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Well, I pulled the cylinder - here are some pics

No case has to be apart.

Interesting. Don't know much about the oil supply to the nozzles. Nozzles screw in here (red circle), so is the passage plugged again somewhere else?

ivhagh.jpg
 
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I thought we were talking about an O-360 that doesn't have the ports drilled (Ney mod). So in this case yes its as simple as taking the pipe plugs out and putting the squirters in since its an IO-360. Case does not have to be apart in that case (pun intended).

Note that the Ney cam squirter mod doesn't point at the pistons, it points at the cam.

The other consideration to IO-360 piston squirters is that once installed, the oil cooling capacity should be up to the task of getting rid of the extra heat. Piston squirters will lead to elevated oil temps and there is some debate about putting too much oil on the cylinder walls.
 
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Yeah, I'm not going to do that. I really want to avoid putting any side load on the big end bearing. They are designed to take thrust, not side loads.

I have ordered a piston pin puller from spruce. If that doesn't work, I will build a tool to use a threaded rod to press the pin out.

That is how it's done. Being an A&P, I've pulled 100's of cylinders and pistons for overhaul. If you heat up the piston the pin will loosen up. You use a 1/2" ratchet extension put the big end on the pin and tap it out with a hammer. You will not be reusing the pin again and you will not damage anything.

Adding the piston squirters will add about 20 degrees F to your oil, about the same it removes from the piston bases. You will see this on the oil temp gauge.
 
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That is how it's done. Being an A&P, I've pulled 100's of cylinders and pistons for overhaul. If you heat up the piston the pin will loosen up. You use a 1/2" ratchet extension put the big end on the pin and tap it out with a hammer. You will not be reusing the pin again and you will not damage anything.

Adding the piston squirters will add about 20 degrees F to your oil, about the same it removes from the piston bases. You will see this on the oil temp gauge.

I'm ok with judicious application of heat. Its the "pounding out" bit I don't like :eek:

I'd much rather press out. Perhaps I'm being over cautious about side loads on the bearing?


Regarding the piston squirters and extra heat. To clarify, the heat is present in the engine regardless of whether or not the squirters are installed. The squirters are not adding heat, they are just assisting the transfer of the heat from the piston to the oil. So, if the oil temp goes up a bit, as long as it doesn't get hot enough to reduce oil pressure or viscosity too much, it should actually be ok. That increase in oil temp represents a decrease in the temperature of the pistons which, assuming the lubrication qualities of the oil are maintained (temp within limits), is beneficial.
 
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This is beyond my shade tree mechanic abilities :D

I'm good enough to do basic things and, hopefully, recognize when its beyond me.

I continue to be amazed by, and grateful for, not only the level of expertise on this site and in this community, but also the level of effort those individuals are willing to expend to share it with the rest of us.

I only hope that I can help expand the collective knowledge here, even if its by asking stupid questions that others can answer.

Don't you just love the Internet and VAF, in particular? Extremely educational thread but as Walkman suggested, I hope I can recognize when to turn to the pros.
 
I'm ok with judicious application of heat. Its the "pounding out" bit I don't like :eek:

I'd much rather press out. Perhaps I'm being over cautious about side loads on the bearing?

I was the same way at first. Then I realize how much twisting you are putting on the bearing just torquing the nuts down during assembly. You don't want to beat on it like you are thinking. I had a friend hold the piston steady while I tapped the piston pin out.

Where is the airplane? I could help you if you need an extra set of hands if it's near Canton.
 
Thru studs

Make certain that you re-torque all thru-studs before turning the prop; you don't want to rotate the journal bearings.

The crank throw for each cylinder must be near top center to install the cylinder using a ring compressor. How would you propose to install four cylinders without turning the crank???
The Lycoming overhaul manual only says to start with cylinder number one when installing cylinders.
If the crankcase halves have been properly torqued I see no way that the main bearings can rotate just from turning the crank.
 
Lycoming suggests you remove and replace the cylinders one at a time on a used engine so that all the thru cylinder bolts aren't all loose at the same time, but there is no chance the bearings will spin. It's not possible, they are indexed.

When installing the new or overhauled cylinders you won't be using a ring compressor, the pistons should be installed in the cylinders, ready to go. You just slide the piston right to the pin opening, push the pin in the piston and rod, then push the piston back down the cylinder and screw on the nuts. Don't forget the O-ring!
 
Lycoming suggests you remove and replace the cylinders one at a time on a used engine so that all the thru cylinder bolts aren't all loose at the same time, but there is no chance the bearings will spin. It's not possible, they are indexed.

