Seems I jumped the gun on this one. I got panicky when after seeing the hose-less connection, did some quick "research", and thought I had a problem. After pulling the filter and running a finger across the airbox wall this morning, I was relieved and confused to find that the box isn't drilled there.

I swear I read somewhere that the early S3's still ran the line from the carbon canister to the airbox. Is that true and someone just installed a newer lower box over the years? If so, do I still have a functioning fuel venting system?

 

Mine doesn't have that line either (early 86)

Unless you are driving through a dust storm or something a little bit of unfiltered air wont hurt a thing.

 

Maybe depends on having the secondary oil bath filter in the U tube under the throttle.

 

 

'85-up have an additional tube which dumps the overflow from the vapor recovery carbon cannister behind the rear bumper (like ROW cars always did, but straight from the separator over the right rear tire).

Might have something to do with the MAF burnoff cycle?

Classic.