My engine fell out

teejayevans said:
Can someone explain the advantages of chrome cylinders...because unless you have a chrome cam, what’s the point (I’m assuming rust resistant is it’s selling point)?
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Chrome cylinders in general,,this is a repair procedure, to get the cylinder back to the OEM size, so standard size pistons can b re-used.
there was a time that cylinders were difficult to get new, so a procedure was approved to plate the bore back down to standard size and start over.
Problems occurred because the chrome plating and the steel cylinders will expand and contract at different rates, thus the internal bore looks like a crazed window with tiny cracks running everywhere.
Chrome is very hard and wears slowly, so chrome rings can not be used, regular old cast iron rings must be used, these wear very quickly, and on occasion would wear out before the cylinder became smooth.
when the bore looks like a crazed window, these cracks must fill with carbon and be polished smooth before a ring will actually stop burning oil.
and yes a chrome cylinder will not rust,, this is not your common bumper pretty chrome
 
Salty said:
The engine looks to be in pretty good shape overall. Interestingly, the top end has been overhauled, but it has some pretty major issues. 3 of the 4 cylinders have broken rings, in one case it's a real mess. The valves don't look to be bad. I haven't removed the rocker covers yet to see how it looks, I will likely buy new cylinders now that I see the situation.

On the bottom end, The intake followers on cylinder 1 and 2 were both badly pitted, and the cam is really munched on that lobe. The crank shaft and all bearings have no issues from a naked eye perspective, and the accessory drive train gears look pretty darn good for 52 years. I haven't disassembled the oil pump yet, so not sure about that one.

Before disassembly
View attachment 57709

Piston #4 is toasted
View attachment 57710

Broken ring from #4
View attachment 57711


The intake for cylinder 1 and exhaust for cylinder 2 were both corroded and pitted badly. They share the same lobe in the camshaft picture that is badly worn.
View attachment 57712

The rods and associated bearings look to be in good shape
View attachment 57713


This is what all but one of the lobes look like
View attachment 57714


This is the lobe that was driving the pitted followers.....View attachment 57715


cleaned up crankshaft
View attachment 57716
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Salty, just curious has this engine been operated using lean of peak procedure versus rich of peak? Thanks for sharing your findings, very interesting!
 
Tom-D said:
Lots of times the rings will break like that when removed with out supporting them. when allowed to snap as they leave the bore, they will break.
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I had an A&P on either side of me when I removed the cylinders and they watched the rings fall out as I removed the cylinders. I thought I'd done something wrong, but they both assured me i did not break them. This is supported by the fact that on cylinder 4 the ring was broken and jammed into the piston, clearly that did not happen on removal, and cylinder 2 the ring is not broken, only stuck and not floating. So, at best I may have broken the ring in cylinder 3 when removing, but I doubt it.
 
Briar Rabbit said:
Salty, just curious has this engine been operated using lean of peak procedure versus rich of peak? Thanks for sharing your findings, very interesting!
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obviously I have no way of knowing how it was operated before I started flying it, but for the last 300 hours it has not been operated LOP.
 
so....were the cylinder walls scored? That should be inspectable....using a borescope.
 
Checkout_my_Six said:
so....were the cylinder walls scored? That should be inspectable....using a borescope.
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I haven't done any analysis of the cylinder walls yet beyond visual inspection. I'm curious why I'd need a borescope to inspect a removed cylinder. For magnification?
 
Salty said:
I haven't done any analysis of the cylinder walls yet beyond visual inspection. I'm curious why I'd need a borescope to inspect a removed cylinder. For magnification?
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you wouldn't need a borescope...but, I look at cylinder every time the spark plug comes out. We're talking about a $40-50 USB dental camera.....or $200 for a nicer one.

My point is that you could have seen this long before you were surprised.....and I bet those were broken for hours. It just didn't happen. I'm fairly certain there are score marks on those cylinder walls with that kind of damage.

I'm not beating on you.....just selling cheap camera (borescope) inspection and the benefits.
 
Checkout_my_Six said:
you wouldn't need a borescope...but, I look at cylinder every time the spark plug comes out. We're talking about a $40-50 USB dental camera.....or $200 for a nicer one.

My point is that you could have seen this long before you were surprised.....and I bet those were broken for hours. It just didn't happen. I'm fairly certain there are score marks on those cylinder walls with that kind of damage.

I'm not beating on you.....just selling cheap camera (borescope) inspection and the benefits.
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I'm not seeing visible issues with the walls. Not sure borescope would have detected it.
 
Even running a nail along the wall doesn't find anything horrible. I'm not expert so I'm waiting for someone with experience to take a closer look, but there's nothing that jumps out to my inexperienced inspection.
 
