Engine Overhaul: Debrief / Component Replace or Overhaul Decision$

Some History - or no History!

The engine i obtained came literally from a facebook post. It had been purchased by the seller from a reputable engine shop in Queensland (Suncoast Aero Engines) - it was on thier 'mezzanine' - aka the parts graveyard, belived to be (to Joel's best memory) from a Seneca.  

The facebook seller had given it to another bespoke engine shop to overhaul, who came from an expermental / racing car background. He had apparently planned to use it in a cub, but his story was that when he did the numbers, it would have been too heavy, so he passed it on for sale. 

No logbooks!

When i went to pick it up, it was sitting on a shelf on a pallet. It had no magnetos, no sump / intake tubes, and no fuel servo. We found a random box which was adjacent to the engine, which had a fuel servo, prop governor, and a random sump / intake tubes (but no dataplate on this mystery sump). This was going to be fun! 

So this meant that we really didn't know what we had, and literally had to assume that every part of the engine was unserviceable, unless we checked it and made certain that it was ok. A total dissassembly was required. 

What MUST we replace at Overhaul

We spent a lot of time researching what this engine was, so we knew what reference documents were needed - these would serve as the 'master parts list'. We would not assume the parts found in the engine were correct, and cross-check everything against the Lycoming Illustrated Parts Catalog. 

To call an engine "overhauled", Lycoming lists a bunch of things which need to be replaced with new, in Service Bulletin No. 240W. This list includes all the obvious (and logical things) such as circlips, locknuts, gaskets etc, but also includes:

• Main and Connecting Rod Bearings 
• Connecting Rod Bolts and Nuts
• Piston Rings
• Exhaust Valves (the intake valves are reused)
• Piston Squirter nozzles
• Oil Vernaterm / Oil Pressure Ball & Spring
• Coutnerweight Bushings, Rollers, Washers, Circlips
• Oil Pump Bodies / Gears
• Hydraulic Tappet Assemblies (lifter bodies) (SI1011 gives correct replacement PN)
• Valve Guides / Valve Seats / Rotator Caps

In fact, it's more interesting the things which we DON'T need to reaplce, such as the pistons, camshaft, and tappets! Hmmm, seriously Lycoming?

Overview

Replaced

• Camshaft
• Tappets
• Pistons / Rings
• Connecting Rod Bolts
• Crankshaft Gear
• Rocker Shafts
• Dipstick Tube
• Rocker Covers
• Flywheel
• Oil Drainback Tubes
• Intercylinder Baffles

Overhauled / Reused

• Engine Case & Sump
• Crankshaft & Counterweights
• Cylinders
• Connecting Rods
• Intake Tubes
• Pushrod Tubes
• Rocker Arms
• Accessory Gears & Idler Shafts
• Intake Valves
• Valve Springs & Seats

Parts we chose to replace anyway

Camshaft

The most obvious thing we decided to replace was the camshaft. This was a no-brainer, as the old one had been making metal and had spread the metal through the engine. 

This is roughly the shape the lobe should be... 

...not this shape! (the edges of this were sharp from being worn down)

We elected to use a genuine lycoming camshaft LW-12312-S instead of the superior part here. 

Note the additional gear at the front (right) of the camshaft, drives the propeller governor gears.

Centrilube Mod

We had the camshaft shipped over to New Zealand and he capped and drilled the camshaft to allow an oil feed to the lobes. Belt and braces!

Oil feed hole in the cam. This interfaces with a channel which was cut in the case to feed oil into the camshaft.

Oil exit for the tappets.

Tappets

The next no-brainer was the replacement of the tappets - these were pretty much all in terrible shape, and it was obvious they could not be reused. Initially we decided to use a Superior replacement tappet SL72877, as these were around $180 per unit, versus the lycoming units at $270 per unit. We figured they would be ok, given the centrilube mod we had performed. 

They aren't supposed to look like this!

In the end, laying in bed one night and reading about Lycoming engine corrision, i had an unsettled feeling, and decided it was in my best interests to buy the new Lycoming DLC (Ceramic Coated) 15B26262 tappets instead. These ended up being around $345 each - so for the whole set was around $1,300 more expensive! Hopefully this gives us good performance going forward, especially for an engine which might not do too many hours a year. 

ooh yeah!

$2700 of parts on this rag alone.

Pistons / Rings

Another no brainer was the pistons - we went with genuine Lycoming pistons 14D23908 here, along with Lycoming Piston Ring set 05K22035. These were around $240 more expenisve than the Superior pistons, but were recommended to be used by the shop. 

We decided to use the Superior Piston Pins SL13444-1, as they were around $100 per pin cheaper, and they had integral piston caps (which you have to buy seperately on the Lycoming units). 

If only people still smoked - i could go into the ashtray business.

Lycoming ring set

Connecting Rod Bolts

The connecting rod bolts are manadatory replacement items according to Service Bulletin No. 240W. We originally ordered 8 x 75060 Lycoming Connecting Rod Bolts based on the removed parts, and the PN from the Lycoming IPC. Once we removed the connecting rods and checked their part numbers however, we elected to replace them with the high-tensile version - SL12596 from superior. 

