Engine Problem

[Mark942]

21 hours ago, carusoam said:

With such low hours over the years... cam performance is always a question...

If the cam has been rusted, it usually leaves plenty of metal bits in the oil for analysis....

But cams don't usually fix themselves and then go back to misbehaving...

Have you seen the cam or any of the lifters? Any metal bits in the oil?

Best regards,

-a-

No metal in oil. Oil consumption good at about a qt per 8 or 9 hours.  Oil analysis at every oil change looks within reasonable range and consistent.

[Guest]

Blue chalk on the exhaust stacks, then run the engine, first to turn white is hotter, last is colder.  You can then do it on one mag at a time to isolate which cylinder.

A poor mans engine monitor.

Clarence 

 

[Mark942]

12 hours ago, Bob_Belville said:

It should not be a factor in the current puzzle but I wonder about the boost pump.

You reported: "Fuel pressure on electric pump alone about 10 PSI. Fuel pressure with engine pump at full throttle 25-30 range and doesn't change with or without electric pump on."

On my E the electric boost pump will hold FP near 25 psi. In cruise, turning on the electric pump will cause the FP to bump up by 1 or 2 psi and make the displayed FP rock solid.

You may has told us but when you're taxiing back and experiencing "backfire" at low power is the mixture full rich? You report you've tried to burn off fouled plugs by running lean at ~2000 rpm but do you lean as SOP on the ground?

On way back to hangar, I tried leaning as far as possible to see if I could find a "sweet" spot. Seemed that running lean helped, but certainly didn't stop backfiring.

[Mark942]

9 hours ago, Marauder said:

Good luck on solving this. As others have mentioned, have them install an engine analyzer while it is in the shop. Based on the number of hours your mechanic could charge you, it probably will have paid for itself.

The three symptoms that bother me are the low RPM on takeoff roll, the backfiring and the low fuel pressure.

You may be dealing with the worst of airplane troubleshooting - the multi problem.

I suspect that a mag problem could result in low rpm and backfiring. But this doesn’t explain the low fuel pressure when just on the boost pump. Like Bob, I will see 27 PSI with the boost on by itself, then the engine fuel pump will be in the 25 PSI range in cruise but will jump up to 27 when I turned the boost on again.

Hope this can be sorted out. As for comment about Savvy, I signed up for SavvyAnalysis and have had Paul help me on a couple of issues. The first being a set of plugs that were intermittently not firing. Was not an easy problem to see without the data being available.

The second issue was a recent power anomaly that only lasted for a few seconds but was very noticeable in the cockpit. I have the JPI 900 set to 1 second collection intervals and it showed very clearly that I lost about 100° degrees of EGT temp on one cylinder for about 5 seconds. I was worried about a stuck valve but the entire flight as well as earlier ones show no evidence of the valve sticking. We are working on the premise that something came through that injector that disrupted the fuel flow for a few seconds. Analyzers really help look at these issues. Good luck.


Sent from my iPhone using Tapatalk Pro

New plugs and wiring harness on order. Talked with A/P today and he is coming over Saturday morning. I want to install new wires and plugs then ground run and see if any difference.  If not, I want him to re-time both Mags.  Ground run.  If no improvement pull both Mags and send to Mag shop for inspection/overhaul.  Also want to check if possibility of vibration causing intermittent grounding of one of the Mag P wires.  Problem is the same if on Left or Right Mag or Both.  That's the plan for now.

[gsxrpilot]

While you're at it... ah... never mind, I'll bite my tongue.

Hope you figure it out before you replace to many parts.

[Mark942]

7 hours ago, M20Doc said:

Barring the obvious things like something broken in the engine compartment, it’s a process of elimination.

General engine health, cylinder compression.

Spark plug condition, internal resistance.

Ignition wire high tension check.

Magneto health, failing coils etc. last engine overhaul may not have included magnetos. Magneto to engine timing.

Buy a shop vacuum and hook the blow side to the tail pipe with duct tape, turn it on with the throttle closed this will pressurize the engine, look for leaks in the exhaust system, intake system, and upper deck air system.

