Io360 a1a cylinder blow by. Replace?

[Teddyhherrera]

Number 2 cylinder fouled a spark plug with a bit of oil. Compression 77, blowby evident at dipstick. Redid run up and spark plug is barely moist but with deposits after cleaning. AP thinks it's time for a new cylinder. All cylinders are nickel and the aircraft was IRAN in 2019, approximately 400 hours ago. 

 

Having just gone down the mile Busch YouTube rabbit hole, I'm thinking I should not change the cylinder. Am I correct?

[MikeOH]

How long have you had the plane vs. how long have you seen this issue?

Has oil consumption changed?  How many hours per quart?

Does #2 run hotter than the others?

[EricJ]

23 minutes ago, Teddyhherrera said:

Number 2 cylinder fouled a spark plug with a bit of oil. Compression 77, blowby evident at dipstick. Redid run up and spark plug is barely moist but with deposits after cleaning. AP thinks it's time for a new cylinder. All cylinders are nickel and the aircraft was IRAN in 2019, approximately 400 hours ago. 

 

Having just gone down the mile Busch YouTube rabbit hole, I'm thinking I should not change the cylinder. Am I correct?

77 is very good compression, so that's certainly not motivation to change out the cylinder, nor is the occassional oil fouling of a plug.   Is there a specific reason the AP wants to change the cylinder?   Nothing you're describing suggests that you need to do that.

[Teddyhherrera]

3 minutes ago, EricJ said:

77 is very good compression, so that's certainly not motivation to change out the cylinder, nor is the occassional oil fouling of a plug.   Is there a specific reason the AP wants to change the cylinder?   Nothing you're describing suggests that you need to do that.

His reasoning is the oil fouling, blow by, and that they're overhauled cylinders 

Edited October 23 by Teddyhherrera

[Teddyhherrera]

20 minutes ago, MikeOH said:

How long have you had the plane vs. how long have you seen this issue?

Has oil consumption changed?  How many hours per quart?

Does #2 run hotter than the others?

Relatively new, I've had to aggressively lean at run up for the last 50-70 hours or so to get the satisfactory 50 rpm mag drop. I've had the plane for just over 300 hours. But the dipstick has always smelled the same and the oil has always turned dark in the first hours after every oil change. Usually 3 is hottest. However on run up after cleaning, get for 2 was momentarily hottest by a good margin. Then it evened out across the board.

Edited October 23 by Teddyhherrera

[MikeOH]

I've had my F for 7 years and about 500 hours and the oil has always turned black rather quickly but compressions have been good (>75) and oil consumption was stable at around 7 hours/qt.  Further my oil temp has always been high; 200-210 in winter, and 220-230 on hot summer days.  I've tried overhauling the oil cooler, new oil lines, new vernatherm, baffles...all to no avail.

#2 has always run hotter than the others and has a little oil pooling when I borescope, but never any plug fouling.  At annual this past June I tried a solvent flush on #2.  Now I'm seeing only 4-5 hours per quart!  So, as much as I didn't want to, my plane is in the shop right now having #2 removed and sent out for overhaul.  I'm crossing my fingers that the cylinder OH will fix my issues.

Your symptoms seem a bit different, but are you seeing high oil temps?

[MikeOH]

32 minutes ago, Teddyhherrera said:

His reasoning is the oil fouling, blow by, and that they're overhauled cylinders 

Hmm, the angle valve cylinders on our IO-360A1As are REALLY hard to come by new.  So, you are likely going to get another overhauled cylinder!

[N201MKTurbo]

If you did want to fix it, which I’m not suggesting, all you need to do is replace the piston and rings and rehone it. Only a couple hundred dollars of parts instead of a couple of thousand.

[201Steve]

Not a cylinder expert, but with excellent compression at 77, isn’t there a distinction between blow by (air escaping from the combustion chamber past the compression rings and into the crank case) and oil fouling (oil slipping from the crankcase and up into the combustion chamber) oil control ring?

 

I had an oil fouling issue after a 50 cent overhaul. They called it an overhaul but it was really a spruce-it-up but really make it worse patch job.
 

Anyway, oil fouling of the spark plugs short of an anomalous rogue event would be unacceptable to me. After my experience on multiple occasions pulling plugs to clean them on an away from home ramp in the scorching sun with my family anxiously waiting in the FBO, I wouldn’t put up with it.  
 

This of course all depends on frequency and what’s required to remedy. If every now and then you have to clear a plug simply by a hard and hot run-up, maybe acceptable. Oil fouled every 10 hours, so bad you have to remove plugs to clean them, not acceptable. 
 

