MichiganMooney1

I found these online. https://www.knots2u.net/he625-he1506-mooney-m20-series-hydraulic-flap-actuator-65-67-m20c-m20d-m20e-m20f/

Yes. I live in SW MI also. I have had (and have today) the same experience in the cold. I am thinking that the fluid gets viscos at freezing temperatures and it "gulps" air. But reading these posts I have understood that the "spring back" of the handle indicates a vacuum in the system aft of the pump. I and my IA are struggling with the bleeding process and it looks like we will have to pressure/vacuum bleed it. If anyone has an answer to the cold temperature problem and as to why air gets into the system I would like to know. Just like your problem, they work great in higher temperatures but when it gets cold problems occur. Thanks for your help. P.S. Those leather seals in the pump piston are a joke. If anyone has a modern fix for this, it would be greatly appreciated!

I hope you have found a solution to this issue. I too have been chasing a very similar issue in my M20E (1964). I get an intermittent smell in the cabin only on a power reduction (like turning base) and dropping the gear. Everything is have inspected is dry. I did see a seepage from my right side fuel sender gasket and replaced it. First flight after that going round the pattern I smelled fuel again. However, all was now dry around the new gasket and everywhere else. Checked all areas on both tanks all is dry with no staining anywhere. This problem is intermittent but always involves a power reduction for landing and lowering the landing gear. The one member who responded with the idea of gas hitting a warm surface is relevant. I may be pursuing that rout soon. Any thoughts? All is appreciated.