Older fuel cap issues

Frank Smidler · #1 03-20-2009, 10:42 AM

I have the older fuel caps with plastic surfaces at the O-ring slope. My understanding is that the newer caps are all aluminum. What issues were the problem with the plastic faced caps? I have noticed if I fill the fuel tanks to the ring I get a lot of leaking (siphoning?) around the caps until I use some of the fuel in the tank. I am tightening up the bottom plate to see if that helps. Do people have less problems with the all aluminum caps?

Thanks

rvbuilder2002 · #2 03-20-2009, 10:45 AM

I think you have it backwards.
I think the all aluminum were the old style.

airguy · #3 03-20-2009, 11:38 AM

I got the all-aluminum caps in my wing kit, delivered March of 2008.

AlexPeterson · #4 03-20-2009, 06:54 PM

To be sure, Frank, you mean the surfaces which contact the large o-rings? In that area, mine are plastic (1994 vintage).

It is very helpful to periodically (every month or two) spray something like Tri-Flow under those big o-rings. It makes a lot of difference in how the rings move when tightening the caps. It will make a large difference in the cap adjustment.

Another thing to look for is the bearing surface under the locking tab. They were plastic in my vintage, but Van's sells stainless steel pieces to replace the plastic parts.

Skid · #5 03-20-2009, 07:45 PM

I had leaks off and on for some time. I tried tightening the seals up but it became too hard to get it on and off. Having it so tight didn't work well either. I finally replaced the o-rings and applied a fuel lube to the small internal o-rings. Here is a link to what I used; http://www.aircraftspruce.com/catalo...ezturnlube.php
The tube is plenty as it only takes a small amount. I have not had any leakage since appling the lube.

Greg Arehart · #6 03-20-2009, 09:21 PM

Another issue that an 8-flying friend made me aware of recently is the pin holding the lever latch, which apparently was a rolled pin in the earlier models. If one tightened the cap too much, the leverage on the latch pin would sometimes break the pin and you would be stuck with an unusable fuel cap. Replacing the pin with a solid stainless pin (appears to be standard in newer caps) helped solve the problem, but it is important not to have the o-ring being squeezed too tightly - just tight enough to seal.

greg