Electro Systems / Prestolite Starter Screws

[RoundTwo]

Can anyone recommend who I can contact for screws for my 24v Electro Systems starter? Two were missing and the other two backed out 1/4”, leading to a slow crank. 

[Fly Boomer]

3 hours ago, RoundTwo said:

Can anyone recommend who I can contact for screws for my 24v Electro Systems starter? Two were missing and the other two backed out 1/4”, leading to a slow crank.

Take out remaining screw.  Check depth of empty screw holes.  If they look the same, buy two more like the one you removed.

[RoundTwo]

Just now, Fly Boomer said:

Take out remaining screw.  Check depth of empty screw holes.  If they look the same, buy two more like the one you removed.

The problem is one of the “missing” screws is actually sheared off, down in the hole. I’m not sure I can drill and easy out my way out of that. No telling how many years ago it sheared off.

[Fly Boomer]

24 minutes ago, RoundTwo said:

The problem is one of the “missing” screws is actually sheared off, down in the hole. I’m not sure I can drill and easy out my way out of that. No telling how many years ago it sheared off.

Oooo.  Depending on where it sheared off, you might be able to pull the end off and get ahold of the screw with vice grips.  Let’s hope it sheared off right under the head.  If not, it’s probably time for the EZ-Out.  Check out some new devices that have a drill bit on one end and the extractor on the other.  The bit is made to precisely limit the depth and is, of course, the right diameter.  And, after all that, measure the depth of those blind holes carefully — one way to shear off a machine screw is hit bottom in a blind hole.  I like to run a tap in blind holes just with my fingers to clean out whatever is in there.  Also, if these screws want to back out, some Loc-tite might not hurt.

[PT20J]

How old is the starter? Might be worth replacing it with a new lightweight Sky-Tec. They spin faster and make hot starts easier.

[A64Pilot]

I rarely have good luck with easy outs myself.

I did learn almost 50 years ago that nothing and I mean nothing can drill out a broken off easy out.

If you’re really attached to the thing, disassemble it and take it to a machine shop, worst case they can drill it out and put in a threaded insert. But they are way more equipped to deal with it than an average mechanic.

[RoundTwo]

1 hour ago, PT20J said:

How old is the starter? Might be worth replacing it with a new lightweight Sky-Tec. They spin faster and make hot starts easier.

Yes, Skytec is the next step, but…$$$

[RoundTwo]

1 hour ago, Fly Boomer said:

Oooo.  Depending on where it sheared off, you might be able to pull the end off and get ahold of the screw with vice grips.  Let’s hope it sheared off right under the head.  If not, it’s probably time for the EZ-Out.  Check out some new devices that have a drill bit on one end and the extractor on the other.  The bit is made to precisely limit the depth and is, of course, the right diameter.  And, after all that, measure the depth of those blind holes carefully — one way to shear off a machine screw is hit bottom in a blind hole.  I like to run a tap in blind holes just with my fingers to clean out whatever is in there.  Also, if these screws want to back out, some Loc-tite might not hurt.

It’s probably 1/8 recessed, so nothing to grab hold of and it’s a torsional shear, so the surface is sloped which will make drilling very difficult.

[RoundTwo]

5 minutes ago, A64Pilot said:

I rarely have good luck with easy outs myself.

I did learn almost 50 years ago that nothing and I mean nothing can drill out a broken off easy out.

If you’re really attached to the thing, disassemble it and take it to a machine shop, worst case they can drill it out and put in a threaded insert. But they are way more equipped to deal with it than an average mechanic.

Yeah, BTDT. Busted easy out quickly turns into torch time.

[A64Pilot]

5 minutes ago, RoundTwo said:

It’s probably 1/8 recessed, so nothing to grab hold of and it’s a torsional shear, so the surface is sloped which will make drilling very difficult.

If you have a press and big vise you can likely get a hole in its center if you drill very slowly and maybe use a center punch to mark it.

I’m not exactly shure what all they do but a good machinist can get just about anything out, you learn that living on a sailboat, Stainless steel fasteners become one with aluminum castings when soaked in salt water and given time.

