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a4cj2a77 View Drop Down
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    Posted: 16 Nov. 2019 at 4:30pm
So l  made it out to the desert with the nos a/c cap with chain. I no longer smell gas, but as you can see it's not a perfect seal. This is a vast improvement over black look alike a/c cap that I was using that would leave 8" wide stain trail on the side of the body. What you see in the pic is from 2 days of jeeping and flat towing. Maybe an issue with the filler neck. Tank is 4yrs old.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote chris Quote  Post ReplyReply Direct Link To This Post Posted: 05 Oct. 2019 at 1:23am
I’m late to this thread, and I hope I’m not repeating info found in an earlier post, but I have a vintage Ivano locking gas cap on
my 2A (#13396). The cap was on the jeep when I purchased it. 

It has an art-deco look.  People comment on it, and some ask if it was standard equipment. 

I believe Ivano was a aftermarket locking cap offered in the 40s and 50s. 

It works great. 

I’ve seen them for sale with prices varying from under $20 to over $50. 

As is often the case, the cork gasket might need attention. 

Take a look around the Internet for one. 

Good luck. 
chris

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Spinnas Quote  Post ReplyReply Direct Link To This Post Posted: 26 Sep. 2019 at 4:04pm
Originally posted by JeepFever JeepFever wrote:

Update to my "fix" . .  (earlier I reported changing to a 3/32" Buna-N gasket).

I moved '2A to level spot and opened cap.   One thing I noticed was that the gasket had clearly swelled.  The material was softer than before.   I thought Buna-N was impervious to gasoline,  but what I got might be an inferior grade?


I am trying some Viton now after the same result you mentioned with Buna
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Stev Quote  Post ReplyReply Direct Link To This Post Posted: 26 Sep. 2019 at 3:51pm
To free up the vent valve / spring/ seat in the old cap -- how about putting it in the ultrasonic cleaner for an hour and see if it frees up.
Stev
1946 CJ2A Trail Jeep (The Saint), 1948 CJ2A Lefty Restored
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JeepFever Quote  Post ReplyReply Direct Link To This Post Posted: 26 Sep. 2019 at 3:00pm
Update to my "fix" . .  (earlier I reported changing to a 3/32" Buna-N gasket).

The cap is harder to remove,  but did not seem to have normal leaks,  until one day recently.

Full tank,  parked off-camber,  driver-side down.      I did not notice any leaking until over 24 hours after parking.    I noticed it on a hot afternoon,  and it was dripping badly.

I moved '2A to level spot and opened cap.   One thing I noticed was that the gasket had clearly swelled.  The material was softer than before.   I thought Buna-N was impervious to gasoline,  but what I got might be an inferior grade?

This swelling might not be the cause of leak though.   In this situation,  a vented cap might always leak.   The gasoline in tank had cooled off,  and contracted overnight.   Then on hot afternoon,  the gasoline may have reached pressure high enough to release the check valve?   Since the checkvalve was below surface of fuel,  it vented liquid, not vapor?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JeepFever Quote  Post ReplyReply Direct Link To This Post Posted: 26 Sep. 2019 at 2:35pm
Originally posted by AKoller AKoller wrote:

I have what I believe to be an original gas cap. Last week while in Colorado I wasn't having any trouble with the gasket sealing. I was having trouble with the cap venting. While climbing in elevation the tank would build so much pressure that it wasn't allowing my added return fuel line to work. If I wasn't returning fuel I was then having trouble with the Jeep wanting to vapor lock. The little brass vent plunger in the cap is free. Is there something else in there keeping the cap from venting? After the first day I started to just install the cap real loosely so it would vent around the gasket. The problem with this is it was dumping fuel out terribly. I wasn't too crazy about that either at $3.65 a gallon for the non ethanol fuel.

One thing I was thinking of trying is to let the cap sit in carburetor dip to see if it will fee anything up inside the cap allowing it to vent. I may try this tonight and report back how it worked. Any other suggestions are welcome.

If I am understanding the link that BobW posted,   the little brass plunger is the vacuum check valve.

Sounds like the larger pressure valve is stuck.    Maybe could try to push thru the vent hole a little harder to free it?   

BobW's  link  again -> www.cj3a.info/tech/gascap.html


Edited by JeepFever - 26 Sep. 2019 at 2:37pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AKoller Quote  Post ReplyReply Direct Link To This Post Posted: 26 Sep. 2019 at 1:11pm
I have what I believe to be an original gas cap. Last week while in Colorado I wasn't having any trouble with the gasket sealing. I was having trouble with the cap venting. While climbing in elevation the tank would build so much pressure that it wasn't allowing my added return fuel line to work. If I wasn't returning fuel I was then having trouble with the Jeep wanting to vapor lock. The little brass vent plunger in the cap is free. Is there something else in there keeping the cap from venting? After the first day I started to just install the cap real loosely so it would vent around the gasket. The problem with this is it was dumping fuel out terribly. I wasn't too crazy about that either at $3.65 a gallon for the non ethanol fuel.

