Another engine question

murphey

murphey

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murphey
From all indications it looks like there's a problem with the rings on the cylinders - blowby, increased oil consumption but it's not horrible (4 qts in 25 hrs), O360 engine. Before I jump off the deep end and schedule the overhaul, I'm thinking a bit of research might be worthwhile (and maybe save a bit of $$$). It's a Lycoming O360-A4A with 2800 hours on it. Replaced 2 cylinders, overhauled the mags, put a Sky-Tec starter on it, new alternator.

What's the process for inspecting the rings and determining if the rings are the real problem?

Does this mean overhauling the cylinders?

Or, what's involved with inspecting the cylinders and what's the best approach? The local shop is highly regarded and does nothing but cylinders (and did one of mine of few years ago)

I seek enlightenment. At this point I think enlightenment is easier/cheaper to achieve than the $18K estimate I just got from XXXX (which is very reasonable)
 
With 2800 hours you got your money's worth out of the last overhaul. However, Pt 91 we can run 'em as long as they hold together.
Your oil consumption really isn't too bad, but when it goes up from what you are used to, I understand your concern. Other than a compression check and a look see with a boroscope there's not much a shop can do. If both of these inspections are good, you have no answer.
I suggest doing a couple of oil changes fairly close together. You may find that your consumption improves just by doing that. Our engines love clean oil. Also, with your hours it would be important to start oil analyses if you're not already getting them.
I speak as an IO360 driver who pays a lot of attention to the well being of that engine, but I am not an A&P.
 
???? 4 quarts in 24 hours in an O-360??? That's not horrible how? At 2800 hrs, you're due to do the bottom end as well as the cylinders. You don't want to junk your crankshaft out, that gets expensive. You should be using 1-2 quarts in 25 hrs.
 
murphey said:
From all indications it looks like there's a problem with the rings on the cylinders - blowby, increased oil consumption but it's not horrible (4 qts in 25 hrs), O360 engine. Before I jump off the deep end and schedule the overhaul, I'm thinking a bit of research might be worthwhile (and maybe save a bit of $$$). It's a Lycoming O360-A4A with 2800 hours on it. Replaced 2 cylinders, overhauled the mags, put a Sky-Tec starter on it, new alternator.

What's the process for inspecting the rings and determining if the rings are the real problem?

Pull the cylinders and have a look at the cylinder bore, and ring condition.

Does this mean overhauling the cylinders?
Not entirely, but with 2800 hours on them, it will probably be the prudent thing to do.yes I know you said you replaced two of them.

Or, what's involved with inspecting the cylinders and what's the best approach? The local shop is highly regarded and does nothing but cylinders (and did one of mine of few years ago)

I seek enlightenment. At this point I think enlightenment is easier/cheaper to achieve than the $18K estimate I just got from XXXX (which is very reasonable)
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I'd go for the rebuild, you have 2800 hours on the lower end, you loose the crank with new cylinders and you are worse off than now, you have a rod bearing failure and ruin the crank and case you will have a junk engine with new cylinders on it.

If it were a 0-300 with 2800 on the lower end I'd tell ya to replace the cylinders and go for it.
 
Lance F said:
With 2800 hours you got your money's worth out of the last overhaul. However, Pt 91 we can run 'em as long as they hold together.
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This is all original other than the 2 cylinders. Never topped, never overhauled.
Your oil consumption really isn't too bad, but when it goes up from what you are used to, I understand your concern. Other than a compression check and a look see with a boroscope there's not much a shop can do. If both of these inspections are good, you have no answer.
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Guess I need to find a shop that does borescopes on a regular basis.
I suggest doing a couple of oil changes fairly close together. You may find that your consumption improves just by doing that. Our engines love clean oil. Also, with your hours it would be important to start oil analyses if you're not already getting them.
I speak as an IO360 driver who pays a lot of attention to the well being of that engine, but I am not an A&P.
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Oil analyses are done every oil change for the 11 years I've owned it. Oil & filter changes usually around 35 hours.
 
murphey said:
This is all original other than the 2 cylinders. Never topped, never overhauled.

