Gas cap.
Thread Starter
Drifting
Joined: Nov 2002
Posts: 1,787
Likes: 261
From: Blue Bell PA
2018 C3 of Year Finalist
Gas cap.
Just got back from our local corvette clubs annual car show.
CCDV. Great time ,I decided to fill up the tank AGAIN.i opened the cap
and the tank was full of pressure. I thought it was a vented gas cap.
its A 69. I guess sitting outside on a beautiful day in the sun maybe
caused the tank to build up pressure but it should be venting from somewhere.
does someone have an answer for this? Thanks in advance.
CCDV. Great time ,I decided to fill up the tank AGAIN.i opened the cap
and the tank was full of pressure. I thought it was a vented gas cap.
its A 69. I guess sitting outside on a beautiful day in the sun maybe
caused the tank to build up pressure but it should be venting from somewhere.
does someone have an answer for this? Thanks in advance.
Safety Car
Joined: Apr 2006
Posts: 4,057
Likes: 421
From: BC
A 69 definitely has a vented cap as the tank isn't vented. If it's the original cap it should even say "VENTED" on it. Replace the cap or drill it until you get a replacement but that cap is the only vent on a 69 tank and it has to be working properly.
Last edited by CanadaGrant; Jun 8, 2019 at 08:08 PM.
Drifting
Joined: Mar 2011
Posts: 1,347
Likes: 121
From: Kernersville NC
I have researched this cap and it is designed to freely allow air in to eliminate a vacuum in the tank. We all know that. I believe it also has a pressure relief valve that allows pressure to escape if it exceeds about 1-2 psi. I have a pressure gauge plumbed so that I can see the pressure on the tank. After a drive on a warm or hot day the pressure is always about 1psi. If I open the cap it drops to 0 psi. The whoosh sound with 1psi is pretty significant but that pressure will not damage the tank.
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