My time for an engine overhaul

[KSMooniac]

Well, it is my first time to go through the engine renewal process... I posted a thread recently about a couple different maladies that I have not been able to solve, and they were seemingly unrelated to each other.  (lean condition on #3, intermittent startup problems on #4)  Last Sunday I decided to try Avblend for a possibly sticky valve on #4 (couldn't hurt, right?) and do some high and low altitude GAMI lean tests to confirm or rule out an induction leak.  At about 500' AGL on takeoff, I had a partial power loss that didn't get better with the other fuel tank, boost pump, MP, RPM or mixture adjustments.  I turned away from the pattern towards fields (vs. city) and managed to nurse it around for a normal landing, fortunately.  #4 was intermittent on the taxi back to the hangar as well.

 

I had planned an afternoon of diagnosing anyway, so I got after it without engine monitor data.  Induction leak test revealed no discernible leaks.  Previously we ruled out spark plugs, leads, fuel flows, etc.  I had come around to suspecting a failing lifter on #4, so I removed rocker covers to measure valve lift and thus cam & lifter performance.  My brother got me some nice Starrett dial indicator bits for Christmas last year, and I had a heckuva time cobbling together all of the pieces in a fashion that would allow me to measure the valves.  After about 30 minutes of that, I discovered the indicators I have don't have enough travel for valves.  Dangit.  I scrounged around in my hangar and decided a white hacksaw blade could be used as a crude measuring scale in conjunction with a sharpie pen.  I started at #1 and made marks at the open and closed positions for the intake and exhaust valves after placing the "scale" down into the head parallel to the springs.  It worked pretty well, actually.  Especially when a very precise measurement tool wasn't needed to see that the #1 and #2 intake valves open about half as much as #3 and #4.    It looks like my engine munched at least one cam lobe, so now I'm planning to remove it sometime in the near future.

 

It still doesn't explain my symptoms with #3 and #4.  I'm anxious to see what I can uncover and learn during disassembly, but for now I'll chalk it up to a little divine coincidence that forced me to go digging and find a problem before it stranded us away from home, or worse of course.  

 

I'm planning to overhaul it myself with help from an A&P friend or two.  I'll send stuff out as appropriate to experts for inspection, modification, etc. I'm thinking about adding Ney Nozzles to the case.  Perhaps sending the cylinders to Lycon for optimization and flow-matching.  I want to balance all of the rotating parts.  I still have my salvage IO-360 and I think I'll send the fuel injection system, oil cooler, and magneto out soon to get a head-start on acquiring the parts needed to build up the overhaul.  I'll probably have to get the camshaft out of it as well.  I'm disappointed with the timing of this but at least I had no big trips on the books for the next few months.  I'm excited about optimizing MY engine and carefully controlling the ingredients.  It will be fun to detail out the firewall-forward stuff so it will be as pretty as the rest of the plane.  I'm not looking forward to being grounded for a while, and especially having to drive through Oklahoma for the holidays!     

[KSMooniac]

I'll add that my last oil change didn't reveal any noticeable metal in the filter.  I have ~25 or 30 hours on the current oil and didn't drain it yet.  I quit doing oil analysis long ago because I'm lazy, but I've heard enough accounts that it doesn't catch Lycoming cam issues reliably.  I wonder if I had some metal flowing in the oil that fouled the #4 lifter.  Hopefully I discover a culprit on disassembly.

[Parker_Woodruff]

  I'm not looking forward to being grounded for a while, and especially having to drive through Oklahoma for the holidays!     

 

Tell me about it...

 

Hope you find the culprit(s) with relative ease. I imagine you will.

[N601RX]

With Hydraulic lifters you are not going to get a very good measurement. The valve springs and lifter leakdown is going to influence it.  Try removing the rocker arm and measure off the pushrod if it is stable or remove the pushrod tube also and measure of the edge off the lifter.

