Burned Valve?

[Dialed In]

Alright guys here it is 1965 E A1A.  I got to annual and was told the shop owner would not allow me to assist in the annual today which changed since the last time I had talked to them, bummer.  The shop started the annual and the compression's were 78/80 on all cylinders cold.  We had some weather move in so I flew to the shop last night and the weather was rainy today so they checked them cold.  They do not typically scope cylinders, I have been looking for an A&P in Montana that does but that has proven difficult, anyway since the original agreement was I could help I felt that this would be one area I would tackle.  I talked them into allowing me to scope the cylinders and the attached photos are of number one I'm sorry they are not the best.  I do read Mike Busch and have looked at the anatomy of a valve poster but I am having trouble deciding if this is the beginning of a burnt valve or possibly some lead build up on the seat that could pass with time as the markings seem concentric.  This engine has just under 2200 hrs on it the cylinders have not been touched.  I do not have an engine monitor yet and have been saving up for one as well as the engine overhaul hopefully it will make it another year or two until my wife is out of graduate school.  The engine starts very well, does not miss at all, and over all feels strong.  I bought this plane with 1900 hrs on the engine and have run it rich of peak due to not having good instrumentation and that has been the way it has always been run so the chamber is not as clean as many of yours.  The cross hatching is still on the cylinder walls and since owning it it has been 76-78 compression so what do you all think? @M20Doc, @N201MKTurbo

-Chase

1.9.bmp 1.11.bmp 1.12.bmp 1.14.bmp

[Prior owner]

I see big black squares....!

[Dialed In]

14 minutes ago, Dialed In said:

Maybe try again I was editing trying to call Rick and Clarence but could not figure it out

 

[Dialed In]

They are saved as BMP files I may have to try to convert them to jpeg.

I converted them to jpeg should work now.

[carusoam]

Looks like you get an A for effort... 

Those look like tired valves... the colored part of the edge is Probably a heat affected zone typically found in valves that are not rotating very well...

Rotation allows for more uniform cooling... sticky valves stop rotating...

Without an engine monitor... it is harder, but not impossible to run an engine LOP, ROP or at peak... The Mooney gods supplied the basic instruments for that... a CHT and one EGT... how much more do you need?

Even modern Long Bodies didn’t get anything better... until the G1000s came along...

Take a look at the cylinder wall pic... is that cross hatches, or just old scratches?   Cross hatch patterns look like an intentional waffle pattern...

Great pics... this conversation would have been impossible without them...

read up on how to clean valves... and valve stems...

read up on burning off lead deposits...

As far as lead deposits and Mooneys go... did you collect any lead BBs out of the lower spark plugs?
 

I almost covered everything... except one important detail....

What is your wife studying?   

Best regards,

-a-

[Dialed In]

Thanks for the reply Anthony, she is studying to become a nurse practitioner she is starting to enter the clinical stage.  Don’t know on the plugs  as the bottom plugs were still installed and I was just trying to scope and head out they are tempest fine wires installed 115 hrs ago.  I have tried lean of peak and the engine seems to run well there and defiantly cooler on the cht’s but when I land I find there is oil splattered on the bottom of the plane coming from the large breather, picture of breather attached. When I run rop I have no oil exiting the breather the engine typically burns 1qt every 9 hours.  Those are cross hatching marks, not the best angle on the pic I have to work on that.  Where can I find how to “call” members on the forum?

-Chase

[gsxrpilot]

Aerotronics in Billings, MT have an A&P/IA on staff who spent some 12+ years at TopGun. He did some work on my Mooney today. I was very pleased and impressed with his knowledge of Mooneys. I know you don't need a Mooney specialist for this issue, but thought I'd mention it.

[Ross Taylor]

1 hour ago, Dialed In said:

 Where can I find how to “call” members on the forum?

It took me a few months to figure that out, myself.  If you type an "@" and then the first few characters of the members name, you should get a pop-up list of options to choose from.  I didn't realize that it takes a bit...sometimes 10 seconds on a slow connection...for the list to pop up.  The more of the name you type, the more narrowed the list will get. Like this:

 

[N201MKTurbo]

I wouldn't pull the cylinder just yet. I would keep an eye on it. Can you get a picture of the valve seating surface under the white spot? If it is eroded, I would start budgeting for an overhaul. Also try to inspect the valve seat all the way around.

[bradp]

Wobble test the questionable valve 

The cynic in me says that if your shop doesn’t know how to scope, they probably don’t know how to wobble and they almost certainly wouldn’t know how to rope trick. 

[N201MKTurbo]

Honestly, you have an engine that is 200 hours past TBO. It doesn't owe you anything. Run it till it looses compression then overhaul it. All these borescope inspections will just cause you to loose sleep. Burned valves usually progress slowly and rarely lead to catastrophic failure.