When installing the new or overhauled cylinders you won't be using a ring compressor, the pistons should be installed in the cylinders, ready to go. You just slide the piston right to the pin opening, push the pin in the piston and rod, then push the piston back down the cylinder and screw on the nuts. Don't forget the O-ring!

or the piston pin end caps (plugs lycoming calls them)
 
Cylinders

Lycoming suggests you remove and replace the cylinders one at a time on a used engine so that all the thru cylinder bolts aren't all loose at the same time, but there is no chance the bearings will spin. It's not possible, they are indexed.

When installing the new or overhauled cylinders you won't be using a ring compressor, the pistons should be installed in the cylinders, ready to go. You just slide the piston right to the pin opening, push the pin in the piston and rod, then push the piston back down the cylinder and screw on the nuts. Don't forget the O-ring!
I have to very strongly disagree. My factory new Lycoming cylinders came with the pistons in separate boxes, the rings packaged separately etc.
I totally agree that it is impossible for the main bearings to rotate IF the case has been properly assembled.
 
Home-made out of a piece of pipe, short piece of aluminum, and some allthread.

Yep, I was working on the same thing last year until 15min with a heat gun did the trick. My process was a bit more of a strap of 16ga.
 
I have to very strongly disagree. My factory new Lycoming cylinders came with the pistons in separate boxes, the rings packaged separately etc.
I totally agree that it is impossible for the main bearings to rotate IF the case has been properly assembled.

Yes, unfortunately Lycoming does not set the ring gaps and install the pistons like everyone else does. But the cylinders should be assembled before installing them to the cases, it's much easier then putting the piston on the rod first.
 
Updated Information - More Pics

So, the jug I pulled that we have been discussing was #1. Tonight I pulled #3.

First, let me say that "tapping out" the pin with a socket drive extension is not the right way to go. Its easy to damage the end of the pin. Don't do it. I should have listened to my gut and ignored that one.

So, the piston on #3 looks very similar to #1. It may be slightly less scored on the top. The bottom is perfect.

I inspected with a dental mirror and (crappy) borescope, and my fingers, all the lifter faces and cam lobes. As far as I can tell, the lifters and cam lobes are gorgeous. They feel silky smooth, there is no burr on the apex of the cam lobes, and as far as I can tell they look great. Perhaps I don't know what I'm looking at, but I think they look textbook for a 900 hour engine. The lifter faces are perfectly flat, shiny, in fact they remind me of a CD. Silver and shiny with a concentric circle.

Pictures of #3 and #1 piston are here. First shown is #3 top, bottom, and various views. Then some of #1.

Pictures of all the cam lobes and lifters are here. Some pics are bad, but all the lobes are lifters look pretty much identical. These pics are working from the rear of the engine to the front.

I'm stumped.
 
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It got hot. Why? Dunno but have the cylinder shop measure. Armed with this knowledge I would get all four cleaned up and a set of new ECI pistons and rings.

Now you know what needs to be done.
Let's Roll!
Pine Bluff Clinic is in 3 weeks:D
 
It got hot. Why? Dunno but have the cylinder shop measure. Armed with this knowledge I would get all four cleaned up and a set of new ECI pistons and rings.

Boy, (hot) it sure did. Pretty clear now. The anti-thrust side is what a piston should look like. One pict had a wear spot near the oil ring, probably due to the piston expansion due to heat.

No hard evidence, but it sure looks like overheating was the root cause of the scuffing/galling. Now, what caused the heat? Clearance? Advanced timing? Leaning? Cooling/heat during break-in? Combination? Temporary marginal lubrication? If it is lubrication, then the other cylinders will look much different.

You might consider cooling jet mod, in this process. (not sayin' it's related to root cause)

Hey Bob, I looked up piston/bore clearances and Superior seems to say .0045" to .0065" at the skirt. Is this typical for this engine, parallel, no turbo, no jets?

I seem to remember conti at 12-15 thou but that was a turbo engine and the pistons got really hot. The clearance was sized for running into a rain storm and shrinking the barrels onto the pistons and stopping the engine. (not through foresight)
 
No hard evidence

Hey Bob, I looked up piston/bore clearances and Superior seems to say .0045" to .0065" at the skirt. Is this typical for this engine, parallel, no turbo, no jets?

The evidence the pistons got hot is judging by the amount of oxidized (burned) oil residue stuck to them.

What I do is measure the piston and aim to hone 0.004" cylinder larger than that. Since I have a Sunnen portable hone it takes a LONG time and some sweat to get to the right bore dimension.
 
It got hot. Why? Dunno but have the cylinder shop measure. Armed with this knowledge I would get all four cleaned up and a set of new ECI pistons and rings.

