Engine scare

[greg51]

I have a 64 E model I bought last year with an engine that had 30 hrs on major overhaul from Jewell in MO. I flew it for about 80 hrs with no trouble until last week. On a short 50 min flt with my family on board, 40 miles out and starting decent I noticed a small vibration in the yoke. I looked over to see my cylinder head temps rising past the green (old engine gauges) as I continued and pulled power back a little temps went into red. I stayed high and went directly for the runway. Pulled power back when I had runway made and started hearing a pop pop pop like a backfire. I landed safely with the engine still running with decreased power. 

I called for mechanic and they told me later one cylinder compression was 20 . They said piston and rings were fine but needed to send cylinder away to be fixed. 

What could cause this? They said there were no cross hatch marks in cylinder indicative of a major overhaul.

Any feed back would be great

Thanks

[1964-M20E]

wow glad you made it to the airport fine.

Infant mortality is a concern on any newly worked items.  I would install an engine monitor at least a G1 while you are doing this.  It will let you see all the EGTs and CHTs.  The CHT is typically on #3 for the old style gauges and you are only looking at that one.

Could it be an exhaust valve was sticking?

Did the MX say what was wrong with the cylinder?

Did you bore-scope the other cylinders and see what they look like?  (camera bore scopes are not that expensive these days try to get one with the highest resolution you can.)

Look at the injectors maybe check flow rates between them while you are down.

 

 

[carusoam]

Congrats on turning the situation into something you can safely look back on...

Does your engine monitor save all the data?

Things to consider....

1) post it here...

2) send it to Savvy

3) Stand by for a lot of questions and experience from everyone...

 

One Pp's thoughts (From what you described)

1) it was only one EGT that went up?

2) the CHT probably dropped as well

3) compression is required to prep the fuel for ignition.  lack of compression sends raw fuel mixture to the exhaust where it gladly ignites from the other fire of the other cylinders.  That gives the wrenching sounds of 'back fire' even though it is in the exhaust, not the carb...(?)

4) the engine is now running on three cylinders.  Check your data the other three haven't changed EGT or CHT?

5) an unintentional three cylinder engine is going to be unfavorably balanced. 

6) something made the compression go away.  That makes you want to look at cylinder walls, rings, and both valves in that cylinder.  Good time to get a camera sent down a sparkplug hole.

7) compression testing is a good idea, but it doesn't tell you which of the four things is quite right.  The camera will be pretty quick.

8) stuck exhaust valves are a more common problem.  Did you hear any valve tapping after start up? Experience any morning sickness issues?

9) looking back, did you get to perform the engine's break-in procedure? Any issues there? Rings can either seat or not seat so well. A ring issue like a broken ring can cause a loss of compression.

10) how does the oil look? Lost rings have a tendency to send exhaust into the oil.  Pressurizing the case can send the oil overboard at a faster rate than usual, turn the oil black and smell a bit like it is cooked...

11) check the oil level.

12) check the oil color/smell

13) check with your mechanic to see if he has a camera for looking into the cylinder.

that is my idea of round one of problem solving.  Determine what isn't working like it should. Starting with the data...

Hope that helps.

PP ideas, not a mechanic...

Best regards,

-a-

[greg51]

No engine monitor, old gauges only. I just got new panel and my mechanic said fancy engine monitors are a waste of money.

The mechanics removed and sent cylinder to engine shop but couldn't tell me what was cause, said the engine shop would tell us cause

[mccdeuce]

So the question I would ask is are these new cylinders? Were they treated at overhaul? Or were they in spec and just reinstalled?

[carusoam]

I mis-understood 'all temps'.  Which temps?

What is a new panel without an engine monitor?  Even if all the monitor's data doesn't mean a thing to the pilot. There are a few people that can use it to tell you what is going on.  Used JPIs cost less than a new cylinder...

In that case, the mechanic may be a better mechanic for somebody else...

The mechanic has the ability to completely remove a cylinder to look inside.  This will work.

Compare that style to the computer nerd style and see which costs the pilot more...

In the end, if the valve bent or broke, the cylinder is probably coming off anyways.

 

Consider getting an engine monitor.  As a pilot, you want to know what is going on.  Like, do I have a problem with one cylinder or do I have a whole engine problem like a fuel issue. One bad cylinder allows the pilot to typically complete a less eventful lap around the traffic pattern.  The wrong fuel in the tanks will be a lot worse.  Both issues will show on the JPI different enough to the pilot to help devise the best plan with very little time.

That's an entirely different thread...

Best regards,

-a-

[Schinderhannes]

9 minutes ago, greg51 said:

I just got new panel and my mechanic said fancy engine monitors are a waste of money.

