Making metal. Here we go.. into the abyss....

[jetdriven]

My owner-assist style A&P shop pretty much doesnt want to get involved in the enigne.  At 1325 SMOH I feel we are leaving money on the table by not doing an IRAN on the cam, lifters, and bearings. I figured I could do that for around 5-7K.  We removed #1 and #3 cylnders to inspect the cam. One is pitted from corrosion too much to be honed and reused. The other looks like it had a leak at the head/barrel junction.  The #4 cylinder is using a lot of  oil.   So I think a simple rework of our cylinders is not an option.  I refuse to use chrome cylinders, I dont know anyone who didnt have problems.

A Zephry OH with new cylinders is 26,400$.   A Lycoming factory overhaul is 29,500.  At this point, I think the roller cam and low time case is worth the 3K

[Lood]

FWIW, landed in South Africa, I paid as follows:

Crank case - $4750
Cam shaft kit - $1900
Crankshaft kit - $7140

 

[M016576]

Quote: jetdriven

My owner-assist style A&P shop pretty much doesnt want to get involved in the enigne.  At 1325 SMOH I feel we are leaving money on the table by not doing an IRAN on the cam, lifters, and bearings. I figured I could do that for around 5-7K.  We removed #1 and #3 cylnders to inspect the cam. One is pitted from corrosion too much to be honed and reused. The other looks like it had a leak at the head/barrel junction.  The #4 cylinder is using a lot of  oil.   So I think a simple rework of our cylinders is not an option.  I refuse to use chrome cylinders, I dont know anyone who didnt have problems.

A Zephry OH with new cylinders is 26,400$.   A Lycoming factory overhaul is 29,500.  At this point, I think the roller cam and low time case is worth the 3K

[John Pleisse]

1350 is a stinker. Re this: an IRAN on the cam, lifters, and bearings. I figured I could do that for around 5-7K....   I doubt you would split the case, do the cam, rods, lifters and bearings and have a good shop sign off on it for less than $15k. Maybe even $17k when it would all be said and done. Do the OH..I suggest the factory. You could demand your $3k back at sale. I know Zephyr is the hot thing these days, but there was a time where they weren't. Tom at Aero in Winchester has come a long way and is a good bet. My A&P and he are good friends.

I am unclear. Is the engine not generating power? Has it siezed or was it symptomatic? Has it been declared unairworthy with failure imminent? (I read back the thread and didn't see this). Your bore scope didn't look good, but was something broken? Waiting and montioring metal content is a common practice (paticularly with the TSIO-520...the engine you improperly use as a 50ROP poster child, when the real issue with the engine is it's horsepower rating). I know of one Malibu shop, where they wait, watch, monitor the metal content, sometimes for 100's of hours until somebody makes a call.

Point is, you know your eventuality, but do you have time?

[N601RX]

Quote: M016576

That doesn't surprise me too much about your shop: mine did basically the same thing.  It's the liability of cracking open the motor that wears a bit too much on the A&P IA's I think.  Sounds like you'd have to go oversized on the barrels if you wanted to make the current cylinders work... it's a gamble for sure.

I'm surprised how many of the posts here are anti-roller tappet... roller tappets are a proven successful technology in modern combustion engines.  If I could justify (or come up with) the extra 13 AMU's to go with a factory motor vs overhauling my current one, I would have gone that route, but with my crank and case being OK (case is at 3700TT btw), and my 200hr old cylinders being re-workable, I couldn't justify the lycoming overhaul / upgrade to roller tappets.  In your case, I think you're right on in going for the upgrade.

[M016576]

Quote: N601RX

That doesn't surprise me too much about your shop: mine did basically the same thing.  It's the liability of cracking open the motor that wears a bit too much on the A&P IA's I think.  Sounds like you'd have to go oversized on the barrels if you wanted to make the current cylinders work... it's a gamble for sure.

I'm surprised how many of the posts here are anti-roller tappet... roller tappets are a proven successful technology in modern combustion engines.  If I could justify (or come up with) the extra 13 AMU's to go with a factory motor vs overhauling my current one, I would have gone that route, but with my crank and case being OK (case is at 3700TT btw), and my 200hr old cylinders being re-workable, I couldn't justify the lycoming overhaul / upgrade to roller tappets.  In your case, I think you're right on in going for the upgrade.