Yes. I'm planning on pulling #2 and #4 this weekend. I anticipate that 2-4 will need rehoning and cleaning, #1 I'm not sure about. New set of rings and pistons

When I pull #2 and #4 I will determine if the wear is on the top or the bottom. If its on the top (non thrust side) it will be a real puzzle.

I actually expected an overheated piston to show wear all around the skirt, not just on one side.....

Now you know what needs to be done.
Let's Roll!
Pine Bluff Clinic is in 3 weeks:D

I know, I know...........fingers x'd I can make it.

Love this stuff.

Pull 2 and 4.

So, now the questions are:

- Do I take this opportunity to put in higher comp pistons? say 9:1 or 9.5:1? Is there any real benefit/drawbacks?

- Do I take this opportunity to install piston skirt nozzles?

I'm inclined to stay with 8.5:1 pistons and to go ahead and install the nozzles. As I understand it, they basically just screw in in place of the plugs. Lycoming says to clean and test they open at (I think) 20 psi. s/b easy enough to do.
 
What I do is measure the piston and aim to hone 0.004" cylinder larger than that. Since I have a Sunnen portable hone it takes a LONG time and some sweat to get to the right bore dimension.

Beyond my skill level. I'm sending them out. :D
 
9 or 9.5:1 is a good compromise. 10:1 seems to be hard on things like prop shank bearings. I have friends that have run 10:1 and they run into those sorts of problems.

I would not put the squirters in unless you have a large oil cooler like the Positech that's used in the RV-10.
 
Martin, I have used Don George in Orlando for cylinder work many times. His pricing and turnaround time is better than most, and the quality of the workmanship has always been very good.

Pistons are cheap, even if you have some that are not worn, the shop labor rate to thoroughly clean and decarbon costs about as much as a new piston.
 
The evidence the pistons got hot is judging by the amount of oxidized (burned) oil residue stuck to them.

Oh-yes, I totally agree. I meant no hard evidence of what caused the pistons to be hot.

7 whys to problem solving.

1. I have low compression. Why - because the piston scuffed and fouled the rings.
2. why did the piston scuff? - the piston overheated - reduced oil film, material strength and resulted in metal transfer
3. Why did the piston overheat? ---here is where the hard evidence is needed

What I do is measure the piston and aim to hone 0.004" cylinder larger than that. Since I have a Sunnen portable hone it takes a LONG time and some sweat to get to the right bore dimension.

Thanks, that is what I was looking for.

Why just one side of the piston? Firing pressures putting side loads on this side after top center due to rod angle as the crank turns. See the linked force vs crank angle for the LSX. This is similar for all engines. Long connecting rods help reduce this force. It is part of the design process.
 
...Do I take this opportunity to put in higher comp pistons? say 9:1 or 9.5:1? Is there any real benefit/drawbacks?...

There are lots of opinions on this and I have no direct experience, but rather than look at the endless opinions from apparently qualified people, you might seek someone who has done the switch on a running engine. There's a member on this forum who's pulled 10-1 pistons out of his 200HP and replaced them with the stocker 8.7 and saw essentially zero noticeable performance change, but improved temp behavior.

My decades of building hot rod cars tells me that there is benefit to higher compression in most cases, but in actual practice with air cooled aviation engines, the problems seem to mount faster than the benefits.

My advice is to look for actual was/is data, and not rely on the single data point dyno claims from an engine builder.
 
It is good to see that the analysis showed some metal showing up. However, what brought you to this discovery is the fact that you could not dial in your idle. Lycomings give lots of warning when something is wrong. The oil analysis provided no value to you other than hind sight....
 
That much aluminum off of all pistons should have been clearly visible in the filter. It shouldn't take oil analysis to see that there was something not good going on in the engine.

Unless of course you just missed it when examining a filter with dirty black oil. When I look at filters I cut them up into two pieces, wrap them in paper towels and squeeze the oil out of the filter media with a vise. Anything shiny is then really easy to see.
 
That much aluminum off of all pistons should have been clearly visible in the filter. It shouldn't take oil analysis to see that there was something not good going on in the engine.

Unless of course you just missed it when examining a filter with dirty black oil. When I look at filters I cut them up into two pieces, wrap them in paper towels and squeeze the oil out of the filter media with a vise. Anything shiny is then really easy to see.

That's the thing, I cut open the filter in april, squeezed the filter media in a vise to remove excess oil, and looked in all the pleats. There were a couple of tiny aluminium particles - literally a couple, some black carbon specs, and next to nothing on the magnet.