Guess I need to find a shop that does borescopes on a regular basis.

Save your money, a borescope will not tell you ring condition unless there is a broken ring creating a groove in the cylinder wall. A bore scope will not measure the wear in the cylinder bore. nor will it measure the ring end gap. which tells you the ring wear.


Oil analyses are done every oil change for the 11 years I've owned it. Oil & filter changes usually around 35 hours.
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and that is why you are at 2800 hours rather than 1800. :)
 
It's not horrible oil consumption, but if it's increased then that's telling you something has changed. You can check to see if you've got some bad rings and if the engine could be "fixed."

At 2800 hours, though, I don't think I'd bother putting a lot of effort in. By the time you've spent the money on that work, you've gone a ways towards just getting your engine overhauled.
 
I agree that 1-2 qts per 24 hours is what you want, but 4 is well within Lycoming specs. So I don't think horrible is the right word.
Sounds like you've done everything right with you engine so far and have reaped the benefits.
I wouldn't run this engine any longer myself just because of the very high time.
 
Lance F said:
I agree that 1-2 qts per 24 hours is what you want, but 4 is well within Lycoming specs. So I don't think horrible is the right word.
Sounds like you've done everything right with you engine so far and have reaped the benefits.
I wouldn't run this engine any longer myself just because of the very high time.
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Lycoming says if you pour in the top and it doesn't run out the bottom, you are good to go. :)

Lycoming = yucky engine.
 
Tom-D said:
Lycoming says if you pour in the top and it doesn't run out the bottom, you are good to go. :)
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Can you reference the Service Instruction that states that?

I'd expect better from you, Tom.
 
Ted DuPuis said:
Can you reference the Service Instruction that states that?

I'd expect better from you, Tom.
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I think maybe he was thinking about Harley instead of Lycoming. At least the old Harley's I used to ride, when I used participate in dangerous activities.
 
murphey said:
This is all original other than the 2 cylinders. Never topped, never overhauled.

Guess I need to find a shop that does borescopes on a regular basis.


Oil analyses are done every oil change for the 11 years I've owned it. Oil & filter changes usually around 35 hours.
Click to expand...

Since you have extensive oil analysis data for this engine and the tests show normal my take on your question is this.

Lycoming 0-360's are probably the most bulletproof engines ever built. If they were properly maintained they will go thousands of hours on the bottom end. Your oil consumption is top end related, ie, rings, pistons, guides, etc.

if it were my engine I would do this.

1-Remove the valve covers and dial indicate every lobe on the cam to make sure the lift is within spec.
2- remove all four cylinders and visually look close at the cam and lifter face for spalling, pitting or any other imperfection. If all looks good then the need to split the case is probably not needed.
3- remove the four rods and recondition them and buy new rod bearings, polish the rod throws on the crank, buy new cylinder assemblies and re-assemble the motor.
4- R&R any accs that need attention, ie, mags, spark plug leads, starter, carb, etc.

If your oil analysis has shown good numbers I would bet the bottom end will get to 4000+ hours, or more.... The deal breaker will be the condition of the cam and lifters though. Just my little ol opinion ya know..:idea:

Ben.
 
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N801BH said:
Since you have extensive oil analysis data for this engine and the tests show normal my take on your question is this.
Lycoming 0-360's are probably the most bulletproof engines ever built.


I know a bunch of 0-200 and 0-300 owners that will debate that with ya.

If they were properly maintained they will go thousands of hours on the bottom end. Your oil consumption is top end related, ie, rings, pistons, guides, etc.

if it were my engine I would do this.

1-Remove the valve covers and dial indicate every lobe on the cam to make sure the lift is within spec.

If you are going to do #2 why?

2- remove all four cylinders and visually look close at the cam and lifter face for spalling, pitting or any other imperfection. If all looks good then then the need to split the case is probably not needed.

at that point you are 30 minutes away from splitting the case and seeing what the mains look like.

