Questions to ask my engine rebuilder

Benjamin

Benjamin

Filing Flight Plan
Joined
Jun 12, 2019
Messages
5
Location
Fullerton, CA
Display Name
Display name:
KFULPilot
Hi there PoA

We're getting ready to rebuild (preventatively) our Lycoming O-320-E2D LyCon conversion in our '71 C172L and I'm trying to understand as much information as possible so we can make good educated decisions on the path forward.

So, without getting into the merits of rebuild/overhaul vs. factory reman vs IRAN etc etc etc, let's assume, for the sake of discussion, that the engine needs to be rebuilt. I'm hoping to find some good tips on things I haven't thought of as I start interviewing my rebuilder(s) about the plan. Here's what I have so far, please chime in with the things I have overlooked:
  1. How far out are you scheduling?
  2. What is the expected down time from when you receive the engine to when it’s ready for pickup?
  3. We have LyCon cylinders - can you rebuild with same?
  4. How does it work? Can our A&P remove the engine and we deliver it to/pickup from you?
  5. Our mags were recently rebuilt (<50 hours ago). Does a rebuild replace these anyway or can we reuse?
  6. Should we plan to overhaul the prop at the same time? If so, who do you recommend?
  7. Is this a “zero-time” overhaul?
  8. Are there other components we should consider replacing, like the alternator (starter is new)?
  9. We don’t really know the age of the crankshaft and we think it should probably be replaced. Does this change anything?
  10. What doesn’t normally get replaced in an overhaul?
  11. Rough cost estimate?
I appreciate the collective expertise, and hopefully this thread will help others!
 
There are a few loaded questions in your list and respectfully it sounds like you don't know what you don't know. I would first recommend you read something like this: https://www.aopa.org/news-and-media/all-news/1998/november/flight-training-magazine/engine-overhauls and watch youtube videos, etc. to understand the process. Keep in mind only Lycoming can "rebuild" your engine and make it "0" time and give you a new logbook. Otherwise it's an overhaul...

Edit: It sounds like you already have an A&P. Spend some time with the mechanic asking questions. The more answers you get are likely going to generate more questions...
 
Last edited:
New or serviceable limits. One costs more. Don’t assume, ask.
 
Right now there are major parts shortages. Small shops without much inventory are hurting bad. Big ones are scrounging up anything available. No signs of it getting better anytime soon. Last I heard, Lycoming was a six month or more turnaround. Not long ago new cylinders were so cheap it wasn’t worth rebuilding your own. Now you’re lucky to find a new set of any brand.

If the crank is good there is no reason to replace it. If a turbo Navajo can run a crank for well over 10k hours, no point in spending what would amount to a gps or adsb install just because yours is “old”.
 
idahoflier said:
There are a few loaded questions in your list and respectfully it sounds like you don't know what you don't know. I would first recommend you read something like this: https://www.aopa.org/news-and-media/all-news/1998/november/flight-training-magazine/engine-overhauls and watch youtube videos, etc. to understand the process. Keep in mind only Lycoming can "rebuild" your engine and make it "0" time and give you a new logbook. Otherwise it's an overhaul...

Edit: It sounds like you already have an A&P. Spend some time with the mechanic asking questions. The more answers you get are likely going to generate more questions...
Click to expand...

You're 100% right that I don't know what I don't know. Thanks for the link and tips on research, that's what I'm after--learning more about the process. I'm wise enough to know that terms like "zero time", "overhaul" and "rebuild" carry very different meanings depending on who you ask, so what I'm hoping to better understand is what different 'types' or 'options' of rebuild are available and/or recommended. We had a top end about 700 hours ago, but the bottom end is nearing 2200 hrs and starting to leak oil from a lot of different places.
 
Rgbeard said:
You need to know the guys at Johnson Propeller in Shafter.

I just had ours resealed there as a fly-in customer.
Click to expand...
I'm intrigued. I have leaks from parts of the case halves and front crankshaft seal. All my prior engine experience (20+ years in automotive) tells me that this can't be fixed without splitting the case. Do you know something I don't?
 
Benjamin said:
I'm intrigued. I have leaks from parts of the case halves and front crankshaft seal. All my prior engine experience (20+ years in automotive) tells me that this can't be fixed without splitting the case. Do you know something I don't?
Click to expand...

yeah, I am talking about a leaking propeller because it had momentarily escaped me that yours is fixed-pitch not constant-speed, sorry.
 
