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Loss Of Engine Power Thursday Night


ziggysanchez

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While taking off from 4O4 (Idabel, OK) at around 11:30pm Thursday night I experienced a loss of power and the engine began to run very rough (felt like I was sitting on an unbalanced washing machine). I turned and retuned to the airport to find oil pouring out of the bottom of the cowling. I noticed before I landed that I had lost temps in my #3 cylinder and #1 was looking suspicious as well. After a phone call Friday morning to Don Maxwell (who I purchased the plane from in Oct. of 2016) he sent his son Paul and one of his mechanics Tom to diagnose the problem. They arrived from Longview at 1pm and by 5:30pm the diagnosis had been made and the parts removed to be sent out for repair. The #1 and #3 cylinders were not producing any power. The blow by pressurized the case and was blowing oil out of the filler tube and the oil vent tube (lost over a quart going around the patch). A great big thank you to Don, Paul and Tom for coming to help me so quickly. Hope to have my bird back in the air soon.

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Edited by ziggysanchez
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15 minutes ago, kortopates said:

Glad you got it down before you lost more than a couple cylinders. This is one thing I much appreciate on the 6 cyl engine versus the 4. Besides more HP, loosing a cylinder is barely noticeable compared to loosing one of only 4.

If 6 are good, 8 is the best!

Clarence

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For those that are curious to what caused my issue I got word yesterday from Gibson Aviation that on one of the cylinders the valve seat had come loose and on the other cylinder there was a crack in it. Hopefully I’ll be back in the air this week.

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That’s wierd though.  What would simultaneously cause two completely different problems in two cylinders?  Perhaps one was bad already and the other suddenly went bad, but you would think that if one had been bad enough for awhile that it was not firing, you would have noticed symptoms. Cracked cylinders can sometimes run for awhile without showing symptoms, but then why all of a sudden would the cracked cylinder decide not to fire at the same time as the valve seat cylinder? I am not convinced the mechanic has found the cause.

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One of the cylinders was intermittently dropping out (the cracked one). I think it was when the cracked one would drop that I felt the power loss. I may have flown with the bad valve for a long time totally oblivious to the impending failure. This engine was sending the message that something was wrong for a long time. I just didn’t know how to interpret the signs. Excessive oil on the belly was one. I owned a Cirrus before the Mooney and it always had lots of oil on the belly. I just figured the Mooney was the same. Fluctuations in manifold pressure was another but was thought to be the wastegate.  There were other symptoms as well but being that this airplane was new to me nothing seemed out of the ordinary until the final failure. We’ll find out when we get it back together if this was the issue. It gets put back together tomorrow.

Edited by ziggysanchez
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2 hours ago, carusoam said:

Great follow-up Ziggy.

Any idea who made the cylinders?  Just wondering...

Best regards,

-a-

No idea who made the cylinders. This engine has a total of 350 hours on it since a field overhaul. After accumulating roughly 10 hours after the overhaul It did sit for almost a year without flying while repairs were being made after a gear up landing. It had flown for a total of about 40 hours before I purchased it in Oct. of 2016 and the remaining time I have put on it since. Getting a feel for the way this engine runs has been a bit problematic due to the fluctuations in manifold pressure I mentioned earlier in this thread. I’m hoping to get all of it sorted out so I can finally have a solid base line for running this engine. Since I’ve purchased this plane I’ve never felt confident that I had an understanding of how the engine was running like I did with my former aircraft.

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On 4/24/2018 at 7:23 PM, ziggysanchez said:

No idea who made the cylinders. This engine has a total of 350 hours on it since a field overhaul. After accumulating roughly 10 hours after the overhaul It did sit for almost a year without flying while repairs were being made after a gear up landing. It had flown for a total of about 40 hours before I purchased it in Oct. of 2016 and the remaining time I have put on it since. Getting a feel for the way this engine runs has been a bit problematic due to the fluctuations in manifold pressure I mentioned earlier in this thread. I’m hoping to get all of it sorted out so I can finally have a solid base line for running this engine. Since I’ve purchased this plane I’ve never felt confident that I had an understanding of how the engine was running like I did with my former aircraft.

You have an engine analyzer? Be curious to see the last flight’s data. 

Edited by Marauder
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Just now, Marauder said:

You have an engine analyzer. Be curious to see the last flight’s data. 

I'll be downloading the data tomorrow and will try to post it when I have some time. I'll probably spend most of the day cleaning the remaining oil off of the airplane, engine and inner cowling. All that oil made a huge mess. If I can I will post it tomorrow evening.

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Great progress, Ziggy!

Variations in cylinders could lead to barely noticeable affects like a measurable change in vibration.  Really hard to tell the difference in vibes, solely with the Levi’s detector. :)

Break-in procedures on the new cylinders may show some higher CHTs on the new ones until the break-in gets finished...

This comes from my experience of mixed cylinders on an O360 with mixed oversized rings and things back in the day...

Best regards,

-a-

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Thanks for posting- these are the best posts to shake off my complacency,  built up over hundreds of hours of the power plant working reliably since buying my plane.  Kudos to the poster for staying cool enough to get it down safely with the violent shaking, and it's fortunate he had the support of such a reputable shop nearby. 

That said, I'm a little dense on engine matters.   Can someone please explain to me why the case got pressurized here and blew oil everywhere?  I thought that pressurization primarily reflected a ring problem. I don't immediately grasp how loss of combustion gas through a failed valve seat or cylinder head crack would do the same thing. 

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The rings need the high compression from combustion to seal. Combustion gases force the combustion ring (the top ring) down so it seals in the bottom of the ring groove in the piston, and also out so it seals against the cylinder wall.  This prevents excessive blow by.  If there is no combustion going on, there is no pressure to seal the ring, and the ring just rattles around.   Ring slap has several bad effects.  One of course is the blow by, but it is also possible for the rings to score the cylinder walls because they are at angles.  Pretty sure it could also lead to piston slap, where the piston does not sit squarely in the cylinder as it cycles, and that can score the cylinder walls also.

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11 hours ago, kerry said:

I noticed you put chrome cylinders on.  Does having mixed cylinders affect the performance of the engine.  Just curious if anyone knows?

I noticed that too, I didn’t think anyone even did channel chrome cylinders anymore?

Clarence

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