Ever seen this?

D

Der Fliegermeister

Pre-takeoff checklist
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Disclaimer: I am not the owner nor the mechanic that found this, though the latter is a good friend who shared the photo with me.

Seems this is a recent overhaul and the entity performing it didn't properly set the rocker clearance or something to that effect. Engine is on a Seminole.

Just thought it was interesting to see. Great day, all! IMG_20210804_155715.jpg
 
I'm curious how this would present itself to a pilot, if at all.
 
Der Fliegermeister said:
Disclaimer: I am not the owner nor the mechanic that found this, though the latter is a good friend who shared the photo with me.

Seems this is a recent overhaul and the entity performing it didn't properly set the rocker clearance or something to that effect. Engine is on a Seminole.

Just thought it was interesting to see. Great day, all! View attachment 98938
Click to expand...
Yes I have seen that before. Is that a H2AD?
 
Gary Ward said:
Yes I have seen that before. Is that a H2AD?
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Not sure, Gary. Sounds right to me but can't guarantee it. I haven't seen this thing in person. I know this isn't the first time something like this head happened to that model
 
Der Fliegermeister said:
Not sure, Gary. Sounds right to me but can't guarantee it. I haven't seen this thing in person. I know this isn't the first time something like this head happened to that model
Click to expand...

So the question is, why are the rocker arms trashed and what is to be done about it? I found one SDR with the control # CA991210021 all it said was the rocker arms were replace after one was found damaged.
 
Dang, that’s seriously messed up! 34 years as an A&P and I’ve never seen one go all the way through a rocker like that. Both rockers at that!
Had one cut into a rocker pretty deep last year, but nothing like this. What caused it? Guessing stuck valves maybe?
 
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Looks to me like during assembly the rockers were tightened down far too much and with no clearance something had to break.

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A Martin said:
Looks to me like during assembly the rockers were tightened down far too much and with no clearance something had to break.
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Appears so but I think the mechanic would feel binding and resistance in the rotation of the engine.
 
Daleandee said:
Appears so but I think the mechanic would feel binding and resistance in the rotation of the engine.
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Not sure if it a hydraulic lifter .... if dry they can be partly collapsed during assembly and everything turns OK ... until running oil pressure gets fluid into the lifter ... just a guess on my part .... also notice the right hand rocker is damaged/split on the lower end (opposite end of the pushrod location) ... some brutal forces required for that ..... I would be curious how many threads down the nut would go in a proper installation compared to these ones .

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That is odd. I would expect the pushrod to bend well before it split through the rocker. Something else going on maybe?
 
Der Fliegermeister said:
Disclaimer: I am not the owner nor the mechanic that found this, though the latter is a good friend who shared the photo with me.

Seems this is a recent overhaul and the entity performing it didn't properly set the rocker clearance or something to that effect. Engine is on a Seminole.

Just thought it was interesting to see. Great day, all! View attachment 98938
Click to expand...

Wonder how many hours are on those rockers? The stamped steel rockers like that do wear out.
 
Gary Ward said:
Wonder how many hours are on those rockers? The stamped steel rockers like that do wear out.
Click to expand...

If this is a Lycoming “76” engine, which it appears to be or at least similar to, the rocker arms are supposed to be replaced at overhaul. Presumably this was done so the hours are probably minimal.
 
Daleandee said:
Appears so but I think the mechanic would feel binding and resistance in the rotation of the engine.
Click to expand...

You assume that the “mechanic” has a feel for things and actually understands what’s going on. Most I’ve seen do not.
 
mondtster said:
You assume that the “mechanic” has a feel for things and actually understands what’s going on. Most I’ve seen do not.
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Well I was trying to use the term "mechanic" in its proper form. ;)

Another poster mentioned that with hydraulic lifters there is some travel in the lifter until the oil pressure fills it. That is true and while it's difficult to know how the damage in the photo occurred it appears to be a lot more pushrod sticking through the rocker than there is room in the lifter after setting the preload.

Having said all of that I can only give my experience from experimental/auto engines so I could be really wrong and talking through my hat. o_O
 
Jdm said:
Dang, that’s seriously messed up! 34 years as an A&P and I’ve never seen one go all the way through a rocker like that. Both rockers at that!
Had one cut into a rocker pretty deep last year, but nothing like this. What caused it? Guessing stuck valves maybe?
Click to expand...

Something is not adding up in that picture IMO

wouldn’t you see some bluing on the push rod tip?

I am not a AP but have removed all 4 clys on a 76 and reinstalled them with a AP/IA help. Then I flew it another 100 hours before swapping out the motor.

I rebuilt my first motor in 1980 out of necessity so I had a car to drive when I was 20. Since then I have built plenty of new motors and rebuilt others.

setting pre load on a hydraulic lifter motor has always been a black art that many mechanics don’t understand.

I have trouble believing that in this case.
I have seen damage from using the wrong push rod tip size that do not match the cup size in the rocker.


I have seen this happen on hi mileage chevy and mopar motors.
 
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Gary Ward said:
Something is not adding up in that picture IMO

wouldn’t you see some bluing on the push rod tip?

I am not a AP but have removed all 4 clys on a 76 and reinstalled them with a AP/IA help. Then I flew it another 100 hours before swapping out the motor.

I rebuilt my first motor in 1980 out of necessity so I had a car to drive when I was 20. Since then I have built plenty of new motors and rebuilt others.

setting pre load on a hydraulic lifter motor has always been a black art that many mechanics don’t understand.