Why would you replace a crank that is in good condition? Newer shafts are often lower quality or have manufacturing defects. If it’s in tolerance, and in good shape, it’s worth more than a new one because it’s been proven to be free of manufacturing defects.
 
The only advantage to overhauling the prop at the same time is to reduce downtime of doing it another time. But if it doesn’t need it, it doesn’t need it.
 
A lot of your questions you want to be telling them, not asking them. In other words, it depends on what you want to get out of it, and how much you want to spend.
 
An engine rebuilder is only going to care about the engine. Accessories such as the prop, alternator, and mags should be a discussion between you and your A&P to determine what you want to do with them.
 
Benjamin said:
We had a top end about 700 hours ago, but the bottom end is nearing 2200 hrs and starting to leak oil from a lot of different places.
Click to expand...

I tend to factor in more than just hours when deciding to overhaul. How many years has it been since the bottom end? TBO is based on hours and years.

Benjamin said:
I have leaks from parts of the case halves and front crankshaft seal. All my prior engine experience (20+ years in automotive) tells me that this can't be fixed without splitting the case. Do you know something I don't?
Click to expand...

The crankshaft seal can actually be replaced without splitting the case. The case half leaks probably not.
 
Benjamin said:
... I have leaks from parts of the case halves and front crankshaft seal....
Click to expand...
As Jdm mentioned above, the crankshaft front seal (nose seal) can be easily replaced without splitting the case. It can be replaced with a one- or two-piece seal.

While the engine is out, have the motor mount inspected and replace the rubber motor mounts (Lords?) and all the associated bolts and hardware.
 
Domenick said:
As Jdm mentioned above, the crankshaft front seal (nose seal) can be easily replaced without splitting the case. It can be replaced with a one- or two-piece seal.

While the engine is out, have the motor mount inspected and replace the rubber motor mounts (Lords?) and all the associated bolts and hardware.
Click to expand...
And replace all hoses and engine control cables....
 
Domenick said:
As Jdm mentioned above, the crankshaft front seal (nose seal) can be easily replaced without splitting the case. It can be replaced with a one- or two-piece seal.
Click to expand...

I’ve only installed the one piece type. Done a couple of them on my 0320E2D over the years. The prop has to come off for the one piece. Then it’s like stretching a gnat’s ass over a telephone poll. Not exactly easy. Probably took 3+ hours all together.
 
Salty said:
And replace all hoses and engine control cables.
Click to expand...

Hoses: Yes. You can pretty much count on replacing all flexible flammable fluid hoses. They should be done every 7 years anyway. 10 years max. Some sources even advise 5 years.

Control cables: I’ve never associated cables with engine change but they should certainly be checked.

Accessories: I tend to send off most accessories for overhaul. If you’re mags were recently overhauled I think it would be useless to repeat. Problem is some engine shops require it if you want to use them.

I’d definitely overhaul the oil cooler, carburetor (send to Marvel), airbox, and engine mount. The steel tube mount that is. If it’s 20+ years old send it off for overhaul regardless of appearance. You’d be surprised what they find after stripping it. There’s and upgraded version you can get for a few hundred more. They’ll probably fabricate yours to match the upgraded version. It’s well work the extra.

inspect everything. Exhaust, mufflers, baffling, everything. Overhaul is a great time to address any upcoming issues.

Jim
 
Somewhat related question. Can you call up a Lycoming distributor and just say "Hey, I want a new engine, not my old one overhauled or reman. Bill me the core charge and get one ordered."?
 
FredFenster said:
Somewhat related question. Can you call up a Lycoming distributor and just say "Hey, I want a new engine, not my old one overhauled or reman. Bill me the core charge and get one ordered."?
Click to expand...
Yes, if you have enough money. But it's still going to be awhile before you see an engine. Last I heard there was quite a waiting list for a new one.
 
Salty said:
Yes, if you have enough money. But it's still going to be awhile before you see an engine. Last I heard there was quite a waiting list for a new one.
Click to expand...
Yeah I'm considering projecting my engine hours remaining TBO and order a full year before I need the engine to minimize downtime.
 
Salty said:
Why would you replace a crank that is in good condition? Newer shafts are often lower quality or have manufacturing defects. If it’s in tolerance, and in good shape, it’s worth more than a new one because it’s been proven to be free of manufacturing defects.
Click to expand...

All crankshafts are subject to metal fatigue with increased use. Age alone is not really a factor.
 
You must log in or register to reply here.
Back
Top