“How much does an overhaul cost?”

[BKlott]

“How much does an overhaul cost?” I have been asked this question twice since last Tuesday so I have been giving this subject a lot of thought.

My wife was the first to ask, following our shorter than expected (12 minutes) flight last Tuesday evening, due to an engine issue. Our engine powered up as usual but I noticed our rate of climb was a bit sluggish. It varied between 500 to 600 fpm, instead of our usual 700 fpm initial climb rate. We leveled off at 3,000 and the engine did not seem to turn up like it normally does. I glanced over at the gauges to see a much higher than normal oil temperature reading coupled with a much lower than normal oil pressure reading. Not good! As I reduced power, the engine began running a little rough, making it an easy decision to reverse course and return to the airport.

Given that the engine was last overhauled in June 1996, that three of the four original cylinders were consistently showing below 70 compression readings and that we had oil leaks from multiple locations, I knew that our engine was near the end of its life and an overhaul was coming. I had already decided that I was not going to spend money on piecemeal engine repairs trying to avoid the “big bill”. The engine owed me nothing at this point with 1474 hours smoh. As I approach the twilight of my flying days, I want to finish up my adventures flying behind a good engine with new cylinder assemblies instead of a tired, worn out engine.

Our son called last night and we broke the news to him by telling him that we would deduct the overhaul costs from his sister’s share of the inheritance instead of his. He liked that and asked “how much does an overhaul cost?” The most honest and truthful answer that I could give him was, chuckling, “nobody ever really knows”.

Over the next few months I will attempt to answer that question by sharing my engine overhaul adventure with you. As I incur expenses along the way, I will update this topic, explaining my thinking and keeping a running total along the way. I will tell you right up front, I am NOT a member of the CB Club. I consider myself the temporary Caretaker of N5479R, with the idea that when my flying days are done, this airplane will continue to provide transportation and joy to the next Caretaker.

On Sunday, April 18th, the engine and accessories were removed in preparation for this project. Total costs incurred for this step was $385.00 paid to my IA.

 

Monday, April 19th. Today I returned to Zephyrhills Airport to meet the guys from Zephyr Aircraft Engines so that they could pick up my engine and take it to their shop. My engine will receive a major overhaul to factory new limits with all new cylinder assemblies, a new upgraded camshaft, an overhauled carburetor, new starter, new magnetos and wires, plus whatever repairs are needed to the crankcase and crankshaft. Estimated cost is $23,600 and I paid a 40% deposit today in the amount of $9,440.00.

I also took my engine mount and exhaust system over to a local pack and ship outfit. These items are being sent to Aerospace Welding in Eagan, Minnesota for inspection and repair. The mount has not been off the airplane since Cessna installed it during the summer of 1974. So it is long overdue for inspection. I am anxious to see how much of it will need to be replaced. The shipping costs for these items, including the custom packaging, Fed-ex Ground and Insurance coverage was $470.01 for the exhaust system and $536.46 for the engine mount. This brings today’s total to $10,446.47.

Total overhaul project cost to date: $10,831.47.

Edited April 19, 2021 by BKlott

[Greg Ellis]

This will be an interesting read as you take us along for the ride.  Thanks for posting.  That base price of $23,600 is right in line with the quote I received from Penn Yan Aero, depending on what you have them due (chrome vs steel cylinders, etc...)  I am not ready for overhaul I was getting a quote to see what I was roughly looking at.  I look forward to your future posts and hope all goes smoothly for you.

[BKlott]

1 hour ago, Greg Ellis said:

This will be an interesting read as you take us along for the ride.  Thanks for posting.  That base price of $23,600 is right in line with the quote I received from Penn Yan Aero, depending on what you have them due (chrome vs steel cylinders, etc...)  I am not ready for overhaul I was getting a quote to see what I was roughly looking at.  I look forward to your future posts and hope all goes smoothly for you.

The engine will receive brand new cylinders from either Lycoming or Superior, depending upon whether or not the Lycoming cylinders will be available. The engine shop advised that Lycoming is experiencing supply chain issues and that may drive the decision. The existing cylinders have been previously overhauled once already. I want new cylinders and that is what Zephyr recommends. 
 

It is nice to be hangared on the airport where one of the top engine shops in the business is based right on the field. Estimated time to complete the engine is “10 to 12 weeks”.
 

Edited April 19, 2021 by BKlott

[Ron McBride]

Is this an 0-320 or an 0-360?

