Bite the bullet - Top overhaul on M20R

[PMcClure]

2002 Ovation 2 with 1365 hours since new, went in for annual last week. Compression check showed three cylinders below 40# and a 1 under 30#. Using 1 qt of oil per 2-3 hours. I have budgeted a top overhaul, for a while now and finally decided to bite the bullet and do all 6 cylinders now. TCM provided one under warranty (crack on fin near spark plug). TCM also offered 50% off labor if I did the work last year but I declined. Tried to call them 4 times in last 2 months with no answer so I am going to do it with my local AP who I like and trust very much. $8.6 AMU for 5 new cylinders. $3.9 AMU for labor. Plus a few odds and ends the estimate is $12.5 AMU.  At the same time, I am sending the exhaust out for overhaul, and replacing main landing gear discs. With the exhaust, landing gear and annual, I may have another $4-5 AMU to pay, making the cost more than my previous 1/3 share ownership cost in a M20F. Ownership is not for the faint of heart. Hope to be back in the air early December. 

It's the first major work on the engine since new. I agonized a little about doing a complete overhaul vs a top overhaul. Partly because I am not sure I will keep this plane forever. But finally concluded the top overhaul was the best return on investment. I am very confident in the engine and expect to fly this set of jugs and bottom half past TBO if I do keep it. 

Just sharing my experiences. Any input or comments welcomed. 

[carusoam]

I am always fuzzy about compression readings on the IO550s...  It seems to take a lot of effort and a couple of tries to get them all right.  

But, oil use higher than a quart in ten hours seems rather high.

How long has it been burning oil like that?  That could be a bad ring or something amiss in one cylinder.  The ordinary annual would have ferreted out a bad cylinder during the inspection of the plugs.

A factory reman starts about 35AMU for the hardware.

Really tough decisions if you are not committed to keeping the plane for a decade.

If this is the turning point where you decide to keep her forever...

Join the discussions on....

- 310 hp IO550(N)

- TopProp (thick, thin, or composite)

Good luck with your next steps.

Best regards,

-a-

 

[PMcClure]

20 minutes ago, carusoam said:

I am always fuzzy about compression readings on the IO550s...  It seems to take a lot of effort and a couple of tries to get them all right.  

But, oil use higher than a quart in ten hours seems rather high.

How long has it been burning oil like that?  That could be a bad ring or something amiss in one cylinder.  The ordinary annual would have ferreted out a bad cylinder during the inspection of the plugs.

A factory reman starts about 35AMU for the hardware.

Really tough decisions if you are not committed to keeping the plane for a decade.

If this is the turning point where you decide to keep her forever...

Join the discussions on....

- 310 hp IO550(N)

- TopProp (thick, thin, or composite)

Good luck with your next steps.

Best regards,

-a-

 

Oil consumption has been on an increasing trend last 2 years and compressions on a downward trend for the same period. Borescope looks good and CHT and EGT Spread looks good. Could be one or more rings but with multiple cylinders showing low compressions it finally felt like the time. I bought it knowing it would likely need a top before TBO. So not a lot of surprises except TCM covering the cost of one cylinder!

It was a really hard decision. I love N1051K but don't know if it will fit my changing missions for the next 10 years. My next agony will be to decide when or if to sell it. 

I already have the top prop and buying the STC and changes to 310hp seems like money I don't need to spend. I have not needed more power yet and am satisfied with the performance I have. If I do keep the plane and do an overhaul or factory new, it will be with the upgrade!

 

 

[Shadrach]

2 hours ago, PMcClure said:

2002 Ovation 2 with 1365 hours since new, went in for annual last week. Compression check showed three cylinders below 40# and a 1 under 30#. Using 1 qt of oil per 2-3 hours. I have budgeted a top overhaul, for a while now and finally decided to bite the bullet and do all 6 cylinders now. TCM provided one under warranty (crack on fin near spark plug). TCM also offered 50% off labor if I did the work last year but I declined. Tried to call them 4 times in last 2 months with no answer so I am going to do it with my local AP who I like and trust very much. $8.6 AMU for 5 new cylinders. $3.9 AMU for labor. Plus a few odds and ends the estimate is $12.5 AMU.  At the same time, I am sending the exhaust out for overhaul, and replacing main landing gear discs. With the exhaust, landing gear and annual, I may have another $4-5 AMU to pay, making the cost more than my previous 1/3 share ownership cost in a M20F. Ownership is not for the faint of heart. Hope to be back in the air early December. 

