Classic Winnebagos & Vintage RVs

Pretty simple. I purchased a vented locking gas cap (ACDELCO 12F20L). Supposed to fit a P30 chassis for my year according to rock auto.

However, this cap - I took it apart, and it only vents pressure - not vacuum. Yeah, I really did put my mouth on it and try it once assembled, and once dissembled - the difference is 100%

Quote from: Rickf1985 on August 23, 2018, 04:46 PMIt is only supposed to vent in, not out. Are you sure the sound you here when you remove the cap is vacuum and not pressure? You have the same unit as me, you should have a large vent line going to the back of the RV from the tank. Why do you think you have a vent issue?

So I guess this part number is incorrect, or I have received the wrong item. Either way, perhaps you'd want to steer clear of this cap.

Is there a locking cap you recommend for a late 80's P30 chassis?

Looking into this cap in particular:
STANT 10591

Stant caps, made of sturdy and long-life materials, are the only aftermarket caps to include all safety features and valving of the original equipment caps.

Features

   
• Pressure relief prevents fuel vapors from exiting the fuel system under normal operating conditions. This allows an escape path for pressure in the event of an impact situation where the fuel tank has collapsed. It also permits pressure to escape if the vapor management system malfunctions.

   
• OE Vacuum relief prevents fuel vapors from exiting the fuel system via the fill tube under normal operations. This allows an alternative path for air to flow into the tank if there is an obstruction in the vapor recovery or vapor management systems. It also permits the fuel system to normalize air pressure during natural vacuum situations.

   
• A "Lost Motion" feature permits the cap handle some freedom to turn while maintaining a seal, which could aid in the prevention of fuel tank leakage during a crash or impact.

   
• A "Breakaway Groove" allows the cap to remain sealed and prevent fuel leakage during a crash or impact, even if some of the cap has broken away.

   
• A "Torque Override" feature aids in the proper installation of the fuel cap. It produces an audible click as the o-ring that seals the cap is properly compressed.

I'll check mine tomorrow..  I bought one 10yrs ago.. LYK if I remember... LOL.  but when in doubt.. Call Sands RV in Madison Ohio which is where I bought it... 

Tina