First annual for my 172 - need new engine!

Discussion in 'Maintenance Bay' started by Hangontight, Feb 12, 2021.

  1. Hangontight

    Hangontight Filing Flight Plan

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    Bought my first airplane in May. 1970 172L w/ 8000+ TT and 1700 SMOH. Took it in for my first annual yesterday. Two bad cylinders, pitted tappets and cam lobes. Shop says I need a new motor (overhaul). I can't say I'm shocked, I did buy a high time airplane. Just wasn't expecting it this fast! Well, I guess a $30k annual is a good way to get accustomed to aircraft maintenance costs!

    On a side note, they can put high compression pistons in and do the 160 HP STC for <$1000.00 Has anyone done that, is it worth the extra 10 HP?
     
  2. Grum.Man

    Grum.Man En-Route

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    Every little bit helps but you loose the option to run Mogas if that’s something though currently consider. You can have the cylinders ported and polished and gain about the same amount for about the same money and retain the lower compression.
     
  3. Dan Thomas

    Dan Thomas Final Approach

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    The prop will also need repitching for the extra horses. Refer to the STC for details.

    There's also a stricter requirement againt corrosion pitting in the crank nose for 160+ hp.
     
  4. Hangontight

    Hangontight Filing Flight Plan

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    Ok I'll ask them about that. they are going to refirbish the prop as part of the engine overhaul anyway.
     
  5. AA5Bman

    AA5Bman Line Up and Wait

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    I am always for more horsepower, but I would think really hard about losing the ability to run car gas - high compression cylinders generally don’t allow it. Avgas has been under attack for a long long time, and this administration will not be friendly to leaded fuel, count on it. Being able to run auto gas could be a huge benefit long term.
     
  6. Hangontight

    Hangontight Filing Flight Plan

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    With the low compression cylinders I've been flying on, the new 150 HP will probably feel like a rocket ship anyway so maybe I'll stick with that. I do run MOGAS once in awhile and I agree about where fuel prices are likely to go.
     
  7. asicer

    asicer Final Approach

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    Is port/polish an option? Powerflow? Electronic ignition?
     
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  8. mondtster

    mondtster En-Route

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    The difference between the 150 and 160hp Lycoming is noticeable. Cylinder kit costs during overhaul will be negligible but as noted, your ability to run car gas will be restricted and what Dan Thomas wrote should be considered.

    If the ability to run car gas in your area is limited or you don’t use it I would strongly consider the horsepower increase.
     
  9. GeorgeC

    GeorgeC Administrator Management Council Member PoA Supporter

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    IIRC the O-360 will run mogas, just sayin.
     
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  10. chemgeek

    chemgeek Pattern Altitude

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    If the cam and lifters are spalled, then you have to split the case anyway to replace them. If you are going to split the case on a 1700 hour engine, one might seriously consider doing the overhaul now instead of splitting the case again in a few hundred hours for a major. Getting the high compression STC has very significant benefits, and if done at overhaul can be done for the cost of the STC paperwork alone. (The pistons, at least for me, were the same price.) The extra power, while it doesn't sound like much, is in fact very significant for climb rate, which is proportional to EXCESS power. With the extra power possible, it is also possible to repitch the propeller as allowed by STC to gain a little extra top end speed at the cost of a little of the extra climb rate capability. The extra pitch also allows you to extract use all the engine power in cruise without exceeding redline. Of course, you will be limited to 100LL for fuel with the high compression pistons.

    I was in a similar situation a few years ago with my AA-5 when my engine was at 1800 SMOH. The cam was worn and most of the lifters were starting to spall, so when I split the case I just decided to to the major, which required replacing a beyond-limits crank as well. During the MOH, I did the high compression STC at no additional cost except for the STC paperwork ($500). The HC STC engine was a bit overpowered for the stock prop (although it climbed like crazy), so I installed an STC bevel-tip prop that had 2 additional inches of pitch. This produced 3-4 knots extra top cruise speed at very little climb penalty, but more importantly, the engine is now more difficult to overspeed in cruise, and I can pretty much maintain rpm up to redline, if desired, as high as 10,000 feet. No way the stock engine does that. And the HC engine will get slightly better fuel specifics. I went from around 8.0 gph to around 7.6-7.8 gph at my usual cruise setting.

    Don't expect a huge power boost by simply overhauling the engine. Moderately low compressions will not significantly affect power output, but it might increase oil consumption. My very tired engine with worm cams still got book speeds and fuel consumption right up until I removed it for overhaul. If you elect to do a major overhaul, there will never be a cheaper time to do the HC STC. The extra excess power is well worth it for a plane in this hp range.
     