As others have probed, there’s other information needed to articulate what “we” would do in your situation, but it’s also been pointed out there is more than one way to skin that cat. An invaluable metric for me would be to see boroscope photos of that cylinder to determine condition of cylinder walls, what the oil pooling looks like, etc. 

[gwav8or]

6 hours ago, MikeOH said:

Hmm, the angle valve cylinders on our IO-360A1As are REALLY hard to come by new.  So, you are likely going to get another overhauled cylinder!

This is the truth.  I checked on new cylinders in January this year and the shop said they were more than 3 months out and $3k per cylinder.  Seems like the A1A cylinders are made of something similar to unobtanium.  I wasn't in need of new cylinders but was checking just in case.  

[47U]

9 hours ago, Teddyhherrera said:

I've had to aggressively lean at run up for the last 50-70 hours or so to get the satisfactory 50 rpm mag drop.

A healthy ingnition system is key to satisfactory run-ups.  What are the condition of the mags/ignition harness?  Have you ohmed the plugs?

Is the Tempest BY plug an option for your A1A engine?

I’m with @201Steve… borescope the cylinder.  

Your A&P must have pretty good ears to hear air hissing in the oil fill tube with an only 3 psi drop during the compression check.  

[Teddyhherrera]

8 hours ago, MikeOH said:

I've had my F for 7 years and about 500 hours and the oil has always turned black rather quickly but compressions have been good (>75) and oil consumption was stable at around 7 hours/qt.  Further my oil temp has always been high; 200-210 in winter, and 220-230 on hot summer days.  I've tried overhauling the oil cooler, new oil lines, new vernatherm, baffles...all to no avail.

#2 has always run hotter than the others and has a little oil pooling when I borescope, but never any plug fouling.  At annual this past June I tried a solvent flush on #2.  Now I'm seeing only 4-5 hours per quart!  So, as much as I didn't want to, my plane is in the shop right now having #2 removed and sent out for overhaul.  I'm crossing my fingers that the cylinder OH will fix my issues.

Your symptoms seem a bit different, but are you seeing high oil temps?

That I don't. And that's part of the reason I'm apprehensive about  changing the cylinder. For the most part, my engine is extremely well behaved, no extremely high cylinder temps. I maybe see 425 on my hottest cylinder on initial climb out, oil runs cool, BUT my MX says it will only get worse

[Teddyhherrera]

3 hours ago, 201Steve said:

Not a cylinder expert, but with excellent compression at 77, isn’t there a distinction between blow by (air escaping from the combustion chamber past the compression rings and into the crank case) and oil fouling (oil slipping from the crankcase and up into the combustion chamber) oil control ring?

 

I had an oil fouling issue after a 50 cent overhaul. They called it an overhaul but it was really a spruce-it-up but really make it worse patch job.
 

Anyway, oil fouling of the spark plugs short of an anomalous rogue event would be unacceptable to me. After my experience on multiple occasions pulling plugs to clean them on an away from home ramp in the scorching sun with my family anxiously waiting in the FBO, I wouldn’t put up with it.  
 

This of course all depends on frequency and what’s required to remedy. If every now and then you have to clear a plug simply by a hard and hot run-up, maybe acceptable. Oil fouled every 10 hours, so bad you have to remove plugs to clean them, not acceptable. 
 

As others have probed, there’s other information needed to articulate what “we” would do in your situation, but it’s also been pointed out there is more than one way to skin that cat. An invaluable metric for me would be to see boroscope photos of that cylinder to determine condition of cylinder walls, what the oil pooling looks like, etc. 

Borescoping today. This is the first time this has happened. I decided to check after an abnormally long rollout resulting in an aborted takeoff. I have had to runup hot and leaned to clear a mag drop on several occasions though 

[Teddyhherrera]

45 minutes ago, 47U said:

A healthy ingnition system is key to satisfactory run-ups.  What are the condition of the mags/ignition harness?  Have you ohmed the plugs?

Is the Tempest BY plug an option for your A1A engine?

I’m with @201Steve… borescope the cylinder.  

Your A&P must have pretty good ears to hear air hissing in the oil fill tube with an only 3 psi drop during the compression check.  

I'm using champions. I can get whatever plug if needed. Timing was checked on the mags. I don't think plugs were ohmed but he did clean,gap, and even replaced one.

[MikeOH]

54 minutes ago, Teddyhherrera said:

That I don't. And that's part of the reason I'm apprehensive about  changing the cylinder. For the most part, my engine is extremely well behaved, no extremely high cylinder temps. I maybe see 425 on my hottest cylinder on initial climb out, oil runs cool, BUT my MX says it will only get worse

I sure wouldn't be in a rush to change out that cylinder.  See what the borescope reveals, but as someone else said, if the plug fouling isn't a constant issue I'd take a 'wait and see' attitude.  If it wasn't for my high oil temps and the sudden change in my oil consumption I would not be proceeding with a cylinder OH.