I have trouble believing that in this case.

I have seen this happen on hi mileage chevy and mopar motors.
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I removed the clys because it was using 1qt oil every 3-4 hours. I found very little wear on clys. I did find the oil control ring and the 2 compression rings lined up with one another on 3 out of 4 pistons.

I spaced them apart when I put it back together and the oil consumption went to 1qt to 8 or 9 hours. Big big difference and the motor ran the best it ever did for me. It had 1700 hours on it and was 40+ years old. Just a FYI.
 
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Gary Ward said:
Something is not adding up in that picture IMO

wouldn’t you see some bluing on the push rod tip?
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I suspect the engine didn't run long enough to have any lube problems causing heat damage. It looks to me like there was probably some component interference and mechanical force that drove the pushrods through the rocker arms.

Without knowing anything else about the engine other than what can be seen in the picture, I'd consider everything in it suspect until it could be proven otherwise.
 
Gary Ward said:
setting pre load on a hydraulic lifter motor has always been a black art that many mechanics don’t understand.
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Indeed, it's a black art. But if the "mechanic" took time to understand the system it really wouldn't be. In more recent times the OEMs have designed out the need to understand the system, probably because so many people didn't.
 
mondtster said:
I suspect the engine didn't run long enough to have any lube problems causing heat damage. It looks to me like there was probably some component interference and mechanical force that drove the pushrods through the rocker arms.

Without knowing anything else about the engine other than what can be seen in the picture, I'd consider everything in it suspect until it could be proven otherwise.
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Good point, it doesn’t look like it ran long.

Wow that is a hi dollar problem to have!
 
mondtster said:
Indeed, it's a black art. But if the "mechanic" took time to understand the system it really wouldn't be.
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Spot on! I've always learned to get to "zero lash" (even that is not well understood) and then use the given specification for setting lifter preload.
 
I saw something very similar once. Right after I missed a shift and the engine hit over 10,000 rpm.

And the rockers were not stamped steel.
 
bnt83 said:
Can I assume the piston hit the valves?
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Wouldn’t assume anything with this one, but I don’t think so. Being the push tubes are busted through the rockers, both valves should be in the closed position, unless they are stuck.
Unfortunately, this might require more than just a cylinder change to correct the problem now.
 
Zeldman said:
I saw something very similar once. Right after I missed a shift and the engine hit over 10,000 rpm.

And the rockers were not stamped steel.
Click to expand...

Reminds me of the early LS1 Camaro with the 6-speed…Trans mounts were soft, so the 6000 RPM up shift became a downshift as the trans rolled over…

GM ate a few engines on that one.
 
How about if, rather than 'jammed' frozen, without slack (which seems like would bend pushrods), this happened because of too much slack, allowing the pushrods to hammer on the rockers, battering-ram style? Maybe valves stuck open, collapsed lifters, or such? (Just a total WAG).
 
I would tend to agree with the preceding post.

It appears to be a “76 Series “ engine such as a O-320H2AD.

Dry Lifter Clearance is the desired “Working Range “ of the Lifter.

Dry Lifter Clearance can be adjusted via shims under the “ pivot block”.

Too many shims will result in excessive DLC.

If the Lifter was flat due to something holding the Check Valve open

it could in hammering drscribed.
 
So it's a TO-360-E1A6D. Nice airplane overall even for a Piper...but this one will be expensive for the guy
 
Magman said:
It appears to be a “76 Series “ engine such as a O-320H2AD.
Dry Lifter Clearance is the desired “Working Range “ of the Lifter.
Dry Lifter Clearance can be adjusted via shims under the “ pivot block”.
Too many shims will result in excessive DLC.
Click to expand...

Great info! I thank you as I learned something about how these liters are set. From the manual:

Be sure that the piston is at top center of the compression stroke and both valves are on the base circle of the camshaft. Check clearance between the valve stem tip and the valve rocker arm. In order to check this clearance, place the thumb of one hand on the valve rocker directly over the end of the push rod and press down so as to compress the hydraulic lifter spring. While holding the spring in the compressed position, measure the clearance between the valve stem tip and the rocker arm. The clearance should be between .028 and .080 inch. If the clearance does not come within these limits, add or subtract shim under the rocker fulcrum as required to correct the clearance. After clearance is set, remove plain 5/16-24 nut and install 5/16-24 self-locking nut on fulcrum stud. Torque self-locking nut to 150 in.-lbs.
Click to expand...
 
Der Fliegermeister said:
Disclaimer: I am not the owner nor the mechanic that found this, though the latter is a good friend who shared the photo with me.

Seems this is a recent overhaul and the entity performing it didn't properly set the rocker clearance or something to that effect. Engine is on a Seminole.

Just thought it was interesting to see. Great day, all! View attachment 98938
Click to expand...

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Several weeks have gone by ..... they should have found the cause by now .... have you heard anything ??? .... thanks

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A Martin said:
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Several weeks have gone by ..... they should have found the cause by now .... have you heard anything ??? .... thanks

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Click to expand...
Well, I do know that they pulled that engine for teardown. But the latest I've heard is that the entire shop came down with covid; vaccinated or non. The chief mechanic is nearly recovered, but was the first to get it. So things have slowed down there quite a bit.

Will see if I can prod the boss man for some more details.
 
Maybe the engine saw 4500 rpm ... but I'd think that you'd see more than one cylinder with damage.
 
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