12/80! That’s a terrible compression test result. And unlike some cylinders, this one did not show any obvious reasons for the low compression… take a look at the valves after the cylinder was removed:
Unless I’m missing something, I don’t see anything that would explain such a low compression number. The cylinder has been shipped to Tim Barnes at Skyline Cylinders for repair, so I’m hoping he will be able to give me more information about it. You can listen to the audio for more thoughts about this whole experience, and maybe I’ll give an update on it in a future episode.
I also mentioned in this episode my latest project in the shop at Classic Aviation – an annual inspection on a nice E33A Bonanza:
It’s a great airplane, with a great owner – now that’s a good combination!
The post “172 – A Perplexing Low Cylinder Compression on a Piper Saratoga” appeared first at AirplaneOwnerMaintenance.com
Can you see the problem with this exhaust muffler?
Maybe a closer look will help: (The cracked area was just inside the shroud that collects heat for the cabin.)
Thankfully Matt, the owner of a nice Cessna 170, had a carbon monoxide detector in his airplane that picked up the small amount of “bad gas in the cockpit.” Check out his panel:
I discovered Matt’s CO detector is available at Aircraft Spruce for $99. He’s been happy with this detector, and I would think it’s FAR BETTER than the little “spot detectors” that are often used in airplanes.
Here’s a link for the CO detector in the above photo:
On another note, I mentioned in this episode that I got to meet General Chuck Boyd yesterday as he was getting ready to depart SHD in his beautiful T34 airplane. It was such a pleasure to meet him, and I want to say “Thank you Sir, for your service in the Air Force!”
I had a surprise call this morning… my friend Eddie called and wondered if he could borrow a borescope. One of the cylinders in his Sonex’s Jabiru engine had zero compression, and he wanted to take a look inside the cylinder, especially at the exhaust valve.
Since I’m always looking for a good story, it didn’t take me long to say, “This sounds interesting… I’ll grab my borescope and drive right over to the airport.”
We got the borescope set up and quickly noticed the exhaust valve appeared to be open a tiny bit when it should have been fully closed. There was just enough leakage past the valve to keep the compression at zero.
We’re still not totally sure about that area at about the 8 o’clock position, but we didn’t see anything alarming when we looked at the valve edge with it open.
Thankfully, Eddie had done some research online and quickly got some feedback about the importance of regularly adjusting the valves in the Jabiru engine.
Sure enough, the exhaust valve had no clearance between the valve stem and the rocker arm (it should be .010)
After adjusting both valves on that cylinder, Eddie did another compression test, and we were pleasantly surprised… 70/80! And it was even a cold compression test!
It’s always great when there’s a simple solution!
Well done Eddie! And thanks for the good story we can all learn from!
In this week’s episode, we also talk about Lycoming SI 1418, a rarely used procedure for cleaning cylinders on the engine using some special equipment and ground up walnut shells.
Listen to this concept and let me know your thoughts… hit that button over to the right and tell me if you think it’s a crazy idea, or a great idea… I’m curious about it.
Reminder: I offer a service to evaluate your borescope photos. If you are not sure what your pictures mean, send them to me and I’ll evaluate them and send you a report within two days.
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