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SkyTec Starter -- Working loose

RONSIM

Well Known Member
Working with a friend on his -7A --- less than 250hrs total, and on his second Skytec starter. The first was replaced under warranty because of looseness between the starter motor and the gear drive. We checked his starter yesterday, during an oil change, and discovered the same loose condition. This starter had the same issue on last oil change and the (2) connecting bolts were tightened and safetied.

What we found, this time, after removing one of the bolts, is that the motor housing bolt holes are significantly larger than the bolt. There are only (2) small (3/16?) bolts holding the motor to the gear drive and the bolt we removed showed significant fretting/stretching/deformed. I believe that the torque is allowing the motor to shift due to the larger hole in the motor flange and wearing at the bolt.

This is the "NL" version of the starter. I was wondering if anyone else has seen this issue? We are placing a call to the Skytec folks on Monday to discuss the issue.

Ron
 
It's been reported here multiple times. I repaired an early NL with a badly fretted case and stripped threads, and flew it a while. Then I upgraded to a new one, which is slowly doing the same.
 
Yes, on two separate aircraft. On the RV, most recent rebuild was installed six months ago (after a cracked bendix housing), and I was told there were "improvements made" for that very problem, but still check it very closely each oil change. Just over 100 hours since and no issues noted thus far.
 
Same issue with my NL. I dont know why they don't put dowel pins in to lock it down. Great starter aside from this issue.
 
I've had 2 of the same issue in 300 hrs. so I'm on my 3rd one now. The screws are found loose with the locking tabs in place, so it seems obvious the threads are pulling or wearing.
SkyTec has stood behind them even replacing it after the original warrenty expired, but they claim this is unusual and I'm pretty sure they see it all the time.
When this one works loose again and I'm sure it will, I think I'll install some Keen-Serts or similar thread insert. My untrained opinion is fine threads in aluminum is generally not a good idea. The dowel pin idea is interesting also, I wonder if there is a good place for one. Perhaps the screw holes could be machined for a dowel sleeve after the thread insert is installed.
Tim Andres
 
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Same issue with my NL. I dont know why they don't put dowel pins in to lock it down.

Likely because the motor itself is a COTS unit from the automotive world that doesn't have features already in the frame to accept dowel pins.

Skylor
 
Any idea which COTS unit the NL starter uses? How do I find this same motor online or, better yet, at my local auto parts store?
 
Any idea which COTS unit the NL starter uses? How do I find this same motor online or, better yet, at my local auto parts store?

I'm not sure specifically which model motor the NL starter uses. The Skytec lightweight starters use motors and solenoids common to later model Fords, such as the 2005 Crown Vic.
 
What is the cause or common denominator in these failures, heavy prop, ign timing to high for start ? thanks for the heads up, guess ill add this to my inspections....
 
What is the cause or common denominator in these failures, heavy prop, ign timing to high for start ? thanks for the heads up, guess ill add this to my inspections....

In my case I'm a stock compression 260, ignition timed to 3 degrees after TDC, and a standard 2 blade Hartzell - pretty easy on a starter.
 
Is the failure the mounting bolts to the engine, or the assembly bolts that hold the starter together? I wish I had heard of this last week before I changed my oil.

-Marc
 
I have found various fasteners loose on my Skytech starters over the years. Always addressed with thread locking compound. They have never recurred.
 
Short M5 bolts?

Do you mean the short M5 bolts - D in this image?