Your mechanic's point of view is not necessarily shared with the well respected experts in this field. At a minimum I would get a second opinion. From my perspective (just a pilot) the 2 most valuable panel investments I made is the EDM700 and FS450. On a side note I didn't want to spend the money on the FS450, but my CFII wife made me. Hate it when I am forced to spend money on the plane...    

[mccdeuce]

An engine monitor will generally tell you whats going on with the engine before it gets to this point.   Engines talk - its a matter of whether or not you are listening.

Overall though nice work to land safely - especially with your family on board.

[gsxrpilot]

33 minutes ago, greg51 said:

No engine monitor, old gauges only. I just got new panel and my mechanic said fancy engine monitors are a waste of money.

The mechanics removed and sent cylinder to engine shop but couldn't tell me what was cause, said the engine shop would tell us cause

I'd get an engine monitor and then also get a different mechanic. I like the G2 from Insight for something cheap and full featured. If you learn to use it properly it could at least pay for its self within a year and at best might save your life.

[greg51]

cylinders were honed. see logbook entry

overhaul02112016.pdf

[carusoam]

See if I have this right...

How many hours over how many years?

30hrs since 2012 (OH date). Now you have put on an additional 50 hours since you bought it....

Did this engine sit and not run for a while?

if this is the case... watch what comes out of the oil when it gets changed...  filter the oil looking for metal flakes.  Open the oil filter also looking for signs of metal...

planes that don't fly often are known to have certain issues. Lycoming cam lobes can be a challenge for this...

Best regards,

-a-

[greg51]

30 hrs over 3 yrs broker said they ran or flew it every couple weeks. I have flown it 80 hrs over the last yr I have owned it(never more than three weeks has it not run)

I changed oil every 25 hrs and had mechanic check every time for FOD, always came up clean

[rbridges]

so glad you landed safe.  I hate to beat a dead horse, but I agree with the others about the engine monitor.  Even in your situation, it could have saved information that could help diagnosing what happened.  Keep us posted if you don't mind.  We could all learn something from your experience.

[carusoam]

Looking back on possible metal being lost from the cam...

A) have you sent oil samples out for testing with the oil changes that you had done?

B ) Do you plan on draining the oil (for a look) any time soon?

 

Looking forward to see if valves are the problem...

The mechanic can determine if air is leaking from either the exhaust or intake valves...

Exhaust valves are the most suspect because of the temperature they reach and their ability to coke the oil in their guides that is supposed to lubricate them.

 

Looking over the cylinder honing...  

they often have a tell tale cross-hatch pattern to them...  if they have unusual pits from corrosion or smooth from wear, that would be a sign of places compression can be lost.  Helps to have a camera for this...

 

Look at the spark plugs...

The lower ones often catch anything errant that was in the cylinder...

 

review...

1) vibrating engine caused by lack of compression on one cylinder.  No compression leads to no firing in that cylinder.  High EGT from raw fuel burning in the exhaust pipe.  Low CHT in that cylinder to match.

2) lack of compression can be caused by stuck or inoperable valves, degraded cam lobe, or broken cylinder rings.

3) A bad cam usually leaves metal flake (or chunks) signs in the oil.  A broken ring will leave darkened oil.  parts of the ring may not leave their channel.  Ring parts are pretty obvious when you see them.

4) a stuck valve may come in contact with the piston, resulting in a bent valve stem.

5) outlook...  rings are cheap, cylinder honing, not to bad, missing a cam lobe can be expensive.

 

lots of PP ideas, still not a mechanic...

 

Best regards,

-a-

[DXB]

Yikes Greg- congrats on handling a scary situation with a level head and walking away, and I appreciate your sharing so that we can discuss and learn.   +1 on engine monitors being extremely valuable, life preserving gadgets.  One may have given much earlier warning here and also narrowed down the problem considerably after it happened. I would certainly lose trust in any mechanic that claimed otherwise.  I'm of course not an A&P, so I cannot not really try to diagnose cause here but I'm very curious what it turns out to be, and here are some thoughts:

-Since you only had CHT on #3, you don't know if just one cylinder was affected or all of them.  Was #3 the one that got pulled for low compression? Could the damage creating the compression issue (presumably valve-related) on one cylinder be a result of the runaway temps and/or whatever caused them rather than the root cause here?

-A runaway CHT past red line (>500F in a lycoming) is a big deal that can cause serious engine damage beyond a single cylinder.   Could this have been a fuel system problem that led to an overly lean mixture in one or all cylinders?  Engine monitor EGT data would reflect this instantly.  Simply pulling one jug with low compression for the engine shop to check out seems like a woefully inadequate initial investigation by the mechanic.  Your freshly overhauled engine might be fine in the end, but it also could be utterly toast.

