Toasted cam options, rebuild or replace

[ERJDriver]

Well started the conditional off with a bang....

Pulling plugs and noticed what looked like a Crack from the plug to the intake valve, borescope confirmed it.

Pulled that jug today, came has minor pitting, no metal in the filter other than a sliver here and there.

So full rebuild via exchange or shipping it off

Local rebuild via myself with supervision with an A/P.

Stuff would be sent out to be checked etc.

Who all has done their own stuff? Mechanically inclined, just never done this.

Not afraid of the labor, just want it done right and solid.

Calling lycon in the morning to see the options.

Tropic air power is right down the road from here.

 

[Ironflight]

There is nothing inherently complicated about a Lycoming engine, but having rebuilt a few, and having taken the factory rebuild course, can tel you that the number of times the instructor says “now the trick here is…..” stunning. If I had an nickel for every time I have been told this by experienced builders, I could probably buy a cup of coffee at Starbucks.

Doing it with an experienced supervising mechanic is a great way to go - but expect some delays in Tulsa (all parts go to Tulsa….) and expect some hiccups with random part availability. Last engine we did here was Louise’s, and I think it was about four months from teardown to assembly day - nothing major, just little things here and there…..

 

[hgerhardt]

I overhauled my new-in-1980 IO-360Ax in 2008. Sent the original 2000-hr cylinders to ECI to get the nickel-carbide treatment and took the crankcase, rods, crank to Tim's in SoCal (he since retired). After 43 hours, I discovered a crack in the crankcase below cyl #1. Took the engine apart again and drove the crankcase to Nickson's in Santa Maria, where they welded it up and added gussets between the cylinders similar to how Lycoming does the crankcase castings today.

It's been 1100 hours and 17 years since I did the overhaul and other than 2x honing valve guides to fix morning sickness, it's been fine since. I had never overhauled a Lycoming before this one, and I did not have the benefit of learning the 'trade secrets' from the factory like Paul did, but I really didn't have any issues with dis- and re-assembly. Used Loctite 518 on the crankcase parting line, and it's still dry today.

I've overhauled and modified many automotive and motorcycle engines before my Lyc, so I had a pretty good idea of what to expect and what clearances are critical. Download the manuals.

Now, @Ironflight , it would be great if you'd put together a story detailing the “now the trick here is…..” tricks. At least to the best of your recollection...

And, yeah, getting parts these days is ridiculous. I just received a new set of cylinders from Lycoming and took 18 months to get. I'm slowly amassing parts knowing the ECI nickel-carbide cylinders probably won't make it to 2000 hours, as Paul knows only too well.

 

[hgerhardt]

Oh, and I have a question too: does anyone have any experience with the new DLC-coated valve lifters (tappets) which Lycoming is selling these days?

 

[lr172]

Oh, and I have a question too: does anyone have any experience with the new DLC-coated valve lifters (tappets) which Lycoming is selling these days?

I put them in my 540 at overhaul. Not crazy expensive or at least weren’t in ‘19. Lyc rep told me emphatically that these put an end to cam spalling. 450 hours now. Had to pull #2 cyl a month ago and got a peek at two lifter bottoms. Looked brand new

 

[Ironflight]

Heinrich - I wrote a two or three part series in Kitplanes quite a few years back about the experience at Lycoming school and the tips and tricks they taught us - finding it is left as an exercise for the student…..

 

[hgerhardt]

Heinrich - I wrote a two or three part series in Kitplanes quite a few years back about the experience at Lycoming school and the tips and tricks they taught us - finding it is left as an exercise for the student…..

OH that's right! Thanks for the reminder! Glad I still have a subscription. And now I'll save these articles.

Paul Dye's Notes from Lycoming Class - KITPLANES

Ed. note: These notes are part of Paul Dye’s article about attending Lycoming’s engine assembly school. For such “simple” engines, Lycoming type power plants, there are quite a few little tricks of the trade that should be used when taking one apart or putting it together that can make or break...

www.kitplanes.com

Learning about Lycomings

Attending the Lycoming Service Class in Williamsport, Pennsylvania.

www.kitplanes.com

Parts Off, Parts On!

