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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.
Rates:
- 4 cylinder engine: $50
- 6 cylinder engine: $70
- Twin engine: $100
Click here to make your payment.
Then email me your borescope photos, and I’ll send you a report.
dean{at}airplaneownermaintenance{dot}com
Thanks everyone, and have a great week!
The post “170 – Eddie’s Jabiru Cylinder Compression: From 0/80 to 70/80!” appeared first at AirplaneOwnerMaintenance.com
Thank You Dean for allowing us interested pilots to become more aware of the machines we operate! Your giving to the GA population should not go unnoticed! Bless you for all your giving! Signed/Still learning
Thank you Scott… I certainly appreciate all you’ve done for the GA community as well!
…. the valve seems broken on the left bottom corner