3- remove the four rods and recondition them and buy new rod bearings, polish the rod throws on the crank, buy new cylinder assemblies and re-assemble the motor.

Where do you find the tools and equipment to do that in the field? remember we must use FAR 43 rules to return to service.

4- R&R any accs that need attention, ie, mags, spark plug leads, starter, carb, etc.

If your oil analysis has shown good numbers I would bet the bottom end will get to 4000+ hours, or more.... The deal breaker will be the condition of the cam and lifters though. Just my little ol opinion ya know..:idea:

Ben.
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when you go as far towards a total overhaul as you suggest might as well go the whole distance.
 
Tom-D said:
when you go as far towards a total overhaul as you suggest might as well go the whole distance.
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Rod bearings take more abuse then the mains do, so if they look good the mains are most probably good to go. Going the route I suggested will cost 5 grand or so. The original poster stated his quote for a rebuild was 18,000.... That 13,000 dollar difference will buy him avgas for many years to come.. As for your comment about field repair and tools... All he needs is cylinder wrenches, a torque wrench and ring compressor.. Any decent A&P has those in their toolbox. NO need to do this in the field. just pull the plane in a hangar and a day, or two at the most and it is ready for the next 2000 hours... Just my opinion and worth all of what you paid for it... 00.0$$$$$

Cheers.
 
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N801BH said:
Rod bearings take more abuse then the mains do, so if they look good the mains are most probably good to go. Going the route I suggested will cost 5 grand or so. The original poster stated his quote for a rebuild was 18,000.... That 13,000 dollar difference will buy him avgas for many years to come.. As for your comment about field repair and tools... All he needs is cylinder wrenches, a torque wrench and ring compressor.. And decent A&P has those in their toolbox. NO need to do this in the field. just pull the plane in a hangar and a day, or two at the most and it is ready for the next 2000 hours... Just my opinion and worth all of what you paid for it... 00.0$$$$$

Cheers.
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Oil comes to the main first, any debris it carries goes into the mains first, the rods are on a centrifuge, it will trap any heavy stuff that gets that far.

IOWs the rods journals, are always scratched less. they go out of round first, and you can bet at 2800 hours they will be.

I just had 4 0-360 cylinders overhauled by Charley Mallot, the bills was over 1000.00 each. that leaves1000.00 for labor and parts. you think that's real?
 
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Tom-D said:
Oil comes to the main first, any debris it carries goes into the mains first, the rods are on a centrifuge, it will trap any heavy stuff that gets that far.

IOWs the rods journals, are always scratched less. they go out of round first, and you can bet at 2800 hours they will be.
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Whatever..............................................
 
Ben's method makes more sense if you can do your own labor and time isn't as much of a concern as parts costs.

Tony can speak to the 172 that was in the rental fleet at Ames, but had something like 3600 hours on the O-360, still running strong, until someone flew it into a snow bank.

As to paying $1,000 a cylinder for an overhaul - why would you pay that much? It doesn't cost much more to buy new cylinder kits, and then you have new pistons, cylinders, rings, etc. When my Aztec's left engine needed a top overhaul, that made the most sense.
 
Ted DuPuis said:
Ben's method makes more sense if you can do your own labor and time isn't as much of a concern as parts costs.

Do you have the tools to re-grind and polish the rod journals in place? very few shops do. It is a external lap, and the cost of it will brig tears to you wallet. ( http://www.americanlap.com/Catalog Scan.pdf scroll way down, you'll see them, call for pricing )

Tony can speak to the 172 that was in the rental fleet at Ames, but had something like 3600 hours on the O-360, still running strong, until someone flew it into a snow bank.

Every body has an example of a long life engine, but the fact is most engines will not go that far with out major maintenance. I have a 0-300 customer who is an A&P that just signs every thing of as a repair the his engine has 8k hours, last I knew.