 

[carusoam]

BK,
 

This was a perfect opportunity to trade in the old steed!   

It finished its job...

Going Mooney at this juncture would have been a natural transition...

Best regards,

-a-

[Hank]

46 minutes ago, Ron McBride said:

Is this an 0-320 or an 0-360?

 

It's a 172-M (I just scrolled up to check), and the one I rented as a student had an O-320. Is there an STC to put in the larger engine?

P.S.--I'm watching this thread with horrified fascination . . . . .

[BKlott]

46 minutes ago, Ron McBride said:

Is this an 0-320 or an 0-360?

 

It has the O-320-E2D 150 hp Lycoming.

 

[Hank]

Just now, BKlott said:

It has the O-320-E2D 150 hp Lycoming.

 

150 has and 40° flaps, right? With preselect detents every 10°?

[BKlott]

41 minutes ago, carusoam said:

BK,
 

This was a perfect opportunity to trade in the old steed!   

It finished its job...

Going Mooney at this juncture would have been a natural transition...

Best regards,

-a-

Wouldn’t be much trade-in value at this point. 

[carusoam]

Hmmmmm ....

O360 would make a nice upgrade.... 

IO360 if you are going for all of the donuts...

-a-

[BKlott]

Just now, Hank said:

150 has and 40° flaps, right? With preselect detents every 10°?

Mine does have the 40 degree flaps but with infinite settings available from 0 to 40 degrees. I prefer that to the pre-select flap positions.

[Hank]

Just now, BKlott said:

Mine does have the 40 degree flaps but with infinite settings available from 0 to 40 degrees. I prefer that to the pre-select flap positions.

Me, too! That's how my M20-C is, just hold the switch and they move, let it go and they stop. Flew a friend's F a few times, those flaps would only stop at three places:  Up (0°), Takeoff (15°) and Land (33°), nowhere else. Didn't care for that . . .  

[BKlott]

11 minutes ago, Hank said:

It's a 172-M (I just scrolled up to check), and the one I rented as a student had an O-320. Is there an STC to put in the larger engine?

P.S.--I'm watching this thread with horrified fascination . . . . .

There are STCs available to go from the 150 hp to either 160 hp or 180 hp. Some of these require that the flap travel be limited to thirty degrees, instead of my forty. Additionally, the higher horsepower increases fuel burn and my airplane only has the 42 gallon / 38 gallon useable fuel tanks. The more modern 172s have 50 gallon tanks. Another reason that I’ve elected to retain the 150 hp engine is that, if 100LL does go away, theoretically I could use the UL 94 AVGAS from Swift Fuels without issue. Can’t do that with the 160 hp or 180 hp engines.

I think that if you really want the 180 hp engine, there are real benefits to getting one of the newer 172S or SP models. These have corrosion proof airframes, 50 gallon fuel capacity, more modern seats, instrument panels and avionics. It’s tough and expensive to try to upgrade a legacy 172 into a modern 172. 

[carusoam]

BK,

Seriously consider the 180hp for a moment...

Kind of like going from 280hp in an ovation, to 310hp...

There are two advantages to it...

1) Shorter T/O runs...

2) Better climb rates...

 

You are not forced to set the power differently for cruise...  so the usual FF that you have now will be the same if you want it to be...

Give the STCs a read to see what the improvement in T/O and climb are...

The extra HP can make short runways fun again...

My T/O roll went from 1200’ to 800’...  which is enough to be climbing away... or stopping hard, at the halfway point, at my favorite airport...

Best regards,

-a-

[N201MKTurbo]

7 hours ago, BKlott said:

“How much does an overhaul cost?” I have been asked this question twice since last Tuesday so I have been giving this subject a lot of thought.

My wife was the first to ask, following our shorter than expected (12 minutes) flight last Tuesday evening, due to an engine issue. Our engine powered up as usual but I noticed our rate of climb was a bit sluggish. It varied between 500 to 600 fpm, instead of our usual 700 fpm initial climb rate. We leveled off at 3,000 and the engine did not seem to turn up like it normally does. I glanced over at the gauges to see a much higher than normal oil temperature reading coupled with a much lower than normal oil pressure reading. Not good! As I reduced power, the engine began running a little rough, making it an easy decision to reverse course and return to the airport.

