How to R&R cylinder on Lycoming

FORANE

FORANE

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FORANE
Discovered we have 20/80 compression on one cylinder of my Titan x-340 in the lancair. It's blowing past the rings. Cylinder was overhauled just 2 years and about 250 hours ago.

I need to remove it and likely send it back to Gibson's. Would like to know tips, tricks, tools needed, gotchas etc for doing so.

Before anyone says leave it to an a&p, I would but he's gone missing. Really missing, as in the TBI is looking for him.
TBI issues Silver Alert for missing Carter County man | WJHL | Tri-Cities News & Weather
 
FORANE said:
Discovered we have 20/80 compression on one cylinder of my Titan x-340 in the lancair. It's blowing past the rings. Cylinder was overhauled just 2 years and about 250 hours ago.

I need to remove it and likely send it back to Gibson's. Would like to know tips, tricks, tools needed, gotchas etc for doing so.

Before anyone says leave it to an a&p, I would but he's gone missing. Really missing, as in the TBI is looking for him.
TBI issues Silver Alert for missing Carter County man | WJHL | Tri-Cities News & Weather
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Do you have cylinder base wrenches? Piston ring compressor? Torque wrench? Those are the "special" tools you're going to need. Everything else is typical hand tools really.

Here is reference to get an idea:


Remove cowl

Turn prop and get affected cylinder/piston to TDC

remove the baffles, spark plugs, wires, exhaust, intake tubes, rocker arm shaft, rockers, pushrods, pushrod tubes, then cylinder. Keep all the parts segregated to return them to the original positions. Don't lose the exhaust valve cap under the rocker tip, and make sure it gets installed.

I would check piston ring gap and dry tappet clearance at assembly too.
 
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I have torque wrench. I also have access to the tools of my missing mechanic. Surely he has the other tools somewhere in one of his hangars.
 
If you have any engine building experience it will be easier. I did it a few years ago during Xmas break.
I had to get cyl base wrenches for the nuts and ring compressor to put it back together. Otherwise it is basic hand tools.
Got to get a manual for your engine.
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One of the toughest part of the job is dealing with the baffle springs. I made new ones out of music wire because a couple broke when I took them out.
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Helps to have some fixtures to keep everything in order.
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Some baking trays to keep the shop floor clean.
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Some type of parts washer is needed. And AC is needed for this time of year.
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I have a manual. Titan largely just references the Lycoming manual as the motor is a clone. Don't have engine building experience; do have engine swapping experience.

My engine didn't have baffle springs wires of any sort last time a certified mechanic replaced cylinders. I discovered the baffles completely unsecured below the cylinders when I got it back from that job. I simply used safety wire.
 
I can't stand when guys cut corners, they have no business working on it if they can't do right. No baffle springs? That is a cyl baffle in the parts cleaner. Make sure you have them in your engine.
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I experimented with different length wires until I found the right length. I had to buy a 25' coil to get music wire so plenty to work with. I replaced all 4 with new wire.
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Gotta get your dog to help.
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Gary Ward said:
I can't stand when guys cut corners, they have no business working on it if they can't do right. No baffle springs?
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Yup, no springs nor secured in any way below the cylinders. Also discovered the bracket for the alternator was loose with its upper bolt not even hand tight.
 
FORANE said:
Yup, no springs nor secured in any way below the cylinders. Also discovered the bracket for the alternator was loose with its upper bolt not even hand tight.
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Unbelievable, seems like it should be illegal to give a customer a plane back in that condition?
I am sorry to hear that you have the low cylinder and that your AP is MIA. Hope he is alright.