It's the first major work on the engine since new. I agonized a little about doing a complete overhaul vs a top overhaul. Partly because I am not sure I will keep this plane forever. But finally concluded the top overhaul was the best return on investment. I am very confident in the engine and expect to fly this set of jugs and bottom half past TBO if I do keep it. 

Just sharing my experiences. Any input or comments welcomed. 

$3900 seems a tad salty for cylinder install. I had my 4cyl Lyc completely disassembled, case repaired and overhauled, new lifters   and cylinders IRAN'd (admittedly they needed almost nothing) for $3900 at aero engines of Winchester. I did all of the engine R&R.

At $100hr, that's 39hrs to R&R 6 cylinders or 6.5hrs per jug. That seems about right for a single Jug, but there are economies when doing all of them.

[PMcClure]

22 minutes ago, Shadrach said:

$3900 seems a tad salty for cylinder install. I had my 4cyl Lyc completely disassembled, case repaired and overhauled, new lifters   and cylinders IRAN'd (admittedly they needed almost nothing) for $3900 at aero engines of Winchester. I did all of the engine R&R.

At $100hr, that's 39hrs to R&R 6 cylinders or 6.5hrs per jug. That seems about right for a single Jug, but there are economies when doing all of them.

Thanks - I had not done the math and it does see high when you add it up. TCM quoted $11,900 with 50% off labor and 1 free cylinder. So my local guy seems reasonable, at least compared to OEM work. This is also an estimate and I am sure he will come in under unless some big problems arise. That's the kind of relationship we have. 

[N601RX]

There is also some concerns when removing all 6 cylinders at once.  Mike Bush has wrote about it a couple of times.

[jetdriven]

If you use factory new cylinders you will be facing this again in 800-900 hours.  The valves don't seal concentrically with the seats and guides.  If you are hard over on a top overhaul, send your jugs to powermasters in Tulsa.  They'll last forever then.  

Also is your leakage through the valves or rings? Curious..

also, 39 hours for R&R  is high, and  I work very slow.  Should've more like 20. A day to get them off. A day to put them on. A half day for the induction, exhaust, etc. 

[PMcClure]

On November 23, 2015 at 6:01:22 PM, jetdriven said:

On November 23, 2015 at 3:32:50 PM, N601RX said:

There is also some concerns when removing all 6 cylinders at once.  Mike Bush has wrote about it a couple of times.

Also is your leakage through the valves or rings? Curious..

 

Leakage is through rings. I have had the valves bore scoped three times now and everything looks good, no air sounds at the exhaust. 

I bought the plane 3 years ago with 1100 hours and compressions were in the mid 60's and oil consumption was a quarter per 5 hours or so. Steady decline since then in compressions and increase in oil consumption. But the plane flies perfectly. I did list the plane last year and the general feedback was that it needed to be topped. As a buyer, I could understand and offered to discount the cost of a top. As an owner/operator, I was content to fly as long as possible, even with high oil consumption. My theory is that I don't want to pull apart a great running engine. It is smooth as silk on the ground and in the air, gets near book performance and runs cool LOP or ROP. I was having plug fouling problems on a couple of cylinders but replaced the bottom set with the fine wire type and it was resolved. Other than this, the low compressions and oil consumptions, I have no complaints. 

But with the trend, it doesn't seem like I will make it to TBO with this cylinder set. If I wait much longer, it seems like a waste to do cylinders on a near TBO engine. Plus if I do try to sell it, owners will want the top already done. Especially now with all compressions down below mid 50's and several in the 40's and even one at 27#. My analysis, wrongly or rightly is that I won't make it to TBO on the cylinders and doing it now has more return than doing it later. I believe that is true rather if I keep it or sell it. Keeping it means I get longer life from the engine. Selling means I get credit for a top overhaul and a bottom half that still has more years of life. 

In this case, I can't see the value in doing only some cylinders and not the others. What benefit could there be of doing a partial top?

 

[jetdriven]

Did they do the compression check per the Continental SB and use a master orifice?

[PMcClure]

12 minutes ago, jetdriven said:

Did they do the compression check per the Continental SB and use a master orifice?

12 minutes ago, jetdriven said:

 

Yes and yes, as well as I know it. And I flew it at 75% power for an hour and pulled directly into his shop and started the tests. Last year I took it to TCM and had them do the compression check after my local AP check. TCM got higher readings by about 10-15# with the lowest at about 54#. I do have oil coming from the breather and oil on the belly and the oil turns dark after less than 5-6 hours. I considered taking it to TCM again for a 2nd look. But to be honest, I don't want to get trapped down in Fairhope with only TCM to deal with. You think I am doing unnecessary maintenance?

