Overhauled angle valve cylinder blues

[garytex]

I bought an M-20F with lots of SWTA mods and poor inter cylinder baffling in Nov.  It had 800 SMOH using OH jugs.  Not much documentation on exactly what was done to the jugs.  Based on paint, one is steel, three were nickel, with 2 longitudinal silver stripes on the head.  One of the 2 stripers (cyl #2 which had been off and on 2 or 3 times shortly after overhaul) showed a wet bottom plug and a polish stripe indicating ring sticking or worse in Jan.  Off with its head, rings all coked up and the overhauler, Custom Airmotive, found a crack too big to weld.  I replaced with ECI Cerminil.  His advice was, it'll go another 800-1000 hrs to TBO, a new jug would be wasted when you replace with all new at OH.  I see the logic.  He also suggested we look for a leaky intake tube on #2 (which we found) and a case crack on the cyl base pad (which we didn't)  Previous owner ran 50 ROP at high %ages of power.  I have about 100 hrs on the plane 20-40 LOP, 8 GPH 

Last month was Annual and #3, which runs hottest, had somewhat low compression with air past the rings, intake, and a small amount of air past the exhaust valve.  It looked good through the borescope.  We filled the cyl with camguard pushed some past the rings and left it overnight.  I flew it another 25 hrs, and brought it in for check today.  60 lbs with a strong intake leak.  Valve had an odd looking spot on the lip through the borescope.  Staking didn't help.  So it is off to the overhauler. Two bottom ring gaps lined up, no coke in the rings.  I won't be surprised if it is cracked too. (I played this same game with O-300 jugs back before the good new Superior jugs came on the market.  The replacement pool of jugs was really tired, and cracked like nobody's business) This is the same jug that showed very high temps when we put the JPI spark plug base temp sender on the bottom plug.  JPI said "Don't do that, you'll scare yourself.  Put it back on top."  So I did, and it reads like all the other bayonet senders.  I keep it less than 385df except for very short intervals when it occasionally gets away from me if I'm heavy, it's hot, and I decide to climb ROP. 

I am wondering what to do if I have to replace the cyl.  I have a strong bias towards new cyls, but am offended by the price difference between the single source angle valve cyls and multi-vendor good, cheap parallel valve cyls, and am loathe to support a company that I think is hosing me.

On the other hand, if I start buying new, and many more crap out, I might have a set of lightly used first run jugs at overhaul time.  

Ideas and comments welcome.

Thanks Gary 

[N601RX]

When buying my plane I remember looking through log books of several IO 360. Most of them seemed to make it ok on new cylinders to around 1000 to 1300 and then they started having cylinder problems. At this point I noticed that several of them had swapped out exchange cylinders from a cylinder shop put on them.  After that I noticed that there seemed to be a pattern of replacing them regularly with more exchange cylinders. At the rate a couple of them were swapping them out they could have got a new set in a few years.  If it was a 0-200 it would be a no brainer to buy new ones.

I do think there is a big difference in simply ordering the cheapest exchange cylinder you can find and removing your old ones and sending them to a good shop and telling them to replace everything.

[garytex]

Yes, the quality of the jug is highly dependent on the shop, and parts used.  I think I have that part under control.  The piece you cant control is the stability of the cast aluminum head.  ECI's IFR process may or may not help.  It is good marketing, but I have seen no statistical analysis.  Anecdotes anyone?

Gary

[garytex]

That's interesting that new jugs seem to have a 1000 to 1300 MTBF.  I hadn't considered asking that one, but it would be an integral part of a comparrison.

[N601RX]

Quote: garytex

That's interesting that new jugs seem to have a 1000 to 1300 MTBF.  I hadn't considered asking that one, but it would be an integral part of a comparrison.

[KSMooniac]

That surely sucks.  Course of action depends on how long you plan to keep the plane, and what you're willing to put into it to fix these problems IMO.

My plane had ~1400 SMOH (from Lycoming in 1991, new jugs) when I bought it, and at 1650 SMOH I had to freshen two of the jugs and did all 4 to level-set everything.  The shop said they were in good shape and would be great candidates to overhaul when my time comes, as an option to buying new.  I'm happy with what I did an interim step to get me confidently to overhaul time, whenever that might be.  I'm around 2000 SMOH right now and plan to keep flying for the foreseeable future.

If your plane is a keeper, you might consider biting the bullet now and start with 4 new jugs for a TOH, and then overhaul *those jugs* when you do a major.  If you take care of the cam, you should easily exceed TBO if you put new jugs on now.  A properly cared-for Lycoming should get more than one TBO run from a set of jugs, so this might be a good choice if you plan to own the plane a long time.

If you will likely sell it in the next few years, then you might as well keep playing whack-a-mole and changing cylinders with O/H ones as needed to minimize the cost.

[garytex]

Scott

Your thinking seems just right for your engine and jugs.   