I took mine apart to find the piston ring gaps lined up to one another on 3 pistons. Only weird thing I saw. Not sure if it was a problem or not? Have never seen that on any other engine I have disassembled.
Everything else looked good on this 1700 hr 0-320. I did have one cyl with a loose valve guide that was letting oil in and fouling the lower plug after 75-100 hrs but it was able to be lived with? I spaced the rings out and cleaned everything and put it back together. I flew it on the 7th day during Xmas break. Then flew it for another 100 hrs. The oil consumption improved by 100%. From 1qt to 4 hrs to 1qt to 8-9 hours and it ran really well after putting it back together. I was really bummed to have to replace it. Long story...It would have ran another 1000 hrs but I inadvertently ordered a replacement engine and had to swap this one prematurely.
 
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Wonder if any other parts of the cyl baffles were not put back in and possibly caused your cyl to overheat?
 
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It's CYL !

Sorry, being a writer, I can't help myself. Otherwise great posts as usual.
 
Gary Ward said:
Wonder if any other parts of the cly baffles were not put back in and possibly caused your cly to overheat?
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I don't think so. All else appeared as originally built by builder. That's not to say the original design couldn't be improved upon...
 
Got an EAA chapter around? Couple more hands who’ve done it before will make it easier.
 
You had an AP with a medical condition that may impair his ability to return home without assistance working on your plane?
 
When you pull it apart let us know what you find. I’m struggling to think of what could cause a cylinder to lose that much compression in just 250 hours unless you broke a ring or something.
 
kmacht said:
When you pull it apart let us know what you find. I’m struggling to think of what could cause a cylinder to lose that much compression in just 250 hours unless you broke a ring or something.
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Ok, last time I broke a ring it had great compression.
 

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Clip4 said:
Or performing a service your life might depend on.
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To be honest and fair regarding my mechanic (and friend) who is missing, he has never shown any signs of dementia. His disappearance is troubling. Many people who know him are surprised, puzzled and concerned.
 
Clip4 said:
Or performing a service your life might depend on.
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It must be amazing to be around you. Everyone you associate with is in perfect health and has never made a mistake. Must be heaven, because apparently they can't even get a health issue after you start associating with them. I guess they all live forever too.
 
Clip4 said:
You had an AP with a medical condition that may impair his ability to return home without assistance working on your plane?
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I know a master mechanic that pulled over on a country road and had a heart attack right there driving home.

Stuff happens

I went home early yesterday, just sent an email out, 20 minutes later my coworker texts me saying "last time you told me you're going home early not feeling well you ended up nearly dying in the hospital, you ok?"
 
The last day anyone saw him he told another friend that he felt sick and thought he was getting COVID again.
 
Don't lay your con rods like this, support them with rubber bands or? When I first took this apart I was only doing it to save the jugs for hangar art because the overhaul shop told me to if I wanted any of the old parts because they do not return any old parts.
Then I decided to put it back together and keep flying it while waiting on a Lycoming rebuilt engine. So I put it back together and thought why in the hell did I order a rebuilt engine since it ran so good.
So at first I was not too concerned with the con rods.
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And I can't remember for sure until I look in my tool box but I think I used a ring compressor for when I was building motorcycle engines?
I couldn't get this pin out with my hands so I left it in there and cleaned the piston ring grooves while hanging on the con rod. To me those rings was sealing pretty good during the previous 1700 hours. Cleaning them up to make the rings free in grooves is where it's at.
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FORANE said:
To be honest and fair regarding my mechanic (and friend) who is missing, he has never shown any signs of dementia. His disappearance is troubling. Many people who know him are surprised, puzzled and concerned.
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Did he leave knowing you needed engine work? lol ;)
 
Don't turn the prop when that cylinder is off. Two of the cylinder mounting studs go right though the case, clamping the main bearings in place. Those bearings can shift with the studs are relaxed, and when the cylinder is reinstalled and the nuts all torques, a bearing that has shifted will be tight and could wreck the bearing. And the engine.
 
Dan Thomas said:
Don't turn the prop when that cylinder is off. Two of the cylinder mounting studs go right though the case, clamping the main bearings in place. Those bearings can shift with the studs are relaxed, and when the cylinder is reinstalled and the nuts all torques, a bearing that has shifted will be tight and could wreck the bearing. And the engine.
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Should the studs be tightened when the cylinder is off? What if I wanted to pull cylinders 1 & 2 on a Lycoming 320, tighten them after removing the cylinders?

