Lycoming rebuilding guildance

I just purchased a 6a kit that had experienced a nose gear failure and subsequent prop strike. The crank dials good, but i'm going to tear the engine down anyway and have the critical internal components magnafluxed and measured just to be sure. I would like to do as much of the teardown and rebuild myself, and wonder if there is a factory service manual or even a video course that someone might recommend to guide me through the process. I built the engine for my last kit (601XL w/Corvair) and am not unfamiliar with engines in general, but need some Lycoming-specific guidance.

TIA,
Jon

Welcome to VAF!

Jon, welcome to VAF

A couple of frequent visitors here recently completed the Lycoming engine course, hopefully one of them will jump in.

Gary---Paul??

Search (either Google or on VAF) for "Lycomign Direct Drive Overhaul Manual" and you'll find numerous links to online versions. They will give you a great deal of the guidance that you need - but I still recommend the on-site guidance of somoene who has done it. These are simple engines, but there are lots of tiny little "gotcha's" that simply aren't documented that can cost you time and money. Besides, building with a buddy has two sets of eyes on the project to spot mistakes, and is more fun!

Paul

Ironflight said:

Search (either Google or on VAF) for "Lycomign Direct Drive Overhaul Manual" and you'll find numerous links to online versions. They will give you a great deal of the guidance that you need - but I still recommend the on-site guidance of somoene who has done it. These are simple engines, but there are lots of tiny little "gotcha's" that simply aren't documented that can cost you time and money. Besides, building with a buddy has two sets of eyes on the project to spot mistakes, and is more fun!

Paul

Click to expand...

What Paul said.

Since you have never done this before, you may want to also look at the Superior Overhaul manual. Superior makes PMA parts for Lycoming engines and also their own certificated Vantage engine. (Looks like a Lycoming clone only certificated.)

The hidden gotchas like splitting the case and removing the connecting rod nuts from the crankshaft can be difficult for someone that has not done it before. There is also a hidden nut on a stud or bolt and nut (depending on when the engine was manufactured) under the accessory case that holds the crankcase together. If you have very good mechanical skills and never force anything apart on your Lycoming engine, you will be able to get it apart.

Thanks. I found the Superior manual and wondered, since it was a clone, how accurate it would be. I would love to be able to take the factory course, but likely won't be able to take the time which is why I was hoping the same content might have been provided as a video course or something.

The basic information you need for disassembly and reassembly is readily available, the problem is getting current service bulletins, service instructions, part numbers etc., i.e. knowing what you don't know.
Most of this is out there on the inter web but knowing you have the latest and most current information is the challenge. Be sure to get a copy of the mandatory replacement parts list, some of the parts like rod bolts you don't want to use over.
If you have a friendly A&P on your field maybe fund his favorite vice for a little help getting the info. I have also had good luck just calling Lycoming and ask for a specific document I needed.
If you have a wide deck engine (A is the last digit in the S/n), you shouldn't need a case splitter. You should have very good mechanical skills and/or get someone who has done a few of these to help with assembly. They are not complicated, but there are some places to get in trouble.
Good luck!
Tim Andres

Good news! I talked with a guy named Tom at Aero-engines of Winchester and have plans to send my parts out for inspection then build it in their shop with someone looking over my shoulder. Look forward to reporting more as this works itself out.

I am currently doing the exact same thing, but prior to making this decision I arrived at an arrangement with a nearby shop owned by a friend. I assisted him in reassembling an engine a few years ago, but I've never experienced this early phase of a complete overhaul.

The last few days have been spent poring over the ADs and SBs trying to organize that information into something manageable.

I have a narrow deck, so I am dreading the case splitting a little bit. Anyone know what year they stopped using the anchored through bolts?

This page has a good how-to. I found it very helpful
http://www.meyette.us/SuperiorTextPics.htm

Kent Ashton said:

This page has a good how-to. I found it very helpful
http://www.meyette.us/SuperiorTextPics.htm

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I think that procedure without the engine stand until after the cases are closed might be an easier way to do it. Gets kind of frantic with two sets of hands trying to hold things in place, bearings etc. standing up.

PS: while looking for the long list of web sites and documents I collected while doing my overhaul I found a link to SBs called prime-mover.org has been hijacked by ransomware - avoid it. Now I have to clean my computer......

Rookie Warning

I almost made the rookie mistake of orienting the rods all out when lining up the direction of the caps etc. per the manual. Just happened upon a web page where the guy said if yours looks like this it's WRONG! Mine looked like that.

Had to buy 4 new bolts, since the old school opinion was to never reuse them, another $100 down the drain....and turned in two of the rods to orient them correctly. Didn't see that warning anywhere else and assumed most knew enough about engine operation not to need the warning....

About the connecting rod bolts, i've read Lycoming instructions to replace them when the rods are removed, but i've always assumed that this was more a reference to removing them at overhaul time. Anyone with some experience have an opinion on this? Would they really need to be replaced if only just installed for a day or two?

j-red said:

About the connecting rod bolts, i've read Lycoming instructions to replace them when the rods are removed, but i've always assumed that this was more a reference to removing them at overhaul time. Anyone with some experience have an opinion on this? Would they really need to be replaced if only just installed for a day or two?

Click to expand...

In the auto world, some engines use a "Torque to Yield" type rod bolt. These can only be torqued to spec once and cannot be torqued again. They have a unique stretch property. I don't believe that I would call these standard. I have not seen any reference to Lycoming using these types of bolts. If they did, you would likely find a warning in the Overhaul manual to this effect or at least an SB, warning mechanics. The fact that many believe it to be true doesn't hold a lot of water with me. I have found many incorrect "facts" that seem to be in the urban legend category. I don't routinely dismiss, but use my own research to validate them.

Have you seen a reference to disposing the rod bolt any time it is removed or when it is removed at overhaul time of for component replacement? The former would imply a torque to yield bolt. I would expect most mechanics install the bearings prior to installation to measure for clearance and if they use new bolts for this, they have torqued twice. I would think this would be more common knowledge if there was a limitation related to torque to yield bolts. I also don't think they existed back in the 50's or 60's when these engines were designed.

I can think of countless reasons that a rod bolt would be torqued more than once during an overhaul/assembly. Lycoming would need to provide clear guidance to the maintenance community that this is not allowed or would be subject to serious liability in a court action. "replacement at removal" doesn't cover someone re-torquing just to be sure they got it right. A standard bolt can be torqued many times without risk. If the rod bolt is unique and can't tolerate that, Lycoming has an obligation to point that out to avoid liability and they have shown a clearly conservative approach in this area.
Larry

When the bolts are torqued, they stretch. There is even a special dial indicator designed to tell you the correct stretch amount.



http://www.hotrod.com/how-to/engine/116-0609-using-rod-bolt-stretch-tool/

Some manufactures dont want to reuse a bolt that has been stretched due to potential fatigue issues when it gets stretched the second time it is used.