-Could the "pops"  have been pre-ignition events resulting from the runaway temps?   Scary stuff. 

-This is truly an infant mortality failure - emblematic of why fresh overhauls are to be feared.   Here's a good AOPA article on that:  http://blog.aopa.org/opinionleaders/2014/04/09/how-do-piston-aircraft-engines-fail/.  I don't have the expertise to predict which of the infant mortality causes is most likely in your case, but there are folks on this board who do.  It would be great to hear from them.  

Your mechanic is not inspiring confidence here. I would contact the overhaul shop immediately for guidance.  I don't know what obligations they have in terms of warranty etc., but they are certainly an experienced, well known shop.  After only 30hrs, it seems like they would be very motivated to help you get to the bottom of this, and also help make it right in case the problem ultimately traces back to them.   

Sorry for your troubles and good luck!

 

[greg51]

It just happened 5 days ago. The mechanics have sent the cylinder out for repair....no word yet. I am having them also do my annual while they have it torn apart and so I can legally fly the plane home. (Had annual scheduled for oct 31 the day I was supposed to fly home) I will have oil samples tested.

OK, you talked me into it. I will get engine monitor, however I am sure it would tell me the same thing my old gauges did. "things are getting hot time to land"

[MB65E]

Sounds like the engine was not broken in correctly. What was your oil consumption? What did the plugs look like? I've seen a few broken rings in those low usage  scenarios. 

-Matt

[neilpilot]

37 minutes ago, carusoam said:

... watch what comes out of the oil when it gets changed...  filter the oil looking for metal flakes.  Open the oil filter also looking for signs of metal...

Also at least once in awhile pull the screen, which can catch relatively big pieces of metal before they get to the filter.

[ArtVandelay]

OK, you talked me into it. I will get engine monitor, however I am sure it would tell me the same thing my old gauges did. "things are getting hot time to land"

The difference is you were alerted by a vibration in the engine, the engine monitor could have alerted you long before the vibration started. If you have the monitor installed on the far right, have annunciation light installed were you can see it.

[greg51]

oil usage was low. about a quart every 6 hrs

Screen was checked every oil change

[greg51]

mechanic did say plugs looked caked and looked like they hadn't been firing in a while. This makes no sense to me as I had full power for takeoff climb and cruise with normal speed and I was at max weight

[Marauder]

It just happened 5 days ago. The mechanics have sent the cylinder out for repair....no word yet. I am having them also do my annual while they have it torn apart and so I can legally fly the plane home. (Had annual scheduled for oct 31 the day I was supposed to fly home) I will have oil samples tested.

OK, you talked me into it. I will get engine monitor, however I am sure it would tell me the same thing my old gauges did. "things are getting hot time to land"

Good decision on the engine monitor. It was the first electronic "gizmo" I installed in my plane back in the early 90s. Even without the data recording capability, it certainly will point out a problem. It certainly did for me on a a lousy IMC day over the hills of central Pennsylvania.

Fast forward to today's "waste of money", you be able to identify and record an anomaly. I posted a thread about a spark plug issue only to have it pointed out to me that I had two spark issues with a cylinder. Later confirmed by doing an ohm test on both.

In addition, a few of us are using SavvyAnalysis. For $129 a year, with unlimited uploads, it is certainly worthwhile having another set of eyes on your plane's performance when concerns arise.

Sent from my iPad using Tapatalk

[carusoam]

9hrs. Per quart is more normal for a four cylinder Lycoming.  (Research around here for that...)

a quart every six hours is a bit elevated.  

Knowing where the quart went is important.  filling the oil sump over six quarts gets the extra quart of oil dumped out the vent and onto the belly pretty quickly... how much was put in the sump?

having the plugs fouled for a while is a sign that the mag check was not done properly or something else is really afoul.

When you say you had full power, how do you know?

full MP and rpm don't tell the whole story.  FF would help.  Climb rate would be a good sign.  T/O distance would work as well...

Again, this is data that would fall out of a JPI so fast, you would look like an engine expert today...

take picures of the things that don't look right...  an iPhone is a really capable device and easy to load a shot or two here... 

Wet plugs happen when oil rings don't seal.  Carbon encrusted plugs happen when that oil is getting burnt. Small lead beads are a sign of too rich a mixture, often while taxiing....

Best regards,

-a-

[greg51]

Well I just did the math, I bought 12 quarts when I bought the plane 80 hrs ago and have 2 quarts left 

[DAVIDWH]

Oh My,

Just spent $5,495 for a EDM930 from Aircraft Spruce.

Don't know how this happened, but pretty obvious your mechanic has been talking to my wife.

I have recently heard several times "Total waste of money".