[kmyfm20s]

Sorry to hear the about the bad luck! I just sent my cylinders to Ly-Con to have them ported and flow balanced. I'm excited to see how they preform. Talking to them on the phone they claim 4 to 5 Hp per cylinder and run smoother! I started making metal and it was all Aluminum. All my research pointed to piston pin end caps but it turned out to be the exhaust valve spring on the #4 cylinder had broke and was rubbing on the Aluminum. The cylinder was still making good compression 74/80 but a few of the cylinders have been weaping at the bases and a thru bolt was leaking so I pulled them all to take care of all my gripes. I will let you know about the cylinder performance.

[KSMooniac]

With Hydraulic lifters you are not going to get a very good measurement. The valve springs and lifter leakdown is going to influence it.  Try removing the rocker arm and measure off the pushrod if it is stable or remove the pushrod tube also and measure of the edge off the lifter.

 

I will very likely do this, or remove a jug like Jim suggests before taking the whole thing off.  What is pretty telling though is that #1 and #2 (same cam lobe) were pretty much the same measurements, and #3 and #4 were the same but larger than #1/#2.  I doubt each pair of lifters would leakdown identically to give me this condition.

 

I have ~450 hours on these refreshed cylinders (first run on factory OH in 1991) and ~2100 SMOH.  I had hoped/planned to go to 2500 unless there was a compelling reason not to do so...

[John Pleisse]

Given you have a salvaged engine, you are past TBO (23 years SOH), competent and motivated, I say OH. Question, did this happen on your first week of matrimony or during your last week of "bachelordom"? Just ask'in.....

[KSMooniac]

Given you have a salvaged engine, you are past TBO (23 years SOH), competent and motivated, I say OH. Question, did this happen on your first week of matrimony or during your last week of "bachelordom"? Just ask'in.....

 

I'm in my last 11 days of freedom, John.      A mechanic friend of mine suggested I propose delaying the wedding due to unforeseen engine expenses.  He then went on to say if she agrees, then I have a keeper, and if she offers to pay for it then I REALLY have a keeper!  I said I doubt there is even a female pilot/owner on the planet that would put off a wedding to pay for an engine.

 

(He is an avowed bachelor and advised me 2 weeks ago that it wasn't too late to back out...    He is also ordained so he can marry people, which is a bit puzzling.)

 

I'm also going to register for wedding gifts at Lycoming in case any one wants to help!

[rbridges]

keep us posted on your progress/decision making.  Given that an OH is the single costliest routine maintenance item, I like seeing how people handle them.

[KSMooniac]

keep us posted on your progress/decision making.  Given that an OH is the single costliest routine maintenance item, I like seeing how people handle them.

Will do.  I plan to document every part, cost and inspection result for my own curiosity as well for the hull value standpoint if I ever sell the plane.  It will also be good to have a record of every part number/serial number for future AD compliance as well.  Maxwell has told stories about field overhauls without records that force you to dig into an engine if you don't know a serial number.

[aaronk25]

Does it make sense to exchange it for a new roller can like Byron did?

[N601RX]

Will do.  I plan to document every part, cost and inspection result for my own curiosity as well for the hull value standpoint if I ever sell the plane.  It will also be good to have a record of every part number/serial number for future AD compliance as well.  Maxwell has told stories about field overhauls without records that force you to dig into an engine if you don't know a serial number.

When I overhauled mine last year I cut the label off the box or bag for each part and put them in a envelope with the aircraft logs. That will give you manufacturer, lot numbers, date codes, part rev, ect.

[jetdriven]

Sucks to hear this, Scott. Our situation was similar but we caught it sooner. Still the iron in the oil analysis only went from 15-20 PPM to 99. It's very subtle but the 1/2 teaspoon of ferrous metal in the filter was not.