Given that the engine was last overhauled in June 1996, that three of the four original cylinders were consistently showing below 70 compression readings and that we had oil leaks from multiple locations, I knew that our engine was near the end of its life and an overhaul was coming. I had already decided that I was not going to spend money on piecemeal engine repairs trying to avoid the “big bill”. The engine owed me nothing at this point with 1474 hours smoh. As I approach the twilight of my flying days, I want to finish up my adventures flying behind a good engine with new cylinder assemblies instead of a tired, worn out engine.

Our son called last night and we broke the news to him by telling him that we would deduct the overhaul costs from his sister’s share of the inheritance instead of his. He liked that and asked “how much does an overhaul cost?” The most honest and truthful answer that I could give him was, chuckling, “nobody ever really knows”.

Over the next few months I will attempt to answer that question by sharing my engine overhaul adventure with you. As I incur expenses along the way, I will update this topic, explaining my thinking and keeping a running total along the way. I will tell you right up front, I am NOT a member of the CB Club. I consider myself the temporary Caretaker of N5479R, with the idea that when my flying days are done, this airplane will continue to provide transportation and joy to the next Caretaker.

On Sunday, April 18th, the engine and accessories were removed in preparation for this project. Total costs incurred for this step was $385.00 paid to my IA.

 

Monday, April 19th. Today I returned to Zephyrhills Airport to meet the guys from Zephyr Aircraft Engines so that they could pick up my engine and take it to their shop. My engine will receive a major overhaul to factory new limits with all new cylinder assemblies, a new upgraded camshaft, an overhauled carburetor, new starter, new magnetos and wires, plus whatever repairs are needed to the crankcase and crankshaft. Estimated cost is $23,600 and I paid a 40% deposit today in the amount of $9,440.00.

I also took my engine mount and exhaust system over to a local pack and ship outfit. These items are being sent to Aerospace Welding in Eagan, Minnesota for inspection and repair. The mount has not been off the airplane since Cessna installed it during the summer of 1974. So it is long overdue for inspection. I am anxious to see how much of it will need to be replaced. The shipping costs for these items, including the custom packaging, Fed-ex Ground and Insurance coverage was $470.01 for the exhaust system and $536.46 for the engine mount. This brings today’s total to $10,446.47.

Total overhaul project cost to date: $10,831.47.

I could tell you exactly what an overhaul costs. But the folks at Mooneyspace forbid me from totaling up the receipts.

[N231BN]

Honestly, the only reason to keep it 150hp is if you want to run 87 auto gas. Both the 160 and 180hp options will be more efficient and suffer less lead fouling. Lycoming Service Instruction 1070 approves both engines for 91 or 94 octane aviation fuel and you can get an STC to run 91 or better auto fuel in a high compression Lycoming.

[A64Pilot]

No, the reason to keep the 320 is money, price what it really cost to do the STC, plus the 360 isn’t needed, cuts into range etc.

Listen to BKlott

If you want a 360 172, go buy one, you will come out better off in the end, but before I put a 360 in a 172, I’d buy a 182 and be way better off, that’s more logical than hopping up a 172.

I had a C-210 and briefly considered the 550 STC when it got its new engine, but the cost was very significant with a new prop and instruments etc.

Now that you’re engine is off, have your mount and baffling powder coated, way better than spray paint and now is the time, it’s not much money and for the little cost you’ll like the results.

I could see changing pistons and going to 160 HP though, I bet the engine shop will ask that.

Edited April 20, 2021 by A64Pilot

[N231BN]

I could see changing pistons and going to 160 HP though, I bet the engine shop will ask that.

That is what I was referring to, the only reason to keep it low-compression is to run 87 auto gas. The 160hp upgrade will pay for itself in fuel savings if you are running avgas.

[BKlott]

Tuesday, April 20th. Big order day...

I started today with placing an order for a new set of baffles from Airforms in Alaska. A number of years ago our right front baffle assembly fell apart. The metal was so thin at that point that my IA said it would be best to replace it as he didn’t think he could even repair it. The baffles were just bare metal that had some black paint sprayed on them without any evidence of priming. The paint was just flaking off and it looked terrible.

I ordered the three front pieces of the baffle set from Airforms and elected to pay extra for the powder coating option. These looked so much nicer. My thinking at that time was that if we had to get the engine done, I would just order the remaining pieces to complete the set. Well....insert laughter here....it turns out that the base price for the needed pieces totals $1,231.86 but you can buy the complete set for a discounted price of $1,255.79. In other words, for $23.93 more I can get the entire set brand new. Add in the powder coating charge for a total of $1,425.42 + $75 shipping = $1,500.42. 

