Airplane Owner Maintenance

A Maintenance Oriented Podcast For Airplane Owners, Pilots, and Mechanics

Tag: exhaustvalves

191 – A Tale of Two Exhaust Valves

November 13, 2021 / / 2 Comments

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In this episode, we are talking about two different exhaust valves, both of which showed signs of burning when we looked at them with the borescope.

One valve was in the beginning stages of burning, and the other was too far gone. Scroll down for more info and some photos.

We also talk a bit in this episode about Arthur St. Clair and his P35 Bonanza. I mentioned him in a previous episode, and recently he came back to Classic Aviation so we could borescope his cylinders and exhaust valves. Thankfully, all his valves were in good shape. Here’s a photo from that day:

Now for the two exhaust valves mentioned in the title for this episode…

Here’s a photo of the one that was too far gone, and the cylinder had to be removed and sent out for repair:

Notice the green edge from 11 o’clock to 2 o’clock on the valve… a badly burning area. The valve guide was also very worn, so we sent the cylinder out for repair.

I also cut the old rotocoil apart for this valve and it had a lot of black carbon bits in it, and the internal spring showed the classic flat spot that is many times seen when an exhaust valve has been burning. Here’s the rotocoil:

The other burning exhaust valve on this same engine was only in the beginning stages, and after lapping the valve and installing a new rotocoil and new valve springs, the compression was 72/80 after runup! What a fantastic result! Here’s what that one looked like:

The small area at 12 O’clock on the valve is starting to burn, but it was salvageable by lapping and installing a new rotocoil to ensure proper valve rotation and better sealing capability.

So the moral of the story is, borescope your exhaust valves at regular intervals, like 50 hours, and hopefully you can catch a burning valve before it’s too far gone and has to be removed.

Have a great week everyone!

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183 – I’m Bringing an Engine Cylinder to Oshkosh!

July 24, 2021 / / 0 Comments

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Here’s a sampling of items I’m planning to use for one of my presentations at Oshkosh this year. It’s called “Lapping Valves & Saving Cylinders.”

Click here for more info

I’d love to see you there if you’re attending Airventure this year. It’s on Thursday afternoon, July 29, from 4-5:15 pm in Workshop Classroom C.

We’ll be lapping the exhaust valve from this Bonanza cylinder, and I invite you to come join the fun!

I’ll also have some other exhaust valves and rotocoils for display. Some of the rotocoils have been cut open so you can see the internal parts.

I’ll also be giving a presentation on Saturday morning about “Borescoping Your Own Exhaust Valves.”

I’ll have some exhaust valves and other items for demonstration at this presentation as well. I hope to see you at one or both seminars!

Click here for more info on this one.

That’s all for this post, and I’ll be back here after Oshkosh!

175 – Shock Strut Servicing Course Coming Soon!

May 8, 2021 / / 0 Comments

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Does your airplane’s shock strut need fluid?

Does it need nitrogen? … or air?

And more importantly, could you service the strut safely?

If you’ve ever had a low strut, you know it can be very frustrating.

Sometimes it can be challenging to sort through all the maintenance manual information, your POH information, your local A&P’s instructions, and your fellow aviators’ opinions, about shock struts and how they should be maintained.

What if there was a simple and clear way to learn about shock strut servicing?

Very soon, there will be a way!

The video training course for “Servicing Landing Gear Shock Struts” will be available in the near future.

Be watching for more details.

Also in this episode, we talk about “FEVA” or “Failiing Exhaust Valve Analytics,” a concept being developed by Mike Busch and his team at Savvy Aviation. If you’d like to learn more, here’s a very interesting article.

This discussion was prompted by an email I received that said, “Dean, what do you think of Mike Busch and his Savvy Aviator columns?” I answered that question in today’s podcast episode.

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146 – Fixing an Obscure Oil Leak

June 27, 2020 / / 0 Comments

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The part in the yellow circle is an oil scavenge pump that returns oil back to the engine oil sump after it lubricates the turbocharger center bearings. The right side of the assembly is the adapter that fits into the engine accessory case. The left side of the assembly is the hydraulic pump that is used for the landing gear system, the flap system, and the nosegear steering system in this Aerostar 601.

Inside the oil scavenge pump, there are two oil seals, (sometimes called garlock seals,) and two o-rings.

In today’s episode, we discuss this type of pump that reminded me of A&P school from years ago… it’s called a “gerotor pump.” It has a gear within a gear.

Listen to the audio for the details on fixing this oil leak.

We also talk about a Mooney M20K engine in this episode… we lapped the exhaust valve in cylinder #5. We might end up checking the exhaust valve in cylinder #2 as well to make sure it’s not sticking, after the owner had some classic “morning sickness” symptoms as described in Mike Busch’s recent article about sticking exhaust valves. The article is well worth reading.

https://www.aopa.org/news-and-media/all-news/2020/july/pilot/savvy-maintance-valves

And while we’re on the subject of exhaust valves, I wanted to remind everyone this resource is available for free… for now. If you want to learn about what to look for when you’re borescoping exhaust valves, this is a great resource. I’m considering moving the guide into the paid section of resources, so grab a copy while you can.

Click here and sign up with your email, and you’ll receive a free copy of the guide, for at least another two weeks.

Click here to get the Exhaust Valve Borescoping Guide.

And if you have a friend, or a few friends who might benefit from this resource, please share this link with them: AirplaneOwnerMaintenance.com/exhaustvalves

Post it on Facebook or Instagram, or wherever you like, so people can take advantage of it while it’s free.

Also in this episode:

  • A big “thank you” to Jeff Claridge who contacted me and did a conference call with me to demonstrate the smoke tester he has to detect leaks in engines. He suggested this would be a great tool for checking exhaust and intake systems for leaks on airplane engines… after seeing it in action, I totally agree! Thanks Jeff!
  • The tester Jeff has is an Autool SDT202. (If you make a purchase with the following link, I’ll get a small percentage… thanks so much!)
  • Thanks also, to Joe Godfrey for talking with us in episode 144, about engine monitoring and data, and how to use SavvyAnalysis.com to analyze that data. Joe used the data from the Cessna 172 Hawk XP that was discussed in episode 142, in the recent “puzzler” in the Savvy Aviation newsletter. Check it out: https://resources.savvyaviation.com/grok-savvy-analysis-puzzler-june-2020/. Thank you Joe!
  • I recorded a conversation yesterday with my friend, Aram Basmadjian, that will appear in a future episode. Be looking for that one. Aram owns and flies a V-tail Bonanza.
  • I also recorded a second conversation yesterday with Jim Weir, a gentleman I only recently became aware of. He has a very unique and strategic way of doing “owner assisted” annual inspecions. That one will also be in a future episode.

Thanks everyone, and have a great week!

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