The Panhead & Flathead Site

Now that I have my 1948 "Crustoration" Panhead on the road (see the series of articles in American Iron Magazine) I noticed the old gas caps gaskets were totally shot. So I bought a new set of rubber ones from the local HD dealer.

The first time I rode the bike and then parked it in the garage the gas tanks overflowed and dumped gas on the floor.

Turns out the new rubber gaskets sealed up the vents in the old factory caps and didn't let the tanks vent properly. They overheated and forced out the gas.

Solution was trimming a V notch in each rubber to line up with the cap vents. No problems now.

i think we have all been there buzz!

welcome to the forum btw!

john

Buzz

There's a good discussion about this very issue on another thread running right now.

New production rubber replacement gaskets have been a problem for quite some time, if we dig back in the knowledge base I'm sure there was a post about the exact same thing that happened to you. You can notch them in several places around the edge to provide some air flow but the cure may not be permanent. The rubber material will swell when in contact with some of today's mystery additives and reseal the air gap. I tried to run some by surgically reducing the entire outside diameter of the gasket but it grew again, in time, and shut me down. Cork or leather is better if you can find them.

As a side note, this is apparantly not a new problem. The first VL I bought was the beater from hell, everything on it had been broken, repaired, and broken again, but not by a factory trained technician. The bike was literally held together by globs of brazing and bailing wire and had obviously had most of its repairs done in the back of the barn or at the local blacksmith shop.

Back to the subject, VL's have 2 gas tanks also but the left tank is just a reserve, they are not connected. When I got the bike it took me a minute to figure out what was screwed into the left tank filler hole. Turns out that someone, probably 50 years ago, cured the same leaking/venting problem by soldering a spiral peice of copper tubing to the top of the cap. It must have served its purpose because it was still on there after all those years.

mike

If the gaskets can cover the vents, they are NOT "old Factory caps":



....Cotten

2 years ago I took the rubber gaskets out and installed what looks like teflon inpregnated gasket material. They have not swelled and I do not need the gorilla grip I needed before to take them off. They were left over after an installation by Mitsubishi at work. I gotta get a camera!!!!

I thought I was logged in "PanPal"

Talk about dumb moves, I think I got you beat.

I was working on replacing the oil pump on my '52 Pan, and I had removed the oil lines from the tank, and capped off the tank oil feed nipple with a tight-fitting plastic cap. I was working for about an hour, when I noticed a rapidly growing pool of oil on the floor-evidently the plastic cap and the oil didn't get along very well, and the cap split, dumping about 3 quarts of Milwaukee Gold on the shop floor. I managed to stop it up before I lost all of it, but it made a heck of a mess.

I've gotta' go dump some more kitty litter on what's kft now.

Yep. Old tank nuts with short 3/8 lines pinched and soldered work great. I like the Harley oil cling. You can feel it between your fingers. V-Twin has the loose nuts in 6-packs (9808-6). That's a Colony® part number. J&P probably has them.

That's a great idea-I have some old "cutoffs" from my '64, that the previos owner had rubber lines clamped to-I knew I should save them! Thanks.

I am a little annoyed-I just got a new set of "oil filter" lines from V-Twin Mfg, and they are the type that use rubber fittings around the oil line, and a short nut-notthe original flared tube type. I guess I can flare them and use some more of my "old nuts" from the '64.

Some of the OE style oil lines do have rubber seals (on the external oil filter line). Have a camera? It's becoming a necessary tool to have now with the "internet garage".
Also, if you don;t have the spare parts book that covers your year, you should have one. You can make up your own lines, but the V-Twin lines are all correct, except they don't make a return pump cover-to-filter line for use with an S&S pump yet. You have to make one of those up yourself out of 3/8 cad plated brake line.

This is not a gas cap seal posting hi-jack. I don't think there is anymore to say about vented or non-vented caps. I wish they still made leather seals for the caps. They feel good when you tighten them. They even squeak sometimes.
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If your just getting to know your machine, I'd suggest buying your parts from Kick-Start M/C. They have more than a few Panhead parts. Main reason, is that who ever answers the phone over there KNOWS Panheads.
I would also suggest investing $5.00 in their catalog and having the Kick-Start part numbers in front of you before you call. (616) 245-8991 (10-5 • EST). The more prepared you are before you call, the more free-time you create to get your questions answered, before your alloted time is used up by fumbling and the buzzer goes off.
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I guess you can reason from all the posts Buzz, that the overflowing left tank is caused by kick-stand lean angle and having too much gas left in the tank when you park it on the jiffy stand for more than 5 minutes. There is no cure for overflowing left tanks with a stock equipped machine.
All the more reason for a new parallelogram lift to be made for the Knuckle and Panhead.....like the old Duo-Lifts of yesteryear.
- Fork install duty.

All the more reason that you would want to be looking at the '49-57 Spare Parts Catalog. Get two copies. One for your shop and one for the bathroom.
p.s. Spell check is a nice feature, be we don;t care how you spell something as long as the message comes across.

The OE lines with rubber fittings-did they have them on the oil tank/oil pump ends, as well as atthe filter ends? That woyuld mean I wiyld have to use an adapter at the tank, and change the oil pump fitting to a rubber one.

back to the gas caps.......

Cotten commented about the older style OEM Eaton which vented through the 4 v-shaped channels to the outside bottom edge. He's correct, the gasket should not be able to seal those vents.

but, what if you have one of the newer style Eaton vented caps? The newer ones vented between the outside edge of the gasket and the inside of the vertical lining of the cap. The gasket MUST be a smaller diameter than the inside of the cap or it will seal the vent outlet holes. I think Buzz has one of these:

mike

cork gaskets work best in these

Mike!

Have you any indication of when it was made?

Eaton is still in business, of course.

...Cotten

Cotten,

Not sure of the vintage of those caps. I have 4 of them and I have had them for a while (don't ask me to define "while"). They may be new production, as you say, Eaton is still in business. The ones I have are the "tall" variety, easy to grab, and they twist on and off very smoothly with the cork gaskets.

mike