Broken header bolts
 

Hi, the pipe header bolts on my O.S. 91 just broke right off today, leaving the ends of the bolts nicely lock-tighted in the engine! Any idea how I can get them out without damaging the engine? Also, has this ever happened to anyone else before, and if so, anyone knows what could have caused it?? I ckecked them a couple of days ago, and they were tight...so I don't think they were backing out or anything....by the way, it happened right after takeoff in my Yellow F-4.
On a slightly different subject, I'm thinking of getting into turbines later on this year. I saw a couple of jets flying out of Markham Park in Florida a few weeks ago. Both were straight wing Italian jets, and I was thinking of getting one of those...anyone knows the kind of plane I'm talking about? And is it a good first turbine job? One other thing, please tell me that turbines are not as much trouble as ducted fans! Man!! it's like every other week something goes wrong!!!!! If it's not the engine head bolts running loose, it's the retracts! When it's not the retracts, it's the pipe coming loose....and when it's not that, it's both header bolts breaking off right in the engine block!!! :eek: :confused: :mad:
Thanks, Lee.

been there - done that
 

Have been in your exact shoes - in fact about a year ago! The reason(s) that can happen vary. I came to the conclusion that I either didn't have the long JMP baseball bat pipe hanging at EXACTLY the center of gravity - Or when I mounted the retaining hook I allowed it to hang a micron too low or too high - or a combination of both. This combined with the vibration from a DF engine and its more than a header bolt can handle. I am assuming if you went with the stock setup that I did - you have a retangular retaining bracket that bolts into the header and then holds the pipe by the lip?? I think this stock setup probably works great for many setups - but it didn't for me. With the help of the great people here on RCU I got a better setup going. I'll describe that in a sec. --- now to the bolts.

I too used locktite as per instruction. I think if you used blue then you are probably fine - I have heard others say the red locktite is pretty tough. Anyway I was able to wrestle my bolts out with needle nose after SOME TIME. You know, put it on the coffee table by the TV - fight with it, put it down, fight with, etc. I think I also used tweezers. Although it did not come down to it some people recommended more drastic things like tapping the bolts with a really small tap then unscrewing etc. I think if you take your time you can get those bolts out with maybe just a few scratches. (be careful to not let any fragments from the bolts make their way into the piston area)

Once you get the bolts out (and get done celebrating:) lose that retangular mounting bracket and invest in a pipe retaining wire from BVM. Like $30 bucks or something and worth its weight in gold. Since that wire goes around the engine head there is not that tremendous pressure on the header from vibration and you will not break anymore bolts!

I can probably come up with some pictures if you would like. BTW - Mine was a Yellow F-16, :)

other stuff
 

BTW - believe it or not turbines do seem to be more user friendly than DF especially if you get a reliable brand. I have a P-80 on a test bench that starts and runs exactly as advertised every single time! Turbines haven't always been that way but these things have come a long way in a short time. With turbines there are just different issues - heat, etc.

The planes you are refering to may be MB339's ????

check out www.tamjets.com
(Products: Aermachi MB339 ARF)

From what everyone says they are great - I am going even simpler and getting a Roo - for the open installation - no tailpipe, and price :)

bolts
 

If there is any thread at all exposed for you to get some pliers around, try heating engine up nice and hot in the oven (use thick gloves to handle hot engine) this should help soften locktite a bit? hopefully enough to allow removal of bolts. Otherwise might have to visit local engineering workshop they should be able to remove 'No Worries'

Turbines have come along way also, and with a well set up engine should be 100% reliable if maintained as the manufacturer recommends. Most issues with turbines are during initial set up and installation with getting plumbing etc sorted and turbine ECU parameters correct for your model during first runs. The thing I notice from my experience is if you are going to have a problem with a turbine it tends to be on the ground not in the air....

Cheers-

Broken header bolts
 

Thanks for your replys guys...nope, no thread at all exposed. Looks like they need to get drilled out, then I'll probably have to re-tap for bigger bolts....EXACTLY what I was trying to avoid!
Smitty, I didn't even know that you had to hang the pipe right at the balance point...and yeah, it is the same setup that you have.
When I get them out...if I don't completely destroy the engine in the process...I'll try the other retaining method. And yup...it's the red locktite!
Lee

Cut slots in the ends of the screw
 

Use a very thin dremel cutoff wheel or a small file to cut slots in the exposed end of the screws, then use a screwdriver to remove them like any other screw.
It would probably be a good idea to heat the case in the oven or with a torch before you start trying to unscrew them. The heat will help in two ways; it should help loosen up the loctite, and it will also expand the tolerances between the screw and the threaded hole.
Make sure you plug the exhaust and carburator while you are grinding (or filing) on the screws, and don't burn yourself!! :eek:

Broken header bolts
 

A fine dental burr in the Dremel works well at getting into tight spaces to cut your screw slot.

Broken header bolts
 

You don't need to drill it out and re-tap. Just get a screw remover. It looks like a grinding bit/drill bit, except the flutes are reversed. You drill a small hole down the center of the screw, then using a hammer, tap the screw remover into the screw, and turn it out. The flutes on the remover dig into the hole while you're turning it out. You should be able to break the loctite doing this.

You can get these removers at www.mcmaster.com or any other place that sells machine shop parts. Do a search for screw extractor, look at page 2653, or look for item number 2563A11.

Good luck.

Russ

Broken header bolts
 

Thanks everyone, I'll give it a try this weekend and let 'yall know how it worked. If I screw it up, I guess I'll be getting into turbines alot sooner than I planned...then I'll be asking a whole lotta "getting into turbine" questions!!
Thanks again,
Lee.

Broken header bolts
 

I had this problem a well, kept breaking the header bolts... I finally pulled the impeller off and checked it for balance :eek: Way outta balance!!! I took the dremel to it and started grinding away at the hub....After about 30mins of grinding, i had the thing balanced! Solved all my problems!

Joey.

Broken header bolts
 

I justed ordered set of 5 diff sized bolt removers from McMAster's based on above info from Rahlberg13 (Russ.) :D
Only $6.52 plus shipping. same number except A27 for last 3digits in product code.

I will also try this on a big gasser engine that sheared off my prop bolts.

Broken header bolts
 

Those screw extracters work surprisingly well. I've seen extracters 2" in diameter. They're supposed to be able to back out a bolt up to 4" in diameter! Aye carumba!

RA