There are left handed drill bits that I’ve heard often work, but I’ve not tried one myself

Edited July 25, 2023 by A64Pilot

[SKI]

When a bolt twists off it's really hard to get a drill started on center. The face is just too knarly even with a center punch. Find a drill bit that's just under the size of the hole through the casting. That'll keep the drill bit straight and on center. Drill lightly cause the bit is going to be large enough to wipe out the threads. All your trying to do is use the larger bit to get enough of a center in the twisted face to use the proper size drill bit for an easy out. Twisted off bolts can be a real bitch. They sometimes throw a burr on one spot where they twist off. LH drill bits are definitely good if you can find one. Have you tried using a dentist pick and see if you can just wind it out? I've had some that a nuclear bomb wouldn't break free and I've had some that you can wind the broken piece right out. Good luck, Sometimes their easy and sometimes anything but easy.  

[RoundTwo]

9 minutes ago, SKI said:

When a bolt twists off it's really hard to get a drill started on center. The face is just too knarly even with a center punch. Find a drill bit that's just under the size of the hole through the casting. That'll keep the drill bit straight and on center. Drill lightly cause the bit is going to be large enough to wipe out the threads. All your trying to do is use the larger bit to get enough of a center in the twisted face to use the proper size drill bit for an easy out. Twisted off bolts can be a real bitch. They sometimes throw a burr on one spot where they twist off. LH drill bits are definitely good if you can find one. Have you tried using a dentist pick and see if you can just wind it out? I've had some that a nuclear bomb wouldn't break free and I've had some that you can wind the broken piece right out. Good luck, Sometimes their easy and sometimes anything but easy.  

As a long time unprofessional wrench, I’ve had many opportunities to remove broken bolts and as many have stated, you win some, you lose some. The one that was wrung off is the bottom bolt, so most likely it will be the worst because everything runs downhill and it’s probably rusted pretty well. My main concern is that these are not grade 5 common and are hardened which means standard twist drills will be a challenge to get a good bite. It’s soaking with Kroil now in the hope something will give to make the job easier.

Thanks for the input.

Chuck

[A64Pilot]

After soaking, try heat, not acetylene heat but maybe propane heat, don’t get it smoking just try to expand the case a tiny bit to loosen the grip

I would use a center punch to mark the broken bolt to guide the bit, and use a tiny like 1/16” Cobalt bit, Cobalt is pretty tough and you want tiny because your just trying for a tiny hole to be a pilot hole, correct size bit, also cobalt after you get a pilot hole, but if you get the tiny one going dead straight I’d slowly take it all the way to the bottom.

Worst case if you bugger the thread you can helicoil it.

At some point though the juice may not be worth the squeeze, but I understand the challenge, your just losing your time.

I think a machinist if I use the term correctly will use an end mill to flatten the broken off end, spot face it, then center punch and drill with a press or lathe, not hand drill. But I’m no machinist so I’m guessing

[chriscalandro]

16 hours ago, RoundTwo said:

 No telling how many years ago it sheared off.

 

hopefully less than one as it should have been inspected at annual. (At least)

[N201MKTurbo]

I have an old starter in my hangar that nobody wants. If you ask real nice, I’ll send you a bolt.

[RoundTwo]

1 hour ago, chriscalandro said:

 

hopefully less than one as it should have been inspected at annual. (At least)

Unfortunately, because of the location and obstructions to vision, it is very difficult to inspect. This one that sheared wasn’t visible until the air box was removed, so no way it would be seen during an annual. 

[RoundTwo]

1 hour ago, N201MKTurbo said:

I have an old starter in my hangar that nobody wants. If you ask real nice, I’ll send you a bolt.

I may come knocking for a case if that’s available. 

[chriscalandro]

4 minutes ago, RoundTwo said:

Unfortunately, because of the location and obstructions to vision, it is very difficult to inspect. This one that sheared wasn’t visible until the air box was removed, so no way it would be seen during an annual. 

It’s not. It’s mounted right there under the prop. 
 

very easy to inspect. 

[RoundTwo]

11 minutes ago, chriscalandro said:

It’s not. It’s mounted right there under the prop. 
 

very easy to inspect. 

Not on a J model. The nose of the bendix is visible but all of the bolts in question are not easily seen. Two are, but not all four. 

[RoundTwo]

Team work makes the dream work!

[A64Pilot]

Congratulations.