Rebuilding a lycoming engine

[MoneySink]

There's an article on the Feb issue of EAA Sport Aviation titled "An Engine Overhaul Part I" that starts on page 90. This article sparked my interest quite a bit in working with motors and save quite a bit of money at the same time.

 

My only experience in overhauling an engine is rebuilding my VW Baja bug when I was in high school.

 

I know I could follow an overhauling manual but how can I make sure that it's done right and that it will be as good as if it came from the factory (or close to it)? Has anyone done it?

[Aiman]

I've been inside some fairly complex engines, and I can tell you, the masic mechanics are all the same. Be sure that you have all the tools called for in the manual, don't try to 'rig' anything. ex: ring compressors, tools to split the boxer block, etc.

 

Boxer/horizontally opposed blocks are a tiny bit more comples than standard piston over crank engines, since you have to remove pistons before you can split open the block.

[Lynn Erickson]

There's an article on the Feb issue of EAA Sport Aviation titled "An Engine Overhaul Part I" that starts on page 90. This article sparked my interest quite a bit in working with motors and save quite a bit of money at the same time.

 

My only experience in overhauling an engine is rebuilding my VW Baja bug when I was in high school.

 

I know I could follow an overhauling manual but how can I make sure that it's done right and that it will be as good as if it came from the factory (or close to it)? Has anyone done it?

They are not hard to do but there are a lot of model specific things that hard are to know about unless you work on them all the time. the overhaul book is very vague on these things. the cost of the overhaul is mostly the parts and parts prep work. most will not have the tools for this work , such as cylinder boring, magnaflux, cam grinding. on most of the larger engines the valve clearance is adjusted by installing the proper length push rod, and you won't know what size you need until the cylinders are installed and checked with and old push rod. the must replace parts are a large part of the expense. the labor for the assemble is really the cheapest part. most shops are only charging between $ 3000 to $4000 for the labor to assemble the engine and even if you get your own A&P to assist you he will get at least $2500. unless you have help from someone with a lot of aircraft engine experience I would say this is not the place to save money. If this part of the project does not work quite as well as planed, well ....

[MoneySink]

Lynn,

 

Thanks for your insight. If I decide to go this route I would be doing it for the experience and knowledge from having done it.

 

I would definitely enlist the help of an A&P so that it's done right. The only problem is finding one that would tolerate my perfectionist attitude .

[Crazycanuck]

Get some torque wrenches and use them properly. I haven't rebuild an aircraft engine before, but most of my problems with my motorcycle engine rebuilds have had to do with improper torque on critical nuts and bolts. I have since become religious about properly torquing nuts and bolts and it saves me many headaches.

[Kent Ashton]

The only problem is finding [an A&P] that would tolerate my perfectionist attitude .

Indeed. I took one apart (a Lyc 0320) sent all the parts out and collected new parts as needed. Took them all to a local A&P to help with reassembly expecting him to mic or plastigage everything. He didn't measure a thing. Just reassembled parts and torqued the bolts. I asked him about mic-ing journals and such and he said, "Well, the crank grinders are pretty good. You bought the right bearings for the oversize grind. When you've done a few, you can tell if the journals are too tight or loose." Made me a little uneasy but I guess he was right, the engine has ran fine.

[MoneySink]

That would really drive me up the walls

 

It maybe ok if he can tolerate all the why's and the what. I may go through a few a&p's before I get the engine done. That's what happened when I wanted to learn how to mig weld. I went through a dozen welding shops offering them to pay their hourly rate to give me some experience but they used the liability insurance as an excuse. I finally found one and didn't care about the insurance bit. He was more than eager to teach than anything.