Fuel tank vent lines

How to keep the Cessna 170 flying and airworthy.

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canderson
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Fuel tank vent lines

Post by canderson »

I know this topic has been discussed quite a bit, as have most topics on this forum, but does anybody know, off hand, what the diameter of the fuel tank vent lines is? I was experiencing fuel fumes in the cabin and found a speed clamp to be decayed and broken. The flexible connectors seem ok, but I'd like to replace everything while I have it opened up. Any other info, such as type of flexible lines and clamps used is appreciated.
The hangar is a forty-minute-plus drive from my computer...
Chris
1953 170B N3234A #25878
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blueldr
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Post by blueldr »

The cross cabin vent system in the C170 is 3/8" tubing.
BL
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GAHorn
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Post by GAHorn »

Another common cause of fuel fumes is hard braking while landing with full tanks. (The goose-neck vomits fuel onto the cabin roof.)
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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canderson
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Post by canderson »

Thanks for the replies. I bought the line and clamps but am having a bear of a time getting the line over the vent line one way and back over the vent "T" side. It's a lot of work for only a half inch gap!
I might try getting some lighter weight flexible fuel rated line and try it.
Chris
1953 170B N3234A #25878
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blueldr
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Post by blueldr »

To provide easier movement of the rubber hoses on dry aluminum tubing, try some of your girl friends cold cream. Works for me!
BL
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GAHorn
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Post by GAHorn »

canderson wrote:Thanks for the replies. I bought the line and clamps but am having a bear of a time getting the line over the vent line one way and back over the vent "T" side. It's a lot of work for only a half inch gap!
I might try getting some lighter weight flexible fuel rated line and try it.
Use lubricant and slip the rubber hoses onto the vent line almost completely, then with the vent line in place, extend the hoses back off the vent line and onto the "T" and gooseneck.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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canderson
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Post by canderson »

I was using my girlfriend's muscle power to try to help instead of her cold cream! 8O I had WD-40 and grease on the parts and it was still difficult. Had to give up after getting only one side done. I am still thinking of trying the Nylaflow Nylon tubing. Might this be a little easier?
Chris
1953 170B N3234A #25878
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GAHorn
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Post by GAHorn »

It would not be an approved part. :(

You could try tubing that is "S-O" ... soft. It is very flexible and manageable.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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canderson
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Post by canderson »

Hmm. Google has let me down. Can you give a little more detail about "S-O"...soft George? :?
Chris
1953 170B N3234A #25878
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GAHorn
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Post by GAHorn »

The "S" is actually an old designation...but it is sometimes still found in-stock at some suppliers. The newer designations disregard the "S".

But the "O" refers to an annealed condition which is very soft and flexible. If you can find some annealed "O" tubing it should be very easy to flex in/out of alignment.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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canderson
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Post by canderson »

Interesting. What I'm afraid of is having to put so much stress on the tank-to-vent line connections that they might start leaking once I've fixed my initial problem. Or breaking the weld on the T portion of my vent system. Perhaps I wasn't using the right lubricant. The original manufacturer probably didn't forsee replacement issues 50+ years out.
Chris
1953 170B N3234A #25878
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ak2711c
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Post by ak2711c »

Use fuel lube, it will slide right on. Your local FBO will have some.
Shawn
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canderson
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Post by canderson »

When I get a change to get back to the hangar I will try again based on this advice. Thanks.
Chris
1953 170B N3234A #25878
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DaveF
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Re: Fuel tank vent lines

Post by DaveF »

Before:
leaky fuel vent lines.jpg
After:
leaky fuel lines repaired.jpg
Fuel smell gone!
iowa
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Re: Fuel tank vent lines

Post by iowa »

hello
where is this linkage located on the airplane?
I think I need to fix mine as well
dave
Image
1951 170A 1468D SN 20051
1942 L-4B 2764C USAAC 43-572 (9433)
AME #17747
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