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Topic: New Oil Fill Cap doesnt fit thanks to rubber sealing ring diameter (Read 77 times) previous topic - next topic

New Oil Fill Cap doesnt fit thanks to rubber sealing ring diameter

So i stopped by to tinker on the tbird for a little bit and throw some of the parts i bought for it on.
I bought a nos oil fill cap w/hose to replace the completely petrified original one it had, like bending steel tubing which i had to remove everytime i went to dig into the carb thing and finally got annoying enough to replace it.

The "new" one is the more familiar black bulky one with yellow ring on it. The original is a yellow flat one. I cut the tube to install the inline filter(new) on it like the original and went to install it.
So for clarity i have an 83 with the plastic valve covers instead of the steel ones and they list these things as 83-87, there is no way that wouldve fit on there without breaking the valve cover from trying to push it down on it because of the rubber ring being thicker than the one on the yellow cap.
The cap diameters and slot locations and thickness all look the same and in the same place, just the rubber seal is much thicker.
Im sure age and compression flattened the original "some" but i couldnt even see the tab slots on the new cap with it on. I took it off and installed the old one from the original on it and it went right on, no slop or play. Wouldve liked to replace that but its not going to happen at that diameter. For all intents and purposes im assuming the rubber ring is correct for it and original to it.
Inspecting the new rubber to see if its swollen and doesnt appear to be.
I didnt have my phone to snap pics but next time im there ill take some of the difference between them.

"Beating the hell out of other peoples cars since 1999"
1986 Ford Thunderbird w/ 3.8 v6, stock.