[jetdriven]

I think you may have a couple weak cylinders and you could change them for 5 grand and run it to TBO.  The lower compression ones may not be the oil burners, but a competent shop can find them. The engine in that plane is very derated and not highly stressed.  Continental engines can go as low as ~40 PSI when used with the master orifice per the continental SB m03-3 and the value should have been written down.  ive seen people do compression tests improperly and it results in more work for the shop, to the detriment of the owner.  3900$ in labor is about 2 times what it should be, for example. It's not a 50 hour job. 

[PMcClure]

10 hours ago, jetdriven said:

I think you may have a couple weak cylinders and you could change them for 5 grand and run it to TBO.  The lower compression ones may not be the oil burners, but a competent shop can find them. The engine in that plane is very derated and not highly stressed.  Continental engines can go as low as ~40 PSI when used with the master orifice per the continental SB m03-3 and the value should have been written down.  ive seen people do compression tests improperly and it results in more work for the shop, to the detriment of the owner.  3900$ in labor is about 2 times what it should be, for example. It's not a 50 hour job. 

I don't disagree which is why the decision was a difficult one. If I was sure I would keep this plane until TBO it would do as you suggest. But with the possibility of selling, buyers will be wary of the low compression checks in the log book. One was done by Coles in Georgia, one by TCM and two by my local AP and the overall trend and oil consumption tells a tell. Thanks for the advice on labor, I'll discuss that with him. 

[PMcClure]

Discussion today with mechanic confirms he gave me worst case estimate and will only charge me actual hours. We discussed the compression check in detail and i still feel confident we are doing the right thing. He also will be able to repair my exhaust without an overhaul saving me a couple AMU. There was a 252 in house who had been watching a few cylinders with low compressions. He had landed at KPLR with oil pressure fluctuating. Turns out he had lost almost all his oil during the flight. Another 252 in the shop for an oil change. That one did a top mid time and flew to 2700 hours before overhaul. 

[StevenL757]

P-

If this is the first top OH, then this is par for the course at 1300+ hours.  Sounds like you've been doing the right homework in exploring options.  Doing a full top is certainly the right choice at this point in your ownership (go with Tempest iridium fine wires...no exceptions!).  Your choice to do exhaust is also a very good one.  You've received a lot of good input here already, and sounds like you have a mechanic who has, and will continue to do right by you.

You're right about the costs...it isn't always cheap, and whilst your concerns about this are certainly more than valid, I hope you decide not to sell.  I've been throught this with my Ovation, as have Anthony, Greg, and most likely others here.  I've flown 30-40 types of AC, and have never flown a more solid and reliable IFR platform than the Ovation.  Now that I have about 140 hours into a new engine and prop, it's at a point where everything is running stable and incredibly solid.  It certainly is an investment, but I couldn't imagine life without her.  Happy to to be a sounding board if you need...  :-)

Regards, Steve

[M20S Driver]

2 hours ago, StevenL757 said:

P-

If this is the first top OH, then this is par for the course at 1300+ hours.  Sounds like you've been doing the right homework in exploring options.  Doing a full top is certainly the right choice at this point in your ownership (go with Tempest iridium fine wires...no exceptions!).  Your choice to do exhaust is also a very good one.  You've received a lot of good input here already, and sounds like you have a mechanic who has, and will continue to do right by you.

You're right about the costs...it isn't always cheap, and whilst your concerns about this are certainly more than valid, I hope you decide not to sell.  I've been throught this with my Ovation, as have Anthony, Greg, and most likely others here.  I've flown 30-40 types of AC, and have never flown a more solid and reliable IFR platform than the Ovation.  Now that I have about 140 hours into a new engine and prop, it's at a point where everything is running stable and incredibly solid.  It certainly is an investment, but I couldn't imagine life without her.  Happy to to be a sounding board if you need...  :-)

Regards, Steve

Do you recommend the fine wire plugs if I fly mostly below 12,000 feet?  My plugs may need to be replaced next year and my research showed that the fine wire helps in high altitude only.  I had only one fouled plug (maybe)  in the past 250 hours of flying it.

[kmyfm20s]

9 hours ago, M20S Driver said:

Do you recommend the fine wire plugs if I fly mostly below 12,000 feet?  My plugs may need to be replaced next year and my research showed that the fine wire helps in high altitude only.  I had only one fouled plug (maybe)  in the past 250 hours of flying it.

Fine wire plugs are better if you run LOP and they also last longer. 

