Advice wanted - O-360 Major OH, teardown, new engine, or . . . . ?

[Rick RV-4]

Looking for advice from those smarter than me. I'm certainly more of an operator than engine mechanic.

I have an older O-360 C2A installed on my RV-4. The engine was overhauled in 2002 and sat (but preserved) until 2009 when I first flew my RV-4. I do not know the total years in service on this engine or number of times it has been overhauled. Oil consumption has always been slightly high (1 quart per 5 hours), I'm guessing due to a less than stellar break-in by me. The perils of a newly OH'd engine and new plane test flight regime. I recently added an air/oil separator and the consumption is down to 1 quart per 8 hours.

I now have 600 hours SMOH and the engine is starting to tell me it's maybe time to take action. A few oil samples ago, the iron went up quite a bit, but has since worked itself most of the way back down to where it was historically, but not all of the way. Silicone was higher on the last sample as well. Compressions are fine (mid to high 70s) and the engine still runs well, and the performance has not dropped off at all. It is leaking oil a bit more than it used to but I have yet to determine where it is coming from. Guessing a few tablespoons per flight based on what I'm seeing on the belly. Not enough to see on the dipstick but annoying for cleanup. I fly the aircraft regularly - 2 or 3 times a week on average, if not more.

Any advice on what path to take? Here are my options: Of course it gets more expensive the further I go down the list but the safety factor goes up as well

- Continue to run it as is, and monitor with borescope inspections, compression checks, oils samples, etc.
- Pay for a teardown and then repair as required
- Suck it up and do a major overhaul
- Screw that old hunk of junk and go new.

I was leaning towards having a teardown done, and received a quote for just under $13,000. The provider of this quote thinks the total price to bring it back up to very good condition will be more once any required repairs are done. So that makes me think more about doing a major OH, but then with the unknown age or total time of the engine, would a major OH be a waste of money in the long run?

I did not put "top overhaul" on the list as I am not too concerened about the cylinders - more the bottom end. Not sure if that is a good thought process or not.

Thoughts?

Thanks,

Rick

 

[rv8ch]

- Continue to run it as is, and monitor with borescope inspections, compression checks, oils samples, etc.

I'm not smarter than you, but from everything I've read from people much smarter than both of us is to keep running it. Unless you have 40k burning a hole in your pocket and you want to stop flying for 9 months.

When you had excess iron, had you stopped flying for a week or more? From what I understand, iron is mostly related to corrosion of the cylinder walls, and possibly the cam. Cylinder wall corrosion is usually not a huge issue if it's a one-time thing, but if the cam is rusting, you will see more and more iron. And then a gradual degradation of performance. Not usually a sudden stop, so you will have time to make a decision then.

 

[joshbrewer]

If Mike Busch were here he’d say to keep running it.
My opinion is the same. Personally I think all aircraft engines ought to be maintained “on condition” rather than some arbitrary schedule set forth mostly by lawyers based on a worst case scenario aircraft (sitting around, not getting flown, and living on the coast).
The exception to that would be magnetos. They should be inspected every 500hrs. They can’t be borescoped, or have oil analysis, or a filter checked like an engine. They have to be opened up to be looked at. And while it’s open, the “might as well while we’re here” philosophy applies.
I happen to know that Mike Busch had an “economical” overhaul done on both his engines back in the 90’s and has run them to 230% of TBO all the while taking extreme care to inspect them just about every way possible to ensure safety and reliability.

I want to make it clear that I have no “insider knowledge”. He writes and talks about this all the time.

There’s a lot of good data that shows there is a definite “bathtub curve” when it comes to engine reliability. Starts with high risk immediately after overhaul which then drops to low risk for an exceptionally long time (often way beyond TBO) and then slowly rises as time goes by.

I am of the opinion that an engine should only be overhauled under two conditions:

1: The engine can be determined beyond a shadow of a doubt by inspection and published data that it is no longer airworthy.

2: The owner can no longer sleep at night.

These are truly amazing airplanes and we should never lose sleep over being afraid to fly them.

Ultimately it is your airplane and pocket book. You should (and probably will) gather as much information as possible, weigh all the options and make the best decision you can based on the data you have available to you.
If you decide to go all the way to buying new, don’t let anyone tell you that you were wrong.
If you decide to continue and operate based on condition and have all the data and inspections to support that decision, don’t let anyone tell you you’re wrong.

Whatever makes you sleep better!

Cheers

 

[jliltd]

I would continue to monitor with oil analysis and cylinder bore scoping. If you decided to do something then I would probably do a TDI/IRAN rather than a major overhaul, especially with 600 hours since major. The last TDI I did in 2019 was at a $8,200 flat rate with standard overhaul kit components (including gasket sets, oil filter, woodruff keys, bearings, O-rings and other types of single-use items) excluding thrust washers. Any extra work like machining or parts repair or replacement was extra. I went with 4 new cylinder assemblies at the time because I had the awful ECI Titan cylinders that caused the trouble in the first place. My case halves had to be machined due to fretting. The crank was lightly ground and the cam was polished. Governor was sent out to MT and P-mags were sent in to EMag Air for inspection just because. When it was all done my charges from the well-known engine shop was just over $13K. That price was pre-covid and pre administration-induced inflation.