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Old 01-16-2010, 05:12 PM
Oracle12345 Oracle12345 is offline
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Join Date: Jul 2007
Location: USA
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Quote:
Originally Posted by hookedon210s View Post
The W126 cars have internal vent valves at the top of the fuel tank that control venting to the charcoal canister. Over time these valves jam in the closed position due to deposits from the fuel or condensation in the tank which prevents the proper venting of the tank. On a warm day the pressure can get quite high. To my knowledge there is no way to remedy this short of replacing the tank or somehow adding a vent line to the tank and installing the external vacuum/pressure valve. I had my 380SE tank professionally cleaned with no resolution of the overpressure issue. No bad effects to the car yet. Mark
there is a vent line/valve on any gas tank and yes when its warm out the pressure on the gas tank is higher than when its cold out for obivous reasons.

this pressure is the reason why you dont overfill a gas tank. the owners manual listed capacity isnt 100% its a 90% to compensate for the pressure
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