[PMcClure]

On November 29, 2015 at 9:11:06 AM, StevenL757 said:

P-

If this is the first top OH, then this is par for the course at 1300+ hours.  Sounds like you've been doing the right homework in exploring options.  Doing a full top is certainly the right choice at this point in your ownership (go with Tempest iridium fine wires...no exceptions!).  Your choice to do exhaust is also a very good one.  You've received a lot of good input here already, and sounds like you have a mechanic who has, and will continue to do right by you.

You're right about the costs...it isn't always cheap, and whilst your concerns about this are certainly more than valid, I hope you decide not to sell.  I've been throught this with my Ovation, as have Anthony, Greg, and most likely others here.  I've flown 30-40 types of AC, and have never flown a more solid and reliable IFR platform than the Ovation.  Now that I have about 140 hours into a new engine and prop, it's at a point where everything is running stable and incredibly solid.  It certainly is an investment, but I couldn't imagine life without her.  Happy to to be a sounding board if you need...  :-)

Regards, Steve

Thank you for the comments and feedback. The decision to sell isn't really related to the cost of ownership. Overall, I am actually very happy with the plane, including the cost/value.  I really enjoy flying and the ownership of such a capable plane. My challenge is that my family has grown (total gross weight is 850lbs with 5 people) but they rarely fly with me anyway.  My business has grown so that I don't have as much time to stay as current as I like it be to take hard IFR business trips. I have decided not to climb the ladder any further (Single turboprop or twin). So for that part of my mission, I probably need to consider the airlines or charter. I may hang on to N1051K if I can fly enough XC to justify such a capable airplane. If not, then I am considering something like a Cub or even an amphibious LSA and convert my flying to a hobby instead. 

[StevenL757]

On 11/29/2015, 1:14:31, M20S Driver said:

Do you recommend the fine wire plugs if I fly mostly below 12,000 feet?  My plugs may need to be replaced next year and my research showed that the fine wire helps in high altitude only.  I had only one fouled plug (maybe)  in the past 250 hours of flying it.

I do, yes - and running LOP whenever possible helps them last longer.

[PMcClure]

Update for anyone interested. Back in the air with about 20 hours and a few XC trips on the new cylinders. Went with factory new. Oil consumption is almost nil (once it got to 6 quarts). Picked up about 5 knots TAS as far as I can tell but burning a little more fuel (75% power, 14.2gph at 20 LOP instead of 13.7). All in labor was $6500 which included annual, top, new main gear pucks, exhaust repair and misc odds and ends related to annual and minor squawks. Overall very happy with the outcome. Glad to be back flying regularly. 

[Godfather]

I'm glad you're back in the air!  You should easily be able to push the tbo to 2200-2500 hrs if you fly a lot.  I'll have to do some research on running LOP on new cylinders. Did you start LOP or switch over after a few hrs?

[StevenL757]

3 hours ago, PMcClure said:

Update for anyone interested. Back in the air with about 20 hours and a few XC trips on the new cylinders. Went with factory new. Oil consumption is almost nil (once it got to 6 quarts). Picked up about 5 knots TAS as far as I can tell but burning a little more fuel (75% power, 14.2gph at 20 LOP instead of 13.7). All in labor was $6500 which included annual, top, new main gear pucks, exhaust repair and misc odds and ends related to annual and minor squawks. Overall very happy with the outcome. Glad to be back flying regularly. 

You did the right thing.  Very glad to hear you're whole again.  You'll sleep better...guaranteed.

[PMcClure]

4 hours ago, Godfather said:

I'm glad you're back in the air!  You should easily be able to push the tbo to 2200-2500 hrs if you fly a lot.  I'll have to do some research on running LOP on new cylinders. Did you start LOP or switch over after a few hrs?

I ran ROP for the 1st 2 hours. But after that it seemed pointless to run hotter cylinder temps and more fuel. So I went back to running LOP. 

 

[Txbyker]

Did you go with Continental cylinders, steel or nickel?  Also, any idea why it may have picked up 5 kts?

Russ

[PMcClure]

28 minutes ago, Txbyker said:

Did you go with Continental cylinders, steel or nickel?  Also, any idea why it may have picked up 5 kts?

Russ

Continental Steel cylinders. As for the speed, I can't say for sure. I would assume the engine is more efficient now that the rings are tighter. But TCM told me that the engine still makes rated horsepower even when the compression reads well below 20. Also 20 deg LOP is now at a higher fuel flow which would indicate more power. Not sure why that would change. Maybe one of the experts here has a better analysis?

[Mcstealth]

This is consistent of what is reported by others on this forum. Seems to be the rule, and not the exception.