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I know the mags have been on and off and thus timed. I think your engine timing is 22+/-1. Your timing can be in limits, but have a 2degree split and get different mag drops. If the timing is a little out of tolerance it becomes more significant. Using the timing cone is not the most precise thing. I know it’s sometimes hard to ask the mechanic these questions, but perhaps ask him what the mags are timed at…..or suggest retiming them both to 22 or 21? It might be that the left mag is clocked in such a way that it prefers more advanced and is causing these issues. Just seems consistent with timing….

Nice!

Could be the switch; could be the relay. Hard to tell which if intermittent. You could replace both to be certain. Or you could start by replacing whichever is cheaper.

The OP said he has a McCauley prop. Those get greased only when taken apart. There are no external grease points like a Hartzell prop.

Here's some info I got today. The Left mag side is definitely hotter. I did the inflight mag check as well. At first I ran it out to LOP and it was in the high 1400's. When I did the Left check, everything immediately went off the scale. The ships single EGT gauge went way past redline so I quickly backed out of that. I went richer with the mixture and got a lower base EGT and ran the same check. The right side was smooth and normal. All EGTS rose some but nothing drastic and the engine was still smooth. The Left EGTs took off in different directions and the engine got rough. I had video and at the bottom is a screen shot just before the mag check, the second screen shot is 4 seconds after turning the key.

Yep. I knew hot starts were very different; this thread points out that ALL starts are very different between the O- and the IO engines!

That’s a very nice and well thought out new panel! Congratulations!

You know the O-360 and IO-360 are very different to start.

I’ve started them in zero degree F weather like that.

If you prime an IO-360, you will fill one cylinder with fuel, maybe. The rest just goes into the sump. If the sump is cold, it will just sit there or drain out the sniffle valve. Once you have fuel pressure, the injectors will provide a perfect mixture for starting. Why mess with it.

Well, THAT is a new one. Start cranking with full rich on a cold engine.

I always start IO-360s the same no matter what the temperature. It never fails. Mixture rich, throttle at ~1000 RPM setting. Crank the starter, if it isn’t making fuel pressure, I’ll turn on the boost pump until I have fuel pressure, then turn it off. The only time I prime is if I think it is flooded, I will prime to make sure it is flooded, then do a flooded start. Hot start is mixture ICO, throttle 1000 RPM, crank till it starts, then advance the mixture. Flooded start is the same as hot start, but with more throttle. When it finally catches, reduce the throttle and when it starts to die, advance the mixture.

One thing for sure… if you have learned to use a certain amount of prime in warm weather… and the temps have cooled a bit… less prime won’t make any sense (to a chemical engineer). 100LL is known for its inability to evaporate as temps cool… the IO550 uses 40°F as the cut-off from normal start to cold start… where additional seconds of prime are used… and running the fuel pump on Lo to keep it running for a few more seconds… read up on various starts to understand them better… as a flooded start may be in your future… Best regards, -a-

All I've ever seen in my Mooney is 0; even my old Ford Ranger showed 0 running the heater in winter. I even checked my gas stove, oven and gas logs in the fireplace--all read 0 in steady use, with an occasional startup reading as high as 6. Any reading of 440, much less 800, requires investigation. Check sealing around all hoses and wires through the firewall, sealing around where rudder pedals and aileron rods leave the cabin, along with the seam tape under the cabin.

Many people swear by a tool made.from PVC pipe and notched to fit over the fuel selector, with the handle end either an L or T to suit pilot preference and storage location. Make the length and handle style to suit yourself. Or learn to lean down and turn it by hand. By the time you finish your insurance dual, you should be pretty proficient; i switch mine on the ground after engine start to ensure that it's trouble-free, then check it's on the fullest tank for takeoff, and again every hour in cruise.

No worries Hank (on derailing). I am going to try and prove I am not crazy (doing same thing over and over and expecting different result) and try less boost pump. (opposite of more cow bell if you are a Blue Oyster Cult/SNL fan).

