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Looking for your opinion of these plugs


Bob

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These plugs were removed from a TSIO-360LB engine.  Borescope shows no issues and cylinder pressures are all even and are all about 75PSI.  Please share your thoughts and also if you are an AP or IA.

 

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There is some oil getting to some spark plugs...

Looks like #5 has an oil deposit on the lower spark plug...

It might have good compression, but the oil ring might be having difficulty...

might be a good idea to scope the inside of the cylinders with a dental camera device.  Looking for the hatched pattern on the walls.  These are the surface marks that help keep oil in place with the rings.  A lot of wear smooths the cylinders and the gap allows more of the oil to pass into the cylinder.

How many hours on these cylinders?

This may look like a high time engine, but with the reported hours of 200 or so.... is it a break-in issue?

Got Any CHT data to share? Typical cruise, under 380°F or over 400°F?

Seeing any oil useage?  Any oil dripping from the exhaust?  Any oil in the intake? How many hours on the turbo?

PP observations only, not a mechanic.

Best regards,

-a-

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I don't suppose you ran a GAMI lean test. It would be interesting to see how the plug colors relate to that. It would also be interesting to see how the colors would relate if you installed GAMInjectors.

Back when I was racing sports cars, my experience was that the colors on the plugs was very dependent on how the engine had been operated in the last few minutes before it was shut down. We typically ran the engine at full power, and immediately shut off the ignition, coasted to a stop and pulled the plugs. 

After I bought and set up my dynamometer, a friend on mine attached an engine (from an MG if my memory is correct.)  After running it at full throttle and full load for a few minutes, we shut it down. The plugs (although well used) appeared brand new. Not a speck of soot.

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I concur with all the comments made above, but Don @DonMuncyis so right above, we could be looking at plugs after a rich descent that went on for a few minutes. If it was very low power, (air driving he prop), it could have even been sucking oil in.

The real story of your engine is told by a modern engine monitor downloaded data as well as warm compression test accompanied with borescope checks.  You have done the compression test and borescope with healthy results, therefore I am confident the why's of the plugs will be revealed by looking at how the engine was just operated through downloaded data.

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- Why is one cylinder oily, one is rich, and the others lean?  (with no cylinder indications,  did the bore scope miss something?)

- how is the bank layout (common intake runners, air leaks,)

- are the injection parameters bank or sequential?

- How is the ignition system delivery (wires good, terminals good, properly timed?)

My guess you have a bad oil ring on #5. or a valve seal or guide but that would show more to one side of the plug than all the way around but still plausible. 

Cylinders 1 and 2 are rich not knowing how the are placed in firing order I would look at how the mags are firing.  possible cross induced leads? 

Those deposits don't look like normal lead deposits to me in the pictures they look like fuel additive crystals.  (I see that a lot in people playing chemist in the wither trying to remove water from gas with over the counter additives)

 

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Thanks everyone!  I hope this answers some of the questions above.

The engine has 210 hours total time.  210 TT on everything firewall forward, plugs, mags, harness, exhaust, turbo, etc.

The plugs looked good and even at 31 hours and 56 hours. Then at 177 and 206 looked close as above pics show.

The engine does have the neutral set Gami nozzles.  The lean test shows 2-6 as all real even and #1 peaks early and richer by about .7 gal.  I have a 830JPI installed.

No fuel additives added.  Fuel rail feeds one side of the motor.  #1, 3 & 5 are all on one rail.

Plugs are Tempest Fine Wire and tested good during last two annuals at 31 hrs & 177 hrs.  I rotated top to bottom and moved both to next cylinder, and weak plug positions did not move.

 

 

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15 hours ago, N201MKTurbo said:

I don't have a lot of experience with that engine, but I seem to recall that they had uneven airflow distribution front to back that causes the uneven mixture distribution. It would benefit from GAMIjectors.

Some cylinders look quite a bit leaner than others. I’d clean the injectors, check carefully for vacuum leaks then run a real inflight GAMI spread. That’s a cross flow induction engine which is way more balanced airflow than the log style Continental runners. It should be a tighter GAMI spread than that. 

#1 looks like it’s pumping a fair amount of oil. 

Edited by jetdriven
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1 hour ago, jetdriven said:

Some cylinders look quite a bit leaner than others. I’d clean the injectors, check carefully for vacuum leaks then run a real inflight GAMI spread. That’s a cross flow induction engine which is way more balanced airflow than the log style Continental runners. It should be a tighter GAMI spread than that. 

#1 looks like it’s pumping a fair amount of oil. 

The injectors have been cleaned and I have about 20+ tests to show a true Gami spread.  #2, #3, #5 &#6 all peak at the same flow. #4 peaks very slightly late with about .1-.2 gal less fuel and #1 peaks early with about .7-.8 more fuel. 

Basically #1 is the only cylinder that peaks away from the group.  I have not ordered the nozzle swap out yet for #1 from Gami due to the oil on the plug.

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1 hour ago, Cruiser said:

Is the engine still under warranty?

What does the rebuilder say?

Yes this is a warranty issue that the rebuilder is currently addressing, but no diagnoses yet.

I do appreciate everyone's thoughts on this!  A lot of productive thinking was shared here. 

