MarkM20C

I'm looking at the ceiling thinking I really don't want to take that apart. Plane is sold, so I want to fix for new owner. I'm an A&P so don't worry, repairs will be legal. I don't work as an A&P, but I am licensed. I don't think I could afford to own an aircraft if I wasn't! Mark

Thank you, I'll look at it that way. According to the Maintenance Manual, the throttle cable switch supplies power to the gear horn and the horn has a ground. But seeing how its 56 years old, who knows what has been changed! When trying to figure out why my tail light didn't work, found wiring not even connected! I guess previous owner never flew at night? Mark

Hello, I have what should be a pretty easy to figure out problem, but could use help from Mooney Space. My gear down warning horn has always been a little sporadic, but now has quit altogether. I can hear the switch on the throttle cable clicking when throttle is pulled towards idle, and get 12v at that switch when gear isn't locked down. What seems strange to me is that the switch on the throttle cable closes when throttle is advanced, so I get 12v from throttle cable switch when throttle is advanced, not when throttle pulled towards idle. In looking at the wiring diagram, seems to me that throttle cable switch should close when throttle is pulled to idle (or approx. 12mp), not when throttle is advanced. Seems like my throttle switch is working backwards, but either way the horn doesn't work and used to (mostly) and nobody has messed with the wiring. Any ideas? Thank You, Mark

My C does OK after sorting out my Carburetor issues. This was last week at 15.5K, 24/2400 around 11.5 gph. I could have probably leaned more, but am being a bit conservative after exhaust valve on cylinder 3 was leaking after 300 hours (New Lycoming Cylinder). I was having a problem with it running lean at altitude when using turbo. Carburetor overhaul fixed problem.

Just an update. I had the carburetor overhauled by Marvel Schebler and now all is well. Flew yesterday to 9500, ran it at 25/2500 and had to lean to get get proper mixture. Was getting just under 150 knots at 25/2500 approx. 12.5 gal/hr. I wouldn't normally run it that hard but nice to see I can. Before carb overhaul it just didn't have enough fuel to keep the EGT's where I want them and I would have to pull back manifold pressure. Eventually I'll take it high enough to really test it out. I have a brand new oxygen system I haven't used yet!

My AV30 has terrible procession, And would be all but unusable as a DG. I have it connected to my GNS430 so I just use GPS heading. I still have my vacuum operated DG.

Okay after re-reading your post, it seems that you want an airspeed switch for gear up/down warnings. The one I used switches at like 35 mph so that wouldn't work for that purpose.

Yes, not sure what you are using it for, but I got one from Aircraft Spruce that is STC'd for use with my Trig transponder for air or ground mode. Works great, I just leave my transponder in ALT mode and half way through my take off roll it goes to ALT mode. One less thing for me to think about. I was getting some air on ground mode errors when checking my ADS-B out after first installing it. No errors after airspeed switch install.

What if any additional items would I need to install in 65C? I have a GNS430W. PC currently not working, but is on my list of squawks to fix.

Mine does it too, drives me nuts. Doesn't use much oil in flight, but makes quite a mess when parked and on start up. It seems to me the check valves should be at the turbo, so the oil in the lines between the check valves and the turbo can't drain into the turbo. On mine, the check valve on the return line is approx. 16 inches from the turbo, probably 10 inches from the turbo on the supply side. At some point I may move them closer, but I'll have to have new lines made at the same time.

Mine doesn't have the automotive style fuel pump, it has the gear driven pump RG15980-P, which is correct and referenced to air box for boost compensation. I have an electronic fuel pressure gauge, which isn't referenced to boost pressure, which is why it doesn't read properly under boost at altitude. The thing is, 3 months ago I didn't have this problem, and no components have been replaced, so something has happened. I'm leaning towards a carburetor issue at this point. Mark

Chessieretriever that makes the most sense to me. I know the fuel in the float bowl needs to be referenced to boost pressure and I was wondering how that happens. I didn't see an external line though, I will have to take a closer look at the carburetor and the installation instructions. I was just figuring the float bowl vent was somehow internal and was referenced that way. Or maybe there is a gasket compromised? Thanks! Gives me more to check. Mark

Thanks guy, I'll see if i can get some engine data posted. Any ideas on a good title to attract other O360 RayJay people? Mark.

Timing is good, both at 25 BTDC. Mag drop both 75ish RPM's. I do have an engine monitor that records on USB stick, not sure how to post it. CHT's are all good, I don't let rear cylinder EGT's run hot long enough for CHT's to increase. Just completed annual and all plugs looked good, but since problem is only at altitude under boost, plugs could clean up on decent when boost removed. I think the turbo is working fine, no problem in boosting, but for some reason rear cylinders are leaner then fronts, only under boost. Possibly carburetor issue? I'm not sure what modifications are done to carburetor when rayjay installed. Mark

Hello Guys, I have a 1965 M20C with a Rajay Turbo. Turbo installed in 1966, not that that means anything. My issue that has cropped up is when dialing in boost, EGT's for both rear cylinders increase quite a bit above fronts. I can run 24/2400 all day long low and normally aspirated. I would even lean a bit to get EGT's around 1300-1350, with all EGT's being within 50 degrees F of each other. But if I try to run 24/2400 up high, even full rich, both rear cylinder EGT's climb over 1450, and I have to back off boost to get them to come down. Front cylinders close to 150-200 degrees cooler. I don't see any air leaks in intakes tubes. Reference line from air box to fuel pump is good, no leaks. I do think my fuel pressure at altitude under boost used to be higher, so I am wondering if that's the issue. I remember my fuel pressure gauge would go red at altitude under boost, previous owner said his mechanic said that was normal due to something with the fuel gauge. I now understand why, the fuel gauge is not referenced to boost pressure, just atmospheric pressure, so reading is off at altitude under boost. Just looking for Ideas at this point, I am an A&P, but have haven't been working on planes or flying for 24 years, just getting back into it. My fuel pump was repaired 4 years ago (around 200 hours ago), not sure what issue was at that time. I called the shop that repaired the pump and spoke to the tech, he seemed to think diaphragm in pump was probably bad, so pump not compensating for boost pressure properly. Any ideas? Kind of a bummer to have turbo but not be able to take advantage of it. Flew it to 9000 feet yesterday and fuel pressure did go up as I climbed, gauge was reading just under 8 psi at 9000 feet, 24/2400. Seems like that should be enough, is around 6.5 psi when low and N/A. Thanks, Mark