Strike two 
Posted: Tue Oct 06, 2015 6:30 pm
by jwd3ca
So today might have been ‘first start’ day for me and my Sonex/AeroVee. Not to be.
This is my typical spark plug insertion method:
1 - a dab of anti-seize compound
2 - finger start the plug for several turns
3 - using a long reach spark plug socket with a 3/8 extension, and finger power only, screw the plug in until it bottoms.
4 - torque it
Worked predictably well until I got to step 3 of #2 cylinder.
At this point, I can spin the plug ad infinitum (with my fingers). As though the machine shop that machined the heads used the wrong tap!
Withdrew the plug, no metal to speak of in the threads (in other words, NOT cross-threaded)
Well CRAP! After my failed sump screen rivet, I’m beginning to regret my decision to go with the AeroVee. To say that the quality control in lacking would be an understatement 
We’ll see what Sonex has to say tomorrow…
Re: Strike two
Posted: Tue Oct 06, 2015 9:22 pm
by Rynoth
I had the exact same issue with one of my spark plugs during engine assembly earlier this year, seemed to easily strip the threads the first time I inserted a plug into one of the holes. For me it was one of the top holes, the aftermarket bottom plug holes seem to have much deeper threads, was this the same for you?
Fortunately for me this was during assembly so I didn’t have to take much apart. Aero conversions replaced the head, but I received no feedback as to why this happened.
Here’s a link to my blog post detailing issues I faced regarding quality control issues with my Aerovee heads, including the spark plug hole.
http://www.rynoth.com/wordpress/waiex/2 … ad-issues/
Long story short, both heads in my kit had defects and had to be replaced. I was extra careful to clean the spark plug threads on the replacement heads and did find what seemed to be residual aluminum in them from the tapping process, but I can’t be sure.
Re: Strike two
Posted: Wed Oct 07, 2015 1:28 am
by mike.smith
jwd3ca wrote:4 - torque it
I would suggest you not torque the plugs. Just seat them firmly. I used the torque values at first and found them way too high for these heads AND for the plugs themselves. I actually snapped the head off a plug (so the threaded end was left in the engine head) before I got to the proper torque value. VW guys have generally said not to bother torquing or you’re going to strip the threads in the heads, and make it difficult to get them out.
Re: Strike two
Posted: Wed Oct 07, 2015 8:27 am
by jwd3ca
Hi Mike… note that I didn’t get to step 4 (torquing). The plug is spinning in the head with finger power only. Never even put the socket handle on, let alone attempted to torque it… Note: this is the upper left front plug.
Re: Strike two
Posted: Wed Oct 07, 2015 8:48 am
by XenosN42
I had the exact same problem with one of my AeroVee heads for my OneX. Sonex replaced the head very quickly. I have 19 hours on my AeroVee now and it is running extremely well.
– Michael
Re: Strike two
Posted: Wed Oct 07, 2015 8:54 am
by vwglenn
QC issues are common for most VW parts. Thorough inspection is a must. All kinds of issues (usually minor and easily corrected) can be found. It’s pretty common to find left over sand from the casting process in things like sumps and such. Doesn’t really make the part bad all the time. Just something you would normally expect to be right.
I never torque the plugs in my VWs. A drop of anti seize and nice and snug. Never had one blow out or anything like that. Did have one where I cross threaded the plug on #3 but stopped before it got bad. Was able to clean the threads and ran it for another 50 thousand miles or so.
Don’t give up on the VW. You’ll get it right and it will be just fine. I’ve had the exact thought about the Jab (Why didn’t I get an Aerovee?)
Re: Strike two
Posted: Wed Oct 07, 2015 10:52 am
by jwd3ca
Torquing is not the issue here. The depth of the spark plug hole threads is the issue. Sadly, I just had the exact same issue with the upper right rear plug. It’s as if the bit used by the factory to drill the holes prior to tapping was too large. As a consequence, the threads are so shallow as to be almost non-existent. Sonex tech line is giving me the recorded ‘after hours’ message although it is 10:30 Central time on a Wednesday, so I haven’t yet been able to talk to someone there. But it’s clear that I will now have to take two steps back from being ready to start the engine, and disassemble both heads. For either RMA return to Sonex for replacements, or machining for heli-coils. Disappointing.
Re: Strike two
Posted: Wed Oct 07, 2015 11:28 am
by 13brv3
Sorry to hear about the problems. As someone who is just about to jump into a Onex project, it doesn’t give me a lot of confidence in the Aerovee.