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Not sure if shutdown procedure is even remotely related to your spark plugs because it speaks more to fouling vs. oil. What I do after landing is spend a few minutes and and give the engine and CHT's time to cool down. The taxi back to the ramp is usually sufficient time. Then throttle up to about 1700 RPM for about 20 or 30 sec and then immediately pull mixture. 

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#1 be oily.   looks like the ones I took out of my 1989 topped engine.   with 600 hours on it.   were manufactures break in procedures followed?   And that would be only one cylinder on mine that has been known to be oil leaky

Edited by Yetti
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2 hours ago, PTK said:

Not sure if shutdown procedure is even remotely related to your spark plugs because it speaks more to fouling vs. oil. What I do after landing is spend a few minutes and and give the engine and CHT's time to cool down. The taxi back to the ramp is usually sufficient time. Then throttle up to about 1700 RPM for about 20 or 30 sec and then immediately pull mixture. 

Good suggestion for a non turbo, but I do not want to throttle up to 1700 before shutdown on a turbo.  I tend to taxi with cowl flaps open and being aware of keeping rpm's low.

As many people have said, how it was run in descend & just before shutdown has an effect on the plugs.  In general the 170 hr plug pics above are a better sample to evaluate.  I feel at 206 hrs it could have been leaned  a bit just before shutdown, since the plugs show a richer mixture across the board.  I personally look at the majority of the plugs and that becomes my base of normal plug condition, then look at the minority to see how it is different.

Yes proper break in was followed, but had a major exhaust leak at #1 cylinder that may have contributed.

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Good suggestion for a non turbo, but I do not want to throttle up to 1700 before shutdown on a turbo.  I tend to taxi with cowl flaps open and being aware of keeping rpm's low.
As many people have said, how it was run in descend & just before shutdown has an effect on the plugs.  In general the 170 hr plug pics above are a better sample to evaluate.  I feel at 206 hrs it could have been leaned  a bit just before shutdown, since the plugs show a richer mixture across the board.  I personally look at the majority of the plugs and that becomes my base of normal plug condition, then look at the minority to see how it is different.
Yes proper break in was followed, but had a major exhaust leak at #1 cylinder that may have contributed.

Also consider on the plugs that these engines can have much poorer mixture distribution at idle as compared to cruise power setting. Looking at size of the EGT spread at idle compared to cruise will give you feel for that. Therefore it’s really hard to make any judgement on rich or lean cylinders based on plugs; especially after a low power rich descent followed by a taxi. I’d stick to gami spreads for such conclusions. The oil is another issue entirely, but even there you have to be sure the engine wasn’t pulled back to near idle descent so that the prop was driving the engine. I.e. things only you can take into account in assessing. But you’ve shown you may have a trend going. But if you did have a broken oil ring for example it should be accompanied with a rise in CHT from the added friction with sign of it in the borescope exam which you remarked was good - so very doubtful. Another possible source is valve guide wear; especially if the guide to valve seat wasn’t perfectly centered which does happen on these cylinders leading to premature valve guide wear and/or valve burning.


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On 2/23/2018 at 6:52 AM, PTK said:

Not sure if shutdown procedure is even remotely related to your spark plugs because it speaks more to fouling vs. oil. What I do after landing is spend a few minutes and and give the engine and CHT's time to cool down. The taxi back to the ramp is usually sufficient time. Then throttle up to about 1700 RPM for about 20 or 30 sec and then immediately pull mixture. 

FWIW, I remember in one of Mike Busch's webinars he was asked if that helps, and he commented there was no evidence it actually makes a difference and suggested the procedure was on par with an OWT.

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27 minutes ago, jaylw314 said:

FWIW, I remember in one of Mike Busch's webinars he was asked if that helps, and he commented there was no evidence it actually makes a difference and suggested the procedure was on par with an OWT.

FWIW, Lycoming recommends it in a Service Letter. 

https://www.lycoming.com/sites/default/files/Spark Plug Fouling.pdf

I have great respect for Mike Busch and have learned a lot from his webinars. I also regard highly Lycoming’s recommendations and guidelines. I have learned and continue to learn from their literature.

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4 minutes ago, PTK said:

FWIW, Lycoming recommends it in a Service Letter. 

https://www.lycoming.com/sites/default/files/Spark Plug Fouling.pdf

I have great respect for Mike Busch and have learned a lot from him.

It's funny, my flight instructor swears by that procedure.  Didn't know it came from Lycoming, though.

I actually do do it most of the time, unless I'm in a noise sensitive area.  I figure it can't hurt

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in the O-235 (C-152) fleet where I went to school, we had a large problem with fouling plugs on taxi. Every runup demanded a high RPM leaning to burn the deposits off the plugs, and they also implemented the 1700 RPM for 20 seconds before shutdown on those as well. But the O-235 is particularly problematic with regards to fouling plugs and chamber deposits. IIRC the heads and combustion temperatures arent high enough to activate the TCP additive and turn the lead oxide into lead bromide where it is carried away.  But this is the only engine I've seen it needed to be done.

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It's funny, my flight instructor swears by that procedure.  Didn't know it came from Lycoming, though.
I actually do do it most of the time, unless I'm in a noise sensitive area.  I figure it can't hurt

It’s suppose to prevent stuck valves.
I use MMO before each oil change, Busch will tell you there is no evidence that works either. But he will tell you camguard works, because he use it in one of his engines...I would not call that evidence either.
Actually there are YouTube videos where they use MMO and then compare before and after, it does clean the engine.
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