[jetdriven]

Quote: N4352H

1350 is a stinker. Re this: an IRAN on the cam, lifters, and bearings. I figured I could do that for around 5-7K....   I doubt you would split the case, do the cam, rods, lifters and bearings and have a good shop sign off on it for less than $15k. Maybe even $17k when it would all be said and done. Do the OH..I suggest the factory. You could demand your $3k back at sale. I know Zephyr is the hot thing these days, but there was a time where they weren't. Tom at Aero in Winchester has come a long way and is a good bet. My A&P and he are good friends.

I am unclear. Is the engine not generating power? Has it siezed or was it symptomatic? Has it been declared unairworthy with failure imminent? (I read back the thread and didn't see this). Your bore scope didn't look good, but was something broken? Waiting and montioring metal content is a common practice (paticularly with the TSIO-520...the engine you improperly use as a 50ROP poster child, when the real issue with the engine is it's horsepower rating). I know of one Malibu shop, where they wait, watch, monitor the metal content, sometimes for 100's of hours until somebody makes a call.

Point is, you know your eventuality, but do you have time?

[M016576]

Quote: N4352H

1350 is a stinker. Re this: an IRAN on the cam, lifters, and bearings. I figured I could do that for around 5-7K....   I doubt you would split the case, do the cam, rods, lifters and bearings and have a good shop sign off on it for less than $15k. Maybe even $17k when it would all be said and done. Do the OH..I suggest the factory. You could demand your $3k back at sale. I know Zephyr is the hot thing these days, but there was a time where they weren't. Tom at Aero in Winchester has come a long way and is a good bet. My A&P and he are good friends.

I am unclear. Is the engine not generating power? Has it siezed or was it symptomatic? Has it been declared unairworthy with failure imminent? (I read back the thread and didn't see this). Your bore scope didn't look good, but was something broken? Waiting and montioring metal content is a common practice (paticularly with the TSIO-520...the engine you improperly use as a 50ROP poster child, when the real issue with the engine is it's horsepower rating). I know of one Malibu shop, where they wait, watch, monitor the metal content, sometimes for 100's of hours until somebody makes a call.

Point is, you know your eventuality, but do you have time?

[jetdriven]

Quote: M016576

 Lycomings use of roller tappets is slightly different than most others manufactures who use them.  Lycoming is using the same lift, duration, and ramp times on their roller and flat tappet cams, so there is no measurable horsepower gain.  Auto manufactures that use roller cams do so in order to use a much more agressive cam profile. They will leave the valves closed longer and then open them at a much faster ramp rate resulting in the HP increase.  In lycomings case the only gain is a small frictional loss at the cost of a much more expensive lifter that has the potential for a more severe failure mode than a flat tappet.  If the cam and other internals corrode, you will still be overhauling the engine, just at a much greater expense due to the cost of the roller lifters.

[KSMooniac]

I thought Charlie Melot has posted on the AOPA Forum about some roller tappet failures.  I'm still not convinced they're worth the premium for our relatively low RPM engines compared to the auto engines that can spin upwards of 7-9k RPM.  

[N601RX]

Rick Romans does a lot of Charlie's machine work and cam grinding.  They didn't have a very good opinion of roller lifters last year when they did my parts.

[jetdriven]

Why not?  If there are no failures then why do they not like them?

 

 

[KSMooniac]

I believe your anecdotal survey of "no failures" might not be correct.  I remember Charlie posting some pictures of failed/rejected cams out of roller tappet engines.  I don't remember if they came in for normal overhauls or prop strikes or what...

Also check into Lycoming's cost and replacement policy with the roller lifters.  I believe I read that their service manual states that they cannot be re-used in the event of a prop strike or even an overhaul, and they are on the order of $400-$500 EACH.

[KSMooniac]

 

Here is a quote from C. Melot in 11/2010 from the AOPA Forum:

Another little factor in the rollwer tappet deal is the cost to overhaul goes up by about $400 a cylinder to replace them. There is no inspection criteria for them so they cannot be reused at overhaul. There's also a Lycoming SI requiring replacement after a prop strike. Thank you Lycoming.

Ed Kollin also chimed in with a pic of a new roller tappet cam that was torn down due to a prop strike with only 300 hours time in service, frequent use, regular oil changes, etc.

