Low Oil Pressure Running Rough

[Yetti]

OH and I we also want to know the year of manufacture of the cam.

[Browncbr1]

1 hour ago, DXB said:

Dang.  So much for a happy ending to this thread.  Informative though.  I'm curious - were there any other signs of corrosion in the engine that would go along with demise of a cam lobe?  Everything else looks pretty clean in the pix.

I think it's pretty happy.  No forced landing causing other damage.  No deaths.   

 

Anyhow, I'm just curious how this engine was operated on the ground since you've owned it?  And how often flown?  I have always understood these engines need at least 1000rpm to keep the cam wet.  

[Cwalsh7997]

Operated great on the ground, will idle at 600 but normally keep it above 1000, flying it around 400 hours a year.

[Guest]

18 hours ago, Cwalsh7997 said:

I know a lot of people on this site, Jake at Daytona aircraft Service is highly recomended! Been with them over a year, and as a Mooney Service Center, they truly care about customer service and quality work, be sure to stop by!

We're lucky to have him.

Clarence

[Andy95W]

As we've discussed before, it appears to be more bad metallurgy from Lycoming and their suppliers instead of corrosion.  

Like Yetti said, I'd really like to know the manufacture date of that cam so I can hope I don't have a similar year.

[jetdriven]

I wouldn't blame the cam more than I'd blame the lifters.  Especially reground lifters.  

[Guest]

17 hours ago, Cwalsh7997 said:

Operated great on the ground, will idle at 600 but normally keep it above 1000, flying it around 400 hours a year.

At that use rate it would be hard to imagine that corrosion could be the cause.

Clarence

[mooniac15u]

22 hours ago, Cwalsh7997 said:

Operated great on the ground, will idle at 600 but normally keep it above 1000, flying it around 400 hours a year.

Flying it 400 hours per year and Jake said it has 850 hours on the engine. Is this really only a two year old overhaul?

[Cwalsh7997]

We bought he plane at 400 hours it had been sitting a while before that

[Marauder]

4 hours ago, Cwalsh7997 said:

We bought he plane at 400 hours it had been sitting a while before that

The reason everyone is interested in the year it was overhauled is to help narrow what we suspect was a period of time where the metallurgy of the components are suspect. People with overhauls before the mid 90s seem okay.

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[PTK]

So a few questions for the experts!

Assuming bad metallurgy is not the issue shouldn't the lifter be a lot more worn in view of the cam lobe?

If that's an exhaust lobe how does an intake lobe look? It must be almost flat!

It'd be interesting to know the history of this cam. Was it factory new or reground?

Of course all bets are off if bad metallurgy is indeed at play. And if that's the case shouldn't all lobes exhibit similar wear?

I would think if the lobe is so worn and the lifter is not then it almost proves in my mind that it was bad cam metallurgy. And if other lobes, especially intake ones, don't show similar wear it almst tells me it was probably a reground cam.

Am I correct in my reasoning? Please help me out I'm learning here! 

[jetdriven]

You'll find the whole face of that lifter is spalled out.  That tears up the cam.  Lifters are made of substandard material whether the steel content itself or improper hardening. Either way, everything goes great until either rust forms pits which compromise the hard smooth surface, or the softer meta below the smooth face of the lifter fatigues and starts to crack, the softer metal below gives way, then the lifter spalls.

 This happens in some engines regardless of how they are treated.  You'd think there'd be more focus on this, since the average repair is 20k or more and we're talking many hundreds of engines. 500 of them is ten million dollars.   This board is full of the same story over and over. 

Edited July 11, 2016 by jetdriven

[Yetti]

Spalling also requires pretty good amount of pressure (at least turning things on a lathe it does).  So if the valve train has abnormal friction then the increase pressure will contribute to the spalling.   Increased friction is caused by oil coking around the valve in the valve guide.   http://generalaviationnews.com/2014/12/28/what-is-causing-bent-rods-and-sticking-valves/

[jclemens]

Here are some photos I took today.  The cam follower is an ECI part and you can see the date 12/08 on it.  All the rest are the same date, they are all fine.  They will all get replaced with new along with the cam during this repair anyways.  The cam is also an ECI part, it was probably purchased together as a kit with the cam followers.  There was no metal at all in the filter, also none found in the screen.  The crank and rods are all in great shape, no damage done there.  Cylinders look good too.  

[DXB]

Fascinating- thank you for posting. So I guess it's not crappy '90s Lycoming metallurgy...  still could be bad metallurgy?  From the pix, I'm guessing there's no significant pitting on the other cam lobes or lifters?  If so, is corrosion from sitting around an unlikely etiology?

