M20E for me

Thanks! I took the Mooney to a shop, Instrument Overhaul Services, at Gillespie Field in El Cajon Ca where they discovered two problems, one the airspeed indicator is way out of calibration and the Dukes airspeed switch leaks. He thinks he can fix the switch and they pulled the indicator to see if it can be serviced. They have a good reputation here in the San Diego area. Hopefully it can be fixed.

Who is rebuilding your ASI? I might need to get mine rebuilt as well.

No, not yet, going to get a JPI 730 with FF.

Yes, we removed it and it was clean, almost new. The ball moves freely and no gunk inside.

I'll give that a try. With it only acting up when warm I'll have to get the set up ready and do it after the engine has warmed up. I was surprised to see there were to different styles of runners on the same engine too!

Yes, I bought it in Oklahoma and flew it out to San Diego with a few stops along the way. Didn't have a problem until landing in San Diego. Nothing was done to the engine/plane between Oklahoma and San Diego. The rough running went away for a flight or two then came back. The A&P initially adjusted the mixture (enrichened it) but the problem came back. He has been pretty sure all along that it is an induction leak but cant seem to isolate where the leak is coming from, hence the replacement of the intake runner O-rings and gaskets. He has talked with a Lycoming engine expert who also isn't sure of what the source could be. After reading Riche's post I'm thinking he might have richened the mixture too much? Something to try,

I should have added that I have the same result with and with out the boost pump on. I'll check the manifold pressure this weekend. I do lean it out quite a bit while on the ground while taxing but, after landing, haven't been leaning it out because I'm just trying to keep the engine from dying. I'll give that a try as well.

On my M20E I'm having problems with the engine wanting to die when it has warmed up. The engine fires right up when cold and idles well, it is only after flying when I have the wanting to die problem. While reducing power for landing there is a lot of back firing and, once one the ground, I need to keep the RPMs above 1400 or the engine WILL die. I don't have a JPI monitor so I can't provide good engine data, this is going to be the first pieces of new avionics I install. I do, however, have an EGT monitor for each cylinder. To trouble shoot I took the plane up to 4000 feet while staying within landing distance of the airport and I cycled through the EGTs at various different power settings. I was thinking an induction leak which should give a higher EGT reading on the cylinder(s) that would have a leak. At all power settings the EGT was consistent across all of the cylinders with the exception of #2 which, was lower by around 200 degrees. At the lower power settings the readings were a bit closer but, #2 was always colder then the other three. Even on the ground after landing they were all close with the exception of #2 being a little colder. I have had all of the intake runner gaskets and O-rings replaced and still have the problem. When the #2 runner was removed the O-ring was split in two with one half laying inside the sump. I thought this was the smoking gun and my mechanic replaced it but the problem still exists. One thing of note is two of the intake runners have a different O-ring configuration than the other two; two are big thick O-rings and two have a much smaller cross section diameter, I read on this forum that can be typical? One thing I did noticed was the bores in the sump for the O-rings, while they are all smooth, they are not straight (if that makes sense). When I run my finger through the bore I can feel some waviness in the bore. my thought is maybe with the thermal expansion the intake runner moves to a position where the O-ring no longer creates a good seal and after the engine cools off it seals again? Any thoughts on where else there might be an induction leak or any thoughts on possible other culprits? Thanks! Scott

I won’t gear up it in the hangar! First thing is to remove the jumpered pressure switch. Then I’ll pull the LG CB and check if the switch works at all and at what speed it it closes the circuit. I think the stall warning indicator works fine is the airspeed indicator that might be giving faulty readings. While practicing stalls and the buzzer going off at the start of the stall the asi was indicating 100 mph. This E has the Britain 6 AP with altitude hold and I know that’s linked to the pitot system. So with the LG pressure switch being bypassed and faulty ASI readings I’m thinking maybe a leak or blockage in the pitot system. Hopefully I don’t have to replace both the pressure switch and the ASI! Thanks for everyone’s help

Hi, I’m new to the forum and just bought a 65 M20E. After flying it back from Oklahoma and starting to really give everything a good inspection I found the previous owner had jumpered the Dukes 3203-00 air speed pressure switch. I’m not sure if this was done because the switch is inop or, perhaps, it was used for overriding the switch for testing the gear and was accidentally left in place. Question is does any one know what pressure should close the switch? I’ll put my multimeter on the contacts while doing the surgical tube with cotter pin on the pitot tube to see if the switch still works. I have also been getting some wonky airspeed readings, practicing stalls the warning buzzer goes off at different speeds, one time it was at 100 mph and the next it was 70. I have a feeling the two might be related. Thought on that theory? Possible leak in the pitot line so the gear wouldn’t go up and the PO fixed the problem with a jumper cable? This forum is an awesome source of information!