I'm really thinking there was an earlier event, possibly much earlier, that caused a lot of damage, and its just been slowly building to this since then.

Yes, point about the oil analysis is taken. Spoke to several people about the analysis, including Blackstone, and was told numbers were not particularly worrisome especially as they were steady over a long time without spikes.

The cam and lifters seem good to me. I'm going to try and get another set of eyeballs on them this weekend. Bob did you get a chance to look at those at all?
 
Scuffing Cause?

T
I'm really thinking there was an earlier event, possibly much earlier, that caused a lot of damage, and its just been slowly building to this since then.

Perhaps the engine had been previously ground run without the cowl? This has been known to cause cylinder problems due to poor and uneven cooling.

Skylor
RV-8
 
Or piston slap due to excessive piston/bore clearance.

I once tore down a big block Chevy with piston slap (could hear it at idle). It had heavy scoring on the skirt, but can't remember now if the scoring was high or low on the piston. The slap was caused by galling in the bore of the piston holding the pin. The inability to freely rotate was causing the slap. Something to look at in your investigation.

Larry
 
An observation or two if I may
1. The piston in question is toast,an oil burner,making metal. It has a specific weight and should match the weight of the other 3 pistons so the replacement pistons need to be matched for weight also.
2. The piston pin in the photo is a one piece Superior pin with the end plugs pressed in. Nothing wrong with this pin,I have a set and plan to use it in one of my engines. A piston pin removal tool (press) with a soft face buffer would be the best way to remove this if your planning to reuse it.
Lycoming has superseded to heavy wall pins with bronze silicone end plugs and must be replaced as a set of 4 (weight issue).
As to the scuffing,I also concur with Rocket Bob, I believe this is a clearance/heat issue.IMHO all four cylinders should be overhauled and new matching pistons & rings gaped and installed by the overhauler.
RHill
 
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My 2 cents.....Doesn't matter if you ruined the piston pin removing it. It was already junk. The piston pin plug is severely worn. Most likely responsible for the elevated aluminum in the analysis, along with any others that are completely shinny and showing a star wear pattern like the one in the picture. To me you have had some heat. The scoring on the piston happens all the time in Lycoming engines and is not directly from the heat, in my opinion. Most times that scoring is from carbon getting in between the piston and the bore. From the appearance of the piston I think you will find the skirt pretty worn and a cause for replacement. Notably, the wear on the top of the piston above the rings makes me think the piston was running slanted due to the presumed skirt wear. You would like to see the skirt clearance in the area of .010 upon reassembly. The book allows significantly more but any more than .012 or so won't work so well in my experience. If the skirt is as worn as I think it is, the heat may have been from the blow by, caused by the rings not seating properly as the piston tilted and stopped the rings from being perpendicular to the cylinder walls. The rings are pretty worn and helping to cause the oil burn issue in that cylinder, as well. In my opinion, there is absolutely no evidence of detonation or pre ignition in the pictures that were posted. Both will cause a very clean combustion chamber, this cylinder and piston, is very carboned up from the oil usage. In addition. detonation will burn the edges of the piston and leave signature scaring on the piston dome. Which is visual, as the piston dome would be clean of carbon and you would be able to see it, had either pre ignition or detonation occurred. I don't see any of these classic signs in any of the pictures. Of course after cleaning some evidence may be there from a long ago occurrence but If it is there, in my opinion, the event was not significant in the overall picture of things.
Don't see anything in the pictures to account for the high steel in the oil analysis.
I think the alum flakes you saw on last filter inspection were from the piston pin plugs and there may be more in the suction screen...maybe not but I would definitely look. Also, if it were mine, I would really clean the cooler well. It is a great place to catch those alum flakes from the piston pin plugs before they get to the filter.
Good Luck,
Mahlon
 
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Hi Mahlon,
Good to see you post. Would you favor the SL one piece pin over the Lycoming heavy wall & silicone Bronze set up? What pin did you use in your engines?
RHill
 
We had problems with both the aluminum bronze plugs and the piloted insertable aluminum plug lw-11775 as well as the one piece pins from eci and superior which had a non removable plug like the lw-11775. So we used the aluminum 60828 plugs. Still would have one go bad occasionally but had the best luck with them.
Pecking order for us was 60828, lw-11775 or equivalent, 72198
Good Luck,
Mahlon
 
This is great stuff Mahlon,Thank You! Man I really miss you guys and the huge base of information that was Mattituck Long Island.Have you and John thought about writing a book on how to build an RV engine that holds up? I know I'd buy 10 copy's
RHill:)
 
I really don't understand why Lycoming doesn't get in sync with the rest of the world and use circlips to retain the pins.
 
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