The International Cessna 170 Association

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...

The cross cabin vent system in the C170 is 3/8" tubing.

Another common cause of fuel fumes is hard braking while landing with full tanks. (The goose-neck vomits fuel onto the cabin roof.)

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.

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

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.

I was using my girlfriend's muscle power to try to help instead of her cold cream! 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?

It would not be an approved part.

You could try tubing that is "S-O" ... soft. It is very flexible and manageable.

Hmm. Google has let me down. Can you give a little more detail about "S-O"...soft George?

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.

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.

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

When I get a change to get back to the hangar I will try again based on this advice. Thanks.

Before:
After:
Fuel smell gone!

hello
where is this linkage located on the airplane?
I think I need to fix mine as well
dave