stoutflier
Active Member
- Joined
- Dec 11, 2020
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I bought a 1961 Aztec a year ago. I have put about 10 hours on it. It is now in annual inspection.
The engines have about 400 hours on them, The overhaul was done in 2014 with brand new Millenium cylinders.
The compressions were 79/80 on all cylinders on the right engine. On the left engine, all but one of the cylinders were 79/80, with # 5 failing at damn near zero. Pulled the cylinder and sent it to Triad, The valve guide was severely worn. The cylinder is fixed with a serviceable exhaust valve, a new valve guide, and a new seat..
When I bought the airplane, the previous owner made a point of telling me that he would lean the airplane to the index he had set on his EGT gauges in the flight deck. When I flew it, I noticed that the left engine ( the one with the bad cylinder) EGT gauge showed a much lower temp with equal position of the mixture controls. In order to match the EGT gauges, I had to reduce the left engine mixture control a full knob-width + to get the temps matched.
I suspected a bad gauge, and pulled the thermocouple. Man , was that thing effed up. Not only that, the wire to the probe was missing insulation in multiple places and was also effed up.
So here is my theory.....The previous owner leaned the left engine to the point on the EGT gauge that closely matched the right, not realizing that he was actually cooking the cylinder with excessive temps.
What do you think?
The engines have about 400 hours on them, The overhaul was done in 2014 with brand new Millenium cylinders.
The compressions were 79/80 on all cylinders on the right engine. On the left engine, all but one of the cylinders were 79/80, with # 5 failing at damn near zero. Pulled the cylinder and sent it to Triad, The valve guide was severely worn. The cylinder is fixed with a serviceable exhaust valve, a new valve guide, and a new seat..
When I bought the airplane, the previous owner made a point of telling me that he would lean the airplane to the index he had set on his EGT gauges in the flight deck. When I flew it, I noticed that the left engine ( the one with the bad cylinder) EGT gauge showed a much lower temp with equal position of the mixture controls. In order to match the EGT gauges, I had to reduce the left engine mixture control a full knob-width + to get the temps matched.
I suspected a bad gauge, and pulled the thermocouple. Man , was that thing effed up. Not only that, the wire to the probe was missing insulation in multiple places and was also effed up.
So here is my theory.....The previous owner leaned the left engine to the point on the EGT gauge that closely matched the right, not realizing that he was actually cooking the cylinder with excessive temps.
What do you think?
