Source for Lycoming ST-122 case split tool

Apparently Lycoming parts dept no longer rent this tool. Used, if you can find them, they are ~$900, or new for a mere $5,000. It feels like the biggest joke in aviation tools, as it's just a set of pressure plates.

Before I start building my own, does anyone know of a place near Portland who might rent it?

I'm aware of the Ryan Machine tool which uses the threaded rod and V-block to push on the crank journal. My mechanic is leery of pushing on the crank.

Thanks.

Lycoming used two different types of through studs over the years. The latest style are interference fit and can be removed with a "Slide-Hammer". Lycoming uses side hammers at the factory to split the latest style cases. The earlier style (both narrow deck and wide deck cases) through studs screw into only one side of the case.

Sometimes but not always, the cases can be split using a "Dead Blow" hammer. I have recently split a narrow deck and a wide deck case with nothing but a dead blow hammer. I spent about 20-minutes with the "dead blow" hammer to get the case apart.

Note: Do not forget to remove the nut and bolt or nut from stud that is behind the accessory case near the cam. You will need a thin box end wrench to get the nut off.

RV6_flyer said:

Lycoming used two different types of through studs over the years. The latest style are interference fit and can be removed with a "Slide-Hammer". Lycoming uses side hammers at the factory to split the latest style cases. The earlier style (both narrow deck and wide deck cases) through studs screw into only one side of the case.

Sometimes but not always, the cases can be split using a "Dead Blow" hammer. I have recently split a narrow deck and a wide deck case with nothing but a dead blow hammer. I spent about 20-minutes with the "dead blow" hammer to get the case apart.

Note: Do not forget to remove the nut and bolt or nut from stud that is behind the accessory case near the cam. You will need a thin box end wrench to get the nut off.

Click to expand...

Thanks RV6_flyer. I have a narrow deck case, which uses all through-studs, which are anchored in the case. No through-bolts are used AFAIK.

I am aware of the bolt behind the cam gear...a sneaky lil *******

I still think the pressure plate, as is recommended in the overhaul manual, is the way to go, but the Lycoming tool seems to be a rare as hens' teeth, thusly overvaluing them. If anyone has pics of their homespun tool, it would help.

stringfellow said:

I'm aware of the Ryan Machine tool which uses the threaded rod and V-block to push on the crank journal. My mechanic is leery of pushing on the crank.

Thanks.

Click to expand...

From their website:

There are two optional plates that allow the engine to be separated without having a crankshaft installed.

flyingriki said:

From their website:

There are two optional plates that allow the engine to be separated without having a crankshaft installed.

Click to expand...

But when there is a crankshaft installed and in the way, that particular feature doesn't apply. The threaded rod must push on something, a crank journal, a rod.

Case splitting

The Lycoming tool is made to push on the crank if it is installed. It doesn't take a tremendous amount of force to split the cases, but the problem is applying the force exactly where needed and keeping the halves parallel as the dowels are separating. Next time I need to do this I'm building a tool. I don't see a problem pushing on the crank as long as the contact point is protected.

Don Broussard. A&P-IA ect.ect.

RV 9 Rebuild in Progress

When we split my O-320 case, I asked 2 local A&Ps who work on Lycomings every day if they use the pressure plates and both said no, just use a soft hammer. Well, the hammer wasn't doing it... maybe because my case hadn't been apart in its 38-year life. So I did a search here and found advice to use PB Blaster. Off to Wal-Mart I went and was surprised to find it on the shelf. I sprayed the thing down and let it soak overnight, then we were able to separate the halves with the soft hammer, but only just part way. It doesn't matter how gentle you are or how soft your pry bars or wood wedges are, don't let anything touch the mating surfaces of the case halves! Light scars from the separation operation cost many extra $$ at DivCo. I felt kinda dumb because I knew better, but I was just happy they could repair it. Now it looks beautiful.

Just another thought.

Would it be possible to leave a piston and cylinder on, then rotate to BDC loosen all the case bolts 1/16" ( or less) then pressurize the cylinder and then use the dead blow hammer to shock the joint. It will snap, but forces are very well controlled, less than a running engine.

I would do this before spending cubic dollars if the flange bolts are in place to hold the barrel. I have had to use the starter to pop loose the heads on a SBC before. Just think about what you are doing and be safe. The process, well thought through, is low risk, although labor intensive.