I'm afraid that someone might move the prop as the plane sits in a community hangar for 8 weeks waiting on return of the cylinder from Gibson's.
 
The Manual does not tell the entire tale.

There are numerous do’s and don’ts that are addressed via

Service Bulletins, Letters and Instructions. Well meaning folks

often use techniques that cause failures later.

You want to know this BEFORE cylinder removal.

Torque Plates after its off?

There is more to torque than just a setting on a wrench.

There is an unusual procedure referenced in these docs

that is quite important.

Do not do anything until you understand everything.
 
For those looking to acquire those "Baking Pans", the culinary industry calls them "Sheet Pans". They come in different sizes; I believe the pictured one below is a a Quarter Sheet Pan. So sayeth my wife!

-Skip

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My late friend who owned a restaurant got me from his supplier 2-3 different sizes sheet pans many years ago brand new and shiny. We used them at the races at first. They are not the same thing as a drip pan that you can get at a auto parts store. Much sturdier.

I also bought some stainless oil drain pans at the same time. Steam table containers? Not sure what they are called? Good quality that never wears out or leaks.
 
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FORANE said:
Should the studs be tightened when the cylinder is off? What if I wanted to pull cylinders 1 & 2 on a Lycoming 320, tighten them after removing the cylinders?

I'm afraid that someone might move the prop as the plane sits in a community hangar for 8 weeks waiting on return of the cylinder from Gibson's.
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Some stuff here: https://www.csobeech.com/torque-plates.html

And some detail on tightening the nuts here: https://www.lycoming.com/sites/defa...%20Procedures%20for%20Thru-Studs%20and%20.pdf
 
There was zero sealant used, only fresh o rings and silicone valve cover gaskets. The new silicone valve cover gaskets will cause high silicone readings at first making you think air filtration is not up to par. The silicone ppm goes down as you change the oil.
The only thing that goes on the cylinder bases is a new o ring. It has to be metal to metal no anything on the cyl bases so you get true torque on the case bolts.
 
Dan illustrated my point perfectly.

The information in SI 1029 D supersedes the SM and should be used.

Now look at Part II - Note

There is a requirement that you SIMULTANEOUSLY tighten both ends

of the through stud. Usually entails disassembly on the other side

of the engine.How often do you think this gets done?

If these instructions are not followed the reassembly is not correct.

Could this be the reason some people say to never pull a cylinder?



FORANE should also become familiar with Dry Lifter Clearance ( DLC)

as this may change with cylinder work.


The Titan may differ but Lycomings have two Rocker Arms that

look similar bit are not the same. Swapping them may be hazardous

to cylinder health.
 
Magman said:
The Titan may differ but Lycomings have two Rocker Arms that

look similar bit are not the same. Swapping them may be hazardous

to cylinder health.
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Some Lycomings have different rocker arms on the intake and exhaust. They are all the same on the newer engines I've worked on. No clue what ECi was doing on the Titan engines.

As far as I can tell, the primary reason for the difference in rocker arms was to discourage oil consumption via the intake valve guide. Lycoming seems to have decided that lubrication was more important than oil consumption concerns.
 
Gary Ward said:
The only thing that goes on the cylinder bases is a new o ring. It has to be metal to metal no anything on the cyl bases so you get true torque on the case bolts.
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That there. There was an accident not too long ago where an engine failed catastrophically in flight. Came right apart. It was a homebuilt, and the guy had "rebuilt" the engine and used RTV on the cylinder base flange. That thin layer let the cylinder move a tiny bit every time the cylinder fired, moving in and out, and it fatigued the studs and they failed and the cylinder blew off. The engine beat itself to death.

Pay close attention to the overhaul manual and to any Lycoming SBs or SLs regarding approved sealants and lubricants. These guys are not kidding around.
 
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