A Cracked Fuel Expansion Tank

[larry47us]

When at Taj this summer, at Dave's BBQ, a bunch of us went out front with beer in hand to look at our cars. We must have been feeling no pain, since it was pretty dark outside. We discovered that on the 73's there is a tank up inside the driver's fender, just behind the headlight. It wasn't on the 71's, and we didn't have a 72 to measure up.

I wondered about it, but never worried about it. I knew it wasn't for windshield washer fluid. And it couldn't be the anti-freeze overflow tank!! We couldn't figure out what it was.

This weekend, I was running AutoX, and after one run, I was told that I was leaking something. There was a clear liquid running out from under the driver's front fender. Lo and behold!!! It was Gasoline!!! What the Hay???

That tank inside the fender was holding gasoline and it was obviously cracked, because there was a bunch of gas running out of it. We pulled back the perlon in the trunk and saw a buncha gas lines, two big ones that went up to the passenger compartment, a small one that went into the fender tank, and the fill hose that went to the fender. What'sit for?? No one knew.

When I got home, I pulled out the ol factory service manual, and saw that this is a fuel expansion tank for "those models with Unvented Gas Tanks."

OK, now I have two questions.

1. Does anyone have a spare tank that I can buy to replace my cracked one? I think that the lost gas is affecting my gas mileage to say nothing of the safety issue.

2. Is there any way of easily clamping that line - or removing the recirculating aspect of the venting system, without affecting the way the car runs?

Does the gas that goes into the tank get sucked back into the fuel tank? Or does it just evaporate and go through the charcoal filter back into the air cleaner to get burned?

Sorry to wax on and on, but I feel talkative tonight.

larry

[RandyWebb]

It is (or can be replaced by) a VW tank - costs about $80 tho. I might have posted the VW part no. on Pelican or here or Rennlist if you want to search.

It is part of the evaporative emissions system - the vapor goes up to the smaller tank under the cowl, then down to the one you found - and is condensed. There are some diagrams posted on Pelican.

[HarryD]

Larry,

Had a similar event several years ago. My "hillbilly enguneering" solution:



Read about it here: http://forums.pelicanparts.com/showt...t=plastic+tank

[larry47us]

Harry:

Read your post on Pelican. Your story sounds VERY VERY familiar. Exactly what happened to me. Mattafak, there was an RSR clone on the course that was built from a 73, and when he was running, he was training a slop of liquid from under his driver's door. He had pulled the expansion tank, and just let the hose run out the bottom of his car. GEEEZ, a bit dangerous!!!

I wonder if I should be concerned about a used 30 year old tank now that you mention plastic fatigue and brittleness. I don't mind having an old windshield washer fluid bottle. But maybe now is the time to break down and buy a "new" expansion tank from Porsche. Remain original, but not ancient.

Especially if it's only $59. (or is that wishfull thinking?)

thoughts?

larry

[RandyWebb]

plastic fatigue and brittleness....


Larry - the first thing you should do is to inspect the (formerly) clear fuel vapor hoses. I f they are hard and brownish then replace them all with new - and don't use regular PVC. Again, there is a thread on Pelican covering this. Fumes here will emerge near the battery....

I would replace fender tank and make sure all the stock stuff in the evap. system is up to snuff.

[larry47us]

Randy:

Makes sense. I have a line on a tank through pelican for $25. The dude is pressure testing it tonight. The lines that I put my hands on still seemed flexible, but I will take a closer look when I replace the tank. I agree that this is a good time to refresh the entire system.

Do you include replacing the charcoal filter in the process? Does it get gummed up with the vapors? I imagine that this is something that I only will have to do rarely. But during the past 32 years, I doubt that anyone has gone over this part of the part of the system.

Do you have a source or recommendatino as to the type of tubing to get? (I'll do a search on Pelican.)

larry

[RandyWebb]

I've always wondered how long the carbon canisters last myself... it just takes up vapor and then 'exudes' it out, same basic idea as a battery, but who knows how long it lasts? Come to think of it, that canister is a VW part no. ...

IIRC, McMaster-Carr has the vapor line, but I found some here (a mid-sized city) and the guy swore up and down it worked - as did the manf. after I checked online - so you should be able to source it locally.

[larry47us]

The Tank pressure and vacuum tested OK. So, now it's a matter of dissecting the vapor system and replacing the hoses that are needed and checking into the charcoal canister. Oh, the joys and mysteries of working on 32 year old cars!!!!!

Another adventure in the offing.

larry