Lycoming IO-540 Camshaft spalling...

dans2992

dans2992

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Dans2992
Has anyone ever gone through a camshaft spalling incident? How much $$$ did it set you back?

I'm starting to be a bit surprised by the bills stacking up for this.

Here's a summary of the issues we had and work that was done. So, anybody want to guess what all this work should cost including removal and re-installation of the engine?

This overhauled engine is maybe 3 years old, 500 hours on it. Sat for 8 weeks while re-doing interior, but we can't figure any other cause for the spalling.

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There are a total of four intake lifters that are spalling. All will be replaced with newer technology lifters and a new cam will also be required. The new lifters are "hyperbolic" which, best as I can tell, means they are allowed to rock a bit in the lifter guide. Apparently overhaul shops are having very good luck with them. I have not done extensive research on them yet, but you can see the Lycoming SI 1011K at http://www.lycoming.com/Portals/0/t...lunger Assemblies and Hydraulic Lifter....pdf

The lifter metal bouncing around the crankcase has put grooves in all of the pistons so they will all be replaced along with the rings. The steel cylinders are hard enough that the marks are not deep and can be removed with cylinder honing.

They will also replace all bearings, low cost and easy to do.

For good measure they will also hone all of the exhaust valve guides. Very easy to do with the cylinders off and a precautionary action to reduce the probability of stuck exhaust valves.
 
I think the best value is just exchange the short block for a roller cam model.
 
I haven't been paying attention. Have the decided that the roller tappets aren't the way to go, and that these hyperbolic tappets are better?
 
I'd go ahead and major it myself. You're going to be almost there anyway.

I had an 0-320B2B that had cam corrosion and overhaul is what I did. I bought a brand new cam. I suspect reground cams are most of the problem with premature cam corrosion. I wouldn't do roller lifters for any 2700 RPM engine, and roller lifters wouldn't prevent corrosion from killing the cam. Fix it, run it, choose your oil carefully.
 
Stewartb said:
I'd go ahead and major it myself. You're going to be almost there anyway.

I had an 0-320B2B that had cam corrosion and overhaul is what I did. I bought a brand new cam. I suspect reground cams are most of the problem with premature cam corrosion. I wouldn't do roller lifters for any 2700 RPM engine, and roller lifters wouldn't prevent corrosion from killing the cam. Fix it, run it, choose your oil carefully.
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I respectfully disagree...

Roller lifters are far superior to flat tappet ones.. Period... Rolling across a surface versus scuffing across a surface in a no brainer.... Friction is reduced... Corrosion is reduced because parent metal from the cam is now rubbed away by flat tappets... IMHO...

On my V-8, I gained 25 HP from the roller lifters and and another 20 HP from the roller cam bearings....

The concept is known and simple..... Reduce friction..... and HP goes up, oil temps go down....
 
N801BH said:
I respectfully disagree...

Roller lifters are far superior to flat tappet ones.. Period... Rolling across a surface versus scuffing across a surface in a no brainer.... Friction is reduced... Corrosion is reduced because parent metal from the cam is now rubbed away by flat tappets... IMHO...

On my V-8, I gained 25 HP from the roller lifters and and another 20 HP from the roller cam bearings....

The concept is known and simple..... Reduce friction..... and HP goes up, oil temps go down....
Click to expand...

The main improvement to roller cams is the slope designes that are available.
 
Norman said:
Was the overhaul done by Lycoming or an outside shop?
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Outside shop. We've been doing business with these guys for years, so I am reluctant to think anything nefarious is going on...
 
We were using "cam guard" and flying it often. Were we just really unlucky?
 
Stewartb said:
I'd go ahead and major it myself. You're going to be almost there anyway.



I had an 0-320B2B that had cam corrosion and overhaul is what I did. I bought a brand new cam. I suspect reground cams are most of the problem with premature cam corrosion. I wouldn't do roller lifters for any 2700 RPM engine, and roller lifters wouldn't prevent corrosion from killing the cam. Fix it, run it, choose your oil carefully.
Click to expand...


With everything being done, yeah, we're pretty much there already. It sucks from a financial perspective that we only got 500 hours out of the engine.

What advantage would we really have by calling this an "overhaul" rather than just doing what we're already doing? We're not bound by the 2000 hr TBO, we'll do the next overhaul "on condition".
 
dans2992 said:
We were using "cam guard" and flying it often. Were we just really unlucky?
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Probably, there are a couple different issues involved with Lycomings. Besides the rust issue, there were other lubrication issues as well as some soft cams that came out. BTW were you using a semi synthetic oil?
 
