Help, engine issue, grounded out of town

[XXX]

Guys, was on my way to OH to bring my daughter back to school. On climb out my EGT and Cyl temps started dropping. Mag check was fine, RPM and MP were normal. Temps continued to drop, diverted to CRG. Landed with rough running engine. Mixture seems to be the issue. Mixture control working properly. Removed cheek panels, no glaring issues.

No mechanic on the field till Monday.

 

[carusoam]

While you are looking for things...

1) do you have an engine monitor data you can review?

2) was it all CHTs and EGTs?  Or just one cylinder?

3) can you perform an engine run-up and collect one more data?

4) is the alternate air stuck open, limiting airflow?

Stuff that comes to a PP's mind not a mechanic...

Good luck.

Best regards,

-a-

[Jim F]

What was your fuel flow?  Is the FF from a fuel totalizer or FF gauge( analog gauge)

[Bartman]

Im not a mechanic but here are some thoughts....

Did you get just before your climb out and did you pump 100LL yourself and confirm no contamination ?

Remove the fuel caps and check for obstruction in the tank vent.

Switch tanks

Check fuel flow. Should be about 18gal/hr on takeoff at or near sea level.

[Yetti]

So running rich.

Check filter and air flow for obstructions. Lots of dirt.

Check Servo cable linkage. It will be on the copilots side looking in.

[kortopates]

Agreed that dropping EGT and CHT together indicate a mixture anomaly which could be fuel and/or air. Could be too rich or too lean. But is this on all cyls or just one or ...? A higher than normal MAP at idle and rough idle could be from an induction leak but that is doubtful given the symptoms at WOT climb unless this is a carbureted engine. Really begs for download engine data.

 

 

Sent from my iPhone using Tapatalk

 

[XXX]

Hey guys, thank you all for the responses. I'm taking my daughter to GNV (rental car)

to catch a commercial flight to DAY. I'll reply after I drop her off in Gainesville.

[cbarry]

Sounds like possibly a clogged injector (especially if the EGT and CHT are from a single cylinder)

[XXX]

Anthony @carusoam, @Jim F, @Bartman, @Yetti, @Kortopates and @cbarry,. Thank you all for the ideas. No engine monitor on board, just factory probes on #3. Consensus seems to point to mixture issue. I checked intake runners for breach, checked alt air door, checked air filter, checked mixture; travel good to both stops and then had to leave. Hot day, full fuel and my Cyl head temps dropped below the green arc. Very odd.

[XXX]

1 hour ago, cbarry said:

Sounds like possibly a clogged injector (especially if the EGT and CHT are from a single cylinder)

Would the engine run smooth with a clogged injector? I also did a mag check after landing with normal indications.

[201er]

How much drop and about what rate? Did you feel a reduction in power or not?

[XXX]

Just now, 201er said:

How much drop and about what rate? Did you feel a reduction in power or not?

Very gradual drop on both about 400 degrees over half hour on EGT, Cyl head temp dropped from slightly lower than center of Green (normal cruise) to just below green arc. Slight anemic feel and about 10 k lower cruise speed.

[201er]

I have another idea. Since you said you don't have an engine monitor (bad), it could conceivably be nothing more than a bad plug. If both the single EGT and CHT probes are on the same cylinder, you may be witnessing a single cylinder issue rather than a full engine problem. Especially since you say you only lost a little power. The power loss sounds on the level of losing a mag and not losing an entire cylinder. Normally you'd expect a rise in EGT along with CHT drop in the event of a bad plug but I dunno, the factory gauges aren't too reliable.

I don't think you can reliably self diagnose without an engine monitor or really getting into that engine.

Edited July 15, 2017 by 201er

[Jim F]

What did your fuel flow do?  

[peevee]

Sounds a bit like induction ice, wouldn't make sense in the summer though.

[N201MKTurbo]

A loose mag changing timing. As one gets more advanced it will advance fire before the other. Did you run on the mags one at a time? More advanced will make it run cooler until it detonates.

[Yetti]

I had this happen once.  I had configured the engine to do this.  I think adding throttle helped things back to normal.   Clogged injector would probably make the engine less smooth.

[carusoam]

The following is only a PP's thoughts. Not a mechanic...

So we have...

0) No engine monitor to observe all four cylinders...

1) one ship's CHT that showed cooling during the climb... odd.

2) one ship's EGT that showed cooling during the climb... also odd.

 

3) Updated statement: The ship's CHT and ship's EGT is on the cylinder #3.  (Detailed in a post below)

4) If a single plug started to fail,

• the CHT would not be as hot as two working plugs...
• the EGT would typically rise with more fuel burning going past the exhaust valve...
• noticeable vibration...

5) if a fuel injector got partially plugged

• this cylinder would exhibit the effects of peaking and going LOP before the other three...
• you would be lucky to see this with only one EGT... one in four, odds...
• the engine runs with a strong hint of roughness.
• running a mag check at altitude while you were up there may have given interesting information...

