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Removing prop hub plug on Lycoming 540

JackinMichigan

JackinMichigan

Well Known Member
We're at the point in our build where we're ready to fill the engine with oil. There's a 1-3/4" diameter plug inside the prop hub that will need to come out (it's part of the constant speed mechanism), so we have 2 questions:

1. Should this plug come out before we fill the engine with oil or after? Does it matter?

2. How do we remove this plug?
 
1. Not sure it matters when, as long as you don't turn the prop and pump oil into the crankshaft.
2. Everyone seems to have a favorite method. Here's what I did: Use an awl or similar to punch a starter hole in the plug. Insert a lag bolt, with washer under the head, thru a hole in a piece of 3/4" x 4" plywood. Place the plywood over the end of the cranckshaft, start the bolt in the starter hole, keep turning until it's out.
3. Clean up any stray shavings from inside the crankshaft.
 
crank shaft plug

As I remember the sheet metal plug has a slight convex shape to it. I was told to hit it with a a ball peen hammer in the center until it was concave at which time it came out easily using a magnet.

driling doesn't soung good. I don't like the idea of left over metal shavings inside the crank shaft
 
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Freeze plug

If you are talking about the forward crankshaft plug i use a slide hammer for removal. Drill the proper size hole almost all the way thru the plug, (it's about 1/8" thick) stop and blow out the drill chips, put a dab of grease on drill bit and drill thru the plug. Screw in slide hammer and 2 taps will pull it out. Normally this process doesn't leave any drill chips or filings in the crank bore. If there is a drill chip left behind it is very obivous, easy to reach and easy to remove. Add oil whenever you wish, makes no difference to forward end of crank.

Don Broussard

RV-9 Rebuild in Progress
 
awmuhs said:
As I remember the sheet metal plug has a slight convex shape to it. I was told to hit it with a a ball peen hammer in the center until it was concave at which time it came out easily using a magnet.

driling doesn't soung good. I don't like the idea of left over metal shavings inside the crank shaft
Click to expand...

Evolution10 said:
I, too, used Alan's method. Do some research before you drill.
Click to expand...

Yup
This method works quite well
A safe wau to do it is hold the ball end of a large ball-peen hammer against the plug, and then hit the flat face of the hammer with another (large) hammer.
 
crankshaft plug

JackinMichigan said:
We're at the point in our build where we're ready to fill the engine with oil. There's a 1-3/4" diameter plug inside the prop hub that will need to come out (it's part of the constant speed mechanism), so we have 2 questions:

1. Should this plug come out before we fill the engine with oil or after? Does it matter?

2. How do we remove this plug?
Click to expand...

Jack, I just did this a month ago under the supervision of a maintenance engineer. We tapped the centre of the plug with a hammer and punch (plug is quite soft metal) until it bent enough to loosen. Seemed kind of radical to do it that way but he assured me that was the normal method. I wouldn't want to drill a hole in it for fear of losing some of the shavings inside the crank.
Rick
#40956
Southampton, Ont
 
Sounds like a soft plug or "freeze" plug we used to have to replace in car engines. Easy to remove, but I was always taught to never strike a hammer with another hammer unless you use a brass or soft hammer to do the striking with.

-Marc
 
Plummit said:
but I was always taught to never strike a hammer with another hammer unless you use a brass or soft hammer to do the striking with.

-Marc
Click to expand...

I figured someone would comment about that....

I have never understood that idea (but am willing to learn if someone has a better explanation than what I have heard in the past).

I don't see a difference between hitting a hardened steel chisel or punch vs hitting another hammer, but use a brass hammer if you prefer.
 
Wear Safety Glasses

I was going to comment earlier but didn't want a thread drift. Just be sure to wear safety glasses when striking any kind of hardened metals. Chips can and will fly off and potentially cause serious damage to your eye faster than you can blink.

Vic
 
yeah...

Mythbusters did an episode on this. I think the premise is that smacking two pieces of hardened steel together may cause the steel to shattered, or at best, shards to go flying.

I don't think they were able to get one to shatter, even hitting it much harder than any human could do but it's better to err on the side of safety. A piece of steel in your eye would put a real quick end to your RV project.

I have used the "grease in the drill flute" technique many times, on many different applications and have yet to have an issue with errant chips...YMMV
 
rocketman1988 said:
I don't think they were able to get one to shatter, even hitting it much harder than any human could do but it's better to err on the side of safety. A piece of steel in your eye would put a real quick end to your RV project.
Click to expand...

I couldn't agree more, which is why I always wear safety glasses when hitting a hardened steel chisel, punch, or another hammer.

In fact I wear them when hitting anything with a hammer......
 
rvbuilder2002 said:
I figured someone would comment about that....

I don't see a difference between hitting a hardened steel chisel or punch vs hitting another hammer, but use a brass hammer if you prefer.
Click to expand...

Wellllll, I was taught that tools like chisels and punches were made with differential hardening techniques that harden the cutting edge while leaving the rest of the tool softer, so they didn't fracture when struck. That is why you are suppose to be careful about sharpening tools on a grinder and not allowing the cutting edge to get too hot. ;-)

-Marc
 
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Chisel

rvbuilder2002 said:
I figured someone would comment about that....

I don't see a difference between hitting a hardened steel chisel or punch vs hitting another hammer, but use a brass hammer if you prefer.
Click to expand...

Scott,
A hardened chisel is only tempered/hardened (actually two step process, which I won't get into) at the cutting edge. The shaft which you strike with a hammer is not hardened (which is why they need to be ground round every so often) . Hope this helpsu
 
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Well we did it...

We drilled.. then tapped a 3/8 thread.. the extracted it with a 3/8 bolt, washers, and plywood.

Some chips.. but we think we got them all. Oil came out.. which was good because we are sure we got all the chips out.

Thanks guys....
 
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