Learning how to disassemble and assemble Lycoming engines.

www.kitplanes.com

Fun With Part Numbers - KITPLANES

As I’m getting ready to re-assemble my wife’s O-360-A1A, I have spent a lot of time looking up part numbers. Not, as it turns out, that I need to buy any of the big parts (everything seems to have checked out just fine at the machine shop), but before I got the good news from […]

www.kitplanes.com

Following the DIY Approach to Engine Overhaul, One Step at a Time - KITPLANES

Following the DIY approach to engine overhaul, one step at a time.

www.kitplanes.com

Overhauling Your Own Lycoming - KITPLANES

Get friendly with the UPS driver who knows his way to Tulsa.

www.kitplanes.com

The Art of Assembly - KITPLANES

The day will come when all of your engine’s parts come home from their exciting trip to Tulsa, Oklahoma. (Remember that, in the last installment, all the big pieces of our RV-6’s Lycoming O-360 had been UPS’d to Tulsa for review and rework as necessary.) So now it’s time to put things together...

www.kitplanes.com

Final Steps to Flight - KITPLANES

Part 4: Overhauling Your Own Lycoming

www.kitplanes.com

 

[Toobuilder]

Stuff would be sent out to be checked etc…

Any reason you would not consider an IRAN? Split the case to replace the cam, but run it through a solvent bath to clean and THEN decide if it needs to go out for O/H. Chances are good it does not need a thing other than new gaskets. Heck, I’d consider leaving the rods on the crank if it had good oil pressure and the bearings pass a wiggle test.

 

[Low Pass]

Any reason you would not consider an IRAN? Split the case to replace the cam, but run it through a solvent bath to clean and THEN decide if it needs to go out for O/H. Chances are good it does not need a thing other than new gaskets. Heck, I’d consider leaving the rods on the crank if it had good oil pressure and the bearings pass a wiggle test.

This^^. Think about a top overhaul too.

 

[RV7 To Go]

Oh, and I have a question too: does anyone have any experience with the new DLC-coated valve lifters (tappets) which Lycoming is selling these days?

Our club has a fleet of 24 Cessna 172's running about 1000 hrs a year each. Our engine rebuilder says that he sees no more cam/tappet issues since they went to the DLC coating. FWIW.

 

[ERJDriver]

Any reason you would not consider an IRAN? Split the case to replace the cam, but run it through a solvent bath to clean and THEN decide if it needs to go out for O/H. Chances are good it does not need a thing other than new gaskets. Heck, I’d consider leaving the rods on the crank if it had good oil pressure and the bearings pass a wiggle test.

This is the route I'm leaning towards, case and everything was worked in 03, I dont want to blow money but I want it done right for sure.

Open for suggestions for sure! Oil pressure is great. Lifters don't look worn from what I can see

 

[lr172]

This is the route I'm leaning towards, case and everything was worked in 03, I dont want to blow money but I want it done right for sure.

Open for suggestions for sure! Oil pressure is great. Lifters don't look worn from what I can see

New cam = new lifters, always. Re-ground are ok, just not a new cam with existing lifters. These parts uniquely wear together into a set. The new dlc may not wear in like the steel ones, so it may be possible with those; outside my experience.

 

[ERJDriver]

New cam = new lifters, always. Re-ground are ok, just not a new cam with existing lifters. These parts uniquely wear together into a set. The new dlc may not wear in like the steel ones, so it may be possible with those; outside my experience.

Yeah id replace the set

 

[JimCMI]

I overhauled my io-540 this past winter. It wasn't hard, but i understand now why all the shops quote at least 6 months. It took me 5, and 4 of that was waiting for the crankcase at divco.

My engine had about 1200 smoh, and had to come apart because the idler shaft in the front governor drive got loose. All the tolerances measured within "new" spec, so machine work was minimal. Cam failed inspection though, so I went with a new lycoming cam kit, which was about $6k. I went with Lycoming to get the dlc lifters; so far, so good, after about 80 hours lol. Total parts & machine work was 22k. I was able to overhaul my cylinders.