As to paying $1,000 a cylinder for an overhaul - why would you pay that much? It doesn't cost much more to buy new cylinder kits, and then you have new pistons, cylinders, rings, etc. When my Aztec's left engine needed a top overhaul, that made the most sense.
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my cost for a new 0-360-A4A cylinder is $1080. and change, and you still must buy a piston pin and plugs, the price new or overhauled still leaves the price much the same.
The price for Lycoming cylinder can very widely, http://www.aeroinstock.com/products/product_cat.php?page=1&subid=5832.

Item #: O5K21112
Lycoming Cylinder Kit
Retail Price: $2401.72

Your Price: $2,281.63

Availability:
In Stock
Buy Now!
Lycoming Cylinder Kit for Models

IO-540: A1A5,G1A5,G1B5, G1C5,G1D5,G1E5, K1A5,K1B5,K1D5,L1A5
HIO-540: A1A
IO-360: A1A
IO-720: A1A,A1B,D1B

One must remember, the skill of the A&P is a biggy when you are talking this type of maintenance, and who will be the one who pays when they fail to do it correctly.
 
A simple way to check rings is a compression check. Warm it up and check the compression with an ear to the exhaust, intake and crankcase vent. Where the leakage is will tell you or at least hint at where your oil is coming from. You will probably find its not only the rings but also valve guides. In any case I'm with the others who suggested a complete overhaul rather than just topping it. At least have a look at the rod bearings when you pull cylinders. Losing a rod or main in flight is more than just an expensive part replacement. It could also be a landing in a bad place. Failed rod bearings can lead to some pretty catastrophic damage. Failed mains can be worse. You're getting into the range where you should be comparing the value of you and your plane vs the much lower cost of an overhaul or engine swap. If you don't want to spend the money on an overhaul look for a low or mid time engine and do a swap. You should be able to find something midway between the overhaul and a set of jugs. The 0360 is really an outstanding engine but there should be a limit somewhere....you're over the 2000hr TBO by 40% already so be happy you've gotten more than your money's worth and think of the future. The investment in an overhaul could pay off big and a top may cost you bigger...

just my opinion

Frank
 
Can cylinder leak down tests be successfully performed on aviation engines?
 
If the price varies widely for an identical product, then why would you buy it from a higher priced place? Find the place that sells the product for less money and buy it.

I paid about the same for new factory cylinder kits for my Aztec as you did for your overhauled units. The discount I get is pretty small vs. the average Joe who calls up.

At any rate, I agree that the engine should be overhauled. My point was that if you're doing your own labor, you can make a strong argument for Ben's idea. If I'm paying for the labor, then at that point I might as well tear down the engine.
 
pilot_dude said:
Can cylinder leak down tests be successfully performed on aviation engines?
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That's the way it's done. Lot safer than spinning the prop to get a pressure, and the leakdown tells us where it's going.

Dan
 
Ted DuPuis said:
If the price varies widely for an identical product, then why would you buy it from a higher priced place? Find the place that sells the product for less money and buy it.

When you have cylinders that are at 1000 TT and knowing the new cylinder record of ADs the manufacturers have shown, you might be farther ahead rebuilding the known good.

I paid about the same for new factory cylinder kits for my Aztec as you did for your overhauled units. The discount I get is pretty small vs. the average Joe who calls up.

that's pretty much beside the point here, a $1000. bucks X 4 leaves $1000 for all other items, it just isn't a reality in today's world.

At any rate, I agree that the engine should be overhauled. My point was that if you're doing your own labor, you can make a strong argument for Ben's idea. If I'm paying for the labor, then at that point I might as well tear down the engine.
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That simply isn't the case with the OP. How many owners are able or willing to do the engine repair in his method?

I do have the equipment to lap and polish a crank here in my shop, I also have the ability to re-Babbitt a bearing and fit it to the crank, but I would never do it to a crank supported by the many machine shops that do the Lycoming cranks, and I certainly wouldn't try to do it in the case. I am doing it to my Warner crank, simply because there is no shops out there that I trust to do it.

No argument, 2800 TT it's ready to go to Charley Mallot, bite the bullet, pay the bill, and fly with confidence.
 
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