One thing I was thinking of trying is to let the cap sit in carburetor dip to see if it will fee anything up inside the cap allowing it to vent. I may try this tonight and report back how it worked. Any other suggestions are welcome.
1950 CJ3A "Thumper"
1966 M151 A1
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Post Options Post Options   Thanks (0) Thanks(0)   Quote smfulle Quote  Post ReplyReply Direct Link To This Post Posted: 11 Sep. 2019 at 5:11am
Just to throw a little more mud in the water, here’s what I’m trying.

First off, I have resigned myself to the fact that if my Jeep is parked with the drivers side down and a tank more than half full of fuel, my gas cap is going to weep some fuel.

I ordered a Jerry can gasket as recommended by 3a Steve. 1st one worked pretty well, but tore after a while. It was a really tight fit. 2nd one was too big and got bigger from swelling after about two weeks. Couldn’t get it to seal after that.

Today I went to the Ace Hardware store and got some of this red rubber gasket material. 


It’s pretty thick and pretty stiff. Probably won’t hold up to the gasoline. The package doesn’t have any info on suitability. 


I cut out a gasket.


Fit in the cap well. Screwed on tight to the filler neck. Time will tell if the rubber holds up.


Stan
48 CJ2A (Grampa's Jeep)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Spinnas Quote  Post ReplyReply Direct Link To This Post Posted: 11 Sep. 2019 at 4:40am
Rick that exact cap was one that I tested. With a good gasket it still never sealed very well and leaked pretty good still. It was one of the 3 Black replacement caps we tried, and it was the best of those 3. See my long post above.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Steelyard Blues Quote  Post ReplyReply Direct Link To This Post Posted: 11 Sep. 2019 at 2:36am
I got a NOS surplus military one with a chain off of eBay. I fill it up all the way to the neck, sometimes past, and it doesn't leak. I did not change the gasket. Just stuck it on.
 
Micah
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1965 Johnson Furnace Company M416 #6-1577
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Stev Quote  Post ReplyReply Direct Link To This Post Posted: 10 Sep. 2019 at 10:14pm
This a NOS AC Cap that does not leak (one on the left).

Stev
1946 CJ2A Trail Jeep (The Saint), 1948 CJ2A Lefty Restored
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 3A Steve Quote  Post ReplyReply Direct Link To This Post Posted: 10 Sep. 2019 at 9:33pm
Look identical to my gas cap. Leaked. Used a jerry can spout gasket. It still has very minor leaks but it is quite satisfactory. Did have to cut the gasket to remove a very small section. It goes on hard but not bad.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote a4cj2a77 Quote  Post ReplyReply Direct Link To This Post Posted: 10 Sep. 2019 at 9:24pm
looks different than the one from Mullins. Mine also came with a chain and clip
Phil
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rick R Quote  Post ReplyReply Direct Link To This Post Posted: 10 Sep. 2019 at 8:53pm
The gas cap I got does not have a chain. The cap gasket seals tightly on the neck and it appears the check valve doesn’t seal.
RWILLYS (Space R)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 3A Steve Quote  Post ReplyReply Direct Link To This Post Posted: 10 Sep. 2019 at 8:42pm
If you don't find the perfect gas cap you might want to order a cheap pack of jerry can spout gaskets off of eBay (these are smaller diameter than the actual gas can gaskets). You may have to cut it to get it to fit but it will still work pretty well. I know I have a collection of non-sealing caps.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Stev Quote  Post ReplyReply Direct Link To This Post Posted: 10 Sep. 2019 at 8:35pm
Rick,

Is it a NOS A/C pattent pending cap with a retaining chain?

Can you post a picture?


Stev
1946 CJ2A Trail Jeep (The Saint), 1948 CJ2A Lefty Restored
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rick R Quote  Post ReplyReply Direct Link To This Post Posted: 10 Sep. 2019 at 7:49pm
Just got a cap from g503 yesterday. It leaks too.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote a4cj2a77 Quote  Post ReplyReply Direct Link To This Post Posted: 10 Sep. 2019 at 6:23pm
Bought a A/C cap from Mullins jeep parts or armytankguy on ebay. Fits great, but won't know if it leaks until I get it back on the road. Doing disc brakes ft and rear(Geo tracker setup) Previous cap I bought, you could hear the ball check valve rattle around and you can see the staining on the body from gas leaking
Phil
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