Thread link:  http://forums.aopa.org/showthread.php?t=69947&highlight=roller+tappets

Hard to say why this new latest and greatest innovation from Lycoming happened... is it a solution that doesn't address the real problem, or a QC screwup from a low-bidder offload vendor, or faulty engineering in choosing the material and heat treatment/processing spec?  

If I were making the decision today I would not pay a premium for it.

 

[KSMooniac]

I found another thread with a good C. Melot quote from Feb 2012:

If I somewhere implied or said I had seen spalling tappets on the roller setup I have not. I did say they CAN rust but have not seen any spalling YET. On this whole deal I have seen many failed cams on engines that never showed anything in the oil analysis. There have also been many that were not picked up in the filter inspection. I think the best check is to pull the pickup screen every annual. We see a lot of those with the factory safety wire in place. Charlie Melt Zephyr Engines

 

[Becca]

Quote: KSMooniac

 

Here is a quote from C. Melot in 11/2010 from the AOPA Forum:

Another little factor in the rollwer tappet deal is the cost to overhaul goes up by about $400 a cylinder to replace them. There is no inspection criteria for them so they cannot be reused at overhaul. There's also a Lycoming SI requiring replacement after a prop strike. Thank you Lycoming.

 

[N601RX]

Unless they decide to pro rate them based on TBO like they try to do with props.

Lycoming only started using them around 2005 so there isn't going to me many people who have ran them to TBO yet.    

[jetdriven]

Quote: KSMooniac

 

Here is a quote from C. Melot in 11/2010 from the AOPA Forum:

Another little factor in the rollwer tappet deal is the cost to overhaul goes up by about $400 a cylinder to replace them. There is no inspection criteria for them so they cannot be reused at overhaul. There's also a Lycoming SI requiring replacement after a prop strike. Thank you Lycoming.

Ed Kollin also chimed in with a pic of a new roller tappet cam that was torn down due to a prop strike with only 300 hours time in service, frequent use, regular oil changes, etc.

Thread link:  http://forums.aopa.org/showthread.php?t=69947&highlight=roller+tappets

Hard to say why this new latest and greatest innovation from Lycoming happened... is it a solution that doesn't address the real problem, or a QC screwup from a low-bidder offload vendor, or faulty engineering in choosing the material and heat treatment/processing spec?  

If I were making the decision today I would not pay a premium for it.

 

[DaV8or]

Quote: jetdriven

I am a camguard user and I like Ed Kollin.  That said, his company, aircraft service specialties, reground my lifters which failed.  Bob there claims they're the same.  The factory subjects new lifters to a 40 or 70 hour nitriding process.  I don't think aircraft service specialties does.  You can find hundreds of examples of cam/lifter failures and perhaps one on a roller engine 7 years after they were produced. A shop overhaul saves us 3-5k and we roll the dice every time it sits over 14 days.   For that, we are going for a factory overhaul.   

[fantom]

Charlie Merlot is a good and honest businessman. I may very well have my O/H done by him when the time comes, if someone around here doesn't get that new TN Lyc IO-360 to market soon ;-)

Keep in mind that Charlie can't sell roller tappet engines, so his viewpoint may be slanted. If I were in Byron's shoes, I'd go for a factory reman, with a "o" time logbook.

 

[PTK]

Quote: fantom

Keep in mind that Charlie can't sell roller tappet engines, so his viewpoint may be slanted. If I were in Byron's shoes, I'd go for a factory reman, with a "o" time logbook.

[smccray]

Just to throw another variable into the mix, you might look into an A3B6 and eliminate the dual mag. I know there's some additional expense associated with dissimilar cores and new mags, but it's an option. 

 

[jetdriven]

Its 3500$ extra and the timing is set at 20 degrees if I am thinking right. So, 3500$ extra for an engine that is 3 KTS  (15 HP) slower and increases the 500 hour magneto inspection costs.  its not over yet, stay tuned.

[jetdriven]

Quote: fantom

Charlie Merlot is a good and honest businessman. I may very well have my O/H done by him when the time comes, if someone around here doesn't get that new TN Lyc IO-360 to market soon ;-)

Keep in mind that Charlie can't sell roller tappet engines, so his viewpoint may be slanted. If I were in Byron's shoes, I'd go for a factory reman, with a "o" time logbook.

 

[OR75]

just curious to hear what the process is and how long it is. do you send the engine first and receive new one ?

also, will you change the rubber engine mounts biscuits (if they need to)?