Lost gas cap

[Hoyt Clagwell]

I have (had) a bad habit of placing my gas cap on the folded down soft top while refueling. Well, I guess I forgot to put it back on and now it's lost. What is the best option for buying a new or used one?

I drove 4 hours before stopping for more gas. After filling and noticing that it was gone didly on, I drove another 2 hours to home. Today when I started it, the CEL was on. I assume this is related to the missing gas cap and will correct itself when I get a replacement.

Also, this may be unrelated and I may start another post for this but around the same time the gas cap was not replaced, I started to notice a whining sound coming from the front on deceleration. It's hard to pin point the location by ear but it seems to be from the front right of the car. It doesn't sound like a belt slipping to me (although it could be) but more like a failing bearing. (AC compressor?)

Any insights would be appreciated.

[KBH22102]

Gas caps vary depending on year and engine so best to check RealOEM for your car and order from a vendor. Since you might need it quick, it should not be that expensive at a dealer unless you are looking for a locking one.

Does the sound vary with engine speed? Can you hear it while parked with the hood up? If you can hear it while stationary, you can safely remove your two belts and run the engine for about 45 sec without doing damage and see if the sound goes away, then it should be a process of elimination with a stethoscope or just spinning the pulleys, etc.

[Hoyt Clagwell]

Thanks Kelvin, I'll check with Real OEM and then try to locate a replacement.

As for the whine, I can only hear it while decelerating at highway speeds. It almost completely disappears with just some slight acceleration. I cannot hear it at all at idle with the hood up.

[KBH22102]

Did you replace your subframe bushings with polys? Diff whine becomes much more noticeable after this upgrade and is most pronounced when you lift the throttle at highway speeds.

[Hoyt Clagwell]

Did you replace your subframe bushings with polys? Diff whine becomes much more noticeable after this upgrade and is most pronounced when you lift the throttle at highway speeds.

Yes I did. Although I I did them last winter and just started noticing the whine yesterday. From the driver's seat, it sounds like it originates near the front right of the car but the location is somewhat vague. I also left in the original diff mount bushing.

[solimans]

Does it sound like diff whine sounds? Does your diff whine?

I noticed more diff whine after poly subframe bushings.

Guess, if it sounds like diff whine, but coming from front, power steering pump


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[Hoyt Clagwell]

After thinking about it for awhile, I'm thinking that it could be diff whine. I usually avoid major highways and rarely drive with the top up. So yesterday I was cruising at 75mph with the top up and that's when I noticed the whine when I took my foot off of the accelerator. The location of the whine was really hard to determine. My best guess was from the front and slightly to the right but it was very vague and difficult to really pinpoint. I had never heard a sound like that before. It didn't sound like a slipping belt, more like a dry bearing and only when I lifted the throttle.

I've got new Amsoil Severe Gear 75W-140 in the diff that I put in last winter. If the sound is just "normal" diff whine from using poly bushings (mine are extra hard 75D) that's actually good news to me. I hadn't ever noticed it with the top down and I rarely drive with the top up so I'd rather have the hard bushings and put up with the whine the odd time that the top is up and I'm cruising at high speed.

[IndianaRoadster]

My top is down all summer, but when I put it up I do hear things a lot more.

[Vinci]

You can use a common non-keyed BMW gas cap. I think the caps interchange between a lot of models of the same age and should be pretty cheap.

[KeysCoupe]

Any junkyards around you? Gas caps are usually abundant in the yards. This would get you by, probably for a long while.
My Coupes use the same caps as my E39, and probably many other models from the same vintage.
-Donny

[Hoyt Clagwell]

Thanks everyone with the help and suggestions. I'm going to assume that the noise is diff whine and I'll start trying to locate a used gas cap. I think I'll paint it orange or yellow and also try to get in the habit of using the little cap hanger on the filler door. I find it a little flimsy and it gets in the way of the fuel nozzle somewhat but I would be way less likely to forget to put the cap back on unless I also forget to close the filler door.

[BimmerBreaker]

There should be a rubber lead off the gas cap that attaches it to the filler door so you can't lose it. Also - the black plastic on the inside of the filler door is specifically designed to hold the cap while you fill with gas



Gas caps are also pretty universal between models - any BMW gas cap from the era will work fine

[Hoyt Clagwell]

There should be a rubber lead off the gas cap that attaches it to the filler door so you can't lose it. Also - the black plastic on the inside of the filler door is specifically designed to hold the cap while you fill with gas

Gas caps are also pretty universal between models - any BMW gas cap from the era will work fine

The lead on mine must have gone missing before I owned the car. I'll try to find a cap that comes with the lead or maybe I can fabricate something.

[BimmerBreaker]

Few on ebay at the moment with the lead for ~$20 shipped

[rasmuw]

I never knew there was a lead, I don’t have it for my cap. I leave the key in the cap, and no matter where the cap goes, finding it is easy since I can’t drive off without the key.

[TexaZ3]

https://www.ebay.com/itm/36359723554...IAAOSwtY1fKPMD

This will fit just fine, comes already with the strap.

Or this:

https://www.ebay.com/itm/26537894652...AAAOSwCmxheQZB

[KeysCoupe]

...and rhey come with a leash!
-Donny

[Hoyt Clagwell]

One of those won't ship to Canada and the other is from China. I've got one ordered from a U.S. company. I could find one locally. Thanks.

[TexaZ3]

One of those won't ship to Canada and the other is from China. I've got one ordered from a U.S. company. I could find one locally. Thanks.

There are literally hundreds of these listings on ebay, shipping from all over the place. Take your pick. You can also get just the strap for like, $3.