Rusty
Re: Strike two
Posted: Wed Oct 07, 2015 11:52 am
by LarryEWaiex121
Rusty,
Get used to being the quality control guy. Its your hide on the line each and every time you bolt something on your plane.
Not trying to be a snob, but welcome to the wild and woolly world of experimental aviation:)
Larry
Waiex121YX
Re: Strike two
Posted: Wed Oct 07, 2015 12:22 pm
by vwglenn
jwd3ca wrote:…or machining for heli-coils…
Not acceptable on new heads. Make them send you replacements. I personally wouldn’t run a heli-coil on my bus let alone a plane. They’re a bandage to get you home or until you can save the money to get a new head in my opinion. I’ve seen (and heard) them blow on several occasions.
Re: Strike two
Posted: Wed Oct 07, 2015 12:33 pm
by jwd3ca
Yeah, Larry, I get it, not my first rodeo, been building engines, cars, motorcycles most of my life, and recently (last 15 years), three experimental aircraft. But sub-standard spark plug threads was about the last thing I expected to run across. I’ll get through this, albeit with a considerable time set-back. Just disappointed, that’s all.
And I’m not sure I agree with your opinion of heli-coils being bandages, vwglenn. Have you had bad experiences with them? I’d sooner believe that they would be a lot more robust than plug holes badly threaded into aluminum . And who’s to say the replacement heads will be necessarily better?
Re: Strike two
Posted: Wed Oct 07, 2015 1:22 pm
by 13brv3
LarryEWaiex121 wrote:Rusty,
Get used to being the quality control guy. Its your hide on the line each and every time you bolt something on your plane.
Not trying to be a snob, but welcome to the wild and woolly world of experimental aviation:)Larry
Waiex121YX
Hi Larry,
This will be my 6th experimental aircraft, and one of them had a Mazda rotary engine, so I’m used to wild and woolly :mrgreen:
Cheers,
Rusty
Re: Strike two
Posted: Wed Oct 07, 2015 6:49 pm
by Rynoth
jwd3ca wrote:Sonex tech line is giving me the recorded ‘after hours’ message although it is 10:30 Central time on a Wednesday, so I haven’t yet been able to talk to someone there.
For what it’s worth, I’ve had better success using email versus phone with tech support concerns, I’ve even received prompt responses on a Saturday (though probably not the norm.) tech@aeroconversions.com
Re: Strike two
Posted: Sat Oct 10, 2015 8:25 pm
by jwd3ca
Follow up: Sonex is aware of this sub-standard plug hole machining in a particular range of cylinder heads (lucky me!). Apparently ‘worn out’ tooling when they changed over to Mofoco. I was given a choice of returning both my heads for replacement heads or installing Time-serts and being credited for my $$ outlay. I’ve decided to go with the Time-serts option, doing all 8 plugs. I’m confident that the Time-serts will be a significant modification/improvement to the aluminum heads. Opinions?
Re: Strike two
Posted: Sat Oct 10, 2015 9:16 pm
by gammaxy
I have the pre-mofoco heads and they seem to have good threads. Due to warnings about possibly stripping out the threads, I have only performed a compression check with the heads cool. If the Time-serts reduce worry about stripping out the threads, they are probably a plus.
Re: Strike two
Posted: Sun Nov 22, 2015 10:26 am
by jwd3ca
As promised, here is a link to the TIME-SERT installation article (photo-documentary, really) I submitted to EAA’s Bits & Pieces:
To their credit, Sonex did credit me with the cost of the TIME-SERT tooling and inserts needed to repair the heads. I only wish that they had pro-actively notified me months ago that my particular heads might have a problem due to known ‘worn tooling’ at Mofoco for a certain range of serial numbers I’m not sure what that exact range is, but my s.n. is 0818.
Re: Strike two
Posted: Sun Nov 22, 2015 10:35 am
by Rynoth
jwd3ca wrote:… ‘worn tooling’ at Mofoco for a certain range of serial numbers … I’m not sure what that exact range is, but my s.n. is 0818.
My s.n. is 812 and I had to have them replace a head due to stripped plug. This was about 4 months after initially delivery of my kit, so hopefully the newer head was made better.
Re: Strike two
Posted: Sun Nov 22, 2015 8:05 pm
by vigilant104
jwd3ca wrote:I’m confident that the Time-serts will be a significant modification/improvement to the aluminum heads. Opinions?
