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[T3] Gas tank overflow hoses


I recently acquired several gas tank overflow hoses from various sources. These 
were used in all type 3s from 68 thru 73. There are 2 versions: early (A), 68 
thru mid 72, and late (C), mid 72 thru 73. The changeover occurred when the gas 
cap went from the 1/4 turn cap to the screw cap. Unfortunately, this part 
cracks and leaks gasoline fairly regularly, and these often need to be 
replaced.

Some of the hoses I had were supposed to be OEM, some reproductions. Once I had 
them in hand, I could tell that even some of the ones that I thought were going 
to be OEM were actually reproductions.  

Since one of the problems with rubber parts like this is that the maker might 
have chosen the rubber compound poorly, I decided to run a simple test to make 
sure that these were made from a compound which was compatible with petroleum 
products. All I did, was place 4 different overflow hoses in kerosene for a 
week. I used kerosene rather than gasoline because it is safer and I had it on 
hand; the effect of gasoline would be the same or worse.

The results surprised me. Here are the results:

1) NOS VW 311 201 179A, appears to be genuine, since it has the same maker's 
logo on it, in addition to the VW logo and part #. Failed, absorbed the 
kerosene and ballooned up to twice normal diameter.

2) New part, marked 311 201 179B (not a real VW number.) Failed, same as # 1 
above. This part came from ISP West; I emailed them about the odd part # but 
got no reply. I have no way of knowing who actually made this part, but if 
someone sells you a part with this odd part # on it you should just return it 
for a refund and let them know why. I'll email them again.

3) New reproduction part from type 3 Konny in Germany, marked 311 201 179C, no 
VW logo, different mold mark. Passed, no effect on the rubber.

4) Old used (genuine?) VW part from one of my cars, marked 311 201 179A. This 
part had clearly shrunk in service and was SMALLER than normal at the beginning 
of the test. At the end of the test it was back to normal size. I gave this one 
a pass, with a question mark. I'm concerned that it may have swollen up when 
new, but that the gas leached out some component that left it shrunken. Thus it 
swelled up only a limited amount when re-exposed.

I will post a photo in a day or so.

I have some more hoses in the kerosene right now, just to check to see how 
widespread this problem is. I'm very concerned that one of the hoses that 
failed appears to be genuine OEM from VW. It's quite possible that even VW got 
careless about this in the later years, and that all my, and everyone else's, 
OEM spares are poor quality. It is just as likely that this part is actually 
NOT genuine VW, but just a visually good counterfeit.

-- 
Jim Adney
jadney@vwtype3.org
Madison, WI 53711-3054
USA

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