RE: {Chrysler 300} Re: 1957 gas cap and tank venting

Hi John, I agree that it seems that the cap SHOULD be vented given that the tank is not. I would think just drilling a small hole in the cap would do it. But it appears that the original factory supplied cap was non-vented – see photos of an NOS ’57 cap part # 1732416. Normally a hole would be found on the underside of the cap – don’t see one here – and the center dome on the outside will “rattle” when shaken. Cap usually marked vented as well??

Carl

From: John Grady
Sent: Thursday, September 15, 2022 12:39 PM
To: Carl
Cc: chrysler 300 club
Subject: {Chrysler 300} Re: 1957 gas cap and tank venting

Hi , I think you have that backwards— 57 requires vented cap , on dodge at least . Someone had put a non vented , on mine , way back in 1960 . It “ ran out of gAs” or “ frozen gas lines” —-all this bs ( hey it always started up after heating lines or new gas) . Caused by a vacuum in tank ! Which slowly fades out as you fix — anything!

I found out doing “ stuff “ in the woods ( Bob Segar) one winter night idling a long time , all of sudden Big Bang behind car, I jump out thought someone out there hit the trunk lid . Kind of scared !!I go to drive away car stalls = Yow !

By then I had gas in can in trunk over this stupid repetitive problem and no $ to fix it anyway .

So I get the gas , open gas filler , huge whoosh inwards but also big bang , as gas tank snapped back out . Aha

So yes , no gas tank vent on car in 57 , only .060 hoke in cap .

The internal or external pipe you see on gas fill neck only vents air back into top of gas filler pipe as you fill tank , has nothing to do with this overall tank air vent ( and also does not work well (!) —thus the big spill out all the time with auto fill ) .

Sent from my iPhone

On Sep 15, 2022, at 9:37 AM, Carl <cbilter@xxxxxxxxx> wrote:

Hey fellas,

It’s been a few years since the listserver has addressed the vented or non-vented gas cap issue on our cars. At that time we determined that ’57 used a non-vented cap, which seems to be the correct answer based on my New Yorker cap and an ebay search of Mopar part number 1732416 which was the ’57 part number. But while under my New Yorker today I could not find a vent from the tank itself, which is original. It does not have the vent tube like 60-63. It also doesn’t seem to have a vent tube in the filler pipe like ’56 has. That might explain why I get a “whoosh’ every time I open the gas cap (outflow- positive pressure). Fuel pump and drivability is not affected.

After searching listserver archives I found a reference from Ron Waters saying that 57-59 tanks are not vented; therefore, one needs a vented gas cap. But the original cap is not vented. Something does not seem right with this design.

Do you guys have any insight? Maybe I just didn’t find the vent?

Carl Bilter
’57 New Yorker coupe

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