This change was needed due to Lycoming SI 1458G. This -C1E6 engine is supposed to have Connecting Rods 77450 insalled, which use bolts 75060. These are the normal stretch bolts. However, a substitution for these rods is LW-13422 and when we checked the part numbers on our rods, they matched the substituted rods. The part numbers on the rods were very hard to decipher - they are laser etched onto the sides of the rods themselves. When i was cleaning them with scotchbrite in the kero bath, i made sure not to scrub the area with the part numbers. 

You would think that the cast in numbers would be the part numbers - but alas, no. These are 'casting numbers' and often did not match the part number.

Before and after cleaning - the laser etched part numbers were on the opposite sides (but i did not manage to get a photo at the time). 

As per SI 1458G, these need different bolts, LW-12596, which are high-tensile stretch bolts. This was a great pickup by the engine shop. 

Crankshaft Gear

The main gear at the back of the crankshaft was showing signs of wear - this is the gear which interafaces with the oil pump drive shaft, and which also interfaces with the idler gears (for the fuel pump drive lobe, and magneto lobe). 

Unfortuantely, no before photos of this gear, but you can see the new one below when we were setting the timing. The bolt and locking plate which hold this gear on the crankshaft are a mandatory replacement item. 

Rocker Shafts

We cleaned up the rocker shafts, but 5 out of the 8 of them were damaged, so we just purchased new ones. 

You can see the wear on this rocker shaft.

After it cleaned up it was verging on ok, but they weren't that expensive. So we replaced all of them.

Dipstick tube

I tried to clean up the plastic stock lycoming dipstick tube, but it really was in pretty bad shape. One of the lockwire ears had broken off - so i filed it off and cleaned it up, leaving only one lockwire ear. It was not sitting well with me, so i replaced it with the Superior SL75767 tube, which is aluminium instead of plastic. It also got a real oil dipstick tube silicone base gasket RG72059.

The superior tube is a very nice product (didn't get a photo before i painted it). 

Rocker Covers 

The rocker covers which came with the engine were chromed - and the chrome was flaking off. When i looked at having the chrome removed and then re-chromed, i was advised that they used acid to etch off the old chrome. It would surely damage the covers, especially the lettering, and may make the silver soldered bracket on the back fall off! Once again, Joel to the rescue, who send me some used ones but in great condition. They were CAD plated, and i painted them. 

If the paint doesn't hold up, i might get these ones chromed.

Flywheel

~The engine did not come with a flywheel. I looked at getting a second hand one and it would have been around $1500 (plus a new ring gear). This made the very nice SDS billet aluminium anodised flywheel very attractive at around $1200. The plus is that it already has the magnets for the SDS system installed, and already had a new ring gear. 

Other Small parts which were replaced

There were a few other small things were we replaced:

- Oil Drainback Tubes - these were purchased new from Spruce. We used the APS parts as these were 65% of the price of the lycoming ones. PN 72702 / 72703 / 74808 / 73027

- Intercylinder Baffles - The engine did not come with these, so they had to be purchased new. I used Superior parts SL75338. They have a hole in them needing a plate - which was $70. So i made my own from some scrap. 

Not a chance i was buying these.

Parts we overhauled or Reused 

No Assumtions - MPI / FPI

When parts looked in good condition, and were not parts which needed to be replaced, we sent them away to be either Magnetic Particle Inspected (MPI), or Fluro Penetrant Inspected (FPI). 

Parts send for MPI Included:

Parts sent for FPI:

Once all these parts came back ok, we were then able to use them in the engine. 

Engine Case & Sump

Once totally stripped and cleaned*, the case was sent back up to Suncoast who inspected it for cracks, cleaned it and alodined it, then machined the mating faces of the case. This meant the lateral dimensions of the case had changed, and so the 'bore' could not be assumed to be round. Suncoast then 'line bored' the hole in the case, ready to accept the bearings. 

They also completed the milling of the channel in the forward bearing area of the camshaft, to give an oil feed to the hole drilled in the forward bearing of the cam (centrilube mod). 

After stipping and cleaning - that was a bear of a job

A big pile of things to go away for overhaul at Suncoast.

Back from overhaul! Much nicer...

The silver rings around the pushrod tubes need to be replaced - these were removed, the area cleaned and replaced with new ones. Not sure why this was not done at overhaul?

You can see the channel milled into the forward camshaft bearing surface to provide oil to the camshaft.

*A note on 'stripping and cleaning' - these engine parts are aluminium and cannot be bead blasted without damaging them, or embedding sand into the castings (bad!). So the case had to be run through the 'decarbonizer' fluid (a hot, stinky, red, very bad for you fluid), then the hot wash. They were then paint stripped, and pressure washed. It was a crappy thing to have to do - but better that i do it than have to pay shop labour rates! 

The very scary red tank

Yes, it was freezing.

 

The sump was in great condition already, so was send for FPI and then alodined and painted. 

