Phil123

Do you know if anybody does overhauls on these old audiopanels?

Switching the buttons helped. Let‘s see for how long

Thanks for the tips, I will give it a try tomorrow. Are there any drop-in replacements for the KA134?

Hi, I am trying to troubleshoot a new squawk in our M20C, our COM2 radio does not work properly anymore. We have a KA134 audio panel, PM1000 intercom, Garmin 430 COM1 and Icom IC-A200 COM2. The radio seems to be working just fine and I confirmed that it is still sending, but I can’t receive anything, and I also won’t hear myself when I send. When I switch the panel to both with both radios on the same frequency and COM2 as sender, I can hear the transmission on COM1. It might be the something wrong in the connection between the radio and the audio panel, or maybe the panel itself as it looks quite old… Any troubleshooting tips on how to narrow down the problem? Thank you Philip

It reads OAT correctly from what I can tell, but haven‘t checked in boiling water, yet

That‘s a great tip, will look into that!

Is this just a run-up on the ground? Or are you getting those low CHTs during climb? If not, what are your temps during climb?

Thank you, great insights!

Overhaul was about 40 hours ago. Oil temp is within expected range as far as I can tell (we only have to analog gauge unfortunately) and the oil consumption is very low. Baffles have been our primary improvement target, especially around the alternator / start. I have a couple of pictures attached. During the next oil change we want to tackle the rearward pieces on the back side.

Mag timing is definitely on the list for the next shop visit. I am not really sure about the Electroair E-Mag. Those definitely advance the timing, but I haven't found any info on when and how they do that.

I am still trying with RPM in climb and I want to go back to the engine monitor data. Airspeed definitely helps, but I am not sure what effect RPM really has. I want to stay WOT, because of the extra fuel flow, but to do so, I have to bring the RPM back, otherwise the CHTs are hard to get back down. What RPM are you at for those 8.5-9p gph? Full throttle?

Hi Everybody! My Co-Owner and I recently purchased a 1962 M20C. The airplane's been great so far, but one thing concerns us - high CHTs. The engine is a pretty new overhaul with one E-Mag and the PowerFlow exhaust. The carb is the high fuel flow version (10-4164-1). During cruise at altitude we are able to keep the warmest (usually #4 or #2) pretty much at 380°F (2400 - 2500 RPM, WOT, leaned out to about 12gal/hr). Spread between the CHTs is around 40°F. Higher power settings or lower fuel flow tends to increase the temps to levels we wouldn't be comfortable constantly. It would be nice if we could lean it further at higher power settings (low RPM LOP works great), but overall cruise isn't a concern. We are more concerned about take-off and initial climb. All of the CHTs will come up to 400 - 420 °F pretty fast and we see 440 - 450 °F on the hottest (again #2 and #4) if we don't take immediate action. We take-off WOT, prop full forward, full rich of course and will see about 16.5 - 17.5 gal/hrs. We try to get gear and flaps up soon and pitch for Vy until we reach about 500AGL. At this point the CHTs are usually in the range as described above and we pitch more for a cruise climb at around 120MPH and reduce RPM to about 2500. From this point one the CHTs come down again and we are able to keep them below 400°F within a couple of minutes. We tried the improve our operation and tested different prop / throttle / pitch settings - so far the described above seems to work best. We discussed the problem with several A&Ps and so far the feedback was mainly that the CHTs we see are pretty high, but that the cooling system on the old Mooneys with the dog house is just not great. The baffling is apparently in pretty good shape and we improved the seals especially around the alternator and the starter with the help of a local A&P. We are both new to Mooneys and are pretty worried about doing harm to the new engine. At the same time, we are not sure, if we really have a problem or if that is just how it is with the M20Cs. What do you think? Anybody else with the same problem? What do folks see in their M20C? Thank you Philip