The International Cessna^® 170 Association

The fuel guage float, is it made out of cork? Someone suggested that to me a long time ago I can't remember where or what we were talking about.

The reason I ask is that mine seems to be sinking since I started burning auto gas. What is really concerning me is the possibility that the cork could be disintigrating and migrating into my fuel system. Do any of you have any experience with these, are they hard to get out of the tank? Can you get them out without pulling the whole headliner? Are there any quirks to look out for when I take a look at this with the mechanic?

Most/many are cork coated with some sort of varnish/lacquer/polyurethane. Steve Grimsley posted an article in the SRAM* about how to overhaul them.
Rochester also makes this gauge offering a "nitrile' chemical resistant float. Perhaps it's possible to simply buy the float? Another member looked into this recently...but I don't recall the name... I'll look for the emails to see what I can re-dig-up.
(Auto gas is especially aggressive with certain materials commonly found in fuel systems. Lately, much autogas is already converted to ethanol... look out. Ethanol is prohibited in airplanes and it's also even MORE aggressive in dissolving certain mateirals.)

*see correction below

Yes it is possible to remove the entire gauge without having to remove the headliner. Most likely you will need to remove the fairing between the wing & fuge. because the headliner sleeve that goes out to the gauge is most likely tied with string to keep the sleeve from coming back inside the cabin. No big deal. I removed one of mine after discussing w/ Steve before he did his article. I found that none of the sources I checked had a cork large enough, so I purchased two of the largest ones at an arts/craft store locally (Michaels as I recall) and glued them together. After the glue dried I used vrs sanding techniques to shape the cork to the same size as the original, then put 3-4 coats of varnish or similiar on it and have not had any problems with it since-----this must have been 6+ years ago. Don't forget to pull the small metal pieces (if they are in you old float) out and put them back in the new one. I suppose it is needed to give the float the proper weight. One thing I did different than Steve's procedure was I did not bend the rod/arm to remove the old float. I filed off the flattened end of the rod sufficiently to allow the washer (keeper) to come off the end of the rod and then removed the float. After replacing the float & washer I flattened the end of the rod enough to prevent the washer from coming off. Much easier IMHO than bending and unbending the gauge rod.

J3 Cub drivers know a lot about cork floats, for some reason. A long time ago some of them investigated various coatings for cork, and found that the two-part varnish available from PolyFiber (http://www.polyfiber.com) is impervious to anything found in fuel, including auto gas, so many of us have used corks coated with that. It works well.

Even better -- for the last few years I've been using a float built out of brass sheet material, cylindrical in shape, and soldered or brazed together. It's much more buoyant than cork, and it works soooo much better! I now have a Cub fuel gauge that's far more accurate than the original, as measured by holding a ruler next to it while parked on the ramp. I can measure the fuel accurately almost to the tenth of a gallon.

I don't know if anyone has used anything like this in older Cessnas, or whether it's even a good idea for them.

Best Regards,

John

* I want to correct my faulty memory.... the article concerning Steve Grimsley's repair of floats is in "Timeless Classic - The Cessna 170", pages 91-92.