Crankshaft & Counterweights

The crankshaft and counterweights needed to be sent away for inspection and overhaul to Joel up at Suncoast. The crankshaft in particular was a big concern for me, as when we removed it and gave it a light emery paper treatment, there were some fairly large scratches in the main bearing surfaces - presumably from the metal which had gone through the engine, which once belonged to the tappet faces. The crankpins were not as bad. 

This scoring scared me! 

Fortunately, when we measured the crankshaft we had a little bit of meat left on the bearing surfaces - by 'meat' i mean 0.0009" to spare! (aka 9 tenths in machinist lingo). The below measurements showed we had between 0.0013" - 0.0020" (13 - 20 thousanths) of extra meteral on the crank pins, and on the main bearings 0.0009" - 0.0016". (9 - 16 thousanths)

Fortunately, Lycoming makes 'oversized' (aka thicker) bearings for this reason. They come in M03 or M06 verions. M03 means they will fit a crankshaft which is 0.0003" undersized. 

So we sent the crankshaft away to be overhauled and there would be one of two outcomes - they crank could be polished to M03 here is Austalia, and hopefully this cleaned up all the scratches. Or, if it got to M03, and needed to go to M06 to remove the scratches, then it would need to go to the US. This is because at M06, you have potentially removed the nitrided layer on the bearing surface - and the crank would need to be re-nitiried. This is not possible in country. 

It took me a bit to get my head around how this works. Basically we are making the crankshaft smaller in diameter. Since the hole is bored into the case the same size as originally, the bearings have to be slightly thicker to take up the space - even though they are called "M03" bearings. 

So i eagery awaited an email back from the shop, and happily the crank polished up nicely at M03 and passed all the other inspections. All positions on the crankshaft get polished to M03. The counterweights were overhauled, and installed back on the crank with new roller pins, washers and circlips. 

It was a happy day when this came back ok!

We went ahead and ordered the M03 bearings - we used genuine Lycoming bearings 18D26096-M03 for the 3 & 4 positions (the small ones), and 18A26093-M03 for the front bearing halves. The conrods (crank pin locations) also got M03 bearings 18M23887-M03.

Cylinders (replaced, then overhauled!)

The main savings were had by overhauling the cylinders, instead of replacing them with new (savings in cost, and time). The original cylinders which were on the engine had very bad corrision. The engine had been sitting with some of the valves open, with no pickling at all. In addition, they were already P10 oversize - not worth saving.

So these cylinders went totally in the bin - the only parts we retained were the rocker arms (as these cleaned up ok). We kindly got sent 4 used clyinders from Joel at Suncoast, which were not new, but had only had one life. This would be their first overhaul. They looked a LOT better. 

A note on the Cylinder part numbers - in the replacement set we recieved from Suncoast, we got 3 x LW12993 and one 30160-01. We needed to check this anomaly, and to do this we refeedr to Lycoming SI1037 - Approved Pistons, Rings etc which shows 30160-01 as an approved cylinder for this engine. 

One different Cylinder part number.

30160-01 is an approved "Alternate Cylinder" for the -C1E6 engine. 

These had some light corrosion but nothing too bad. 

After a light honing.

After a very light hone:

The cylinders were send back to Joel at Suncoast for overhaul. This entailed the replacement of the inlet guides and seats and the exhaust guides and seats. The cylinders got new exhaust valves, and we resued the intake valves. The valve springs were reused (after testing), and new keys and rotator caps were used. They came back looking like new:

I was unfortunately not present, but Jack reamed the guides, lapped the seats and installed the valves.

Connecting Rods

The conrods are not an automatically replacement part, unless they are damaged. We had concerns that the level of corrosion on the tops of 2 of them may have rendered them unserviceable. However, after sending they up to Suncoast for overhaul they came out fine! Suncoast also rebushed the small end, and they get new bearings at the big end. 

I was very concerned about the corrision on the tops of these rods.

This was how they came back from Overhaul:

Intake Tubes

The intake tubes which came with the sump were in an acceptable condition - they had a couple of dents etc but nothing too drastic. One had a hole drilled in it however (?), so this was sent down to Brian Taylor in Latrobe Valley who welded it closed for me and also worked out the worst of the dents. I was then able to give them all a light sand, a bead blast, and repaint. 

What was this hole even for?

Other small items which we reused

- Pushrod Tubes - These were all in good condition, so were stripped, cleaned, alodined and painted.

- Rocker Arms - These were cleaned up on the wire wheel, sent for MPI then reused. 

- Accessory Gears / Idler Shafts - These were cleaned up in kero and a scotchbrite pad, then sent for MPI and resused. 

Idler shaft before

After

This is the oil pump drive shaft which interfaces with the gear on the back of the crankshaft.

Propeller Governor drive components.

- Intake Valves - the intake valves were cleaned up, measured for spec and reused. 

Before

-Valve Springs and Seats - The valve springs and seats were re-used once we cleaned them up on the wire wheel, tested the springs using the spring tester, and the seats passed MPI. 

Couple of hours on the wire wheel here.