Stewartb said:
I'd go ahead and major it myself. You're going to be almost there anyway.

I had an 0-320B2B that had cam corrosion and overhaul is what I did. I bought a brand new cam. I suspect reground cams are most of the problem with premature cam corrosion. I wouldn't do roller lifters for any 2700 RPM engine, and roller lifters wouldn't prevent corrosion from killing the cam. Fix it, run it, choose your oil carefully.
Click to expand...

I tend to agree in the OP's case. Now my long story...

I own an O-540 and we discovered spalling cams during pre-buy and rejected the airplane unless seller agreed to have the repair done at Western Skyways.

Lo and behold, they did agree. The removal, shipping, repair*, and reinstall cost them over $23k.

For another $10k or so I could have had a fully overhauled engine, which would have been a smart thing to do if I intended to sell it any time soon.

But for $0 to me I basically ended up with a MOH anyway because they inspected everything for tolerances or other problems the way they normally do for an overhaul and only replaced items that didn't meet those tolerances or things that were requested.

I doubt that sitting for 8 weeks would cause the spalling you saw but perhaps I'm underestimating the corrosion rates seen in some parts of the country.

In my airplane's case it had sat in coastal Oregon for a long time. That owner did avionics and pretty paint but apparently didn't fly much after a certain point. There was some non-structural/skin corrosion from that too, but not enough to kill the sale.

The pitting on the cylinders was bad enough that my mechanic said he could detect three distinct regions of increasing corrosion as if the piston had been sitting in one position for a very long time. There was also longitudinal scoring from (IIRC) the floating(?) piston bearing. See pics.

Good luck with your engine.



*Services & parts (IIRC) included:


  • Honing Cylinders (due to pitting) by 0.010" (P10 I think it's called?)
  • New P10 Pistons and rings
  • new cam (pretty sure not roller cam)
  • Bunch of testing on the crankshaft
  • New Oil Pump
  • New Vac Pump
 

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Advantage? Market value of a zero SMOH versus a major repair of a 500 hr SMOH engine. The market never views major repairs of low or mid time engines favorably. But that's just me. The real question? What would Henning do?
 
Stewartb said:
Advantage? Market value of a zero SMOH versus a major repair of a 500 hr SMOH engine. The market never views major repairs of low or mid time engines favorably. But that's just me. The real question? What would Henning do?
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LOL, Factory reman to get the roller cam. Engines are the best place to put money in a plane with regards to residual value.
 
Henning said:
The main improvement to roller cams is the slope designes that are available.
Click to expand...

Cam lobe profiles ( slope designs) are a positive aspect of roller cams but not the "main" improvement.... On my motor I designed my cam to fit my needs... Because I want alot of torque and not revving my motor up too high I run a high lift and pretty short duration with minimal overlap... That request needs fast ramp speeds and the ability to set the valve back onto its seat without slamming it down and causing valve cratering..... .

You last answer to the OP is right on though...:thumbsup:
 
N801BH said:
Cam lobe profiles ( slope designs) are a positive aspect of roller cams but not the "main" improvement.... On my motor I designed my cam to fit my needs... Because I want alot of torque and not revving my motor up too high I run a high lift and pretty short duration with minimal overlap... That request needs fast ramp speeds and the ability to set the valve back onto its seat without slamming it down and causing valve cratering..... .

You last answer to the OP is right on though...:thumbsup:
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You just described the advantage I was talking about, the ability to create much steeper and exacting slopes/profiles.;)
 
Henning said:
You just described the advantage I was talking about, the ability to create much steeper and exacting slopes/profiles.;)
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It is an advantage.... But not the main one.......

Reduced friction outweighs advanced profiles....
 
Stewartb said:
Advantage? Market value of a zero SMOH versus a major repair of a 500 hr SMOH engine. The market never views major repairs of low or mid time engines favorably. But that's just me. The real question? What would Henning do?
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That makes sense, if I were planning on selling soon. I have two partners, so any changing hands would likely be among us. This is really motivating me to go fly the hell out of the plane to ensure I get my money's worth!

I almost feel like "hell, if I'm going to be paying this much, I should just go ahead and start flying that Malibu I've been lusting after". Then again, perhaps it could find ways to break even more expensively.... ;)


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dans2992 said:
That makes sense, if I were planning on selling soon. I have two partners, so any changing hands would likely be among us. This is really motivating me to go fly the hell out of the plane to ensure I get my money's worth!