I though of putting the O2D2 controller somewhere in line of sight, but could not come up with a solution that would be somewhat elegant. my O2 ports are in the ceiling (1990 Bravo) above/behind the front seats and running hose to front panel would not look very good. Thus, I chose to attach the controller with 3M Dual Lock Strips bewteen the rear seats where I can easily reach it and manipulate the control knob. There is arguably no need for visual confirmation of function with this unit as you can clearly hear the pulses being delivered (I now that some pilots do not like this, but I got used to it quite quickly). I can still glance at the box periodically to see the green lights and confirm that battery is OK. All the hoses are out of the way behind the seats and the setup works really well. No overheating issues as the box never gets direct sun.

@Vance Harral, I'm not aware of ANY carbureted Mooneys with separate primer functions like found on the 172s I trained in. When cranking in very cold weather, I sometimes also pump the throttle a few times as the engine turns over, especially if it fires unsuccessfully a couple of times. Unless the engine is flooded, there is little risk of an engine fire. At the risk of derailing discussion here, this is from my Owners Manual:

Fresh out of annual? Fresh grease gets pushed into the hub causing some to escape out the seals… deep cycling the prop? another reason some grease may get past a seal that has been sitting awhile… when grease comes out three inches of prop blade… it will leave small bits of grease on the windscreen… a clean windscreen is required to see it… let’s invite… @Cody Stallings for some insight on prop grease leaking… Best regards, -a-

Mine was overhauled around the time of the Aeroshell issue. But it leaked before and after, so who knows? I think Nyco is the new recommendation, but can’t be mixed with the Aeroshell. However, you can mix Aeroshell 5 with 6, FWIW.

@Hank probably knows this, but just for others reading the thread... some carbureted aircraft don't have a primer systems that inject fuel directly into the cylinders. Including some Mooneys, and I'm guessing Hank's is one of them. Pumping the throttle to force the accelerator pump to spray atomized fuel up into the carburetor throat is the only way to prime the engine in these airplanes. But please be careful about dispensing "pump the throttle to prime" advice, even in carbureted aircraft. Most carbureted airplanes have updraft carbs (fuel/air path into the engine intake is opposite gravity), and some of them don't atomize the fuel all that well, especially when it's cold. In these aircraft, some of the fuel you shoot into the carburetor throat by pumping the throttle runs back down over the carburetor, into the engine cowl, onto the ground, etc. This is a fire hazard, and not just a theoretical one - a 182 at our flight school suffered significant damage in a carburetor fire caused by someone who wasn't very skilled getting the engine started, and managed to light off an engine compartment fire after excessive throttle pumping. It's definitely safer to use a primer vs. pumping the throttle, though the risk reduction is hard to quantify. If you must pump the throttle to get the engine started, one way to mitigate risk is to only pump the throttle while actually cranking the starter. With this method, the vacuum generated in the intake by the moving cylinders will draw more of the fuel droplets up into the engine, less of them will rain down on the ground. I'm aware this isn't the POH procedure, but it has been effective for me in a number of carbureted airplanes, and I think it's safer. The "hot start problem" in fuel injected engines is almost entirely caused by the the fuel injector lines being routed right over the cylinder heads, such that the fuel in them is baked and vaporized by the hot cylinders as soon as cooling air stops flowing over them, i.e. immediately after shutdown. Lycoming/Continental carbureted engines don't have this problem because the entire fuel/air intake system is below the hot cylinder heads, so there's really no comparison between carbuerted/fuel-injected with regard to hot starts. Indeed, carbureted engines are almost always blissfully easy to start when warm. For what it's worth, your engine would likely start with zero throttle pumps when warm, albeit after a few more blades than with pumping. Reduces the admittedly small risk of a carburetor fire, at the expense of more wear on your starter.

Given those two data points, it sounds like a real issue. Are you sure that the oil cooler lines are connected properly? What does the overhauler say?

I have come to the opinion that if you service the prop every annual, it eventually gets full (12 years or less if over serviced) and further grease needs a way out. Seems to coincide with recommended OH time. So, full hub….some migrates out the seal. The risk of not servicing is corrosion in the hub and/or dried grease. So, it’s possible you simply have a slightly over serviced hub. The grease breaks down and the oil seeps out. As Yetti said, Arroshell grease got worse over time and is no longer the preferred grease after overhaul.

The McCauley manual says to cycle the prop all the way to the low speed/ high pitch stop a few times. I did this and it stopped my minor leaks.

Well dang. I’ve heard similar from a friend on the field. Once I realized how many years it had been since overhaul it got me a little rattled, but I guess it’s somewhat common.