6) on the ground is it running rough?

• Helpful for diagnosing the situation.

7) are the spark plugs Champion?

• high resistance plugs have a way of interrupting the ignition cycle...

8) To get a cool CHT and EGT it would probably require two dead or dying plugs in one cylinder.

• Somebody has reported this at least once before, as unlikely as it sounds...
•  

9) Continue to look into the three holy ghosts of combustion...

• Spark...plugs, wires, magnetos (loose?)
• fuel... injectors, filters, air leaks, fuel leaks... any unusual blue stains..?  Fuel leaks out when not running, air leaks in while running...
• air... blocked intakes, leaking intakes

10) Start planning some ideas for the future...

• Looks like you may have some time to think...
• A used engine monitor is not all that expensive... we have a guy here...
• A FF gauge is super helpful when collecting data...

What's next in the plan?

Best regards,

-a-

 

 

[XXX]

Back home now, talked to a couple mechanic friends and each is leaning towards a mixture issue. My plan is to meet up with the local mechanic on Monday (Thanks @Hector) . I'll address a couple of the questions you guys asked here...

I did a mag check while airborne with the same results as ground check. Normal 75-85 rpm drop each. Runs smooth at 1700 RPM on ground.

Fuel flow normal range according to my steam gauge.

I thought about induction ice, but hot day and no visible moisture yet.

Yes, Champion plugs.

I will consider an engine monitor but not until I pass my instrument check ride. (otherwise I'll never get it done).

So, in my haste I didn't explain about the rough running engine. Everything appeared normal in cruise except the temps and the slower air speed. Diverted to Craig (Jax Exec) and remained at 8500. I asked to spiral down over the field. During GUMPS check at full forward mixture, the engine started running rough. I pulled out quite a bit and it smoothed out. Then tried leaning and saw some rise in the EGT and very rough running (normal). So the odd thing is the engine was only smooth at a very precise mixture setting (I have a throttle quadrant) a tad rich and rough engine a tad lean and rough engine. I had about 1/4" of movement that allowed the engine to be smooth. At 2000' feet went full rich and engine smoothed out somewhat. Landed and taxied with no issues and smooth engine (leaned for taxi).  Parked and did mag check on ground.

Sincere thanks for all the ideas and suggestions. I will follow up once I have an answer. It has been a long day.

 

[201er]

Induction leak???

[Raptor05121]

If my plane were operational, I'd offer to ferry you back and forth as needed, sorry. I hope you manage to get it all worked out

[Yetti]

 

3) Question: Is the ship's CHT and ship's EGT on the same cylinder? (Probably not)

They are both on number 3 with the factory thinking that this is the cylinder that runs the most hot.

i would probably start with a compression test and a timing check.

How many hours on the mags?

How many hours on the cylinders?

[XXX]

4 hours ago, Raptor05121 said:

If my plane were operational, I'd offer to ferry you back and forth as needed, sorry. I hope you manage to get it all worked out

Thanks Alex, I appreciate that. Same here if you ever need a ride, let me know.

[XXX]

29 minutes ago, Yetti said:

 

3) Question: Is the ship's CHT and ship's EGT on the same cylinder? (Probably not)

They are both on number 3 with the factory thinking that this is the cylinder that runs the most hot.

i would probably start with a compression test and a timing check.

How many hours on the mags?

How many hours on the cylinders?

Yetti,

Correct, both on #3. Just came out of annual in June, good compressions. 25 hour oil changes and Blackstone analysis. Timing check sounds in order. Roughly 220 hours SMOH including rebuilt mags.

 

[Jim F]

So it sounds like your engine slowly went rich. No roughness and when you rich end the mixture it got rough. Your FF indicated normal. You say you have a steam gauge and then the fuel flow is really a pressure gauge from the flow divider and marked in GPM. 

Information needed:

is the mixture arm on the Bendix fuel servo hitting its stops?  

Is the air filter clear? I don't think this is it but checking is easy

check the mags to see if they are tight. N201MKTurbo recommended and again it's easy

run up, at 2000RPM what is the EGT,FF? Lean to peak, what is the EGT,FF? Boost pump on, what happens? Caution the engine might die because it went to rich.  The fuel servo should compensate for the increase incoming fuel pressure.

i am thinking that you fuel servo went rich. The servo has two diaframs one has incoming fuel( from fuel pump) and out going fuel ( to the flow divider)   A leak in that diafram would make you go rich. Now that said I think this senerio would make your FF increase.  The other diafram sees incoming air(before the throttle plate) and MP  

On the engine monitor:

With our engines there is a lot going on and information is critical to keep us safe and the first part of troubleshooting. I am to the point that I think twice before flying without an engine monitor. 

Jim F