Salty said:
Even running a nail along the wall doesn't find anything horrible. I'm not expert so I'm waiting for someone with experience to take a closer look, but there's nothing that jumps out to my inexperienced inspection.
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interesting....if it was scored, you'd feel it with your finger nail.
 
Checkout_my_Six said:
you wouldn't need a borescope...but, I look at cylinder every time the spark plug comes out. We're talking about a $40-50 USB dental camera.....or $200 for a nicer one. My point is that you could have seen this long before you were surprised.....
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And this is why I held my breath while you inspected my cylinders/valves a coupla weeks ago... need to look cuz if it's bad, it's only going to get worse and fail at the most inopportune time. But do I want to see what's there? Yes... but...?
 
Checkout_my_Six said:
you wouldn't need a borescope...but, I look at cylinder every time the spark plug comes out. We're talking about a $40-50 USB dental camera.....or $200 for a nicer one.

My point is that you could have seen this long before you were surprised.....and I bet those were broken for hours. It just didn't happen. I'm fairly certain there are score marks on those cylinder walls with that kind of damage.

I'm not beating on you.....just selling cheap camera (borescope) inspection and the benefits.
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Chrome cylinders seem to be resistant to the scoring you are talking about. One of the worst looking pistons and set of rings I’ve pulled out of an engine came out of a chrome placed bore which showed no signs of damage prior to removal. In fact, you could have stuck a new piston and ring set in that bore and ran it as is.

But I agree. In my opinion, from what I’m seeing in the photos there is no way those rings just broke recently. I suspect they were broken for quite some time. I also suspect this engine was making metal for a while but not noticed, with the condition that cam is in.

I’m no engine expert but I’ve overhauled a number of these engines and know what I’ve seen with them. I’d be very surprised if there weren’t some warning signs, however subtle they may have been.
 
mondtster said:
I suspect they were broken for quite some time
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If you get enough broken rings per cylinder, you can make a pretty impressive smoke screen, but the engine tends to keep running. (I had a car that was so bad that you had to roll the window down to see when a traffic light turned green...)
 
Capt. Geoffrey Thorpe said:
If you get enough broken rings per cylinder, you can make a pretty impressive smoke screen, but the engine tends to keep running. (I had a car that was so bad that you had to roll the window down to see when a traffic light turned green...)
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if the bottom ring stays in tact....no smoke will form.
 
Capt. Geoffrey Thorpe said:
If you get enough broken rings per cylinder, you can make a pretty impressive smoke screen, but the engine tends to keep running. (I had a car that was so bad that you had to roll the window down to see when a traffic light turned green...)
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an engine will run without rings if you get it spinning up fast enough. Friend tried that with a two stroke racebike. Had to really get it rolling on the starting rollers before it made enough compression to run, but it ran.
 
Salty said:
I had an A&P on either side of me when I removed the cylinders and they watched the rings fall out as I removed the cylinders. I thought I'd done something wrong, but they both assured me i did not break them. This is supported by the fact that on cylinder 4 the ring was broken and jammed into the piston, clearly that did not happen on removal, and cylinder 2 the ring is not broken, only stuck and not floating. So, at best I may have broken the ring in cylinder 3 when removing, but I doubt it.
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I didn't mean to imply you broke these, from what I read here, I see the cylinder walls were OK, then why were they rejected?
 
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Tom-D said:
I didn't mean to imply you broke these, from what I read here, I see the cylinder walls were OK, then why were they rejected?
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Rejected by what?
 
Tom-D said:
I read that you were buying new, and made the assumption they were rejected for a reason.
OBTW I'd buy new too.
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Oh, gotcha. They were rejected by my lack of faith in them based on what little I've seen of them already, and the lack of information I have on them.
 
UngaWunga said:
an engine will run without rings if you get it spinning up fast enough. Friend tried that with a two stroke racebike. Had to really get it rolling on the starting rollers before it made enough compression to run, but it ran.
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It's true. Engines really just need the compression rings for the sake of starting the engine. Once the engine is running, they really aren't needed. This is why there is no special graph in the POH showing different performances for take off and climb as the engine ages. The OP's engine was likely making 180 HP. His new engine will Make 180 HP. An O-360 with no compression rings in it that is running will make 180 HP.

Once the pistons are up to speed, the amount of fuel air mixture leaking by a piston with no rings during the time it has to do so in the compression and power strokes is negligible. In theory the ringless engine will make less HP, but it's so small it's barely measurable.
 
Dav8or said:
It's true. Engines really just need the compression rings for the sake of starting the engine. Once the engine is running, they really aren't needed. This is why there is no special graph in the POH showing different performances for take off and climb as the engine ages. The OP's engine was likely making 180 HP. His new engine will Make 180 HP. An O-360 with no compression rings in it that is running will make 180 HP.