[Guest]

That amount of metal didn't just disappear, it's either in the piston skirts or the oil filter over a number of oil changes.  This particle size is often not found in oil analysis.

Clarence

[jclemens]

You're right, it doesn't disappear.  The piston skirts are imbedded with metal, also the bearings have a little bit imbedded in them as well.  Both will get replaced.  This has probably been like this for a long time, many oil changes ago.  

[jetdriven]

that metal scores the cylinders, the crank, the oil pump, the crankcase where the cam rides, and the governor. Wash the filter in mineral spirits, put a magnet under the plastic cup i bet you find iron fines, what was the oil analysis? Anything over 50 PPM is suspect, 100 PPM something interesting is definitely happening....

Edited July 11, 2016 by jetdriven

[Yetti]

On 7/8/2016 at 5:04 PM, jclemens said:

 

Well, we found the problem.  Cam lobe gone on the #2 exhaust valve :/  First pic is the bad lobe, second is a good lobe for comparison.  

 

You can see the shiny little metal specks in the drop of oil that is is on the follower.

[jclemens]

As stated before, there is no oil analysis.  I don't know what good it would do now.  It's pretty obvious that there was metal in the engine.  This engine is going to get the what would pass for an overhaul if it wasn't aviation.  It will be a "Repair" only because we don't plan on doing the fuel or ignition systems.. All the internals will be dimensionally inspected and dealt with accordingly.  We won't be doing NDT,  a little metal contamination doesn't warrant the crank to be magnafluxed.  It will go on the crank polisher and get cleaned up.  It will be reassembled with all new bearings, new cam followers, new cam, new set of pistons and rings, and new a gasket set.  

[cnoe]

I find it incredible that such deterioration doesn't throw up a red flag during oil changes. And if the filter didn't show metal then surely oil analysis would show elevated values. Perhaps both, or one-or-the-other, but surely SOMETHING! SOMEWHERE!

Please tell me I'm not wasting my time with meticulous filter inspections and regular oil analysis. I have to believe that there were signs being ignored at some point in the past with this engine.

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[N601RX]

When we overhauled my engine I sent the new cam out and had it modified to provide direct pressurized oiling to each cam lobe. Each lobe and bearing journals has 2 small holes drilled in it and both ends of the already hollow camshaft are plugged off. This pressurized the inside of the cam and allows the oil to spray out on the lifter as the cam rotates. The cost was around $500. It appears they put some effort into determining the cause of the failures. 

http://thenewfirewallforward.com/linked/centri_lube_info.pdf

[MooneyBob]

Just now, cnoe said:

I find it incredible that such deterioration doesn't throw up a red flag during oil changes. And if the filter didn't show metal then surely oil analysis would show elevated values. Perhaps both, or one-or-the-other, but surely SOMETHING! SOMEWHERE!

Please tell me I'm not wasting my time with meticulous filter inspections and regular oil analysis. I have to believe that there were signs being ignored at some point in the past with this engine.

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I am just curious as I do my regular oil analysis and filter inspection. 

1. What engine you have in your J?

2. How many hours SN or SMO

3. Do you find anything in your filter ever? Small shiny flakes?

4. What is your iron and other metals level from the analysis? 

Thanks. 

[Guest]

You'd think with a history as long as that of Lycoming's they would have camshaft so figured out by now.

Clarence

 

[cnoe]

41 minutes ago, MooneyBob said:

I am just curious as I do my regular oil analysis and filter inspection. 

1. What engine you have in your J?

2. How many hours SN or SMO

3. Do you find anything in your filter ever? Small shiny flakes?

4. What is your iron and other metals level from the analysis? 

Thanks. 

Since I was quoted I guess you were directing this question to me, so...

I have the IO360-A3B6D w/ 559 TSMO at my last oil change. My camshaft and lifters were "new", not reground (circa 2008).

I have found a very few (3-4) tiny thin shiny specks in my filter on a couple of occasions but they didn't stick to a magnet and typically dissolve when rubbed between my fingers. I suspect that they're carbon. I actually expect more particles to be found in a healthy engine than what I've seen in mine so far.

My last oil analysis showed: aluminum 6, iron 19.17, copper 3.00, nickel 1, chromium 2, and silver <1. Iron has always been 20 or less except for one analysis when it was 27.02 at the end of last winter when my flying was less active. I chalked that up to minor cylinder corrosion.

I've averaged 160 hours/yr flight time for the past 30 months. Still I worry about self-destructing camshafts and followers.

Also, I use Phillips XC 20W50 w/Camguard. Even if it does nothing more than give me false peace of mind it's worth it to me.

If anybody has more advice to stack the odds in my favor I'm all ears. I'm interested in the centrilube mod but it will (hopefully) be a while before I get to personally spec out a rebuild.