Some background for your solution. Read this : http://www.hexagon.de/rs/engineering fundamentals.pdf

Edit:
I have found various fasteners loose on my Skytech starters over the years. Always addressed with thread locking compound. They have never recurred.
Likely due to the lubrication of the threads resulting in higher applied tension (see reference above). Excellent data leading to a durable solution - it says, the bolt and threads are strong enough. It might be enough just lube the threads for torquing, maybe a clue for SkyTec engineers. Locking does not hurt though.

y7lqQkvOBdAE33nLGiD4Gp-us_IzkchND_IEXzHv5s-Xif_2BsGVZJuejRelolo30G7SK_VJ9oH3CNPZirnqXYVcdypIdkX-Hu2Elc-kLXfofSf2jSzwn26UJHlEa8DdxgavfTmVeiR-f7TLE8LRwNZ-FwoMTKbbdxh1y4oRo3h8IymaGmOVgdJa7_uvLlWFSG-dPE4mhtDIbufC8BYAd0WbvmZr_dn0V2xueY75Tzkkd3j-zjG3TzZmPY7lLv_jjK53pP_1rg8XCTWWXEHbSbstnxboFJ4Kv6B0vXoLIVjGPiW1RxzVDqSSW-dPKOrriYZcxX_eU6t21Oz2oxuT2Y3tDOLsOX0JoQUG_fRp6NatrdoMOe1kNBbn4JNHlVuai2yauiaJaDLQwVA7GHXHs5NRNFex-AKW0A5lAYAKauffSfwUIqp2SFLUdFkzpjbMLjetqeLEY4Q1YF6Susr7_1ex-0oLyBKoARhJrYxUsCaRj7DwqtuCWdIPMFBE-9d94Q24oGsGnQukziSvGUF3tRoc_0YO0g3SaYcwyGepkOFuy4JTbiWFIa09KZDA-0twXuBQgq4z9_z7d1NKYoQU-5mqWysV1lI=w1231-h416-no
 
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Does any one has a picture of these bolts? Since Skytech replaced my first starter under warranty, I have not had any issues with mine and have been checking the two long bolts that hold the case together with no looseness. It has been over 500 hours since mine was replaced.
 
Skytec has a new one on the way

My buddy talked with Skytec and they have shipped a new unit. Good for them. Always great service! But, this will be the second replacement, for the same problem. We will inspect it at the next oil change (and subsequent).

I will take a look at the old one, before we ship it back, and determine if I can put a bushing in the motor flange bolt hole, to take up the extra space. If so, we will do the mod on the new starter, before we install it.

Ron
 
This is a funny thread, I had a Saturn . . . my daughter had a Saturn, and it developed a large rust hole under threshold plate on the sill under the left side back door. She found it just 2 months past the 8 year rust through warranty, the service manager said - "I'm sorry your warranty has expired . . . . we have never seen that before. "

I went directly to parts (100 ft away), the parts guy said -yeah it happens all the time, we have a special kit for that. Yeah, funny. Ever so happy to sell that car. I wonder that happened to that company:eek:
 
Even with 2, maybe 3 occurrences of finding a loose fastener on my Sky-Tecs in 1839 hours and 16 years, I am *really* glad I wasn't hauling around one of those ~15-20-lb Prestolite starters.
 
My SkyTec NL starter did the same thing. That is why I replaced it with a B and C.

The two cheeseball metric M5 bolts that hold the starter motor to the drive stretch, bend and deform. I was replacing them all the time and finally got rid of it to Mike Bullock to deal with!

Good luck Mikey!!! :D

;) CJ
 
I started a thread on this exact subject, Feb. 2015. There are some 3 pages of answers. Click on my avatar, go to threads created by donaziza, scroll down to the 7th thread, "Fretting on a sky tec starter"
 
Skytec design change

I have had to send my Skytec 149 in for repair for loose threads and /or coming apart 3 times. I had heard they had effected a fix for this and today I noticed for the first time that the new unit they sent me last has a design change. The old design used long screws that passed through 3 sections of the starter. My new one uses short screws that thread into the center section to attach the end cap to the center section, and I assume 2 more short screws threaded in from the other end.
I hope it works, so far so good at 35 hrs.
Tim Andres
 
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I have had to send my Skytec 149 in for repair for loose threads and /or coming apart 3 times. I had heard they had effected a fix for this and today I noticed for the first time that the new unit they sent me last has a design change. The old design used long screws that passed through 3 sections of the starter. My new one uses short screws that thread into the center section to attach the end cap to the center section, and I assume 2 more short screws threaded in from the other end.
I hope it works, so far so good at 35 hrs.
Tim Andres

Tim, could you post a picture when able? Thanks . . .

