Chessieretriever

Check the external spider vent line for fuel drips once you are operating (someone outside has to do this). It does happen that once you have a small tear on the diaphragm of the spider plunger you are just not moving the same mass flow of fuel (dumping some overboard which can be seen on the vent line) and requiring the idle mixture to be richened to keep it idling or overcome this lower flow with intermittent primer pump squirts when richer mixture is required to operate (cold). This is not very common but has happened before and it can be masked by tech's simply adjusting the fuel system pressures to compensate for the leak and provide idle speed stability (but not sufficiently off-setting the lower flow at priming conditions).

In my humble opinion a broken compression ring started the problem increasing blowby (and heat to the piston where these hot gases streamed by) which pressurized your crankcase and created your never ending leaks (out of every joint that was unable to handle about 5 inches of water column of crankcase pressure). Your second compression ring shows signs of carbon and temperature on the bottom half wear surface which indicates that it was not sealing either and you were hot enough to carbonize the oil that the oil control ring downstream of it accumulated until most of that oil turned into carbon and the oil ring stopped working altogether. Blowby of hot combustion gases will create very high oil temperatures which may stretch the on board oil heat rejection device beyond its capacity. I would think that any A&P that has been around these engines would look a little further if they saw a skirt that is caked with black carbon but then again maybe times have changed.

Try doing an in flight mag check and see if one of the two spark plugs on this cylinder is not firing. A bad plug will result in a higher EGT for that cylinder since the flame front travel is much larger causing a delayed peak pressure in that cylinder and subsequent higher energy in the gases exiting the cylinder when the exhaust valve opens.

Does your engine have blowby? This does contribute quite significantly to increased oil temperatures and obviously is not good news. Oil consumption may be a tell tale sign; the best way to find out is to measure the pressure in the engine case during 'hot' operation (requires some instrumentation and a willing A/P to work with you). On a separate note, the oil is totally fine in the temperature ranges you are experiencing but the pistons on your engine are being cooled (underside spray jets) with a medium that is hotter than engines with lower oil temps and hence see a little more trauma in cruise (linear relationship with oil temp). I would not be alarmed at 200F to 220F just yet.

Maybe your engine is producing a beneficial incremental amount of power due to your power flow exhaust and therefore could benefit from the carburetor main jet change that Mooney proposed (larger main jet with different atomizing hole patterns on the jet). I know of a person with a C that uses this mod and requires 19.2 GPH on take off at sea level (also has to climb at 120MPH) and is able to keep temps on the 2/4 bank below 400F. Obviously he is cooling the cylinders with fuel. If all of this does not help perhaps you can take 1 or 2 degrees of timing out (retard it) to reduce the thermodynamic load on the cylinders and hence reduce your temperatures; this may be great on take off but will produce a slightly lower performance at altitude in cruise power settings. Last but not least maybe a little adjustment on the cowl flaps (trailing more open in the fully closed position to allow for a steeper angle when in the open position) associated with that side of the engine can help (mentioned already); there is a little room on the heim joint threads that could be utilized and still meet the specs.

It sounds like you need to slightly reduce the gain in the proportional part of the P&ID control loop (Proportional, Integral and Derivative) on the AP to correct for the slightly lower hysteresis of the new attitude indicator. I am not sure how comfortable avionics shops are at making these adjustments (typically they rely on factory test equipment that 'does this for them' as mentioned above).

Sounds like a very reasonable offer. What is the new price?