Clarence 

 

I'll try the vacuum blow test for leaks this weekend.  Sounds like a good trick.  I assume, I use soapy water and a tooth brush around seals to look for bubbles??

[Guest]

2 minutes ago, Mark942 said:

I'll try the vacuum blow test for leaks this weekend.  Sounds like a good trick.  I assume, I use soapy water and a tooth brush around seals to look for bubbles??

A plant squirt bottle with soap and water works well.

Clarence

[Mark942]

16 minutes ago, M20Doc said:

Blue chalk on the exhaust stacks, then run the engine, first to turn white is hotter, last is colder.  You can then do it on one mag at a time to isolate which cylinder.

A poor mans engine monitor.

Clarence 

 

I'll try that this weekend and report back.  Thanks

[carusoam]

Review of the basics...

• air
• fuel
• spark

And, Speaking of poor man's engine monitor...

There are a few methods of getting temperatures while on the ground.

IR thermometers and surface TC thermometers can be borrowed or found on the net...

Sounds like raw fuel may be making its way to the muffler...

Something may be interrupting the spark.

• Mag timing...
• Wire shorts...
• Champion spark plugs... check logs, check the label, Check resistance...
• deposits on the plugs... lead, oil, or carbon...

PP thoughts only, not a mechanic....

Best regards,

-a-

[Aviationinfo]

I am still concerned about the cam being spalled  as mentioned previously.  Unless you had taken oil analysis regularly over time you wouldn't have a trend of increasing metal in the oil.  

Had a friend with very similar symptoms in a Franklin engine;  it  turned out to be a badly worn cam.  His engine sat around a lot like yours used to.  You won't be able to tell on your Lyc unless you remove a cylinder or two but  I wouldn't do that until you've tried everything else first.   Of course none of this speaks to your 3.7 hours of good operation before it deteriorated again.   

[Skates97]

On 12/11/2017 at 7:10 PM, carusoam said:

I seem to be bothered by the rpm situation... full power  & 2300rpm?

While on the ground, the prop won't need much power to go full rpm, 2700...

I don't have any experience of full power and Lower rpm...

Most Mooneys gov will fail to fine pitch even if you run out of oil...  Missiles and Rockets will fail to the feathered position.

It might be possible all the back firing could be related to trying to run over square...

Good time to check the mag timing. They have a tendency to slip and give funky results...

Get a JPI immediately.  Learn to post the results.  About 50 of us read and comment on what they see not working right... an one of is really good at it... quite Savvy I might say...   

I think I would start with why the prop is stuck in a place it doesn't belong.  Could be the gov not Working, or the prop not working but something is funny there...

Retirement and flying go Nicely together... so I've been told...

Best regards,

-a-

The OP is having other issues besides the full power and low RPM so this may not apply but I had a similar situation shortly after buying my plane. I was originally getting 2700 but about a month later was only getting 2500 or so. Turned out that the prop cable had slipped in the clamps and was not hitting the stop.

 

[Mark942]

Update on replacing wiring harness and all plugs:  No real change. Engine still backfires and runs rough. Max static RPM did go up a bit to just under 2400 RPM.  I think this small improvement in max power is a result of all new wires and plugs.  Just like doing a tune up on a 1963 Chevy. If you wanted it to start in the winter in northern Indiana you did a tune up of new plugs and points every fall and new wires every two or three years.  Next steps are to pull Both Mags and take them to a Mag shop and have them bench tested under load.  Overhaul if anything is abnormal.  Have also decided to shut the door after the horse ran away, and when I am finally able to get the plane to the avionics shop, I am going to have a JPI 900  installed.

I'll keep everyone posted on progress with the Mags.

-mark

[eman1200]

Had some similar issues on a recently purchased F. Started and idled fine. On roll out, low rpm, massive backfiring popping burping coughing. Long $tory $hort, SO FAR it’s running good.....

Problem was intermittent. Well, ‘worked fine’ when mechanic ran it, same issue when I drove 40 minutes to test it. Finally replaced the nozzle, two flights good.

[Yetti]

Did you replace the timing chain.... Oh wait not a Japanese car

[carusoam]

Nice video, Eman,

Thanks for sharing...

