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Eagle1671's after-fire turned out to be a cracked engine mount. Problem diagnosed and fixed. Great outcome! But let's return to the subject of after-fire. Experienced Mooney owners already know about this, but since there are a fair number of new folks on the forum, let me describe a dangerous situation that is easily avoided. With my carbureted M20C there have only been a couple of times I've had issues with fuel burning somewhere other than inside the cylinders. One time was years ago when probably I didn't pull the mixture control completely during shutdown, and got a backfire on startup that blew out a muffler baffle. Expensive lesson but otherwise harmless. The other time was recently. After a long flight my son (who is also a pilot with about 100 hours in this aircraft) and I landed to refuel. After refueling we decided to park the aircraft. My son was at the controls and I stayed outside and went over to the tie-down spot to help guide him in. He cranked the engine but it didn't start at first. He cranked a couple more times and I walked over toward the aircraft and yelled "lean it out more." He opened the little pilot's window to hear me better and cranked some more -- at which time I saw flames coming out of the bottom of the engine! I yelled "lean it out, start it NOW!" He did and the engine then started; that extinguished the flames. It all happened so fast that I hadn't even had time to look for the fire extinguisher (which was close by). We shut down and inspected for damage - and fortunately nothing. Paint not singed, fabric and nylon fasteners unaffected, etc. The flames had lasted for maybe five or six seconds. We figured out what happened: He didn't realize you don't prime a hot engine. He just went through his checklist, and priming -- that is boost pump on, give the throttle a couple of squirts -- was part of the checklist. When the engine didn't start the first time, he kept boosting and squirting. We were fortunate that he finally leaned the engine, which then started immediately. Lesson learned: My fault for not giving him sufficient information. We revised our checklist.

I know bits a pieces of this have been discussed before and I've researched other forums but I haven't been able to draw a useful conclusion. My engine misses at idle and then has an after fire in the muffler. I don't like this happening although it doesn't happen in flight. I'm installing a JPI 830 soon but don't have engine monitoring yet. In searching for the problem I checked the intake bolts and they were fairly loose taking at least a turn to get 96 in-lbs. After twerking the bolts to 96" the misfire seemed to disappear and the engine ran smoother (could have been in my head). Its a week later and the pops and farts are back and my engine is also misfiring. Time to change gaskets, I've ordered both the lycoming and superior gaskets. Three questions: I also ordered the red o-ring gaskets for the other end of the intake tubes. Do the large O-rings have to be changed after removing tube or can I clean up tube, lube the end with clean oil and stick it back in? Do you guys use goop such as permatex #3 avaition, on the paper gaskets or do it dry? If you are in the pro-goop crowd, which is your favorite gasket sealer for this purpose? How about power grab, hold it tight for 30 seconds and go fly! Thanks, Adam