[KingFatty]

Anyone know how to disassemble the gas cap?

Mine stopped clicking. I ordered a cheap aftermarket replacement and it clicked for a bit then stopped clicking.

I'd like to figure out what goes on inside the gas cap, without destroying the gas cap. I can't see how it comes apart.

Also, just wanted to confirm that the filler neck of the car plays no role in the clicking, because all the elements that make the click happen are contained in the gas cap (to rule out a problem with my filler neck, like there doesn't need to be a special tab of the filler neck that sticks out to engage the cap to trigger the cap's clicking mechanism, right)?

 

[chauncey]

Anyone know how to disassemble the gas cap?

Mine stopped clicking. I ordered a cheap aftermarket replacement and it clicked for a bit then stopped clicking.

I'd like to figure out what goes on inside the gas cap, without destroying the gas cap. I can't see how it comes apart.

Also, just wanted to confirm that the filler neck of the car plays no role in the clicking, because all the elements that make the click happen are contained in the gas cap (to rule out a problem with my filler neck, like there doesn't need to be a special tab of the filler neck that sticks out to engage the cap to trigger the cap's clicking mechanism, right)?

I bought my SX CPO and don't remember the gas cap ever clicking or ever having a light on so I never thought there was an issue.

 

[BlackKiaOptima16]

Mine does not click, don’t think it ever did.

 

[Turbonut]

If you look in the owners manual it will say, tighten the gas cap until it clicks one time, otherwise the CEL will illuminate.
As far as taking it apart, I'd say get a new cap and then destroy the other one during the investigation.

 

[KingFatty]

Here is the procedure. The assembly is held together by a friction snap ring kind of retainer. You pry off the ring like this, using the space created by the outer leash ring that makes room for your screwdriver. You can rotate the outer leash ring to work your way around to pry multiple locations of the snap ring:

Once the snap ring is removed, things come apart into 4 main pieces:

The handle piece (farthest on the right) is spring-loaded for rotation of the inner white disc connected to it, where the spring allows the white disc to snap back rotationally relative to the outer black handle part. I think you can pry the disc out of the outer handle but I didn't try that, seems like you'd need to reset the spring if you did.

The pressure-relief barrel shown 2nd from the right has a snap-together assembly too, where there is a center disc with prongs. The disc is located on the back of the barrel assembly, and holds in a spring for the valve disc. If you want to take it apart you can probably pry the prongs back. I didn't try it, but here's what it looks like. If your gas cap fails, it's probably this spring-loaded vent either stuck open or stuck closed:

As for the clicking, I believe it's from the little tab that passes over the line on the handle assembly's disc, here:

The problem is the tab on the left assembly is too short, and only contacts the line on the right assembly if you squeeze the two assemblies toward each other and then the tab will click as it goes back and forth over the line. If you just rely on the snap ring holding them together, there is too much slop and no click.

I'm guessing over time, the tab will wear down and become too short. This is all speculation based on how I could try to get a click by mashing/holding them together toward each other. Once I assemble things back together and let them relax, I can't get it to click.

This disassembly is using a brand new aftermarket cheap Chinese gas cap. Now that I know how to disassemble it, I'll take apart the OEM gas cap that came with my car to compare and see if it's tab is worn or broken off etc.

 

[KingFatty]

Here is my old original Kia OEM gas cap. First difference is the OEM Kia barrel assembly includes a metal disc and a prong to stabilize it, instead of the aftermarket plastic disc with nothing to stabilize it. The gasket that seals against the filler tube is bigger. The various plastic pieces broke off of the barrel assembly. Not just the clicker tab, but also the four prongs that give a spring-loaded effect.

Broken pieces:

Kia redesigned the gas caps, so technically there may be official Kia differences from my old Kia OEM gas cap and the modern redesigned gas caps.

I wonder if the broken pieces fell off onto the road? There is a chance they might have fallen into the gas tank if I was unlucky right when removing the cap. Otherwise, it seems the gasket would prevent the broken pieces from falling in.

 

[upacrk1]

Here is my old original Kia OEM gas cap. First difference is the OEM Kia barrel assembly includes a metal disc and a prong to stabilize it, instead of the aftermarket plastic disc with nothing to stabilize it. The gasket that seals against the filler tube is bigger. The various plastic pieces broke off of the barrel assembly. Not just the clicker tab, but also the four prongs that give a spring-loaded effect.

View attachment 252250

Broken pieces:
View attachment 252251

Kia redesigned the gas caps, so technically there may be official Kia differences from my old Kia OEM gas cap and the modern redesigned gas caps.

I wonder if the broken pieces fell off onto the road? There is a chance they might have fallen into the gas tank if I was unlucky right when removing the cap. Otherwise, it seems the gasket would prevent the broken pieces from falling in.

You obviously are a mechanical engineer (or similar). Don't think I've ever seen an OptimaForum posting as detailed as yours! 😉 ps. My 2012 Optima's LX gas cap clicks just fine. 🙂

 

[tlmullens]

Anyone know how to disassemble the gas cap?

Mine stopped clicking. I ordered a cheap aftermarket replacement and it clicked for a bit then stopped clicking.

I'd like to figure out what goes on inside the gas cap, without destroying the gas cap. I can't see how it comes apart.

Also, just wanted to confirm that the filler neck of the car plays no role in the clicking, because all the elements that make the click happen are contained in the gas cap (to rule out a problem with my filler neck, like there doesn't need to be a special tab of the filler neck that sticks out to engage the cap to trigger the cap's clicking mechanism, right)?

Not that this is what you asked for, but mine stopped clicking about 2 years ago. I just left it alone and haven’t had any issues with it.

 

[KingFatty]

The OEM Kia gas cap just arrived. $25 including shipping.

The OEM looks identical to the old one from my car, except they've changed the printed text on the cap to just symbols/pictures. So the modern gas cap doesn't say "TIGHTEN UNTIL ONE CLICK." There is also an orange dot on the snap ring of the OEM replacement, but maybe my old one had that but it just wore away over time.

The OEM Kia cap appears to include the metal like the original. And the snap ring holds everything nice and snug/tight together so it has a crisp click regardless of how you hold it.

Unlike the OEM Kia replacement, the cheap chinese aftermarket gas cap had a looseness to its snap ring that allowed the slop to prevent the click so it was a waste to buy it. Luckily, the merchant refunded me immediately after I submitted a return request saying it was defective for not clicking, without me needing to even send it back, so kudos to that vendor.

Bottom line, it's worth paying double for the OEM Kia gas cap compared to the Chinese aftermarket, because it's still relatively low cost. Happy to get the click back, and nice insurance having the new cap that will be less likely to get a check engine light compared to my 12 year old original that was already breaking apart. I like that the OEM still uses the metal disc inside (based on the appearance, I didn't disassemble it), and likely better valving/springs than the Chinese.

Here is the appearance of the new OEM Kia gas cap (on the left) next the the old original 2012 OEM Kia gas cap (on the right):