Seth, I would disassemble the new unit and take the housing to a good machine shop and have them turn the flange area down and make both sides equal so that you can go back with your hose arrangement. Let me know if you need a recommendation on a shop that can do this well. Good luck

I used to fly a M20C with a Rajay and my guess is that the line from your manifold to your carburetor bowl so that your carburetor (fuel level in the bowl) references the pressure in the intake tract (above atmospheric) may be leaking a little allowing the bowl pressure to lower than what it needs. The same thing would happen if your carburetor is leaking (air now for this pressurization event) at the seam where the unit comes apart (there is a gasket there that may be compromised). The Rajay is a blow-through system which needs the top of the fuel level in the bowl inside the carb to be at a pressure that is higher than atmospheric when your turbo is operating (with a manifold higher than the then current atmospheric one); it appears that you may be stratifying your mixture. Ironically I remember that my little C would actually fly LOP when the turbo was working but not down low without it; I always attributed that to having warm air from the compressor discharge which helped with the atomization. Why you have a front and back difference could be a could be something else (like ignition) that is unable to work as designed with a mixture that weak and therefore hard to fire. Worth the look. Good luck with it.

I understand the challenges associated with QC in manufacturing but have to say that purely from a statistical perspective (and as a turbo engine user) I am a little alarmed at the frequency of "missing center electrode" reports. My recommendation to the nice and customer friendly folks at Tempest is to start treating this as a "statistical run" (read "emergency") and dedicate engineering resources to determine the actual root cause of it (and then change the process to eliminate it). It does not matter who has the problem (contractor or "in house") if the failure is inherent in the process used to manufacture the part (such process may not even have the capability to produce a part with the proper QC standard desired which I would assume should require a standard of "x" failures per million parts produced rather than something several orders of magnitude lower). If a center electrode goes through a turbo it will do damage regardless of how "lucky" someone might get. I hope Tempest can update this group on progress once they get on top of this to allow those of us who use fine wire plugs (by choice or SME recomendation or some other reason etc.) to regain the confidence in the product that it is capable of.

From memory (I used to have an M20C with a Rajay) it uses a blow through system with a different carburetor that is vented to the pressure side of the intake system (sees above atmospheric when turbo is operational) and a different fuel pump that is also able to reference the atmosphere of the intake system to keep the pressure needed to get fuel into the bowl. I hope this helps. Cheers, Chessie

My 88 year old friend owns a '67 C that will do 160kts TAS every time we fly. He has all of the mods described before but uses a cowl that resembles the J. This guy has owned this AC since it was 2 years young and at the time he was Director of Maintenance for all 747s Worldwide at Pan American Airlines. As a result he did all of the mods himself and still "works" on his airplane every chance he gets. Here is a picture of N9738M in level flight with 3 on board at 11,500. I know that the air speed indicator was close as we had Airport radio hang a mercury bar on the pitot system and check how far out of "calibration" it was (it was off by a few 2 MPH). I have another friend who has a well equipped J and this C walks away from it every time regardless of load. Don't know exactly why. Cheers, Chessie.

To clarify: The M20M (not L) with the TSIOL-550 is "de-rated" to 335HP from the original 350HP by reducing the speed to 2600 from 2700. I can't speak for the "L" as it has other components that may be a little different than the "M" (like the gear etc.). The charts from TCM (I have them) go above 400HP if the manifold pressure is increased to 40" at the rated speed of 2700RPM (the Extra 400 operates with this set up). I have owned our Liquid Rocket more than 10 years and have enjoyed a dispatch performance that is as good or better than my fellow aviators on the field with TSIO-550's. In 600+ hours I have never experienced a cooling related problem. It appears that the expertise associated with maintaining these engines is the differentiating factor in availability and reliability (not too much experience in the field with details like how to properly de-aerate the cooling system at each cylinder head or how to re-fill it etc.) From discussions with Conrad one of the areas of concern with higher power ratings on my particular airplane (it was the one used to get the STC and was flown to 35,000ft) is tail authority when just getting into motion and low speed conditions. This is the reason why the TBM 950 does not produce the full 950HP until after it attained a minimum airspeed. I hope this helps clear a few questions up. Cheers, OFB

Folks thank you for the due diligence from several members who kindly informed me that I overpaid for unit. I do that from time to time; someone will get a good deal on this modern avionics part. The unit is new (even though it has re-manufactured paperwork from the OEM) based on everything you can see.