Trent's RV14 Build: Engine Overhaul: Build Day 1!

Build day is here! It took a while, as i needed to fit in with the availability of the engine shop - they run a very large fleet of twin engine pistons, so it only takes a couple of engines deciding to end their lives early, and the engine shop becomes flat out (and i get put at the end of the list).

Anyway, the time finally came and i headed out to the airport!

Prepping the Case for Work

Work started by carefully borescoping all the oil galleries - to be sure nothing was lodged inside.

The right side of the case was attached to some shop made legs for ease of assembly.

Before we lifted the case onto the legs, the piston squirters were installed.

The piston squirters in position

A Note on Torque

Every threaded fastener was installed in accordance with the torque limits in the back of the Lycoming Overhaul Manual. This lists pages and pages of 'special' torques, in the 'service table of limits' section, and you refer to these if the part you are installing is listed. If it is not listed, then the 'Standard Torque' applies. Whenever anything was installed, it always got some oil mix onto the threads.

In order to use the torque table, you need to know what row applies! You start at the first page of the 'service table of limits' and there is a list of engines, along with some letter codes. The codes are heirachical - this engine (being an IO-360-C1E6) is a "S" code, "S5" (aka -C Angle Valve) and "S6" code (aka governor at the front) - you use the highest code listed. S6 trumps S5 trumps S etc.

An example is the torque needed for the Conrod Connecting Bolts. There is a listed torque of 480 in-lbs for an "S" engine, but for a "S5" or "S6" engine, there is a stretch value given - so we used the stretch value instead of the torque in this case.

Lifter Bodies (Tappets)

Next up we started on the lifter bodies - these (along with every other part which went into the engine, were cleaned of any perservative oils using avgas, then installed using a mix of engine oil and STP (as per SI 1059)

Generous lubrication of everything!

Main Bearings

We had previously test fit and measured the crush of all the bearings, and they were labelled where they belonged in the engine. These were cleaned with avgas then thinners, and installed. One of the only exceptions to lubrication - they were pressed into the case with no oil underneath.

Labels checked, then cleaned and installed in the matching location

Accessory Case Idler Gear Posts

While we had easy access, the lock plates were prepared by slightly bending up one side, then the idler gear posts were installed and the lock plates bent up using some parrallel pliers. Some earlier engines call for these bolts to be lockwired, but this engine got the lockplates (from the gasket kit).

Pre-bending up one edge slightly.

Camshaft

We had a mod done where a channel is cut into the forward cam bearing surface to provide lubrication oil inside the cam (it comes out of weep holes in the lobe faces). We checked that the supply hole lined up with this channel.

The cam had a heap of interesting markings - some stamped by the factory, and others engraved in by hand. Who knows what they all mean!

You can see an oil weep hole on the lobe on the right.

Propeller Governor Gears

This engine has a forward left hand governor pad, so the shaft and gears were installed. The shaft is held stationary by a grub screw in the case, and the gears rotate on this shaft. They are powered by a gear on the front of the cam. There are amended instructions in the Overhaul Manual to install the little grub screw with loctite, as well as 'stake' the threads to prevent the screw from backing out.

The tapped hole is for the grub screw.

Grub screw is torqued into position

'Don't worry, the case is only worth 10k'

A kind of bad photo, but this shows the grubscrew threads staked.

The front of the prop governor idler shaft gets a cap.

Some other little jobs

Other little jobs before the case can go together included installing plugs in the open ends of the oil galleries (which can't be accessed later). The externally accessible oil gallery plugs are left open, to allow air out when we prime the engine with oil later on.

We also installed the o-rings around the case dowels, forward case bolts, and grooves around where the through bolts will eventually pass.

These are the dowels in the centre of the case near #3 bearing

Forward case bolts - the top one is a stud on this engine due to the prop governor assembly being in the way.

#4 bearing - these are also studs on this engine

Forward thorugh bolts for the #1 cylinder get o-rings.

As per SI1059 the cam lobes, the tappet faces and the thrust faces all got a lathering of Molykote. This is there to prevent scuffing / damage in the first few seconds of engine operations while the oil pressure comes up and the oil starts to get to where it needs to go.

Preparing the Crankshaft

Unfortunately i was working when the day came to install the rods onto the crank, and this was done by the shop. The counterweights were also installed, along with the main crankshaft gear. We removed the crank from the engine stand onto the bench.

The front case seal on this engine is a non-split version, so we softened it in boiling water, then using a screwdriver in one of the prop flange holes to hold one side, pulled the seal over the crankshaft flange using this cool tool. Jack had done this many times before and it took him 2 seconds.

You can see a video of how it was done here:

The seal was also glued in place

Sealant on the case for the front crank seal.

Prepping the case for the big join

To prep the case for the big join, the case flanges were meticulously cleaned. A thin even layer of Loctite 515 was applied, then 2 lines of silk thread was used. One was looped around each bolt hole. This is literally commercial grade '00' silk thread available from anywhere! The cheapest component in the engine i think. Interestingly, this method has just been published as an approved method by Lycoming in SI1125.

Loctite 515 applied to BOTH case halves

'00' Silk thread is then applied to only 1 case half.

The outer line loops around each bolt hole, while the inner line does not.