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  11. Magman

    Magman Pre-takeoff checklist

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    My suggestion is to do the AD Dan referred to ( aka Lyc SB 505 ) before going

    any further.

    Worst case = New Crank$$haft.

    Make sure whoever does it really understands the options.
     
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  12. texasclouds

    texasclouds Cleared for Takeoff

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    Of course you want more horsepowers, are you mental? Keep us updated on your journey.
     
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  13. Hangontight

    Hangontight Filing Flight Plan

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    Roger that. I fly at max gross a fair amount so I'm thinking the 160 option is probably the way to go. I really trust my mechanic, I have the luxury of being on the field of one of a very well known engine shop so I'll see what he has to say. The price doesn't really scare me away, I just like the comfort of knowing I have the MoGas option. When you say better climb, are we talking like +100 fpm or better?
     
  14. Hangontight

    Hangontight Filing Flight Plan

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  15. Hangontight

    Hangontight Filing Flight Plan

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  16. GRG55

    GRG55 Final Approach

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    Yup. Your mechanic was correct...looks like that #2 cylinder needs a bit of work. ;)
     
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  17. TCABM

    TCABM Pattern Altitude

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    There is a 180hp STC from Penn Yann that will drastically improve climb rate across the board.
     
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  18. Hangontight

    Hangontight Filing Flight Plan

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    I gotta draw the limit somewhere! Also, I really want my shop to do the engine rebuild and not get a Penn Yann.
     
  19. mondtster

    mondtster En-Route

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    So will the 160hp o-320, but both require 91 octane minimum. That further restricts the ability to use car gas in many locations.
     
  20. Hangontight

    Hangontight Filing Flight Plan

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    The non-ethanol gas at my local station is 91 octane, but it looks like the 160 HP Ly-con STC requires 100 octane according to what I read....?
     
  21. Grum.Man

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    Where did you see that? I am not aware of any 160hp o320 that is approved for mogas.
     
  22. mondtster

    mondtster En-Route

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    Petersen's website is terrible but it is there. The 160hp engine has been approved for a long time.
     
  23. Grum.Man

    Grum.Man En-Route

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    Well I’ll be a monkeys uncle the Ram STC is listed. Had no idea.
     
  24. mondtster

    mondtster En-Route

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    Any o-320 with a B or a D suffix is a 160 as well, unless it has been altered.
     
  25. Magman

    Magman Pre-takeoff checklist

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    The high compression upgrade for some Grummans takes it to 159 hp.

    You may want the inspection completed before committing on an o/h.

    Just in case.
     
  26. Dan Thomas

    Dan Thomas Final Approach

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    Sometimes it's better to just order a Lycoming factory overhauled engine and send in your core. You get an awful lot of new stuff, and it's assembled and tested by the guys who do it all day, every day. And it will come with roller lifters.
     
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  27. Tom-D

    Tom-D Taxi to Parking

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    Why no go for a NEW engine? and get all mew parts. The overhauled engine can use parts that are already at low limits.
     
  28. Dan Thomas

    Dan Thomas Final Approach

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    Why not? Because Lycoming doesn't fool around with trying to save marginal stuff, that's why. I must have bought ten engines from them, factory overhauled, and once in a while those were brand-new engines because they didn't have enough cores. A brand-new engine at overhauled price. The other option is factory Rebuilt, which brings the engine up to new standards.

    Field overhaulers will sometimes hone the cylinders and put in new rings. Lycoming replaces the whole cylinder and piston assembly. They don't mess with corroded cranks. They install brand-new mags and a new or overhauled carb. Cam and lifters are new, and if the core wasn't a roller-tappet engine, it gets converted to that, too.

    Definitions of Rebuilt and Overhauled:

    https://www.lycoming.com/services/rebuilt-engines

    https://www.lycoming.com/services/overhaul-engines

    Here's an excerpt from the Overhauled page:

    We stay true to any price quoted regardless of the condition of your Lycoming core. Return your like-model complete operating engine within a specified period for full core value without experiencing hidden freight costs, penalties, or chargebacks.

    Now, they don't want that core apart and in boxes. Or with good stuff robbed off it. But at least they eat the cost of a new crank, if necessary (and it often is necessary) while the field overhauler has to buy a new crank if the old one is shot and he has to charge you for it. New cranks are obscenely expensive at the retail level.

