Scott is absolutely right. As soon as you shut down the engine you lose your cooling airflow and the temp between the top of the engine and cowl starts going up quickly and cooks the fuel in the distribution block and the line going to it. I used to teach pilots to open their cowls to promote faster cooling after shutdown. Saved a lot of starters and batteries that way.
John El Paso In a message dated 10/13/2009 5:30:28 P.M. Mountain Daylight Time, jscott.pi...@juno.com writes: Vapor lock is common in almost all fuel injected aircraft engines, but it's not the gascolator that overheats. It's because the fuel injection distribution block is sitting on top of the hot engine, so gets heated enough to easily boil the fuel following engine shut down. Thus the hot start problems with most injected aircraft engines. In flight it is cooled by the air intake on top of the engine, so never vapor locks once there is sufficient cooling air moving through the air inlets. The warm air coming off the bottom of the engine typically isn't hot enough to create a vapor lock problem. However, exhaust routing is really critical as the exhaust pipes are the really hot components that may run near the gascolator. On my plane, the exhaust routes down either side, so my gascolator is mounted at the bottom center of the firewall with no extra cooling and has never presented a problem. (770 hrs so far that include long climb outs from Phoenix and Tucson in the summer.) However, if I had a crossover exhaust to heat the already warm air coming out the bottom of the engine, then a cool box and blast tube would be a must. On my other plane with a crossover exhaust, the gascolator and electric fuel pump have their only little box at the lower left corner of the firewall with a small NACA scoop in order to keep the fuel cool. Jeff Scott Los Alamos, NM ---------- Original Message ---------- My friends plane had been flying several years before his problem arose, who would of thought a flying plane could develop problems under the wrong circumstances. I also forgot to suggest what Larry Flesner stated and that is to add fireproof temperature insulating covers to all fuel lines in the cowling that are near the engine if possible. Vapor lock caused by a hot engine was common on a Cessna 210 fuel injected aircraft I once owned when I would stop for fuel. It happens. Larry H. ____________________________________________________________ Click now and choose from a selection of top performing bonds! http://thirdpartyoffers.juno.com/TGL2141/fc/BLSrjpTIy7d79JLoqnwKyrOooGuFCt6r adUeIj6M8DEbFtH1C01oa8XaLyY/ _______________________________________ Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html