Angle valve cylinders were, as mentioned above, about 18mo lead time then. That's going to be your biggest hurdle I think.

Best tip i can give are that divco, aircraft specialties, etc. offer "expedite" fees. Well worth the money. I discovered during assembly that i had a rod that was out of round. I overnighted it to ASS, they reworked it that day, and overnighted it back.

The Lycoming Direct Drive Overhaul manual is really great. Find someone (probably your mechanic) with a "veron" subscription to get all the updates.

I had an issue with rod bolts. They've changed a couple times. I wound up having to buy 12 new ones at $100+/ea. Lycoming still uses both part numbers in different engines, so it probably doesn't matter in an experimental, but mine is certified. Also they're torque to length in the angle valve engines, and I had a couple that just wouldn't stretch the right amount within the torque limits. Between that and the bad rod, i spent a lot of money on those stupid bolts, and lost a good week waiting on shipping. Point being, buy a couple extra up front.

I really enjoyed doing mine. Paul's articles linked above were invaluable. I'm looking forward to building the engine for my RV. It is time consuming. It took me 229 hours. I think i could cut that in half, having done it before. Spent a lot of time reading the manual and planning my next step. I figured i got paid $152/hr compared to what I was quoted for an overhaul.

 

[ERJDriver]

Thank you everyone for the info. Lycon is a month and a half out on port work, they mentioned high compression pistons with some coating on them.

Any reason to avoid those and just stick with standard compression? Open to opinions

 

[Freemasm]

Thank you everyone for the info. Lycon is a month and a half out on port work, they mentioned high compression pistons with some coating on them.

Any reason to avoid those and just stick with standard compression? Open to opinions

Long story, very short = the higher the compression -> the lower your options for fuel, timing to a somewhat lesser degree, etc.

If you have no plans to have anything beyond fixed OEM timing and burning Avgas, the higher comp pistons are OK.

I spec'd out and bought my Lyc clone with 9.6:1 pistons. That was when I perceived a EAGLE/PAFI/Etc. solution was eminent. Though I'm still not flying. I wish I'd stuck with 8.5s. My airframe should be able handle the lower associated VP. Testing will confirm. I would then stick with MoGas with less on my mind and more gas money in my wallet.

Just a single perspective. You'll get lots of comments by people trying to justify their own personal decisions as best. You have lots of options.

 

[ERJDriver]

Yeah i dont NEED anything more than what it's already got. Called JB aircraft engines in Sebring and they said cam, lifters, new bolts, etc about 9500 for them to do it

 

[JimCMI]

Yeah i dont NEED anything more than what it's already got. Called JB aircraft engines in Sebring and they said cam, lifters, new bolts, etc about 9500 for them to do it

That's pretty cheap, and from what I hear they are an excellent shop. What's their time frame?

 

[ERJDriver]

That's pretty cheap, and from what I hear they are an excellent shop. What's their time frame?

Ive called so many ive forgotten.

 

[ERJDriver]

That's pretty cheap, and from what I hear they are an excellent shop. What's their time frame?

8-10 weeks when I just called back

 

[ERJDriver]

What are the opinions on nickel cylinders

 

[ERJDriver]

Got a call back from JB. Quick breakdown is no choke left in cylinders, case needs worked apparently. No idea on the crank. Said he'll call Monday to discuss options

 

[Freemasm]

No choke, wow. How many hours? Who’s cylinders?

 

[ERJDriver]

No choke, wow. How many hours? Who’s cylinders?

Well the yellow tags in the logs say lycoming, and the Hobbs is about 700 hrs. So assuming that. There's a prop strike A1A on barnstormers Im trying to get in contact with thats 130 SMOH

 

[Full Throttle]

Got a call back from JB. Quick breakdown is no choke left in cylinders, case needs worked apparently. No idea on the crank. Said he'll call Monday to discuss options

Did he say how much choke it had. Lycon takes choke out when they hone new cylinders to their spec.