The crankshaft was then lifted into position! The front bearing was attached to the crankshaft with some oil, and a bit of masking tape along the top (right side). We had previously marked the side (top) of this bearing, so we knew that it has settled into the corrected location, before closing the halves.

Here you can see the pencil line so we knew when the bearing was located correctly.

In the opposing case, the cam was put into position and lockwire used to hold it in place. This will be in the 'top' half of the case as we lower it down. The cam is put in this half, in order to stop the tappets from falling out.

Ready to go!

The Big Join!

After a short pause, and a cross-check we had gotten everything done we needed to have done, the left case half (and cam) was lifted onto the right half.

When the case comes together, it does not sit down properly at first. It sits on the dowels and needs to be pulled together evenly using the through bolts. The through bolts themselves are a friction fit into the case, and often need some tapping in. Instead of risking this tapping spinning or moving a bearing, we used some 'shop tool' through bolts which had been taken down a few thousanths along their middles. This meant they just dropped in and didn't need to be tapped. These were marked with a paint pen, so we knew they were not final install parts. These were all torqued to spec, and were only removed a pair at a time when the cylinders were installed.

This shows how far apart the cases sit, when resting on the dowels.

The blue painted ends of the through bolts, mark them as 'shop tools' and not 'final parts'.

The overhaul manual gives an order to tightening the larger studs and through bolts. We followed this order a few turns at a time on each nut position, and slowly pulled the case together.

Finally, the case was torqued and the seams visually checked. We got some nice squeezeout of the 515 along the whole case seam all the way around. Fingers crossed for no leaks later on.

The tails of the silk thread were cut of later when the sump was installed. At the front end, they were tucked under the crank seal into the grey expoxy glue.

A last look at the internals - the clearances with the case are tight!

Ready for the stand

Once all torqued, we were able to attach the engine stand to the crankshaft flange and lift it onto the floor. We used a tooling flywheel for referencing the timing marks, as this does not have a ring gear and makes working on the engine easier (and less likely to scratch my nice anodised flywheel).

Lots more little jobs

Once on the stand we installed all the case flange bolts, then started on a bunch of little jobs such as the prop governor blanking plate (we will run it without a prop governor), and the metal retainer rings around the pushrod holes.

Intead of the normal nuts on the forward case bolts, we used the SDS Crank Sensor Mounting nuts.

The crank sensor mounting plate will bolt to these 'nuts' later.

The starter (Skytec 149NL) was installed

Accessory Case

While i was working on all the small jobs above, Jack prepped the accessory case for install. This included installing the old meahcnical tachometer shaft - even though we are using electronic engine control, this still gets installed as otherwise there is a hole in the case which needs to be filled somehow.

Jack installed the nuts along the bottom of the case (inside the sump) and these were neutrally lockwired. As well as installing the hidden nut behind the camshaft gear (and also lockwiring this).

I mean, why is this here?

Jack had also built up the oil pump, including new gears and a new housing. This was installed and also lockwired.

It's all about the timing!

Next up, we marked the cam and crank gears were the timing marks were stamped on with blue paint pen. These timing marks are just little 'O' marks stamped on. The crank gear marking is on a single tooth, so mates with two teeth on the fuel pump idler gear. Likewise, the cam gear is marked on two teeth, so mates with a single tooth on the fuel pump idler gear. Incidentally, we left the fuel pump pushrod out of the engine, as it's not needed with an SDS installation.

Timing marks all lined up.

The magneto idler also has a timing mark, but really isn't used for anthing.

Installing the accessory case

Once that was done, we used some Hylomar sealant on the gaskets, then installed the accessory case. As a note for gaskets - if the part being installed would never need to come apart (like the fuel pump hole cover or crankcase halves), we used Loctite 515. If it might need to come apart, but hopefully not (like the accessory case), then we used Hylomar. If it definitely needed to come off, we just used grease.

We also used all brand new washers, split washers and nuts. The bolts were reused if they were in good condition, cleaned and CAD plated.

Looking up into the accessory case.

Fuel pump cover

These didn't need drilled bolts, but this was all we had. So we lockwired them, just because.

The SDS coil packs mount on plates which cover the magneto holes - since this engine had a impulse couplng on one magneto, one set of studs were too long. So a special tool was used and we replaced the studs with shorter ones.

The SDS coil packs will bolt to these plates.

The tachometer got a little aluminium cover, to keep the dust out.

AN fittings installed for the oil cooler hoses.

The dipstick was installed, and since we changed the sump on this engine, we checked that it was a good length and cleared the bottom of the sump. It sits about a 1/4" above the bottom.

This sits about 1/4" above the bottom of the sump

Fuel filter and vacuum pad cover were installed. There will be a generator on this vacuum pad, so the cover was not painted.

Installing the Sump

The sump was prepped, then installed on the engine with a combination of 1/4-20 bolts into tapped parts of the case, or nuts on studs which are installed into the sump.

Sniffle valve installed

Oil suction screen installed.

Sump drain plugs installed. One will be replced with a quick drain later on.

The custom dataplate.

The gasket got some Hylomar, then the sump was installed.

Where the sump would bridge over the transition between the accessory case and the main case, and also where the main case halves join, some extra hylomar was added to help prevent leaks.