Got it, That helps.
 
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Data point: just did the annual on the Arrow, two year old 149-NL with 430 hours, still solidly together, no fretting. Same for the rebuild previously mentioned on the RV, 200 hours now and all good as of last oil change.
 
It's not a great pic or I would have posted it yesterday. You can see the threaded screw hole boss cast in the case near the drive gear. The old one had very long screws that passed all the way through the center casting into the next section. I think it was the length of these screws that allowed the torque from the starter to "rack" the assembly and eventually loosen the screws, but I'm no engineer. This definently a change from the 2 previous starters.



Tim Andres

Note, this is on a pusher and yes I see there is a rivet missing.
 
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Skytec 149-NL Starter issue

While changing the oil today, I noticed that my Skytec 149-NL starter had an issue with the bolts holding the starter motor to the starter gear drive. This starter has 1350 Hrs on it with no issues. I removed the starter from the engine, and removed the two 8 mm hex head screws that hold the motor and gear section together. After cleaning them up, I locktited the screws into place again with Locktite #680, then bent over the metal tabs onto the bolt flats.

One point of interest is that one of the 8mm bolts required a ground down socket (VERY thin wall on the socket) to remove, and later tighten that bolt. The other bolt didn't require the thin-wall socket.

I'll examine it again on the next oil change to see if it's loosened up again....


Working with a friend on his -7A --- less than 250hrs total, and on his second Skytec starter. The first was replaced under warranty because of looseness between the starter motor and the gear drive. We checked his starter yesterday, during an oil change, and discovered the same loose condition. This starter had the same issue on last oil change and the (2) connecting bolts were tightened and safetied.

What we found, this time, after removing one of the bolts, is that the motor housing bolt holes are significantly larger than the bolt. There are only (2) small (3/16?) bolts holding the motor to the gear drive and the bolt we removed showed significant fretting/stretching/deformed. I believe that the torque is allowing the motor to shift due to the larger hole in the motor flange and wearing at the bolt.

This is the "NL" version of the starter. I was wondering if anyone else has seen this issue? We are placing a call to the Skytec folks on Monday to discuss the issue.

Ron
 
I *just* installed a new NL starter on my RV-7, I sure hope it turns out to be the new improved version and trouble free. I have exactly two (very quick) starts on it and no flights yet...
 
See posts 23 & 26 above.
This new design failed in less than 40 hours (came loose again). Once again skytec replaced it free after it was out of warranty.
This time they told me it had been "improperly assembled"
It will remain to be seen if the excellent CS continues with the new owner Hartzel?, I hope so as I expect to need it just one more time.
Tim Andres
 
Starter

I'm on my second Sky Tec starter and now it's going back for warranty. Spoke with them today , the latest version Does Not have tab washers on the bolts ( as per my phone conversation). The Serial number code is the first two numbers are the week and the next two are the year , not sure what month they started the latest "Fix" . The one I'm returning is 4015xxxxx
 
I had to tighten the bolts on my Skytech this afternoon with just over 160 hours, was starting to work loose. I'm well past the warranty since I bought the starter in the middle of my build, looking for a permanent option that does NOT include this through-bolt design.
 
Starter

I had to tighten the bolts on my Skytech this afternoon with just over 160 hours, was starting to work loose. I'm well past the warranty since I bought the starter in the middle of my build, looking for a permanent option that does NOT include this through-bolt design.

I would check with them about warranty, it's a known problem that they have dealt fairly with (at least with me ) . Give them a call .
 
My warranty was also expired when my starter failed for a different reason, but Skytec honored the warranty and sent me a new unit. It only had 150 hours time in service since the first start, and that's what they went by.

-Marc
 
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