 

[ERJDriver]

Was a quick call on Friday. I'll get details tomorrow

 

[lr172]

Did he say how much choke it had. Lycon takes choke out when they hone new cylinders to their spec.

And many years ago, lycoming sold straight bore cylinders. I have them on my 320.

 

[FlyerJim]

And many years ago, lycoming sold straight bore cylinders. I have them on my 320.

How many years ago are we talking? 50? 25?

 

[lr172]

How many years ago are we talking? 50? 25?

I believe my cylinders are from the 60's. I wasn't suggesting that the OP has these, only that Lycon is not the only outfit that has used non-choke bores. Not sure when lyc moved away from these,. but suspect 40+ years ago.

I had put on traditional; rings and couldn't understand why blowby was so high> When I honed them for new rings, I put a bore gauge in there and found no taper. Did some more research and found the details.

 

[FlyerJim]

I believe my cylinders are from the 60's. I wasn't suggesting that the OP has these, only that Lycon is not the only outfit that has used non-choke bores. Not sure when lyc moved away from these,. but suspect 40+ years ago.

I had put on traditional; rings and couldn't understand why blowby was so high> When I honed them for new rings, I put a bore gauge in there and found no taper. Did some more research and found the details.

I was asking just for knowledge. I remember being taught about choked bores in college in the early 90s, so I figured it was before that, but I have no other data point than that.

 

[ERJDriver]

Whats the advantage of choke vs no choke?

 

[lr172]

Whats the advantage of choke vs no choke?

The top of the barrel expands from heat. The choke is designed as a smaller diameter so that it will match the rest of the bore once up to operating temp. In theory, this keeps the ring gap a bit tighter up near the top, where the pressure is much higher. Therefore less pressure lose. Though all of this stuff is a series of trade offs. This type of stuff is unique to air cooled engines that do not have consistent temps across the engine.

 

[ERJDriver]

Ah I see thanks. JB is slammed sii I won't hear back for a few more days

 

[Freemasm]

The top of the barrel expands from heat. The choke is designed as a smaller diameter so that it will match the rest of the bore once up to operating temp. In theory, this keeps the ring gap a bit tighter up near the top, where the pressure is much higher. Therefore less pressure lose. Though all of this stuff is a series of trade offs. This type of stuff is unique to air cooled engines that do not have consistent temps across the engine.

Wasn't ring fatigue failure a not uncommon issue with the straight bore lyc cylinders?

 

[lr172]

Wasn't ring fatigue failure a not uncommon issue with the straight bore lyc cylinders?

have no idea. no one really talks about them. I kind of doubt it though. there is just not that much movement. The bore is only growing a few thou, so the ring is not really moving much. 1600 hours on mine with no cracked rings. Pretty confident lycon wouldn't be making them straight bore if this were a thing.

 

[mahlon_r]

have no idea. no one really talks about them. I kind of doubt it though. there is just not that much movement. The bore is only growing a few thou, so the ring is not really moving much. 1600 hours on mine with no cracked rings. Pretty confident lycon wouldn't be making them straight bore if this were a thing.

Back in the day Lycoming made plain steel straight bore 320 cylinders that were used on low compression O-320's only. All other engines used nitride choked cylinders when they left the factory. A long time ago they decided that they would only manufacture one type of cylinder barrel and stopped production on the plain steel cylinders. Thus, later model low compression 320's have nitride choked cylinders and older ones had plain steel straight bore cylinders when they left the factory.

 

[lr172]

Back in the day Lycoming made plain steel straight bore 320 cylinders that were used on low compression O-320's only. All other engines used nitride choked cylinders when they left the factory. A long time ago they decided that they would only manufacture one type of cylinder barrel and stopped production on the plain steel cylinders. Thus, later model low compression 320's have nitride choked cylinders and older ones had plain steel straight bore cylinders when they left the factory.

Thanks Mahlon! I forgot they were plain steel. Mine were already bored 10 over when I got them. Should I expect to have to do that again if I plan to keep them? Also, are these any more prone to lose compression? I have 1600 hours on these and compressions still all over 70, but now low 70's. Oil burn has been pretty consistent at 1 in 12 hours or so, but I expexted something like that, as I honed them myself by hand.