Had my shop been willing to help me with tear down and reassembly I would have done what you are planning to do, but they didn't want any part of it. I'd recommend pulling two jugs off one side and a rod off the crank and inspecting what you have before committing to any further work on it. In our situation we found a leaking cylinder head-to-barrel joint, ruined pistons, scored cylinders, a scored crank and a trashed prop governor. Further the oil pump and gears were probably bad and after adding it all up, ate the big one and ordered up the equivalent of a new Chevy Silverado.

Check the case carefully and the crank tag. Our case was from 1977 and reworked twice, welded at least once. It would probably pass but the crank was most worrisome of all. You can turn an -A3B6D crank to .003, .006, and .009 undersize. Ours was already cut to .006 so any scratches deeper than .0005 would trash it and that particular crank is unique to the -A3B6D and -A1B6D due to the crank end in the accessory case being a non-common size. We were quoted 8 grand for a used serviceable crank which is what sent us over the cliff.

In any instance I would only use a new cam and lifters in your rebuild, it's not a lot of money but I think the reground lifters are what took ours out. The cam still had full lift and it would run 188 MPH but 3 of the lifter faces were completely spalled.

[aaronk25]

Sucks to hear this, Scott. Our situation was similar but we caught it sooner. Still the iron in the oil analysis only went from 15-20 PPM to 99. It's very subtle but the 1/2 teaspoon of ferrous metal in the filter was not.

Had my shop been willing to help me with tear down and reassembly I would have done what you are planning to do, but they didn't want any part of it. I'd recommend pulling two jugs off one side and a rod off the crank and inspecting what you have before committing to any further work on it. In our situation we found a leaking cylinder head-to-barrel joint, ruined pistons, scored cylinders, a scored crank and a trashed prop governor. Further the oil pump and gears were probably bad and after adding it all up, ate the big one and ordered up the equivalent of a new Chevy Silverado.

Check the case carefully and the crank tag. Our case was from 1977 and reworked twice, welded at least once. It would probably pass but the crank was most worrisome of all. You can turn an -A3B6D crank to .003, .006, and .009 undersize. Ours was already cut to .006 so any scratches deeper than .0005 would trash it and that particular crank is unique to the -A3B6D and -A1B6D due to the crank end in the accessory case being a non-common size. We were quoted 8 grand for a used serviceable crank which is what sent us over the cliff.

In any instance I would only use a new cam and lifters in your rebuild, it's not a lot of money but I think the reground lifters are what took ours out. The cam still had full lift and it would run 188 MPH but 3 of the lifter faces were completely spalled.

Wonder what wrecked your pistons and scored the cylinders?

[John Pleisse]

I'm in my last 11 days of freedom, John.    

 

I'm also going to register for wedding gifts at Lycoming in case any one wants to help!

 

Now that's funny....a wedding registry at Lycoming.

[fantom]

Every dark cloud has a silver lining, Scott. You're going to know more about the intimate details of your engine than most of the rest of us ever will, and you did a fine job nursing your sick engine back to a safe landing. Now it's just going to take time and cash to make things right, and you're very qualified for the job. Hopefully that goes for getting married as well. Several points, observations and questions about both your problem and some of the posts about it. What were you seeing in your oil filter inspections? I believe this is much more telling than oil analysis, and please check your oil suction screen where those possible cam lobe pieces may be. The big stuff never gets to the oil filter. Intake valves are rarely the cause of low compression leaks. It's most usually the exhaust valves or rings. Boroscoping every cylinder could be very informative and reduce the urge/need to pull cylinders. Probably not in your case, but pulling cylinders is a grossly overdone 'first step' procedure. That boroscoping of every cylinder needs to be done at every annual but few get it. TBO, both hours and years, is a discredited concept, usually touted by inexperienced pilots, shops in need of immediate work, lawsuit fog attorneys, and plane buyers looking for a price concession. It's a general guide only. If you haven't read Lycoming SI 1492d, I suggest it would be worthwhile. It's happened to you and Bryon, so it can happen to anyone. Learn you engines people, and don't rely on someone else to save your ass or wallet. Learn how to inspect your oil filters at every oil change YOURSELF, what someone else does is too often just perfunctory; demand oil suction screen inspection at annual or better yet at each oil change....yes it's difficult; oil analysis and boroscoping at every annual. It's YOUR engine, wallet and ASS. Scott, I was really looking forward to what those GAMI lean tests would tell you and us. Best of luck with the engine teardown and the wedding buildup.