These photos show the difference between the Airforms powder coated baffles and the original baffles.

My next order for today was with Aircraft Spruce. Four new Lord mounts to replace the Barry mounts that were installed back in June 1996, new hardware for connecting the engine mount to the firewall, new hardware for the new Lord mounts, a new Alcor EGT probe as the existing one looks cruddy, an overhauled Rapco Vacuum Pump as the existing one was installed in September 2013 and has 448 hours on it and a new Lycoming Alternator belt. It would be silly to not replace this since the prop is off the engine. Aircraft Spruce was able to supply all the hardware needed for this order except for the self locking nuts and two types of washers needed. I had to go to two other suppliers to get the three remaining pieces of hardware needed.  Aircraft Spruce should be quite happy with my $1,388.75 order which did qualify for free shipping.

Next stop was Spencer Aircraft to order 8 nuts of two different types. The nuts cost $10.08 and the shipping cost $10.90 for a total of $20.98. Maybe I am the third kind of nut....

Finally, my last transaction of the day was with Cessnaparts.Com to get 4 washers. These look like pretty special washers as they cost $36.64 plus shipping and handling.

This brings today’s total to $2,946.79 and our project total to date is now $13,788.26.

Edited April 20, 2021 by BKlott

[BKlott]

4 hours ago, A64Pilot said:

No, the reason to keep the 320 is money, price what it really cost to do the STC, plus the 360 isn’t needed, cuts into range etc.

Listen to BKlott

If you want a 360 172, go buy one, you will come out better off in the end, but before I put a 360 in a 172, I’d buy a 182 and be way better off, that’s more logical than hopping up a 172.

I had a C-210 and briefly considered the 550 STC when it got its new engine, but the cost was very significant with a new prop and instruments etc.

Now that you’re engine is off, have your mount and baffling powder coated, way better than spray paint and now is the time, it’s not much money and for the little cost you’ll like the results.

I could see changing pistons and going to 160 HP though, I bet the engine shop will ask that.

The mount and exhaust system are both on their way to AWI (Aerospace Welding, Inc.) for inspection, repair and refinishing. They do not recommend powder coating the mount but it will be refinished, probably painted white as that helps to identify cracking. The new baffle set will be powder coated, see today’s write-up.

I agree with the 182 option. One of, if not “the”, best all around airplanes ever made. 

 

[BKlott]

16 hours ago, N201MKTurbo said:

I could tell you exactly what an overhaul costs. But the folks at Mooneyspace forbid me from totaling up the receipts.

No worries, I’ve got you covered. I am doing the totaling for you!

[A64Pilot]

Trust me, powder coat the mount, there is no reason not to, and a few to. People why say powder coat hides cracks are uninformed, same for those that say it changes the heat treat, it takes about 800F to change the heat treat of 4130, and a powder coat oven isn’t close to that.

After seeing the history of Maules airframe powder coating I went through the pain of getting the Thrush airframes powder coated, for the last I’d guess 15 years all Thrush airframes, engine mounts, landing gear etc are powder coated, white

[BKlott]

1 hour ago, A64Pilot said:

Trust me, powder coat the mount, there is no reason not to, and a few to. People why say powder coat hides cracks are uninformed, same for those that say it changes the heat treat, it takes about 800F to change the heat treat of 4130, and a powder coat oven isn’t close to that.

After seeing the history of Maules airframe powder coating I went through the pain of getting the Thrush airframes powder coated, for the last I’d guess 15 years all Thrush airframes, engine mounts, landing gear etc are powder coated, white

 Why won't AWI use powder coating on my engine mount?

ANSWER: We strongly advise against powder coating any structural airframe component. This can cause cracks and chafing to go unnoticed. Powder coating is also impossible to remove for future inspections.

[carusoam]

Does the inside of the tubes get a coating?

We saw a rusty tube pic yesterday...it was a tube that the engine mount bolts to...

Coatings today are hundreds of times better than they were back in 1965...

Best regards,

-a-

[EricJ]

1 hour ago, BKlott said:

 Why won't AWI use powder coating on my engine mount?

ANSWER: We strongly advise against powder coating any structural airframe component. This can cause cracks and chafing to go unnoticed. Powder coating is also impossible to remove for future inspections.

This is usually the issue.   Powder coating used to be all the rage in race cars, etc., but not so much since people figured out how difficult it is to inspect or work on.   Need to add an electrical ground to it?   Sure, spend a day grinding that crap off.   Dye pen?   Three days...