[rjcthree]

I'm debating the path which my 2058TT O-320-H2AD will take, new or overhauled cylinders.

The engine has never been opened, built in 1982, 70/70/73/75 at 2052 hours in Jan 2007. As you could guess, the key things were done: flown regularly and oil changed @ 50 hour intervals, meticulous maint practices. It is CLEAN, just for grins(and I had access to the tool), I borescoped it, and could not believe how good the bores looked. T-mod lifters - also with 2058 hours, looked new.

Does anybody know of data available regarding the reliability of OH cylinders versus new? Obviously head cracking is my primary concern.

Yes, it's a bit of a financial question, with the difference between an all-Lyc parts OH being about $500 less per cylinder than a new Lycoming cylinder. And I'm a genuine kind of guy, besides, there really isn't much choice on the H2 motor.

Thoughts? Direction?

Rick 90432

 

[Mel]

My thoughts are "why do anything?" Is it burning oil? These engines will go a long time between overhauls when treated right. Sounds like yours is in good shape. If you're getting at least 8 hours on a quart, fly on.

 

[RV6_flyer]

I'm debating the path which my 2058TT O-320-H2AD will take, new or overhauled cylinders.

The engine has never been opened, built in 1982, 70/70/73/75 at 2052 hours in Jan 2007. As you could guess, the key things were done: flown regularly and oil changed @ 50 hour intervals, meticulous maint practices. It is CLEAN, just for grins(and I had access to the tool), I borescoped it, and could not believe how good the bores looked. T-mod lifters - also with 2058 hours, looked new.

Does anybody know of data available regarding the reliability of OH cylinders versus new? Obviously head cracking is my primary concern.

Thoughts? Direction?

Rick 90432

Rick:

I placed NEW cylinders on my engine when I rebuilt it 10 years ago. I now have 1,988 hours and am planning cylinder work in October. I am using about a quart of oil every 6 hours. I have 10:1 pistons. They are not worth the extra money. Better rate of climb but no additional speed.

My plan is to remove the cylinders and PAY to have them stripped, cleaned, and inspected. If there are NO cracks in the heads, I will REBUILD (similar to overhaul but ALL parts to NEW limits). If there is ONE crack, I will buy new cylinders.

IMHO, you may need to spend some money before you make the decision. The price of NEW cylinders is very close to the cost of what I am planning to do.
___________________added 15 April 2007_________________________

3 out of 4 cylinders on my engine had cylinder head cracks when I rebuilt it 10 years ago. You could see the cracks without doing anything other than taking the cylinder off the engine. The 3 cylinders had 1,742 hours SMOH. The engine had 3,300 hour TT. The cylinder that did not have any cracks was replaced 100 hours earlier for a valve problem.

IMHO, the blow by past rings in a worn cylinder will allow the engine to keep operating for many hours but the extra contamination getting into the oil will shorten the life of the parts in the lower end.

My father would not replace parts in his vehicles till they break. I tend to do preventive maintenace replacing parts at my convenicene before they break.
____________________________________________________________

I have 1st generation Superior Investment Cast Cylinders S/N: 8, 9, 10, and 11. I will end up paying to see if they were worth the extra money. I may still end up buying four new cylinders if they have just ONE crack in one cylinder.

Your description sounds like you may have cylinders that are worth rebuilding. (new guides, valves, springs, keepters, piston, and rings) Unfortunately one does not know till the head is inspected and the bore mic'ed.

 

[Rivethead]

If treated well these engines can go way beyond 2000 hours. I assume you already know this though.

 

[rjcthree]

Reply

Thanks all for you contributions so far.

Here are my thoughts.

Why touch it at all? It's the risk of something bad happening at say 2200 hours, and the overall cost now including a crankshaft or ???. Second, once I spend 2000 hour putting this silly aluminum origami project together, the last thing I'm going to want to do is pull it all apart the first or second year to rebuild the engine.

