Cylinder Work

[Alan Maurer]

Having read Mike Busch's new book 'Engines" and dislike of changing a cylinder, I have a question. I was told today by my mechanic that Continental says that if a cylinder

was removed that the deck bolts and thru bolts should be replaced dry. Mike says to slather oil on it first and of course use a calibrated torque wrench.

Thought I should check with Mooniacs!

[KSMooniac]

I would read the Continental manual and not rely on what we say. Having said that, Mike has run his Continental engines for a long time and removed plenty of cylinders. I don't know if his method is by the book or not. I've only done Lycoming so far, and followed the book. Lube or not is important, as is ensuring the flanges have no paint or other debris, damage, sealer, etc on them too.

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[kortopates]

45 minutes ago, Alan Maurer said:

Having read Mike Busch's new book 'Engines" and dislike of changing a cylinder, I have a question. I was told today by my mechanic that Continental says that if a cylinder

was removed that the deck bolts and thru bolts should be replaced dry. Mike says to slather oil on it first and of course use a calibrated torque wrench.

Thought I should check with Mooniacs!

I think you miss understood or their was a miscommunication. What Mike and Savvy recommends is that all the nuts on the studs and 2 thru bolts all be replaced, but not to replace the thru bolts (not unless there is a issue requiring replacement). Then virtually all torques on the engine are specified as Wet - therefore the need to put some engine oil on the nuts/threads before torqueing. That's not an opinion but a requirement or they won't get properly torqued. The other critical step is that the 2 thru bolts need to be torqued on both sides. This will require quite a bit of disassembly on the opposite side of the new cylinder to get access to the thru bolt nuts on the opposite side. 

And Scott is absolutely right above, the pertinent guidance for this is all in TCM M-0 manual which should be followed. (unfortunately its not available for free on the internet)  

[Guest]

Manual cost is an issue.  It costs me $1000 per year for Lycoming, $1000 per year for Continental and $1000 per year per airframe model for everything I take care of.  Go check out what ATP charges and you’ll under stand why your shop charges what they do.

Clarence

[geoffb]

M-0 manual is your friend.  TCM charges as Clarence says, but I think that gets your update subscription service, etc which a shop needs.  A little time on Google and you'll find a .pdf of the manual.  Most of what you need is in the generic standard practices manual.  There's also a family specific manual.  Again, you can find a pdf out there.  

[A64Pilot]

I’ve never heard to torquing a cylinder dry, wet only, and then only engine oil, not anti-seize or anything but engine oil.

Many apparently don’t retorque both sides of thru bolts using the logic of if I tighten one side it pulls thru to the other side. But if often doesn’t and for the same reason whenever possible you always torque the nut on a nut and bolt and not the bolt head

Unfortunately, if there is any friction in the thru bolts then it won’t pull thru to the other side, and engine failures from improper torque when replacing a cylinder are common.

The reason some don’t  torque both is often the baffling has to be removed on the other side and that’s time consuming, and they are lazy or won’t take the time.

 

Also when a cylinder is removed, hang a flag on the prop that says don’t touch, and don’t touch it, with a cylinder removed that portion of the crankshaft doesn’t have the proper torque applied to its main bearing and turning a prop could possibly turn a bearing slightly.

[Guest]

I’ve often wondered how Lycoming, Continental and hundreds of engine shops assemble the crankcase, main bearings and crankshaft then turn the engine over to get the connecting rods to TDC in order to install pistons and cylinders and yet never have bearing shift of fall out?  Magic I assume.

Clarence

[cliffy]

11 minutes ago, M20Doc said:

I’ve often wondered how Lycoming, Continental and hundreds of engine shops assemble the crankcase, main bearings and crankshaft then turn the engine over to get the connecting rods to TDC in order to install pistons and cylinders and yet never have bearing shift of fall out?  Magic I assume.

Clarence

Because there is no load on the bearings or crankshaft as there would be if it was running

The bearing have tangs that hold them in place until proper torque is applied so they will stay in place with a load

[MikeOH]

44 minutes ago, cliffy said:

Because there is no load on the bearings or crankshaft as there would be if it was running

The bearing have tangs that hold them in place until proper torque is applied so they will stay in place with a load

I'm not following this logic....if this is true, why would I need to hang a "don't move" sign on the prop when a cylinder is off?  The engine isn't running, then!  I'm pretty sure that was Clarence's point.

[cliffy]

Maybe so the connecting rods don't bang on the cylinder holes?

[MikeOH]

9 minutes ago, cliffy said:

Maybe so the connecting rods don't bang on the cylinder holes?

I thought that's what the dirty shop rag is for

Seriously, I'd always "heard" that it was so you don't 'spin' a bearing.  Which never made sense to me since, as you say, the bearing inserts have tangs. BWTHDIK?

[N201MKTurbo]

The bearings are always just slightly larger diameter than the bores. You have to squeeze them just a little bit to get them in. This holds them in place pretty well. The exception is the big front bearing. It splits 90 degrees from the case halves. It is kind of a pain to install. You have to stick it to the crank with assembly lube and keep it precisely aligned while you drop the heavy crank assembly into the case. Oh, the fun of airplanes.

[hais]

On 7/14/2022 at 3:30 AM, M20Doc said:

Manual cost is an issue.  It costs me $1000 per year for Lycoming, $1000 per year for Continental and $1000 per year per airframe model for everything I take care of.  Go check out what ATP charges and you’ll under stand why your shop charges what they do.

Clarence

And I suppose they don't change the content year after year, how is that justified? 

[cliffy]

Its their ball in their court!   M20doc is correct

If you can't afford the manual you sure as hell cant afford to try the overhaul yourself.

[Guest]

1 hour ago, hais said:

And I suppose they don't change the content year after year, how is that justified? 

There are changes and updates, whether they’re worth $1000 per year, who knows.  Continental has a much more complete manuals than Lycoming , who’s overhaul manual is nothing more than a set of loose leaf shop notes.

The problem is that manufacturer’s have turned manuals into a profit centre.  When I started fixing airplanes a Cessna paper printed manual cost about $250 each, microfiche manuals were $8, now they’re done electronically and they’re $1000.

Clarence

[EricJ]

30 minutes ago, M20Doc said:

There are changes and updates, whether they’re worth $1000 per year, who knows.  Continental has a much more complete manuals than Lycoming , who’s overhaul manual is nothing more than a set of loose leaf shop notes.

The problem is that manufacturer’s have turned manuals into a profit centre.  When I started fixing airplanes a Cessna paper printed manual cost about $250 each, microfiche manuals were $8, now they’re done electronically and they’re $1000.

Clarence

"Recurring revenue."   It's the same idea that drives "software as a service" and why we don't own media that we purchase any more and so manh other things.

It's worse with some of the business aircraft, where you cant own the engines, you just pay the recurring service contract to somebody to populate an engine.