Prestolite starter brushes

Domenick

Domenick

Pattern Altitude
Joined
Sep 11, 2019
Messages
1,829
Display Name
Display name:
Domenick
My Warrior has a Prestolite MZ4222R starter. At some point I will need to replace the brushes again. The last time I replaced the brushes I spent over an hour with a guy at an auto parts store trying to find one that matched my example. Eventually, we did, then dumb me either lost the part number or I never recorded it.

The brushes are the same across many of the MZ models.

Does anyone have a current automotive equivalent for any of the MZ starter series?

Page 33 and 34 in the PDF:
www.dropbox.com

00.Prestolite.Starter.Alternator.Manual.pdf

Shared with Dropbox
www.dropbox.com www.dropbox.com
 
Domenick said:
Does anyone have a current automotive equivalent for any of the MZ starter series?
Click to expand...
You simply trying to save a nickel as the OEM brushes are still available? Don't have an alternate but there are several vendors out there that can help match them like this one but there are others.
 
Bell206 said:
You simply trying to save a nickel as the OEM brushes are still available? Don't have an alternate but there are several vendors out there that can help match them like this one but there are others.
Click to expand...
Yes, Aircraft Spruce has a Hartzell brush kit described as Major overhaul kits for its line of lightweight Lycoming and Continental starters.

If you have a confirmed OEM source for MZ4222R replacement brushes I'd appreciate a link or phone number.
 
Why don’t you just put a SkyTec in? We took that boat anchor out last annual in the Archer. The SkyTec is so much better!
 
RyanB said:
Why don’t you just put a SkyTec in? We took that boat anchor out last annual in the Archer. The SkyTec is so much better!
Click to expand...
My "boat anchor" is working perfectly. :)
And I don't need the few extra useful load pounds.

Have you yet had a shear pin go on your Skytec?
 
Domenick said:
My "boat anchor" is working perfectly. :)
And I don't need the few extra useful load pounds.

Have you yet had a shear pin go on your Skytec?
Click to expand...
I installed Skytecs on the flight school's airplanes. All of them. And had no trouble with shearing the pin.

The Skytec uses the same technology that modern car starters use. It's a geared starter that uses a smaller, permanent-magnet motor that gets more torque out of less current. It starts cold engines faster.

That old Prestolite was a good starter in its day. I did run into an issue with a Lamar starter replacing a Prestolite on an O-470; that Lamar would not let the engine's starter drive reverse a little to relax the clutch spring in it, causing some hassles. That was fixed long ago, but I would still use the Skytec.

Sooner or later the commutator on your Prestolite will be shot, and there are no replacement armatures. It happens to all of us, with many components. Old generators, old magnetos, old gyros, old radios, old beacons, old brakes (like Goodyear and B.F. Goodrich), old engines (O-290, GO-300, etc.), wet vacuum pumps. All obsolete and disappearing. Incandescent lights, too.

I just finished fixing up an ancient RCA Victor console radio, built in 1941. 82 years old. I have a big boxful of vacuum tubes, and that box had none of the relevant tubes in it. This stuff is scarce. I replaced several resistors and one or two capacitors in it, robbing them from another old radio. Just try finding capacitors rated for 600 volts anymore! Or one-meg potentiometers. Transistors use low voltage and higher current, and available components reflect that demand.


There are 82-year-old airplanes out there. There are a lot more 60-year-old airplanes, built just before alternators supplanted generators. People trying for authenticity in restoring old airplanes or cars spend a lot of money finding those old components. When I restored my 1951 International pickup, I committed the sacrilege of converting it to 12 volts and used an alternator and 12-volt lighting. Heresy! But affordability and reliability were the criteria here, and you will find the same need with that old Prestolite someday.
 
Last edited:
Domenick said:
Have you yet had a shear pin go on your Skytec?
Click to expand...

Not all of them have shear pins. But for the record, no aircraft that I’ve owned that has a shear pin style Sky Tec starter has ever needed a replacement.

While the newer permanent magnet starters aren’t a solution for every application, I have generally found them to be a big improvement over the old Prestolite style starters. Obviously the OEMs feel the same way, as they have abandoned the old starters.
 
Domenick said:
My "boat anchor" is working perfectly. :)
And I don't need the few extra useful load pounds.

Have you yet had a shear pin go on your Skytec?
Click to expand...
Negative. It’s a great improvement!
 
All good feedback.
I'll fly the OEM Prestolite until I can't. Then its a Skytec NL 149 tooth.

I do see Starter commutators on eBay, but I didn't investigate.
 
In a service manual for some legacy Cessnas we find this in the inspection checklists:

1699550528014.png
Every 200 hours the brushes need checking. I know, I know, most will never get looked at until one day the starter just refuses to work, and by that time the brush springs have gouged the commutator and wrecked the whole armature.

