Gas cap...

[Spencer]

When I bought my e30 there was a generic NAPA gas cap on the car. In the glove box I found the NAPA box with the original BMW gas cap inside.
What would have been the reason to replace the BMW cap? Do the caps lose their ability to seal the tank over time? The BMW one seems to work fine but there must be a reason it was replaced.

Any insight?

-Spencer

[fretburnr]

the rubber seal on the cap gets old... can cause funny running due to vacuum leak, or if parked on a sideways slope you may leak fuel out of the overflow pipe from the poor sealing on the top end.

[timothy100]

The gas caps do wear out over time and it is probably a good idea to just keep using the napa one, unless you want to shell out some $$ and get a BMW one. Whatever you do don't put the old one back on. I failed emissions because my gas cap didn't provide a good enough seal. The lady told me I was losing a lot of gas because of it. "Luckily" a Schucks is literally a block away from the emissions station, so I got a new one there for $4 and passed emissions.

[Bimmerista]

Check on eBay....I picked up a plastic one for $10 shipped.

[Spencer]

Well I put the BMW cap on as soon as I found it – when I first got the car. My e30 is/has always been getting TERRIBLE gas mileage. Perhaps this is the cause. I’ll put the NAPA one back on and see if my range improves.

Thanks