Inactive Engine regarding C145/O-300

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anejohn
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Inactive Engine regarding C145/O-300

Post by anejohn »

I’m on the hunt for a C170B and my question to the group pertains to the C145 & O-300 Continental engines. How long can these engines sit inactive before it becomes detrimental and an end up as a major repair. TBO according to Continental Motors Service Information Letter SIL 98-9E states 1800 hours or 12 years which ever comes first. Here’s the quote, “ Regardless if the engine has been operated regularly or has been in storage; gaskets, seals, and synthetic and natural rubber goods deteriorate over time. Replace or overhaul the engine no later than the operating hours or number of years for the engine model listed in Table 1 on page 3.”
I’ve seen advertisements from sellers of low SMOH times like 500 hours yet the overhaul date may have been in the 1990’s, 80’s or even the 70’s. When an engine reaches its TBO, sellers may claim it still holds great compression but in my opinion, TBO is TBO when negotiating or buying an airplane. What would you say about exceeding the time limitation of 12 years? Is 12 years the limit, 20, 30 plus years since the over haul date?
Thx for reading
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ghostflyer
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Re: Inactive Engine regarding C145/O-300

Post by ghostflyer »

At the end of the day it’s all about how an engine has been operated and cared for . I have seen engines that are 4 years young and in my opinion should be scrapped due to them being flogged . It’s all how the owner[operator] has serviced the engine and operated as per the manual . I saw one operator that had IO-540 engines clocking nearly 4000 hours [not a miss print] and had only a top over haul. He kept getting extensions after extensions from the authorities for his engines ,but the engines never stopped . His aircraft was always near max weight also .[Rockwell Shrike 500U] . Where the aircraft is stored is also a major factor too. eg out in the open can’t be good for an engine . It’s always best to borescope an engine before purchase ,check the oil color and smell.Read the log books and see what has transpired over time . What AD,s and service instructions have been carried out. And by WHOM.
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GAHorn
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Re: Inactive Engine regarding C145/O-300

Post by GAHorn »

anejohn wrote:I’m on the hunt for a C170B and my question to the group pertains to the C145 & O-300 Continental engines. How long can these engines sit inactive before it becomes detrimental and an end up as a major repair. TBO according to Continental Motors Service Information Letter SIL 98-9E states 1800 hours or 12 years which ever comes first. Here’s the quote, “ Regardless if the engine has been operated regularly or has been in storage; gaskets, seals, and synthetic and natural rubber goods deteriorate over time. Replace or overhaul the engine no later than the operating hours or number of years for the engine model listed in Table 1 on page 3.”
I’ve seen advertisements from sellers of low SMOH times like 500 hours yet the overhaul date may have been in the 1990’s, 80’s or even the 70’s. When an engine reaches its TBO, sellers may claim it still holds great compression but in my opinion, TBO is TBO when negotiating or buying an airplane. What would you say about exceeding the time limitation of 12 years? Is 12 years the limit, 20, 30 plus years since the over haul date?
Thx for reading
The only opinion which counts when it’s Your Money…. is Your Opinion (which you’ve already stated.)

However, you have acknowledged the common matter that chronology is often ignored in privately owned aircraft….and that’s because most of these airplanes are operated Part 91…while Continental has published their recommended TBO to meet commercial operations (Pt 135, etc). Continental is considering the fact that hoses, gaskets, accessories, etc. have shelf-lives and so their recommendations take that into consideration.

Your purchase-inspection of any airplane will have to meet your personal requirements. While chronology influences value… actual condition of the machine carries more weight in my personal opinion. If an engine has been inactive for long periods then I’d look for whether or not the airplane was placed into proper “storage” or was kept in “readiness” (more likely) while it was inactive. Inspect for internal cylinder corrosion/rust above the ring-line in the cylinders and drain the oil and boroscope the cam/crank for obvious pitting/rust/corrosion…. but that’s about all you can do other than apply annual-inspection-standards to the machine. IF it passes annual inspection in good condition…. make your offer accordingly. But keep in-mind that just because that’s all you’re willing to pay….doesn’t require the seller to agree.

Personal note: I bought my airplane with only 220 hrs since total restoration. But the engine had been “overhauled” (major repair actually, but that’s what is commonly called an “overhaul” by private owners) and sat for over a decade before it was put into service as the airframe underwent a 17-year rebuild. Did that make it unairworthy? (I’ve flown it now for 22 years putting 1K hrs on it, it’s been reliable and I still trust it, …. yet Continental would consider that engine past-overdue for Three Full Overhauls.)
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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Richgj3
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Re: Inactive Engine regarding C145/O-300

Post by Richgj3 »

Two separate thoughts:

1. Replacing gaskets and seals (if needed!) doesn’t require a major overhaul. Rod bearings don’t age by sitting. Connecting rods don’t age by sitting. You get the picture. Corrosion is the major risk in a sitting engine. If it has been stored in a dry heated hangar there’s a good chance corrosion has been minimized. A look into the cylinders with a bore scope is a good idea always.

2. In January of 2020 I purchased a 1952 C170B that had been dormant for 13 years in a hangar in Illinois. It had 2700 hours TT airframe and engine with 250 SMOH done in the late 1990’s. I’ll spare you the details, but a lot of work went into getting it flying again. Actually it flew before the work as my mechanic changed the fluids and put a new battery in it and flew it to his shop about 30 miles away. Jumping to the end I now have about 200 hours on it and the only issue I’ve had is two stuck exhaust valves. After the second one I decided to change all the valve springs assuming having them sit in one position for 13 years might not be optimum. At the same time two exhaust valve guides were tight, so they were cleaned. Now, about 150 hours later everything is fine. This is my experience. Your mileage may vary, as they say.