[Ragsf15e]

My cylinders always have a little oil in them as they are chrome and the channel chrome doesn’t seal as well with the rings.  Anyway, they do have a little oil, they also have good compression, but they have never (kow) fouled plugs.  Now I’m using the slightly longer tempest fine wires, so i wonder if that’s the difference?

While it’s not cheap (the plugs are ~135 ea), I might change my bottom plugs to the longer fine wires before I start removing cylinders.

[Ragsf15e]

9 minutes ago, MikeOH said:

I sure wouldn't be in a rush to change out that cylinder.  See what the borescope reveals, but as someone else said, if the plug fouling isn't a constant issue I'd take a 'wait and see' attitude.  If it wasn't for my high oil temps and the sudden change in my oil consumption I would not be proceeding with a cylinder OH.

Wait until the shop gets it and says it can’t be overhauled!  Ha, I had that happen, it’s not fun.  Also, is it getting oh or “repaired” because you’ll be thinking of all the stuff they didn’t have to do to “repair” it when it’s having issues in 300 hours.  I wish new ones were available because 3 of mine are “repaired” and one is oh and I would have been better off with 4 new or at least all 4 oh…

[EricJ]

11 hours ago, Teddyhherrera said:

Relatively new, I've had to aggressively lean at run up for the last 50-70 hours or so to get the satisfactory 50 rpm mag drop. I've had the plane for just over 300 hours. But the dipstick has always smelled the same and the oil has always turned dark in the first hours after every oil change. Usually 3 is hottest. However on run up after cleaning, get for 2 was momentarily hottest by a good margin. Then it evened out across the board.

What is the Density Altitude at your airport when you have to lean to get a good mag drop?    That's normal at high DA.

[Teddyhherrera]

5 minutes ago, EricJ said:

What is the Density Altitude at your airport when you have to lean to get a good mag drop?    That's normal at high DA.

3950. West tx so da is normally was higher 

[MikeOH]

11 minutes ago, Ragsf15e said:

Wait until the shop gets it and says it can’t be overhauled!  Ha, I had that happen, it’s not fun.  Also, is it getting oh or “repaired” because you’ll be thinking of all the stuff they didn’t have to do to “repair” it when it’s having issues in 300 hours.  I wish new ones were available because 3 of mine are “repaired” and one is oh and I would have been better off with 4 new or at least all 4 oh…

Yeah, all of what you say...many of the reasons I did NOT want to go down this path. I, too, would rather have spent the money for a new cylinder.  As it is, I'm spending the bucks for an OH so, hopefully, it doesn't have issues 300 hours from now.

[EricJ]

I'm still not hearing anything that would suggest a cylinder needs to be pulled, but I'm not there looking at it.

A cylinder with 77 compression that's running well and not using an excessive amount of oil is not likely to be having ring problems, imho.

Blow by is pretty normal with these engines.   My oil turns black within a few hours after an oil change as well.   Some don't, but those are usually newer or just exceptionally good engines.

Leaning for takeoff or to get good mag drops is not unusual on hot days at high airports.   It's typical behavior, and leaning for takeoff in high DA is normal procedure for many people and good safety practice, imho.

A borescope inspection is a good idea, but often won't tell you much about the rings.   You should be able to see if there is any bad scoring on the walls, though.   Regardless, the high compression suggests it's not a big problem even if there is scoring.

[hammdo]

Maybe try the cylinder ring flush first as Mr. Busch suggests….

-Don

[MikeOH]

30 minutes ago, hammdo said:

Maybe try the cylinder ring flush first as Mr. Busch suggests….

-Don

Maybe,.... that's what I did.  And my oil consumption went from 7 hours/qt to 4-5 hours/qt!  Just sayin'!

[Teddyhherrera]

1 hour ago, MikeOH said:

Yeah, all of what you say...many of the reasons I did NOT want to go down this path. I, too, would rather have spent the money for a new cylinder.  As it is, I'm spending the bucks for an OH so, hopefully, it doesn't have issues 300 hours from now.

I was hoping to find one that has a cylinder exchange thing...

[MikeOH]

2 minutes ago, Teddyhherrera said:

I was hoping to find one that has a cylinder exchange thing...

That was my goal...and, I failed.  To be honest, though, I didn't really try that hard.  I wanted a relatively nearby shop with a good reputation.