Were you able to clean it out for re-use?

Or was it damaged and tossed?

Best regards,

-a-

[eman1200]

9 hours ago, carusoam said:

Nice video, Eman,

Thanks for sharing...

Were you able to clean it out for re-use?

Or was it damaged and tossed?

Best regards,

-a-

replaced.  so far so good.

[75_M20F]

On 12/17/2017 at 12:53 AM, Aviationinfo said:

I am still concerned about the cam being spalled  as mentioned previously.  Unless you had taken oil analysis regularly over time you wouldn't have a trend of increasing metal in the oil.  

Had a friend with very similar symptoms in a Franklin engine;  it  turned out to be a badly worn cam.  His engine sat around a lot like yours used to.  You won't be able to tell on your Lyc unless you remove a cylinder or two but  I wouldn't do that until you've tried everything else first.   Of course none of this speaks to your 3.7 hours of good operation before it deteriorated again.   

There would be a lot of metal in the oil filter with a spalled cam / lifters. (Oil analysis might not even show it), the metal particles get caught in filter and are too large to make it through the filter to the oil pan.

[jetdriven]

The spalled lifters show up on oil analysis  and in the filter. Usually above 30 PPM increasing to 100 PPM/50hr.   It’s often a fine grey iron powder but it’s there. 

[jaylw314]

Is there any chance this is morning sickness?  By the time you bring the engine back, the culprit exhaust valve might be unstuck.  This could account for the power reduction and backfiring, and without an engine monitor there would be nothing to see on EGT and CHT unless it happened to be the monitored cylinder.

[Mark942]

Update on engine: A/P was over and we pulled both Mags.  He removed all bottom plugs and rotated prop to get compression on Cyl #1 and set engine to 25 BTDC before removing Mags. That makes timing easier when reinstalling.  I just happened to be looking at the 4 plugs we had removed and set in a box. These plugs have no more than 10 minutes run time on them. What I found was amazing.  One of the four was as clean and unblemished as it was when it came out of the box.  Obviously, that plug is not firing, which most probably means one of the Mags is acting up.  Only problem is I didn't keep track of which cylinder each plug came out of.  Mags are on their way to G&N for bench testing.  There is light at the end of a long dark tunnel.

[carusoam]

Mark,

First, was the dead plug a Champion?  Usually they die an early death.  Not usually dead out of the box...

Another funny question...

During the usual engine run-up... didn't the non-working plug show a sign of not working?

• on one mag, the single plug continues to fire.  Oddly, Very similar to both mags operating.
• on the other mag, one plug is off and the other is dead...  the engine must be shaking with the power imbalance and raw fuel is being dumped to muffler and igniting there...

The normal run-up is pretty smooth.  If you haven’t ever had a smooth run-up, Something has been amiss for awhile...

Now you know exactly which plug is not working... trace it back to the mag that is not delivering the spark... no need to check both at one time. When you know this.  Looks like you are pulling both mags anyways...  OK, but some prefer to have their mags on different life schedules... have one age different than the other...

When were they inspected or overhauled last?  Less than 500 hours is usually good...  could have a lot more than that...?

Keep in mind, this is why we do the run-up.  Without an engine monitor, it is the best thing we have before committing to flight...

Even then, the ground run-up isn't perfect.  See threads regarding in flight mag checks....

Now, since this is a restoration project...  'better than new' wants a decent engine monitor. This plug issue just gave you all the reasons you ever needed to justify a nice monitor.  There are at least three manufacturers of independent devices... or you could go G1000... 

Except for the big G jab, I’m Trying to be helpful...  pp thoughts only, not a mechanic...