But that labor every 200 hours adds up. The Skytec is good for the whole TBO of the engine, no inspections other than the electrical cables and the mounting. Just eyeball work, no fooling with brush port covers or blowing out accumulated carbon and copper dust or taking the whole thing out to dismantle it for a brush change.

There are no published life limits for the Skytec, but I would replace it at engine overhaul. Skytec has an exchange/rebuild program. I don't see that any parts are available for field repair or overhaul.
 
Dan Thomas said:
In a service manual for some legacy Cessnas we find this in the inspection checklists:

View attachment 122220
Every 200 hours the brushes need checking. I know, I know, most will never get looked at until one day the starter just refuses to work, and by that time the brush springs have gouged the commutator and wrecked the whole armature.

But that labor every 200 hours adds up. The Skytec is good for the whole TBO of the engine, no inspections other than the electrical cables and the mounting. Just eyeball work, no fooling with brush port covers or blowing out accumulated carbon and copper dust or taking the whole thing out to dismantle it for a brush change.

There are no published life limits for the Skytec, but I would replace it at engine overhaul. Skytec has an exchange/rebuild program. I don't see that any parts are available for field repair or overhaul.
Click to expand...
Every time you post an inspection list with the required time intervals, it reinforces my opinion that most GA aircraft are not in compliance. I just don't believe the service book is opened and every item on page after page is properly inspected as indicated.
 
3393RP said:
Every time you post an inspection list with the required time intervals, it reinforces my opinion that most GA aircraft are not in compliance. I just don't believe the service book is opened and every item on page after page is properly inspected as indicated.
Click to expand...
You are right. I used those inspection checklists. I wanted to know that I had caught all possible defects. A 200-hour was a lot of work, as the interior had to come out to inspect the structure, the control cables, wiring and hydraulics, and so on. Most of the inspection panels got opened.

FAR43 Appendix D (in the US) or CAR625 Appendix B (Canada, nearly identical to the US Appendix D) sets out the minimum requirements for an inspection. If one compares the Appendices with the Cessna checklists, you won't find all that much extra stuff in the checklists. For example, alternator, starter and generator brushes and magnetos, are addressed in the Cessna lists, but not in the FAR/CAR Appendices as specifically detailed items. But if an accident arose out of a failure of such a component because it wasn't checked, the FAA investigators (for example) might point to this line in Appendix D:

(d) Each person performing an annual or 100-hour inspection shall inspect (where applicable) components of the engine and nacelle group as follows:
....
(10) All systems - for improper installation, poor general condition, defects, and insecure attachment.

"All systems." That is a really big bite of the pie, there. If the alternator fails at night or in IMC because its brushes weren't checked at 500-hour intervals and were worn right out, wouldn't that constitute a defect in the alternator?

And yet, this stuff (along with vacuum pumps) are run to failure as a matter of course. It's insane.

I can't find the alternator brushes mentioned in Piper's checklists, but you will find such stuff in the manufacturer's manuals. Mechanics should have those manuals.

The last line in that excerpt from the inspection checklist I posted mentions the carb and drain plug. That plug is supposed to come out every 100 hours and fuel run through the carb bowl to flush out any debris or water that got past the screens. That almost never gets done even once between overhauls.
 
The carb and drain plug line led to my comments. I was thinking "No way that ever gets done."
 
3393RP said:
it reinforces my opinion that most GA aircraft are not in compliance.
Click to expand...
Unfortunately that is solely up to the owner which guide is used. And while a pure OEM inspection guide has its own issues, a combination of Appx D, OEM inspection guide, and OEM bulletins usually provides a solid reference to catch the usual issues and definitely catch those not inspected at all plus keep the costs for your average owner within reason.
 
3393RP said:
The carb and drain plug line led to my comments. I was thinking "No way that ever gets done."
Click to expand...
I have drained the fuel bowls on dirt bikes years ago, so when I saw the drain plug on my plane it was a automatic thing to do.
008_30.jpg

I do it every time I clean the fuel inlet screen on the carb. That is white grease on the threads.
007_33.jpg

A couple years ago I started printing out the inspection pages from my service manual for a guide for my inspections. File them in my logs for the next owner I guess?
(edited)_IMG_3042.png

Makes me feel a little more confident in my inspections. My AP don't mind either.
Old picture, the first time I pulled the inlet screen. By the amount dirt on the outside of the carb I'd say it was the first time in a long time. Luckily the screen itself was pretty clean. I have a Skytec starter also, it has been flawless for more than a 1000 hrs.
036_9.jpg
 
061_5.jpg

I really didn't know what I was looking at but I knew it was 40 years old. And from experience with gear reduction starters on cars and trucks I bought the Skytec, no regrets.
074_4.jpg
 
You must log in or register to reply here.
Back
Top