[PTK]

@Dialed In, would you happen to have any engine monitor data you can post? Curious if the EGT trace for this cylinder shows any anomaly that is rhythmic. Typically the valve rotates a tiny bit at every open/close cycle according to RPM. This is to keep the seating interface clean and equalize the heat around the circumference of the valve. If there is gas leakage it should show up in the corresponding EGT trace almost exactly rhythmic.

[kpaul]

12 hours ago, Dialed In said:

I do not have an engine monitor yet and have been saving up for one as well as the engine overhaul hopefully it will make it another year or two until my wife is out of graduate school. 

 

Just now, PTK said:

@Dialed In, would you happen to have any engine monitor data you can post? Curious if the EGT trace for this cylinder shows any anomaly that is rhythmic. Typically the valve rotates a tiny bit at every open/close cycle. This is to keep the interface clean. If there is gas leakage it should show up in the corresponding EGT trace almost exactly rhythmic.

He does not have an engine monitor. 

[Rwsavory]

The valve doesn’t look that bad, in my non-expert opinion. If it were me, I would run it another 25 hours and then scope it again.

[hammdo]

If a valve has wobble or guide is giving up the ghost, wouldn’t an oil analyst show more nickel if it’s wearing out? I don’t see the ‘hotspot’ (maybe my old eyes) where it’s burned off the deposits. 

 I’m with N201, keep an eye on it. I’m sure other pros (I’m a former auto ASE cert mechanic - not an A&P) will have better insight...

-Don

[Dialed In]

Paul, thanks for the heads up they were the ones that put my GNX-375 and g-5 in last year I was pleased with the work but did not realize they had a Mooney specialist.  I like the suggestions I’m thinking of running it another 25-50 hrs and bore scoping again. Rich is right this engine does not own me anything and I’m happy it is running as well as it is however I do have the scope so might as well use it. I have really been struggling trying to decide if I want to go the replace on condition route and try to get over 3000 hours out of it or whether I should just bite the bullet and get the full overhaul in the next 200 hrs. Going through the logs it looks like this engine has not had much done to it, wobble test done at 1600 hrs passed but other then that really nothing internal has been touched since 96. That being said it has been 24 years it is probably just time to get the overhaul done. 

[Matt Ward]

On 6/8/2020 at 9:43 PM, Dialed In said:

I have tried lean of peak and the engine seems to run well there and defiantly cooler on the cht’s but when I land I find there is oil splattered on the bottom of the plane coming from the large breather, picture of breather attached. When I run rop I have no oil exiting the breather the engine typically burns 1qt every 9 hours.

I'm curious about this.  I've been trying to track down some higher-than-normal oil usage and I think I lost it out the breather on a really long LOP (~20 degrees LOP, ~8.5 GPH) trip - that also happened to be in hot, humid weather.  That was surprising to me as I hadn't understood LOP operations as contributing to breather tube loss.  How LOP are you running, either in GPH or on the (single?) EGT you have installed when you see that?  And how much oil are you seeing on the gear doors - assuming that's where it is showing up first.

[Dialed In]

When I was running lop it was approximately 30-35 degrees lop on the single egt. I would lean until rough then richen slightly. I was trying it out wot at 8,500 then 9,500 ft both flights were about 90 minutes each. Typically I do not get any oil on the belly while flying however during these flights I ended up with a good amount on the gear doors that steamed down the belly a bit. It was not real large amount but when your used to nothing it was enough to be concerned about. I am curious how it could pressurize the crank case enough to blow oil out but I resigned myself to the fact that this engine is just happier rop until I get better monitoring equipment. Both times I was right around that 8.5 gph when I topped off after the flights. 

[cliffy]

What scope do you have?

[Shadrach]

On 6/9/2020 at 9:49 AM, bradp said:

Wobble test the questionable valve 

The cynic in me says that if your shop doesn’t know how to scope, they probably don’t know how to wobble and they almost certainly wouldn’t know how to rope trick. 

Rope trick is pretty common procedure. I’ve done 3 of them in the last 20 years and I’m not an A&P. I think almost anyone out of A&P school has heard of it, if not done it. Lyc SI 1425 spells it out clearly.

[Dialed In]

The borescope I have is the Vividia VA-400 hooked up to my laptop I will get some better pictures when annual is done and I have some time. I did find a shop that has done the rope trick several times with success close by and will be flying down there likely in September to have him look at it. Thanks for the help guys. @cliffy

[slowflyin]

I’ve had really good luck lapping the valves without pulling the jug.   Check again in 10 hours.