Hello all, I have an old Black & Decker generator I've been resurrecting, and it has a Briggs 5 HP engine, type 130232-0169. I've got it repaired and running, but it has one annoying thing that I haven't been able to resolve yet. The gas cap oozes gas. The lip isn't bent, and the cap seems to tighten OK, but with the fuel sloshing around from the vibration, it eventually gets wet around the cap, and trickles down the side of the tank. I've tried making a new gasket out of rubberized cork material and out of gasket paper, but no improvement. It looks like in both cases, the lip of the tank left an even groove in the gasket, so I'm pretty sure it's sealing evenly. Any ideas?
Thanks, so would cork be a better material to use? The old one isn't cork, but more like a cardboard material. The gasket paper seemed to work until I poked a small hole in the center for a vent. I suppose I could order a new cap, but it seems like the gasket in the old cap could be replaced. No rust in the threads.
#5
sgkent
is the cap itself vented or unvented? My briggs caps have a deflector down inside that causes fuel being splashed to remain in the tank.
If you lookup the part number I posted, you’ll notice that both the gasket and cap are vented on these older style setups. At the time these were used, this was the way to reduce splashing.
So here's a picture of the gas cap with the old gasket. It's grooved from the lip, but if I slip in a different gasket that's cut to the same size and has even a small hole in the center, gas still eventually seeps out from between the threads. If I don't poke a hole or make one that's too small, it either stalls after a while, or I'll shut it down and a minute later the heat from the muffler causes the tank the heat up, which then forces gas into the carburetor, which floods it and leaks out from the choke pull.
OK, but are the threads supposed to contain the gas? Trying to figure out how it's supposed to seal if a new gasket doesn't seem to fix it, unless the gasket is supposed to be glued to the cap somehow.
The original gasket is bigger than the hole in the cap so it is held in there like a welch plug in your engine block .
Over time the shrink or go soft & fall out
If the fuel is leaking out the holes in the top of the cap, the gasket is not sealing. If it is leaking around the base of the cap, the cap is bad or the threads on the filler neck are bad.
Bought a new cap, made zero difference. Filler cap threads are not damaged, and the new cap gasket has a nice ring where the lip is sealing. Just seems to be that fuel splashes up, gets through the air holes, seeps around the edges, and oozes out from between the threads. As a test, I tried wrapping the threads with electrical tape. On the plus side, it stopped leaking. On the downside, the gas dissolved the tape and made a black, gooey mess. I can confirm that if I make a gasket without any holes in it, it seals fine and doesn't leak, except the engine stalls eventually because the suction builds up in the tank.
Any ideas? Almost seems like I was on the right track with the electrical tape. Maybe I need to find something equivalent to teflon tape that is fuel proof and wrap the filler neck.
Get a fuel rated O-ring at the hardware store. Install around the threads. Or 5 of them if it takes that many to seal. Think those are 1.5" fuel caps. Lube the rings with silicone plumbers grease.
Fixed it. Got some of this stuff, trimmed the width down a little, wrapped a turn around the tank neck, and no more leaks. Cap makes a snug fit, but no gas oozing out on to the tank.
www.permatex.com
