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Splitting Lyc case, bolt under cam gear...

P

pilot2512

Well Known Member
Almost ready to split case on O-320. There is a nut under the camshaft gear that I cannot get a wrench on. Is there a special tool for this? Do I need to modify some kind of wrench? Then how do I torque it again later? Any ideas?

Jay
 
Cylinder wrench

Use one of the cylinder base nut wrenches. You may have to grind down the outside diameter a bit, but it should work.
 
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I attended a Lycoming disassembly/assembly forum at Airventure years ago and when addressing the nut in question the top man stated that that nut is torqued to "GNT" specs or "Good and tight". His exact words. No way to get any type of accurate torque reading so snug it up tight. And don't forget to safety the nut after its "torqued"! I used one of the cylinder wrenches to loosen/tighten the nut IIRC.
 
Just did that with my recent overhaul. $5 wrench from Northern Tool. Ground the top and bottom of the neck down and heated with a propane torch to dull red. Bent, cooled, ready to use in just a couple of minutes.

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Cylinder base wrench worked great. Lots of swings with a rubber mallet later and both halves are split.

Thanks for all the help.

Jay
 
Case

One should use some kind of case splitting tools. Home made tools can be made that bolt to the cylinder studs and push against two crank throws with a threaded rod into a fixed nut at each location. Aluminum spacer shaped to fit the crank throws to prevent crank damage.
There are much better tools commercially available but a lot pricier.
One should also have the tools shown in the OH manual for joining the case halves back together.
 
jrs14855 said:
One should use some kind of case splitting tools. Home made tools can be made that bolt to the cylinder studs and push against two crank throws with a threaded rod into a fixed nut at each location. Aluminum spacer shaped to fit the crank throws to prevent crank damage.
There are much better tools commercially available but a lot pricier.
One should also have the tools shown in the OH manual for joining the case halves back together.
Click to expand...

The Lycoming school has a home-made slide hammer that works great for this. They welded a socket that fits the large through-studs on to a regular slide hammer. You screw it on the studs, and bang away, pulling the studs. Then remove all the case edge bolts (including the one behind the cam gear!), and the case pretty much falls apart.

Paul
 
Ironflight said:
The Lycoming school has a home-made slide hammer that works great for this. They welded a socket that fits the large through-studs on to a regular slide hammer. You screw it on the studs, and bang away, pulling the studs. Then remove all the case edge bolts (including the one behind the cam gear!), and the case pretty much falls apart.

Paul
Click to expand...

Unless it's a doweled case
 
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