C150 or C152

Looking at a couple of planes for time building. I am at 350 hrs trying to get to 1200+ hrs. Local airport C172 rents for $150/Hr. I am going to fly a ton to get those hours as soon as I can.

So,

The C150 (N5523G)is 1969 model with just shy of 1100 SMOH. So, 700 hrs left before an overhaul is needed?!? VFR but has two nice radios and in somewhat decent shape. Will need a transponder and ADSB compliant. Asking price is 30K. I think I can get it for 25K.

The C152(N4590P) is a 1980 with 900 hrs SMOH. So, 1500 Hrs before an overhaul is needed?!? Again basic VFR but in decent shape. Has pretty much everything I need except really old radios and no GPS. I would need to spend a little on it to get it to my liking. Perhaps 5K? Asking price is 55K. I am thinking I might get it for 50k.


My CFI is pointing me more towards the C152 but again this will be mostly for my time building.

Need your opinions please
You said nothing about how much these planes have been flown RECENTLY, That is VERY important. Even more important for the 152 because it has high cam. If it sets a long time it is a prime candidate for corroded lifters which result in metal once it begins being flown again.

Very important.
 
It seems like the 150 is fairly priced while the 152 is overpriced. You are correct on the TBO times.

The Continental engine in the 150 is more susceptible to stuck exhaust valves due to the high lead levels in 100LL. The Lycoming in the 152 may have better longevity hour-wise but not age wise and long periods of disuse is harder on it.

The extra 10hp of the 152 is quite noticable when hot/high/short runway but not much difference at low DA.
The so called “valve sticking” is due to valve guide wear. This is easily prevented by using an upper lube such as Marvel Mystery Oil. If I could start with an O200-A with fresh valve guides so that I could keep it healthy with an upper lube, I would strongly prefer it to the high cam Lycoming if it has had any chance to set up and corrode the lifters.

Both of them have their achilles heel.
 
The so called “valve sticking” is due to valve guide wear. This is easily prevented by using an upper lube such as Marvel Mystery Oil. If I could start with an O200-A with fresh valve guides so that I could keep it healthy with an upper lube, I would strongly prefer it to the high cam Lycoming if it has had any chance to set up and corrode the lifters.

Both of them have their achilles heel.
Valve sticking is usually caused by valve stem clearances being at the minimum, not loose. It takes only a tiny bit of oxide and varnish to make them stick. They're work fine when hot, since the bronze guides expand at twice the rate of the steel valve stems, and clearances increase somewhat, but after cooldown the guide has shrunken and now has friction on the stem.

As far as Lycomings corroding faster when sitting? Not really. Sitting is the least of the worries. My old A-65 sat in an airplane, outside, in a swampy area for thirteen years, very rarely flown, yet had no corrosion in it. Corrosion is largely the result of really short flights, or ground-running the engine without flying it. That pumps massive volumes of water and other junk past the cold ring clearances into the crankcase, and it doesn't get burned out before shutdown. I've had experience with such engines; the owners thought they were doing them a favor.

https://www.lycoming.com/content/frequency-flight-and-its-affect-engine

From that:

1714571684217.png

The time spent ground-running never shows up in the logs, so a buyer can't know what's inside that engine unless it's looked at. It's easy enough to borescope the cylinders, and it's easy enough to remove a magneto and look at the gears in the accessory case and on the mag drive. Pitted cylinders and rusty gears indicate that the cam and lifters are probably in trouble, too. Corrosion isn't limited to just the cam and lifters, after all. It's just a big, popular scarey boogeyman on piloting forums. I'd be more worried about corrosion on the magneto drive's impulse spring; those springs break when they're pitted, and being high-carbon steel, they pit easily. A broken spring takes the mag timing to near TDC, and at that point the spark is useless. If the engine has the Bendix dual mag, that spring drives both sides of the mag, and the engine pretty much dies when the spring breaks.

An oil sump heater can accelerate cam and lifter corrosion by causing evaporation of moisture in the sump, and it then condenses on that cold cam in the top of the case.
 
What is usually called “sticking” should be called “hanging.” It is not because of tight guides. It is caused by worn completely out guides and stems. They get so worn out that they cock sideways so far that they hang on the edge of the seat, and the inner, flat edge of the valve among the taper.

Growing up in my Dad and uncles auto repair business in the days of valve jobs and in frame overhauls, I’m not a neophyte when it comes to piston engines. I ground more valves, seats and knurled more guides than I can remember. When learning to fly in 1992, there was a rental 150 that the guys would say the valves were “sticking.” I could never really envision guides and stems in the process of wearing, getting tight enough to “stick.” A couple of years ago, a friends RV he had recently bought, had some super low compressions and we pulled cylinders and investigated. That’s the first time that I ever saw such a radical amount of guide/valve wear. It was indeed so bad that a valve was cocking sideways and hanging.

