The last few times I've been aloft in my 415-C (4/46, #1286), the cowl tank quantity indicator, a glass tube, apparently, with a plastic cap, and the rod from below with an kind of ovoid shaped (looks metallic) topknot for one to see has been the scene of weird activity.
The behavior is, after climb out, which can depress the indicator maybe 1/2" or so for a while, pumps back up on level off. Then all seems right with the world. After about 20' of this reverie, I would start to get bubbles coming into the bottom of the tube. This in the next 10' to 20' it would get worse - it looks like a stinkin' coffee percolator, albeit no column of fuel seems to crawl up into the tube, but just lots and lots of bubbles. It seems to cause 0 ill effect, beyond the natural anxiety that any odd fuel system behavior might engender. After landing and subsequent climb out all seems fine until about another 20' pass. Background: I had a leaking terneplate tank that seemed incorrigible and John Wright, Jr. sold me a stainless steel custom made cowl tank which I had installed summer before last (2005). Roughly in that time frame I replaced the fuel tank gaskets with new ones from Mr. Cooper (100 Lotsa-Lead versions). All seemed ok. This "perking" effect I think I've only noticed in the past month or two (maybe more - my mind is gone). Seems totally nutty, as the top cap of the cowl glass seems to be sealed properly and no fuel escapes up and out. Oh, by the way, wing tanks are capped with float-wire-"meter"-caps with the obvious central vents. I leave them in as I keep it under a roof (I used to swap them with solid caps when it was tied down in the weather - I carry them along just in case). ?????? Jim Brennan NC63963 / #1286 / 4/26/46 WST / RI