The Time-serts are supposed to be a significant improvement over helicoils. They are solid and provide good, hard threads that are much less likely to strip out than the stock threads in the AL head. Some VW racers put the Time-serts in when the engine is new just for this reason, and it might be something those running VW engines in their airplanes consider doing, too. With twice as many plugs per cyl (= more opportunities to have a problem), with the lower one a bit hard to get to/thread straight, and with frequent plug changes/inspections,compression checks, etc, these plug holes get a lot more wear than they might in a car.
Re: Strike two
Posted: Sun Nov 22, 2015 10:40 pm
by jwd3ca
I agree, which is why I opted not to exchange my heads for new ones. The TIME-SERTS look like they are extremely robust and I’m happy with my decision. That said, if one had to spring for the tool(s), it does represent a significant expense (~ $150 USD for the 12 x 1.25).The inserts themselves are negligible, < $2 each.
Re: Strike two
Posted: Sun Nov 22, 2015 10:41 pm
by Bryan Cotton
jwd3ca,
Good writeup, thanks! Did you buy or rent the tools?
Re: Strike two
Posted: Sun Nov 22, 2015 11:58 pm
by vigilant104
jwd3ca wrote:I agree, which is why I opted not to exchange my heads for new ones. The TIME-SERTS look like they are extremely robust and I’m happy with my decision. That said, if one had to spring for the tool(s), it does represent a significant expense (~ $150 USD for the 12 x 1.25).The inserts themselves are negligible, < $2 each.
A tool like that might make a good start for a “Sonex Builders and Pilots Foundation Virtual Loan Locker”. Pay the whole price up front, get $130 back when the tool is returned.
Re: Strike two
Posted: Wed Nov 25, 2015 3:36 pm
by vwglenn
jwd3ca wrote:And I’m not sure I agree with your opinion of heli-coils being bandages, vwglenn. Have you had bad experiences with them? I’d sooner believe that they would be a lot more robust than plug holes badly threaded into aluminum . And who’s to say the replacement heads will be necessarily better?
I haven’t had any issues with them but I simply don’t use them on the spark plugs based on other peoples experiences. Most of the guys I’ve known who used them said they didn’t last very long (not a very large sample of guys 2-3 maybe). I heard one let go at a cruise-in. The engine kept running but the noise it made coming out and afterwards was terrifying. Plug and coil came out together. Possibly installation error? Ya never know with VW guys. Enough to convince me I don’t want that to happen? You bet.
I don’t think its a function of the helicoil itself but a matter of meat. Most VW heads crack between the valves over time. This is pretty much because of the small amount of metal between them. If you look at the amount of meat between the valves and the amount of meat between the plug hole and the valve (on a stock head) you’ll see a very similar correlation between the distances. My assumption is the more meat you take out (ream it for the coil) the more prone the head is to cracking and releasing that coil or the plug. A helicoil is just basically a spring. If the metal around a helicoil weakens from a crack, so does the ability of that coil to hold the plug in place.
I will never profess to be an expert on the VW engine. I’m far from it. I just go with what I know/learned after driving one around daily for almost 20 years. My opinions are just personal opinions but they’re usually based on practical real world experience. I believe the readers here can benefit from that but, like all internet message boards, your mileage may vary.
TIME-SERTS look like a better option and are more along the lines of a “case saver” which appear much more robust.
Strike two
Posted: Wed Nov 25, 2015 5:42 pm
by Sonex1517
vigilant104 wrote:
jwd3ca wrote:I agree, which is why I opted not to exchange my heads for new ones. The TIME-SERTS look like they are extremely robust and I’m happy with my decision. That said, if one had to spring for the tool(s), it does represent a significant expense (~ $150 USD for the 12 x 1.25).The inserts themselves are negligible, < $2 each.
A tool like that might make a good start for a “Sonex Builders and Pilots Foundation Virtual Loan Locker”. Pay the whole price up front, get $130 back when the tool is returned.
We would be happy to add this to the tool loan list. I have to admit though, few have taken advantage of the program.
Robbie Culver
Sonex 1517
Chicagoland
Tails and Wings complete - finishing fuselage.
N1517S reserved
Re: Strike two
Posted: Thu Nov 26, 2015 9:29 am
by DCASonex
Robbie,
Please add my tools for grinding inside of fuel tanks for oops fittings to the foundation’s tool rental.
David A.