As far as Lycomings not making metal initiated by corroded lifters, tell that to the very long list of those people who bought a low or mid time Lycoming that had not been started for a lengthy amount of time. The cam is high where oil can drip off and maybe they have different alloy lifters, but it is VERY common for a Lycoming that has been put back in service after lengthy storage to make metal after a period of time. What happens is that the corrosion, however minor, on the face of the lifter makes microscopic pits. as the cam wipes across the lifter, it peels tiny pieces of metal out off of the lifter face. it is much like a pothole. Every time a car drives over a pothole it peels a rock out of the pothole. After a period of time the small hole turns into a large pothole. as that metal breaks out, it circulates and makes even more metal. I have a number of these lifters in my shop. I will try to remember to post a picture. Believe me! This is a common problem. To make it worse, the case must be split to change the Lycoming lifters. If they were barrel lifters that could be changed without splitting the case, changing them before putting the engine back in service, would be a process very worthwhile.

Lycoming now has lifters called “Diamond Like Coating(DLC) that prevent the corrosion problem and in the long run will save many lycomings that come out of storage. I bought a plane that had sat up for several years, but cylinders were pulled, lifters inspected and given a green light. About a year later, I got to be the one to pay for the overhaul. This was a 900 hour since new engine. The DLC lifters were very hard to get at the time, but fortunately I got a set before it went back together.

Don’t EVER believe that nothing can deteriorate in an engine because it was stored for an extended period. You might get lucky, because I’m sure that some come out okay, but it’s a big risk. Approach an airplane for sale after extended storage with a healthy checkbook. Been there! Done that!
 
What is usually called “sticking” should be called “hanging.” It is not because of tight guides. It is caused by worn completely out guides and stems. They get so worn out that they cock sideways so far that they hang on the edge of the seat, and the inner, flat edge of the valve among the taper.
I have found that, but it showed up on compression testing LONG before the valve ever hung up. The valve starts striking the seat just a little off-center, and it wears the valve and seat so that it can no longer seal. I NEVER found any aircraft engine valve worn to the degree you describe. That would require a fantastic amount of negligence. The only valve sticking we aircraft mechanics encounter is due to valve stem/guide interference. It can cause bent pushrods, which show up as bent pushrod Tubes, like so:

1714676416385.png
Pushrods get bent when the valve sticks closed, not open. That picture is from a Lycoming publication, and they also say this:

1714676605889.png

As far as Lycomings not making metal initiated by corroded lifters, tell that to the very long list of those people who bought a low or mid time Lycoming that had not been started for a lengthy amount of time. The cam is high where oil can drip off and maybe they have different alloy lifters, but it is VERY common for a Lycoming that has been put back in service after lengthy storage to make metal after a period of time.
Like I said elsewhere, the logs will not show any ground running, and after long periods of storage there is a good chance that someone has run the thing. Sometimes it's after an annual, after which the airplane is not flown, but the engine was run up during the annual after oil and filter change and other maintenance. One simply can't say that the engine corroded just because it sat for a long time, unless the prop was off, maybe, and it couldn't have been run.

Some people will crank the engine without starting it. That does lots of damage, too.
Lycoming now has lifters called “Diamond Like Coating(DLC) that prevent the corrosion problem and in the long run will save many lycomings that come out of storage.
Lycoming also has roller lifters, eliminating the wiping action altogether.
 
I didn’t say that every engine that sat for long periods developed such corrosion, but I am saying that it is a common result. Read on the Mooney sites about it. There are numerous experiences of the lifterscenario that I described. Moral? Be wary of a Lycoming that has been stored for an extended period.

I made no comment regarding valves sticking closed. That’s a pretty radical situation. I did so such radical wear that caused the hanging I described.
 
I don't agree that stuck valves are always caused by worn out valve guides/stems. Excessive deposits in the guide will stick the valve. One source of deposits is excessive lead build up. Dropping the valve and reaming out the guide will fix it.
 
I did not intend to imply that valve “sticking” is ALWAYS due to guide wear, but I have seen it happen and it’s a quite surprising sight. Yes, gooky guides can also be a cause.

A friend of mine is quite skilled at pushing valves into the cylinder, cleaning the guide and using tools through the spark plug holes, getting the valve back in position.
 
Lycoming published, in 2004, an SB regarding valve guide wear. The new guides in 1999 eliminated the problem, but there were and are still a lot of older engines with the old guides, and savvy owners and mechanics will know about it. Anyone that has a guide wear to the point that it cocks so far that it doesn't close is both ignoring this SB, and is not doing the regular compression checks.

https://www.lycoming.com/sites/defa...Exhaust%20Value%20and%20Guide%20Condition.pdf
 
Back
Top