I almost feel like "hell, if I'm going to be paying this much, I should just go ahead and start flying that Malibu I've been lusting after". Then again, perhaps it could find ways to break even more expensively.... ;)


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:rofl: Yeah, you wouldn't exactly be stepping into a maintenance free plane.:rofl:
 
dans2992 said:
That makes sense, if I were planning on selling soon. I have two partners, so any changing hands would likely be among us. This is really motivating me to go fly the hell out of the plane to ensure I get my money's worth!

I almost feel like "hell, if I'm going to be paying this much, I should just go ahead and start flying that Malibu I've been lusting after". Then again, perhaps it could find ways to break even more expensively.... ;)


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Click to expand...

Before you buy, look under the "hood" and see how they stomped the engine in there. It's a maintenance nightmare.
 
I'm not sure the P210 is any better. Were I to ever upgrade, I'd want pressurization and FIKI, but if I can't get those, I have no reason to upgrade. I think 210 or Malibu are the only singles that would fit the bill. I could go multi, but I think you're talking g a whole different league of MX requirements.


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So, is this kind of mx incident about the most expensive "unexpected" maintenance occurrence that could reasonably happen in a piston single?

I'm trying to convince myself that if I can stomach this, I should be able to handle any unexpected piston maintenance. ;)


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Checkout_my_Six said:
I think you hit the maintenance nightmare jackpot....:rofl:


I'm sorry....:(
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With this incident, yes. I'm trying to put a positive spin on it though!

So, $20k to fix this mess is not out of line then from what I'm hearing from you guys...?


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dans2992 said:
With this incident, yes. I'm trying to put a positive spin on it though!

So, $20k to fix this mess is not out of line then from what I'm hearing from you guys...?


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No, as an 'all in' price it's not horrendous as long as they don't take long to do it. It all depends on exactly what gets done.
 
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Henning said:
You just described the advantage I was talking about, the ability to create much steeper and exacting slopes/profiles.;)
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Can you tell me where/ how you would get authorization to change the cam lobe profile in a certified engine?
 
Henning said:
No, as an 'all in' price it's not horrendous as long as they don't take long to do it. It all depends on exactly what gets done.
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It's all in. We are having them do the annual and the gear AD at the same time, but that's not included in he $20k.

It took them longer than it should, but that was due to the fact that they had other people in front of us (who had reservations) and two of the mechanics got sick (pneumonia, and that knocks you out a while). Sort of a perfect storm.
 
Tom-D said:
Can you tell me where/ how you would get authorization to change the cam lobe profile in a certified engine?
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The manufacturer does. You can't hardly help but have a better profile when you make the switch in design. Look at the difference between a roller and flat tappet cam lobe.
 
Henning said:
The manufacturer does
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That is the only way.

Every Radial engine way back to the 30s have roller tappets. But only the latest versions combined them with hydraulic 0 lash lifters.

They are not the end all for lifter problems, they do wear faster, and are sensitive to debris in the oil. The roller will run over trash in the oil and the wear looks like a frosted finish on the cam and roller. then the rougher it gets the faster the wear.
 
Henning said:
The manufacturer does. You can't hardly help but have a better profile when you make the switch in design. Look at the difference between a roller and flat tappet cam lobe.
Click to expand...

So if the cam profiles were better, then wouldn't the roller tappet engines make more power? Hint: they don't.

Also, note that most turbo Lycomings don't get roller tappets. In fact I think the TIO-540-AK1A (T182T) is the only one that gets it, but it might also include other parallel valve turbo engines.
 
so....we don't get to hear about the hardness issues from the tappet supplier?:D:stirpot::ohsnap:
 
Ted DuPuis said:
So if the cam profiles were better, then wouldn't the roller tappet engines make more power? Hint: they don't.

Also, note that most turbo Lycomings don't get roller tappets. In fact I think the TIO-540-AK1A (T182T) is the only one that gets it, but it might also include other parallel valve turbo engines.
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TiO-540-AJ1A also has them. I just got a look at mine unfortunately.:)
 
Looks like we're just at $15k now... Some of the other stuff was unrelated.

Just told my wife. I expected some concern, instead she said "'eh, that's cheap.... We own an airplane."

:)
 
Alexb2000 said:
TiO-540-AJ1A also has them. I just got a look at mine unfortunately.:)
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Ahh! Learned something. I didn't realize the AJ had them.
 
PPC1052 said:
I haven't been paying attention. Have the decided that the roller tappets aren't the way to go, and that these hyperbolic tappets are better?
Click to expand...


What, no commentary on this? I expect you guys to know about this and educate me.
 
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