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engine trouble on take off


larrynimmo

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Things that go with misbehaving valves...

1) The wobble test...

2) The rope trick...

3) Reaming the valve guides...
 

4) There is a particular temperature where the LL gets converted... to something else... down in the low 200°F

5) Car experience usually doesn’t apply very directly for this because the car engine typically has water cooling.
 

6) It takes winter weather, and LOP (Or excessive ROP), to get cold enough CHTs to be concerned about the LL not getting converted...
 

7) Keep your mind open to everything....with such low Engine hours... misbehavior of anything isn’t usually going to be expected...

 

PP thoughts only, not a mechanic...
 

Best regards,

-a-

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15 minutes ago, larrynimmo said:

Skip, 

I do value your opinion.   I've been running my M20J really cool.  In the winter, my cylinder temperatures were as low as 300 degrees...#2 has always been my coolest head.  I am always reading about aircraft engines and looking for the optimum operational balance encompassing longevity, economy, serviceability....I read the Mike Busch article...why wasn't it out years ago?  It has been my belief, the cooler the heads the better....Ive been cruising for the last year  LOP 25MP, 22RPM 7GPH and yielding about 20 statue miles per gallon...when its cold out, there are some really cool cylinders....but now my operational values are at fault, because I need to cruise at over 350 cylinder temps

Don't feel bad. We've been told for years that high CHTs are bad, the red box will destroy your engine, running deeply LOP is better for your engine, and the engine manufacturers don't know how to operate their products. These engines are expensive and we want to do whatever we can to increase their longevity. Not until recently has anyone told us that too much of a good thing is bad. I took the APS course in Ada a few years ago and I don't remember anything about low CHTs causing valve sticking. Since Mike Busch credited Ed Kollin, I looked on Gamguard's website and found this more length dissertation:

Camguard-Parts-1-to-3.pdf

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I think this is more of a fuel problem with #2 then a valve sticking issue.  Question? Fuel flow is by a fuel flow transduce, right? 

@60 #2 EGT 1327F fuel flow 17.6

@61 #2 EGT 1124F fuel flow 15.3  If the valve  was sticking I think the fuel would still be 17ish

@62 #2 EGT  956F  fuel flow 13.1

@63 #2 EGT 1192F  fuel flow 17.1 

@64 #2 EGT 1278F fuel flow 17

Back in the day when I was flowing injectors on a flow bench I would see contaminates cause the nozzle fuel stream to bounce around looking like a wild water hose spraying any old way.  At some fuel pressures the stream looked good and then as the fuel pressure was increased the stream would get fuzzy and then the stream would flip wildly around.  With more pressure the stream would clear up and look fine.  Normally you could see the contamination in the nozzle when looking through the nozzle into a light after you blow the fuel out of the nozzle.  After ultrasonically cleaning the nozzles the stream would look clean and straight through the pressure curve. 

I would clean the nozzles first before messing with the valve. 

I worked at an engine shop and I have changed maybe 10 valve springs using the "rope trick" but I don't think I ever reamed a valve guide.  You would need to push the valve into the combustion chamber and fish it back out into the guild. 

I would also make sure ALL JPI inputs are calibrated like HP%.  The JPI gives an amazing amount of information that allows you to troubleshoot in flight and on the ground but bad data could cause bad troubleshooting.  I love my JPI830 and really question why I get in a piston aircraft without a engine monitor. 

Jim

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2 hours ago, carusoam said:

Things that go with misbehaving valves...

1) The wobble test...

2) The rope trick...

3) Reaming the valve guides...
 

4) There is a particular temperature where the LL gets converted... to something else... down in the low 200°F

5) Car experience usually doesn’t apply very directly for this because the car engine typically has water cooling.
 

6) It takes winter weather, and LOP (Or excessive ROP), to get cold enough CHTs to be concerned about the LL not getting converted...
 

7) Keep your mind open to everything....with such low Engine hours... misbehavior of anything isn’t usually going to be expected...

 

PP thoughts only, not a mechanic...
 

Best regards,

-a-

I would add a few more things that can come with valve sticking.  Valve sticking causes increased load on cam lobes and lifter faces, accelerating wear.  Push rods can bend and bent dislodge pushrod shroud tubes leading to uncontrolled oil leaks.  Bent pushrods can lead to fractured lifter bodies which means pulling the engine and splitting the case to replace.
 

Clarence

 

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5 hours ago, PT20J said:

Don't feel bad. We've been told for years that high CHTs are bad, the red box will destroy your engine, running deeply LOP is better for your engine, and the engine manufacturers don't know how to operate their products. These engines are expensive and we want to do whatever we can to increase their longevity. Not until recently has anyone told us that too much of a good thing is bad. I took the APS course in Ada a few years ago and I don't remember anything about low CHTs causing valve sticking. Since Mike Busch credited Ed Kollin, I looked on Gamguard's website and found this more length dissertation:

Camguard-Parts-1-to-3.pdf 1.06 MB · 6 downloads

Bush should have enough uploaded data to do univariate and multivariate analyses to confirm or refute Ed’s hypothesis.  
 

Beside that Larry should borescope and at least valve wobble test. Baby bottle flow test would be useful as well.  Do it before and after injector cleaning to see if number two is blocked.  There are reports of blockages higher up the line so don’t rely on the injector cleaning alone.  Also you need to know what you’re doing with injectors and lines - treat them gently.  Lines can crack at the solder neck.  Torques are important.  Do it with your AP. 

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Update....After i posted, I ran the plane aggressively with 380 degree cylinders, rich of peak for three successive flights. From the first flight on, I haven’t had any issues including at start up and warm up

today, I pulled all my plugs and installed  tempest fine wire plugs (pre gapped)

old plugs...top and bottom #2 cylinder...had balls of lead (or what ever)

Much more than the other plugs
i am going to try to fly LOP only when I can keep the heads in the sweet spot...and try this...I have issues going forward I’ll get my A&p do the rope trick...

9E3DCB94-6D25-420D-BBD0-FCEC3D58439B.png

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Update...I wrote mike Busch ...but didn’t mention the one in flight blip..but I did focus on “morning sickness” because of his recent article...I do know that many of you recommended I do a borescope inspection, and I will do so soon...I just wanted to pass on what Mike said...

AE1A7928-5858-4E13-91B0-32B4AE8BEC23.png

47C9F6E4-4DD1-40CD-92CF-CA3ADABA3E58.png

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On 6/17/2020 at 4:01 PM, larrynimmo said:

i am going to try to fly LOP only when I can keep the heads in the sweet spot...and try this...I have issues going forward I’ll get my A&p do the rope trick...

Likewise, I had been running deep LOP for a while because it seemed smoother, and ran cooler, etc., etc., and I kept getting lead fouling on the plugs.   So now I only run LOP once in a while if there's really a reason to do it, which isn't all that often.

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