Best regards,

-a-

[Mark942]

Thanks for your support,

The new plugs were Tempest.  Back when the engine first presented the problem, the start, idle, taxi and run-up was all normal as was Mag check and Prop cycle.  Engine ran smooth and had been operating from initial start to the start of the aborted take off roll was probably about 10 minutes.  After pulling power back to idle and getting off the run way, I went through a normal run-up with Mag check and Prop cycle and all again seemed fine.  Then ran at 2000 RPM and leaned to max Cyl #3 EGT for a minute.  Then another run-up with Mag check and Prop cycle.  Everything still seemed fine, but when I tried second attempt at take off - 2300RPM max, so I brought the throttle back and headed for the hangar.  2 or 3 minutes into the taxi the engine began to back fire ( RPM=1000), and continued to get worse and seemed to be more violent in amplitude and frequency as I rolled along on my way back to the hangar. I tried gradually leaning all the way to the point the engine started running really rough from starvation, and also tried 700 and 1200 RPM but nothing helped.

Fast forward to now, when I replaced all plugs and wiring harness.  Pulled to plane onto the taxi way between the row of hangars and started engine easy, and let it set and run at 1000 RPM to warm up.  Ran good, but I could feel a slight roughness just setting there.  After gauges all in the green (about 4 or 5 minutes) I started advancing RPM.  At about 1200-1300 RPM occasional backfiring starts. As I increase RPM to 1500 then 1700 RPM backfiring is pretty constant.  I never tried doing a Left/Right Mag check.  Tried leaning engine but that didn't help.  Decided to shut it down, but wanted to see if max static RPM had changed so advanced to full throttle for about 4 or 5 seconds. Max RPM was up just a bit, maybe an increase of 50 or 75 RPM over last test.  Plan was to pull Mags if this didn't help, and I was so resigned to just shutting it down and yanking the Mags off, I didn't have the foresight to do a Left/Right Mag check.  Also, I noticed the one clean plug only after we had all four bottom plugs removed, and I was just handling them out of curisity so I have no idea which cylinder/Mag is the issue. I know we could do some looking in the cylinder with the bore scope again, etc, but have elected to go ahead and pull both Mags and they are now over at a shop for a bench test.  I guess there is a possibility of a wire issue with the new harness or even a bad plug out of the box, but I really think I will hear that one of the Mags is the issue.

Have not looked back through the log book to see when the Mags were last overhauled.  The engine had a field major OH just under 200 hours ago.

Thanks for everyone's input.  I'll keep posting what I find out.

-mark

[bradp]

Well at least when you have to do more invasive stuff the accessories will all have been overhauled.  

Joking aside - Even a rudimentary engine monitor would have alerted you to an ignition issue in that very first flight.  

If you run into additional issues Lycoming technical support can be very helpful.  

 

[carusoam]

Don't be afraid to talk with the mag shop technician.  There is probably something in one of those mags that isn't working right. Tell him you are interested to know what failed... finding the smoking gun will be helpful later...

It is better to know what it isnt working right, Than to just get it fixed and ignore that it happened...

It is Part of recognizing the failures (and causes) that happen on your own plane...

If he can't find anything...  you are back in that loop... is it a wire?, which cylinder did that plug come from?

So many details...

Now go read the logs... page by page... looking for anything related to the mags. Take notes... what when who where....

When your mechanic set the timing on the mags, was either mag timing way off the mark?

Was one of the mags loose?

What you might be describing is a mag that became loose.  As in loose mounting bolts.  This alters the timing some.  It may result in one or more plugs not operating...

Back in the day... Mechanics would reuse the star washers out of convenience... this lead to many loose mags over time...

Modern day PPs are even aware of this, and tend to oversee new hardware being used....

Stay on top! 

Best regards,

-a-

 

 

[deanders]

I had a similar Issue with my E model. Mine had sat for four years before a complete restoration. I overhauled all components firewall forward except the engine itself and the fuel distributor. On my first test flight it started to backfire on the downwind leg however I was able to make it back. Turns out one of the injectors clogged even though the fuel system was new. I removed the fuel distributor and found it was corroded causing the injector to clog. Over the next four or five flights I had high EGT on Cylinder number two. I swapped injectors around and no changes. I removed the stainless line from the distributor to the injector and ran safety wire though it and cleaned it with pressure. This worked and all EGT run the same. I think a piece of corrosion had broken off and got stuck in the line reducing the fuel flow enough to cause high EGT but enough fuel to run. 

I hope this helps.