stevengrasley
Member
Over the last few months I have been noticing a small amount of dirty fuel/oil dripping out of the nose gear faring onto the nose wheel pant. Nothing really significant and I chalked it up to little leaks, dribbles and dirt on a 5 year old O-360 that I fly behind 300+ hours every year. Nothing else to note in terms of performance anomalies (fuel consumption, power, engine performance in general) except that I seemed to be having to diddle with mixture more and more in the last few months to get nice stable performance at altitude.
Yesterday after a 1 hour flight I pulled up to the hangar and was shutting down. Low and behold the mixture cutoff was fully pulled but it just would not shut down. Would slow way down and then burp and cough and rev up a little more and keep coughing. Seemed like it was definitely not "cutting off". Shut the dual PMAGs off and after a little dieseling it quit.
Pulled the cowl and noticed a lot of fuel sitting in the FAB. (Wow! Where was this fuel coming from? No external leaks anywhere around the carb.) Took off the airfilter thinking the fuel sitting in there was the cause of the continued running as it vaporized. Fired up without the FAB and everything seemed OK. Did a run up and all good. , But, then it started running rough at idle and I had to lean quite a bit for the engine to run smooth. I am at sea level and it was 75 degrees. Odd. Like it was way too rich for some new reason. Tried a shut down and similar story. Shutdown the dual PMAGs and finally got it to quit.
After shut down I noticed a fair amount of fuel dripping off the back of the FAB mounting plate. It was not obvious to me where it was coming from but I think it was internally coming out of the carb...like a float was stuck down and the residual pressure in the engine fuel pump was forcing fuel out...but the mixture was supposedly cutoff? This must have been what has been getting worse over time.
I bought my Lyc O-360 from Van's and it came with an Avstar 10-4164-1 carb. Compared to the carb that I had on my 1972 C172M the Avstar is built like a tank. But something is not right.
I have decided to replace the carb before contemplating any flying. Really get frustrated when I am AOG. I am suspicious of damaged floats and/or mixture valve but I am not sure. Carbs are one thing I have never gotten deep into understanding. Can anybody give me a more definitive answer based on what I have written here? Up until now this carb has 1,260+ trouble free hours on it.
Yesterday after a 1 hour flight I pulled up to the hangar and was shutting down. Low and behold the mixture cutoff was fully pulled but it just would not shut down. Would slow way down and then burp and cough and rev up a little more and keep coughing. Seemed like it was definitely not "cutting off". Shut the dual PMAGs off and after a little dieseling it quit.
Pulled the cowl and noticed a lot of fuel sitting in the FAB. (Wow! Where was this fuel coming from? No external leaks anywhere around the carb.) Took off the airfilter thinking the fuel sitting in there was the cause of the continued running as it vaporized. Fired up without the FAB and everything seemed OK. Did a run up and all good. , But, then it started running rough at idle and I had to lean quite a bit for the engine to run smooth. I am at sea level and it was 75 degrees. Odd. Like it was way too rich for some new reason. Tried a shut down and similar story. Shutdown the dual PMAGs and finally got it to quit.
After shut down I noticed a fair amount of fuel dripping off the back of the FAB mounting plate. It was not obvious to me where it was coming from but I think it was internally coming out of the carb...like a float was stuck down and the residual pressure in the engine fuel pump was forcing fuel out...but the mixture was supposedly cutoff? This must have been what has been getting worse over time.
I bought my Lyc O-360 from Van's and it came with an Avstar 10-4164-1 carb. Compared to the carb that I had on my 1972 C172M the Avstar is built like a tank. But something is not right.
I have decided to replace the carb before contemplating any flying. Really get frustrated when I am AOG. I am suspicious of damaged floats and/or mixture valve but I am not sure. Carbs are one thing I have never gotten deep into understanding. Can anybody give me a more definitive answer based on what I have written here? Up until now this carb has 1,260+ trouble free hours on it.