Once the pistons are up to speed, the amount of fuel air mixture leaking by a piston with no rings during the time it has to do so in the compression and power strokes is negligible. In theory the ringless engine will make less HP, but it's so small it's barely measurable.
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Depends on how you define "need". You will have a lot more blow-by without rings, and ultimately you'll have less power to some extent and also shortened engine life as a function of the blow-by.

However, it will run.
 
what is the effect of the two exhaust valves not opening fully due to the lobe wear? What happens when an exhaust valve doesn't fully open?
 
Capt. Geoffrey Thorpe said:
Less poop going to the fan.
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Can I get a more useful description?

would less exhaust be expelled? This seems unlikely. More likely logically I would think it would produce drag on the exhaust stroke (more air resistance against the stroke), but most if not all of the air would be exhausted. I would also assume higher cylinder temperature from more friction / higher pressures, but I'm stretching on that one.
 
Salty said:
Can I get a more useful description?

would less exhaust be expelled? This seems unlikely. More likely logically I would think it would produce drag on the exhaust stroke (more air resistance against the stroke), but most if not all of the air would be exhausted. I would also assume higher cylinder temperature from more friction / higher pressures, but I'm stretching on that one.
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Airflow is a function of area and differential pressure. You're reducing the area, thus your flow will reduce. Not a ton, but some. If you put that engine on the dyno I bet you'd have seen a power loss on it.
 
Ted DuPuis said:
Airflow is a function of area and differential pressure. You're reducing the area, thus your flow will reduce. Not a ton, but some. If you put that engine on the dyno I bet you'd have seen a power loss on it.
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I think you're saying the same thing I am. Squeezing the air out of a smaller hole will take more power from the power stroke of another cylinder that would have otherwise been used to turn the prop.
 
Salty said:
Can I get a more useful description?

would less exhaust be expelled? This seems unlikely. More likely logically I would think it would produce drag on the exhaust stroke (more air resistance against the stroke), but most if not all of the air would be exhausted. I would also assume higher cylinder temperature from more friction / higher pressures, but I'm stretching on that one.
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Less opening results in less exhaust flow - you are pushing though a smaller hole. This results in higher exhaust residuals in the cylinder which, in turn, means less fresh charge mass during the intake stroke. Less charge mass, less power. Exactly how much, well it depends on how much flow was lost. It's all about getting the burned gas out, and the fresh charge in. Secondary effect would be more pumping work loss due to higher pressures in the exhaust stroke.

When you build a hot rod, you get a cam with more lift and more overlap to allow more exhaust / intake flow. Restricting that flow limits how much poop the engine has.
 
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No. :( I've been out of town all week.
 
Salty said:
I think you're saying the same thing I am. Squeezing the air out of a smaller hole will take more power from the power stroke of another cylinder that would have otherwise been used to turn the prop.
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Engine is an air pump. Restrictions in the flow of air through it reduces power.
 
Ted DuPuis said:
Depends on how you define "need". You will have a lot more blow-by without rings, and ultimately you'll have less power to some extent and also shortened engine life as a function of the blow-by.

However, it will run.
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True, but hypothetically, would it not more or less perform normally other than starting, if you removed the compression rings, but retained the oil ring?
 
First feedback from the experts in now...

Crankshaft is not bad. They will need to grind it down, but it's well within tolerance. Their recommendation is to replace most of the gears, which I will follow. A few of them appear to be ok, but they need to clean and inspect closer. Oil pump parts are all disposable. AD's require replacement of all but one part and it's worn.
 
His theory regarding the bad cam lobe is that the followers pitted before I purchased the plane, and they ground the camshaft down in the last year I operated it.

I still haven't gotten the results back from the oil analysis yet to see if it's worthless or not.
 
Salty said:
First feedback from the experts in now...

Crankshaft is not bad. They will need to grind it down, but it's well within tolerance. Their recommendation is to replace most of the gears, which I will follow. A few of them appear to be ok, but they need to clean and inspect closer. Oil pump parts are all disposable. AD's require replacement of all but one part and it's worn.
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Two thoughts.

1. Did the shop actually recommend gear replacement or did they reject the gears? I've never had a shop recommend replacement, they either pass or fail.

2. Which AD is requiring oil pump replacement? If it is the one I'm thinking of, the AD should have been complied with over 10 years ago. I'm not surprised it's not though, nearly every mechanic I've worked with doesn't read it right.
 
1. He hadn't even cleaned them yet. I rejected them based on his recommendation after a quick glance at them.

2. He didn't cite the specific AD. I also am not surprised. If you come across the one you're thinking of let me know.
 
oil pump gears are typically on the 100% replacement parts list for overhaul IIRC
 
bnt83 said:
oil pump gears are typically on the 100% replacement parts list for overhaul IIRC
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I think I remember reading that in the manual.
 
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