    You get what you pay for. One has to decide whether the old 172 is worth the extra cost of a factory overhauled engine. The OP should at least find out what the cost differential would be, and understand that he's taking his chances once the engine is apart and some ugly stuff might show up.
     
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  29. Bill

    Bill Touchdown! Greaser! PoA Supporter

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    We did the Lycoming factory overhaul and exchanged our core. When we specified we wanted factory new cylinders and pistons in our quote, we found Lycoming to be competitive with the major engine shops.
     
  30. Dan Thomas

    Dan Thomas Final Approach

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    I don't think Lycoming any cylinders or pistons. The dismantling, cleaning, inspecting, honing or resizing, and valve work (including replacing valve seats and guides where necessary) would all add up to their cost of a new assembly. A lot of the core cylinders they'd get would already have been reworked once or more. And if the cylinders are pitted (a lot are, from sitting for years or ground-running and other destructive habits) the allowable metal removal often won't save them anyway.

    In fact, this page here: https://www.lycoming.com/factory says this:

    Every cylinder, whether installed in a factory built engine or prepared for shipment into the field, receives the same robust assembly and test processes in the cylinder cell. Each genuine Lycoming cylinder meets our specifications, not just the minimum industry standards. Factory new, rebuilt, and overhauled engines leave the Lycoming Factory with brand new, genuine cylinders.
     
  31. Tom-D

    Tom-D Taxi to Parking

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    You get what you pay for..

    cost? new vs overhauled.
    no core?
     
  32. Racerx

    Racerx Line Up and Wait

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    Well, it's not "car gas" since it's ethanol free. Plus the FAA is kind of the hang up on everything and they understand the consequences of the sudden elimination of avgas for a large part of the GA fleet.
     
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  33. Magman

    Magman Pre-takeoff checklist

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    It should be noted that the mfg can do things no one else is allowed to.

    Not always good.

    At first Case split is was discovered that the Crankcase had porous areas.

    Lycoming would not accept as a core.

    Why then was is all right to assemble and sell it?
     
  34. JOhnH

    JOhnH Touchdown! Greaser!

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    I wonder if @Hangontight 's plane is eligible for the 180hp upgrade? My 172(n model) had the 180 and it had the mogas STC.

    A friend of mine recently bought an A36 Bonanza with 1500 hrs on the IO520. He got it cheap and he knew he would need a new engine soon, but he too didn't expect it on his first annual. $55k for the engine yielded a $65k annual.
    I warned him that a low purchase price doesn't mean he is saving money. He now agrees with me.
     
  35. Dan Thomas

    Dan Thomas Final Approach

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    Things change. From https://www.lycoming.com/services/overhaul-engines .........

    We stay true to any price quoted regardless of the condition of your Lycoming core. Return your like-model complete operating engine within a specified period for full core value without experiencing hidden freight costs, penalties, or chargebacks.
     
  36. Hangontight

    Hangontight Filing Flight Plan

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    Which 180hp upgrade are you referring to specifically? My plane is an L model (built October of 1970) with the O320-E2D I would possibly be interested.

    For the record my shop (and home airport, and personally know the ownership) is Poplar Grove Airmotive. I know they have a good reputation in the engine world which is why I put a lot of faith in them. I realize a factory Lycoming is an option, just not sure its worth the extra hassle when I've got a shop right here. Plus I think it will be cool to visit the shop and watch mine go through the process.

    In the end, for what I paid for my 172 plus what this motor is going to cost, I'm still 'ok' given what current 172 prices are trending. I'm going to have a solid 172 that I can fly (and hopefully teach my kids to fly with) for a long time, to me that's more important than anything else. It will be sweet to know I'm sitting behind a brand new motor, regardless of 150, 160, 180 hp.
     
    Last edited: Feb 13, 2021
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  37. mondtster

    mondtster En-Route

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    It would be best not to apply local requirements for ethanol content universally. There are still many states where ethanol free gasoline is still intended for and used in cars every single day.
     
  38. asicer

    asicer Final Approach

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    Is a Surefly SIM4P an option for your engine?
     
  39. Hangontight

    Hangontight Filing Flight Plan

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    I believe it is, but not sure it's worth the extra $. I guess I don't know enough about them to be sure though.
     
  40. Ravioli

    Ravioli Final Approach PoA Supporter

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    The world is bigger than you may think, and there are a good many people who don't fancy them.

    That said, they did my tear down inspection after a prop strike and the engine EVENTUTALLY came back in great condition. It took around 8 months.

    YMMV
     
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