I honestly have no qualms about the H2AD engine, nor do I suspect it to be any less reliable than (insert favorite Lyc engine here).

I expect to have to either 1) invest the $ to have the jugs inspected before making a decision, or 2) just buy new and call it good. If one is bad, I will not weld, I will buy new. With inspections running $300 each, the math gets kinda tough, it becomes a risk call.

$300 + $1300(new) if cracks are found (each) = $6400
$300 + $600 (good OH) is no cracks are found (each) = $3600
$1300 new (each) = $4200

So, back to my original post: what do the stats say? Lyc says all new cyl, no exceptions, even EXP. Articles in Flying, others, report risk of cracking in 2nd cycle to be >4x first run, making it sound like a crack is expected in the second run on at least on cyl, but this data also seems to be related to high-hp 6cyl engines. Still, no real DATA to work with that I've found.

Still there are lots of people selling OH replacements out there.

Looking at the numbers above, the 20% premium of new isn't so bad.

Boy, are we having fun now!

Rick 90432

 

[odlee]

Rick,

The maintenace shop I have used over the years with my store bought planes also has a small flight school.

They run their Lycomings up to 3000 hours. The chief mechanic and owner does his own overhauls and they do 100 hr inspections while watching the engines closely. IMHO no reason to touch the engine unless you are getting telltale signs such as bad compressions, excessive oil burn, etc. These smaller Lycomings are some of the best around.

Good luck,
David

 

[N62XS]

Inexpensive?

Second, once I spend 2000 hour putting this silly aluminum origami project together, the last thing I'm going to want to do is pull it all apart the first or second year to rebuild the engine.

Rick 90432

Rick:

Great statement and I think you already know the answer. The difference between cheap and inexpensive often lies in how you value your time. My experience is with friends using overhauled cylinder assemblies. Most never make it to TBO and many are pulling them at 400 hours for repairs, with the hindsight of new jugs looking like the inexpensive option. I think overhaul is only a valid option if you know the engine from new and know the logbooks are accurate.

My recent experience was with a C85-12, with logs reflecting 300 hours SMOH and 1800 hours since new. I pulled the jugs to repair the leaks in the push rod tubes. While off I sent them for overhaul. The shop failed all at at least 30 over and indicated none had never been touched(log books indicated differently). At this point the entire engine was torn down and everything sent out for inspection. The case, crank and rods were OK, but the cam failed. I purchased a new cam and new Superior jugs, overhauled the alternator, mags, new starter, new fuel pump, added an oil filter, overhauled the carb, overhauled the exhaust, etc. I will never use used/overhauled jugs again, trust a log book on a TBO engine or run a used engine.

With the oversight of an A & P, an IA, tons of online and written refernces and several others with deep knowledge in engines I am overhauling two O540s. One I will use on my RV-10, the other was for a friend, but is now going to be sold. These engines, as well as the 4 banger for my next RV-8 will be fanaitcally inspected and assembled by me and my "team" because I want to know that what goes into the is right and is to new limits.

Ask yourself this question, can you pull over to a cloud and check under the hood if the engine quits? If gambling is your game, go to Vegas, but do the engine right, finish the "Oragami Project", then fly to Vegas with the extra money and time you saved from not having to do a top overhaul at 400-800 hours.

To all FWIW and IMHO.

 

[frankh]

$1300??

I thought new ECI cylinders could be had for $850 or so??

If thats the case it seems hardly worth bothering to have $300 inspections done...

Yeah, yeah I know ..."throwaway society" and all that..

Frank 7a

 

[gmcjetpilot]

You are right, its financial.

I agree if its running fly it.

From rick numbers the price diff from new and rebuild is not much. Also if there is a crack its trash. Never ever never weld a crack in the heads. It will not last.

Will the overhaul repair station/shop warranty they jug for what a new one is? Nope.

Overhaul/Rebuild was the obvious choice when new Lyc jugs cost crazy money. Now with competition from ECI and Superior, new jug assemblies are a bargain and more competitive and desirable to rebuilding.