Just as an aside, in 2005 I bought the first Legend Cub sold. It came with a brand spanking new (not overhauled, not remanufactured. BRAND NEW) Continental O-200A). Two hundred hours later I had to remove two cylinders for leaking exhaust valves. Seems the factory had an issue with getting the valve guides properly aligned. Then after that the new and improved scheme they invented to retain the rocker shafts resulted in the rocker shaft coming through the side of the rocker cover, dumping lots of oil. Didn’t happen to me but it did cause an AD that had them send me new (old style) shafts to install and told to toss the other ones. So, new, low time has its issues too. Just ask the guys with brand new big bore Continental engines that have to pull two cylinders to see if the factory put the counterweight retaining clips on the crankshaft right side up or upside down.

Rich
Rich Giannotti CFI-A. CFI-I SE.
1952 C170B
N2444D s/n 20596
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GAHorn
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Re: Inactive Engine regarding C145/O-300

Post by GAHorn »

Another thought: (not a criticism…just a comment): This may be an example of the mis-use of the word “overhaul”… A true overhaul would have either replaced with new, or tested the 11-yr old springs to certify they met proper dimensions/strengths…. thereby relieving that concern.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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Richgj3
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Re: Inactive Engine regarding C145/O-300

Post by Richgj3 »

Never said the engine was overhauled. Last overhaul was late 90’s. At that time valve springs were new, so I guess valve springs go on the list of calendar time limits just like hoses and gaskets. Not an overhaul, just a good idea. The idea first came to my attention when reading C172 forums (Continental powered) and Globe Swift forums. Changing the springs using the rope trick was not very hard or time consuming even considering the two valves we had to push all the way in to clean the guides. And get them back!

Rich
Rich Giannotti CFI-A. CFI-I SE.
1952 C170B
N2444D s/n 20596
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GAHorn
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Re: Inactive Engine regarding C145/O-300

Post by GAHorn »

Richgj3 wrote:Never said the engine was overhauled….
I get it, …and is the reason I wanted to emphasize I was not offering criticism…only a comment…about the misuse of the term. (not accusing you, Rich) :wink:
Richgj3 wrote:…It had 2700 hours TT airframe and engine with 250 SMOH done in the late 1990’s.
SMOH = Since Major “OverHaul”

This use of the term SMOH is one of the terms which is often misused. Many airplanes are offered/bought/sold using the term SMOH, when in-fact, the actual work performed did not meet the definition of “Overhaul”…but instead, were actually “Repairs”. Perhaps the springs were indeed new at that last major…. but new springs do not an “overhaul” make. ALL the other specified actions must accompany the work, is my only point.

I’m guilty too of using the term inappropriately. Folks ask me “how much time on your engine…?” …and because I know what they really mean… I often reply “about a thousand hours”…. when the True-Answer is 3750+ Time….. and two major REPAIRS in that period….the last “Major Repair” is about 1000+ hrs….and THAT is the more accurate reply.

And Yes, Rich..you are correct…. ALL my valve springs (and 3 of the cylinder assys) have been replaced with new (and 1 been “repaired”) since I became its’ caretaker in 2000….because these things suffer chronologically.

The multi-piece construction of these engines is both a “curse” and a “blessing”…. the individual components are not always as durable as we’d like and the many seams/joints leak…. but at least when they do fail or leak… they are individually repairable or replaceable… as opposed to having to do the entire thing. (I’m reading a book just now about a WW-II diesel-electric submarine and how the starboard engine blew a main-bearing… and the crew was able to repair it at-sea while underway on the port engine and electric-motors…. because they had on-board tools, parts, machinery and machinists who could manufacture just about anything except castings without returning to port. Pretty amazing in war-time conditions.
It’s pretty amazing how these old engine designs on our Cessnas can also be kept-going under a shade-tree…. :lol:
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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anejohn
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Re: Inactive Engine regarding C145/O-300

Post by anejohn »

Hi all and thanks for the responses. A couple of take always are, metal parts don’t wear while sitting. Atmosphere and surroundings have a lot to do with it. Valve replacement might be a good preventative maintenance suggestion for sticking valve problem in the future. Also, I read the same article about the Swift and the C145 vs the O-300 series engines. What a wealth of information with that post.
Good point regarding the 12 year overhaul recommendation by Continental Aerospace that their audience is for commercial operators. But it is a recommendation we can use as a guide.This aircraft no doubt was operated for pleasure but the question remains, how long is too long before it should be overhauled again? In this case the last overhaul was 48 years ago.
I was hoping to have the aircraft registration on this 170 by now but unfortunately I don’t. So I have no idea where or what condition it was kept in. A good thing about Continental engines are they hold up better than the Lycomings engines during long periods of inactivity because of the position of the cam and lifters. The Lycoming cam position is near the top of the engine and with prolonged periods of inactivity oil drips away leaving metal exposed. That being said my concerns still remain. Spalding to the cam lobes and lifters or pitting to the cylinders. A borescope can reveal pitting or rust to the cylinders but to my knowledge the only way to check a cam or lifter is to pull a jug. Something you do after the purchase.
Another concern is the engine model, a C145. Though a great engine, any damage due to corrosion could lead to parts problems, expensive repairs or both. I’m told any damage to the cylinders, you buy new ones at $600 each according to one post. I’m not really sure if that’s correct or not. While I’m on the topic of repairs I’m also learning I can’t find a A&P in the area (Montana) to give a pre-buy or annual inspection. The annual is due next month for this airplane and the three shop owners I contacted near the area suggested something like November, maybe.
So there’s just too many variables here but I really appreciate the feed back.

Thanks all
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