[fantom]

I did note there was no ferrous metal during your last oil filter check, Scott.

[mike_elliott]

Had my shop been willing to help me with tear down and reassembly I would have done what you are planning to do, but they didn't want any part of it. I'd recommend pulling two jugs off one side and a rod off the crank and inspecting what you have before committing to any further work on it. In our situation we found a leaking cylinder head-to-barrel joint, ruined pistons, scored cylinders, a scored crank and a trashed prop governor. Further the oil pump and gears were probably bad and after adding it all up, ate the big one and ordered up the equivalent of a new Chevy Silverado.

Check the case carefully and the crank tag. Our case was from 1977 and reworked twice, welded at least once. It would probably pass but the crank was most worrisome of all. You can turn an -A3B6D crank to .003, .006, and .009 undersize. Ours was already cut to .006 so any scratches deeper than .0005 would trash it and that particular crank is unique to the -A3B6D and -A1B6D due to the crank end in the accessory case being a non-common size. We were quoted 8 grand for a used serviceable crank which is what sent us over the cliff.

In any instance I would only use a new cam and lifters in your rebuild, it's not a lot of money but I think the reground lifters are what took ours out. The cam still had full lift and it would run 188 MPH but 3 of the lifter faces were completely spalled.

 

Did Lycoming accept this as a core, Byron? I had heard they would reject a core if it had been disassembled and found to be in this condition. Great news if that isn't true for those that want to make an informed decision on  rebuild vs reman.

[Seth]

Scott-

 

Sorry to hear about your engine issues.  The most important fact is you were able to nurse your plane to a safe landing.  Good luck with the overhaul.  You may want to also replace/rehab other accessories at the same time - probably flush your prop if there was any metal circulating, etc . . .

 

-Seth

[mike_elliott]

Nothing like the "I need a new airplane engine" true love test. It is far better timing now, than say in 5 years when the honeymoon is over . It would cost you far more JMU's (jewelry monetary units) then.

All said, sorry for the bad luck, Scott, but you are in an envious position if it has to happen. Spare motor, skillset to do it properly etc. You might consider the drilled cam STC from FF also, along with Nye nozzels

[garytex]

Doing your own overhaul, especially with the help of a knowledgable mentor, can be in retrospect, a very soul satisfying experience.  It will also at some point be very frustrating.  Still worth it.

Gary

[jetdriven]

Wonder what wrecked your pistons and scored the cylinders?

The metal particles from the lifters embedde themsves in the soft aluminum skirts of the pistons and that scored the cylinders.

Regarding core acceptance, we treated it like a "detailed borescope inspection". We carefully put the jugs back on and reassembled it. Technically it was in the same airworthy condition or status it was in before (minus the making metal part). Had there been nothing wrong I would have flown it afterwards. Lycoming took it as a core. We made the 35 year deadline by just a few months.

[jetdriven]

Scott-

 

Sorry to hear about your engine issues.  The most important fact is you were able to nurse your plane to a safe landing.  Good luck with the overhaul.  You may want to also replace/rehab other accessories at the same time - probably flush your prop if there was any metal circulating, etc . . .

 

-Seth

I sent my prop to be disassembled , repainted, and resealed. Flushing I don't think will do it for a prop or governor.

[fantom]

I sent my prop to be disassembled , repainted, and resealed. Flushing I don't think will do it for a prop or governor.

 

Was it sent to Byam Propeller Service, at Meacham in Ft. Worth?  A superb and reasonable shop, BTW.

[Shadrach]

I'd go with the FF drilled cam and forgo the Ney nozzles.