 

[sansoneservices]

As long as you are mechanically inclined and know when to seek assistance, do your own teardown. You may need to send the case halves to Divco, Cylinders may need to be shipped out as well. New camshaft installation can require line boring of the case halves

 

[mahlon_r]

Thanks Mahlon! I forgot they were plain steel. Mine were already bored 10 over when I got them. Should I expect to have to do that again if I plan to keep them? Also, are these any more prone to lose compression? I have 1600 hours on these and compressions still all over 70, but now low 70's. Oil burn has been pretty consistent at 1 in 12 hours or so, but I expexted something like that, as I honed them myself by hand.

They always stood up very well bore wise. I wouldn't expect any further abnormal wear. As going to p.020 why not. Not sure if p.020 pistons are still available. Most times cracks in the head retired them before max oversize. Good Luck, Mahlon

 

[ERJDriver]

As long as you are mechanically inclined and know when to seek assistance, do your own teardown. You may need to send the case halves to Divco, Cylinders may need to be shipped out as well. New camshaft installation can require line boring of the case halves

Looking that way, still no call from JB. But the more I look into it, the more simple it looks. Wondering if anyone offer case exchange or something of that sort in order to prevent having to wait 6+ months

 

[ERJDriver]

Finally got it back from JB. She's on the way to aerosport. Here's the two worst tappets . The other 6 looked fine. The cam looked worse than it was, couldn't feel the corrosion that was visually present

 

[ERJDriver]

Got the bad news from aerosport just now

 

[blaplante]

Looked for it above, didn't see. How many hours? How many years? Cracked cylinder, lifter & cam issues, and a cracked crank? Yikes.
Reminds me of that 'core' engine I bought for my plane 15 years ago or so.

 

[skirting_virga]

Got the bad news from aerosport just now

You and I are pretty much in the same boat, I think. I can't explain the low reliability and that scares me. Crank was inspected by Western Skyways 260 hrs and ~8 years ago. Now cracked and needed replacement at a cost of $10k.

Looked for it above, didn't see. How many hours? How many years? Cracked cylinder, lifter & cam issues, and a cracked crank? Yikes.
Reminds me of that 'core' engine I bought for my plane 15 years ago or so.

Must be an epidemic because mine was the same. 260 SMOH. Terrible cam wear, terrible lifter spalling, cracked crank, piston caps badly worn. Seriously, WTF - do I even want to be flying behind one of these engines? Some of that attributable to bad/incompetent assembly, but the CRANK?

 

[blaplante]

I see this is an angle valve, but a 360 or one of those 'upsized' variants?

 

[lr172]

Got the bad news from aerosport just now

Well that sucks. Makes me wonder if the thrust face on the case where this interfaces was a bit out of parallel. A hard slam of that slinger with a small concentrated interface could have caused the crack. That slinger doesn’t typically get loaded very much, as the crank is always try to pull itself out the other direction.

 

[Tandem46]

Got the bad news from aerosport just now

How old and how many total hours on that engine/crank? Just curious.

 

[ERJDriver]

Well that sucks. Makes me wonder if the thrust face on the case where this interfaces was a bit out of parallel. A hard slam of that slinger with a small concentrated interface could have caused the crack. That slinger doesn’t typically get loaded very much, as the crank is always try to pull itself out the other direction.

Aerosport said most likely due to disassembly, which JB did in Sebring.

They said the same thing as far as load and such on that surface

 

[ERJDriver]

How old and how many total hours on that engine/crank? Just curious.

Not sure, 700hrs since everything was worked or inspected back in 2000 in Orlando at air tec. I havent even begun to look at the prop yet. That was atleast new from vans in 01

 

[lr172]

Aerosport said most likely due to disassembly, which JB did in Sebring.

They said the same thing as far as load and such on that surface

Another possibility is shipping damage. If something heavy puntured the shipping box in thast area, it would make sense, but there would be visible package damage. I built wood crates due to that exact fear when I shipped mine in.