PT20J

The original tach was probably not mechanical but a B&D electric tach which did not include an hour meter (tachs with hour meters are called "recording tachometers"). The remote meter was driven by the tach as @LANCECASPER described. It measured what is colloquially referred to as tach time. This is what is usually used for maintenance records. Hobbs meters are usually driven by on oil pressure switch or something similar and record hours that the engine is running. This is usually used by flight schools and rental airplanes for billing. Neither tach time or Hobbs time are technically correct for maintenance or pilot flight time. According to FAR Part 1. Time in service, with respect to maintenance time records, means the time from the moment an aircraft leaves the surface of the earth until it touches it at the next point of landing. Flight time means: Pilot time that commences when an aircraft moves under its own power for the purpose of flight and ends when the aircraft comes to rest after landing. Skip

I'm based on the west coast and have owned two M20Js. I used to fly a lot over and around the Sierra Nevada mountains and I've flown quite a bit in the Rockies including getting my T-shirt at Leadville many years ago. I've had no problems flying a J VFR at high density altitudes but you have to know mountain flying and you have to plan carefully. But if you need to fly consistently in the high country IFR, I would get a turbo. The margin for IFR ops is just not there in a NA airplane. Just my $.02.

I bought the Mooney material through OasisAero MSC in bulk in 2020. It cost me $475 for enough to do everything but the side panels which were already done on my1994 MSE. Mooney provided me with the burn cert to make my IA happy. It is half inch foam with metalized mylar on one side and self adhesive on the other side. It probably helps with the sound, but it really helps with the cabin temperature. Skip

Really nice to see a rehab well done.

I'd call a MSC and find out the manufacturer and part number for the probe. It may be in the IPC or service manual, but sometimes they only show only a Mooney part number. Someone like Dan Riesland at LASAR or Don Maxwell may know the vendor part number. After you get the OEM gauge working, you have the choice of connecting the engine monitor #3 input to either a spark plug ring thermocouple or a smaller ring thermocouple that fits under the bayonet socket for the factory probe. The spark plug thermocouple will usually read about 20 deg F high and the bayonet will read about 20 deg F low compared to the factory gauge. Skip

30 years ago I added an intercom to a 1978 M20J with a KMA 20 audio panel. I had the interior out for rehab, so it wasn't difficult to wire the rear seat jacks. Because the audio panel is at the top of the stack and less deep than standard rack mount radios, it wasn't hard to get to the connections. The hard part was getting another breaker in the circuit breaker panel.

What load and power supply did you use?

The pump is actually under the exhaust cavity which is in front of the the panel marked, but as @EricJ pointed out, the two panels are riveted together on later model Js and come off as one piece.

That’s the one. I can’t quite make it out in the picture, but you should see the pump drain protruding through the cover which Mooney refers to as an exhaust cavity. There are screws in the firewall and you have to remove the gear door screws to get it off. Aeromotors currently has my pump for overhaul. Skip

Garmin must have sourced a replacement. Why not just have your dealer order a fan?

I believe the 7xx and 8xx are all approved under the same STC.

Within each brand, there are different products at difference price points. Get the premium versions - they will be better. There are subtle differences between brands, but less so at the premium level.

Can you get DLC lifters for Continental engines?

BTW, it's not a seal. It's just a cushion. It's not critical and I haven't bothered to replace mine, though the handle is a bit recessed without it. You can replace it with any type of foam cut to fit.

I would look up the installation drawing to see what options are available. PS Engineering should have the documentation on its website.

There is no reason you cannot install a PS intercom as you desire, but if you are on a budget, I would only install pilot and copilot positions. Running the wires to the rear seats requires removing a lot of interior panels and greatly increases the cost.

You can buy blank covers to fit instrument panel holes and radio stack openings after you remove the equipment and tie up any loose wires so they aren’t flopping around behind the panel. EDIT: I should mention that removing equipment requires a logbook entry and a weight and balance update and you should update the equipment list.

Well, this is a Modern Mooney thread and the OP apparently has a M20J

The floor light doesn't dim -- only the annunciator panel light dims when the nav lights are on.

The IPC is not always accurate for electrical components. The IPC only shows a GE330 which is a 14V bulb for all serial numbers, but clearly that is not correct for 28V airplanes. The schematic reference for the bulb is 21WE06A. The service manual for 91-20-01 ELECTRICAL HARDWARE CHART for S/N 24-0001 through 24-1685 lists 21WE06A as a GE 327. Skip

You have to check the schematic for your serial number and the electrical parts list at the end of the service and maintenance manual to know for certain what was installed at the factory. But I believe that the 14V airplanes had 28V bulbs installed to make them dimmer at night. There is no reason that you cannot use a 14V bulb. A lot of people also use LED replacements although I found that too bright at night for my taste. Skip

Current measurement shunts of the type used in this instance are rated in millivolts/amp. The current through the meter is so small that it doesn’t affect the measurement appreciably, so the macro effect is one if measuring voltage. But you are of course correct that current through the meter coil creates the magnetic field which creates the force on the armature to rotate the needle. But this esoterica probably doesn’t help the OP much

Looks like a load meter. Ammeters have zero in the middle and read amps into (+) or out of (-) the battery. Load meters read total current draw from the electrical load. Either way, the meter actually reads the voltage drop across a shunt (the difference is where the shunt is placed in the electrical system). So, if the electrical system is working properly, it’s most likely either a bad meter or a broken wire between the meter and the shunt.

You might want to email him directly. He doesn’t check in here often.

Sounds like a bug. I’d send it to Garmin support. They have fixed some things I’ve complained about in the past.