I have had other expenses bringing this plane to minimum acceptable condition that are approaching 25% of the purchase price, and I am not a profligate spender, and the plane wasn't in too bad a shape to start with.  That, and the sequential nature of the failures has got me into the mole bashing mode, and I am not very comfortable with that game.  I also have some doubts about running the bottom end past (or even making) TBO.  If the same judgement was used in decision making for the bottom as the component selection for the top at the last OH, then to me, the bottom is suspect also.  I think I will keep this plane a long while, and expect to go through an overhaul cycle.  I don't think I want to spend the money right now for an all new cyl. top, although I think that would be a good way to structure the process, and I'm letting 9 Gs make that decision for me.  Also if the cam goes, then those would be toast.  If new cyls were a G each, instead of 2 and change, thats probably what I would do.  Damn single source angle valve cyls.

Thanks for your insight.

Gary

PS I was up your way this spring, flew to Russel for some PD hunting near the thriving megalopolis of Waldo, KS.  Pretty country, nice people, we don't see much Midwestern Americana like that, especially in deep S. Texas.  I really enjoyed the whole experience. Those 900 lb. stone fenceposts everywhere sent a shiver down my spine, though.  Man I hate to think what misery it took to produce, transport and set them with hand drills, freezing water, and horses.  I became much too familiar with cedar posts in my youth, but those stone posts take the cake.  I literally couldn't look at them without admiring the fortitude of, and cringing at the effort spent by the men that settled that country.  Thats some sturdy stock that you all come from up there.    

[KSMooniac]

It is a tough call, and I don't envy your position trying to get what you thought was a plane in good shape up to your specs.  I still wonder why none of the aftermarket companies have entered the angle valve market!

FYI, if the cam fails it shouldn't trash your cylinders, so don't let that impact your decision on what to do with them.

Also BTW, I'm a native Texan and will forever claim that as my home!  ;-)  Kansas has been pretty good to me, but I still like Texas.  I wish we had more of an aircraft industry going in Texas so I would have more options.  There are some remarkable stone structures all over the state that are quite admirable.  I'm also glad I didn't have to build stone fence posts back in the day!

[garytex]

ECI has a new angle valve jug with roller rockers they are selling into the experimental market.  Big X preceeding the part number, and $1900.  We just can't catch a break.

They say that the certification process is too expensive.  

I wonder if I could use them under the "owner supplied part" rule. He says jokingly.

Gary

[1970m20e]

Quote: garytex

I bought an M-20F with lots of SWTA mods and poor inter cylinder baffling in Nov.

[DaV8or]

Quote: KSMooniac

I still wonder why none of the aftermarket companies have entered the angle valve market!

[garytex]

 

Dave

The same story for years is "they are considering it" and there have been several "they"s.  I hadn't considered the 'couldn't do better on price' side of it.  But that might be really valid.  Just how many angle valve engines are there.  Not that many 4-bangers.  Just us, the retract Cardinals, Arrows and a few Sierras.  Aren't lots of the 540 series injected? Or are they injected parallel valve?  

Everyone seems to do OK on the now 50% less than they were compared to the monopolistic price Lycoming charged for jugs when they were single source.  I just assumed that we were being treated as a high margin line sort of purchaser that keeps the business solvent, like the 40% margin on a shirt in a sporting goods store where the guns turn 7%.  In that case, there would be plenty of margin to bring the product to market, and still profit.  I'm thinking of the excellent small barrel Continental jug that Superior brought out in the early '90s.  A much much better product than a new Continental, at a much lower price. For an engine that hadn't been put in an airframe to sell new since the 1967 Cessna 172.  But maybe there were more O-300s, O-200s in Cessna 150s and C-145s out there than I am imagining.  On further consideration, probably a lot more, and they sure needed better jugs than they were getting from the OH exchange pool at that time.  I do know that everybody flocked to them.

But I think you are right, and I think we're stuck with single source for the foreseeable future.  Damn the bad luck.

Gary 

[cujet1]

I have a good, long history with angle valve cylinders as an A+P and pilot/owner.

A quick story: BPA built us a wonderful, high compression, ported, and modified angle valve engine for our "experimental exhibtion" Extra 300L.  4 of the 6 brand new cylinders failed at 90 hours, with compressions in the 50's and 30's. Being a bit annoyed with Lycoming's quality control, I personally overhauled the cylinders. Over time, I came to the conclusion that the cylinders actually failed due to localized bore overheating and that "new" is no assurance of reliable performance. Air cooled engines really are a different animal, with uneven, localized cooling.

I clearly understand your reluctance to play the musical cylinder game. Certainly, you could install 4 new units, and "if" they are problem free at overhaul time, simply overhaul the cylinders. They won't have many cycles on them (like you might find with OH-exc cyls) , and they won't be at additional risk of early failure (vs. new) .

However, if, you have a known good cylinder, with a simple problem (leaking valve, for example) I believe it's worth considering a simple IRAN (inspect and repair as necessary). Not only does it cost far less, but when done properly, it's as reliable as any other option. The exception would be high time units that have known weld repairs.

It is not uncommon for new cylinders make several hundred hours, only to lose compression, then be IRAN'd and make overhaul with ease!

 

[garytex]

The cylinders I am replacing had baffelig with no wrap fore and aft as part of the SWTA mods, which may have yielded hot spots.  Who knows.

Thanks for your response.

Gary

[jetdriven]

Im pretty sure that no wrap baffles would lead to hot spots. Air is supposed to be rammed through those fins.

Now, interestingly enough, adding spacers at the front or rear baffle where it contacts the cylinder head is proven to lower CHTs.

[garytex]

Yeah, my mechanic thought mine is a little tight there.  But I didn't do anything about it.  I may wish I had, as I wil be breaking in a new #3, which runs hottest ordinarily.  I'm going to fly it AUS to Del Rio early in the morning tue, at high % power, and hose the fuel to it, all hoping to keep the cyl cool enough to keep the power up.  It wouold probably stay cool at 8.5 gal LOP, I wonder how that would work.  As a joking aside, maybe the excess fuel will cause enough oil dilution to break the rings quickly, and then I can fly merily on my way.  Actually Ram and others think that going full rich in the last part of landing with cool CHTs may actually cause some wierd ring wear due to oil dilution.  But that is in low power operation.

How's your break in comming?  Any cooler? 

[jetdriven]

It is cooler, and the last flight the CHT are like 320 now, down from 380.  Baffle spacers helped 20 degrees or so.  Getting readt to turn up the timing soon.  Retrieve some of that lost 5-7 knots in cruise and ten in race mode.

I never go full rich for landing.  That is far-far-far too rich for that mode. Full rich if for a 10% extra fuel margin from detonation on a sea-level zero degree takeoff. Any other time its too much.

[garytex]

320, thats great.  It will be interesting to see if the sole difference is the timing.

The spacers are to set the back baffle plate off the rear of #3 and 4 heads?  How thick?  How far back is the plate off the face of the head?

What do you think of LOP climbs?  They will certainly recuce CHTs.  I have doubts about the big pull when things are hot.  Maybe nose down a little, reduce MP for a while, let things cool (but for how long and how much?) a little, do the pull, and feed MP back in?

[M016576]

Quote: KSMooniac

It is a tough call, and I don't envy your position trying to get what you thought was a plane in good shape up to your specs.  I still wonder why none of the aftermarket companies have entered the angle valve market!

FYI, if the cam fails it shouldn't trash your cylinders, so don't let that impact your decision on what to do with them.

Also BTW, I'm a native Texan and will forever claim that as my home!  ;-)  Kansas has been pretty good to me, but I still like Texas.  I wish we had more of an aircraft industry going in Texas so I would have more options.  There are some remarkable stone structures all over the state that are quite admirable.  I'm also glad I didn't have to build stone fence posts back in the day!

[garytex]

Job:  Ouch!  Any idea why your cam went?  

 "Personally, I'd go with OH'ed and save the new until you hit TBO or your bottom end goes...."

Yeah, thats how the cow is going to eat the cabbage.  I have a good cylinder overhauler, and a mechanic that has played the game enough times to get all that done without much input on my part and my ac back in the air promptly, so promptly that I didn't have time to perseverate over the decision, as I like to do."It all happened so fast, it's just a blur".  

And of course, with overhauled cylinders, which I am biased against based on my small barrel Continental jug experiences of the '90s, back when those heads were cast out of floor sweepings and a few pop tops, on their fifth tbo run and cracked at the drop of the hat.  I should just shut up and go with the flow, be glad I have a good mechanic and cylinder overhauller who are trying to do the right thing, and get out of their way.

Gary 

[KSMooniac]

Job, that is terrible!  How much calendar time on that overhaul, and is Lycoming doing anything to help?  Did you have a roller cam engine?

[garytex]

The problem with the jug was a warped intake valve.  What warps an INTAKE valve?   Maybe I'll ask the group.

[M016576]

Quote: KSMooniac

Job, that is terrible!  How much calendar time on that overhaul, and is Lycoming doing anything to help?  Did you have a roller cam engine?

[DaV8or]

Quote: garytex

The problem with the jug was a warped intake valve.  What warps an INTAKE valve?   Maybe I'll ask the group.

[N601RX]

Quote: M016576

It's probably my own fault- the motor was a factory OH in 2001.  It was broken in, then pickled by the owner for 6 years.  He started running it again in '08 and I bought the plane in 2009 with about 130 hours on the motor.  There was a little corrosion on some of the cylinder heads, so I popped off #2 during the pre-buy and the forward cam lobes looked good.  The aft lobes felt alright, but I couldnt really see them well (and didn't have a borescope.). Compressions were all nice (76-78).  I flew the plane about 200 hours in 2 years, and after two oil changes with increasing iron in the oil analysis, I pulled quite a bit of metal out of the oil filter.  Spalled out tappets and a pitted cam... The front lobe wasn't too bad, but the aft most one was pretty awful.  

My guess: lack of use + corrosion prior to me purchasing the aircraft.  Kind of hard to believe it takes a couple hundred hours of flight to manifest itself though... Hard to say.  I've gone the "more affordable" route than Byron and had the motor overhauled by a local shop and the jugs overhauled rather than new: total cost of OH: 17.5 AMU's... About half of what a FRM on a A3B6 costs from Lyc.  We'll see if it goes past 1000 smoh to make it worth it!!