My ST 40 has finished its breaking and i realized that both the muffler (stuck to the manifold) and the prop are stuck. I am thinking that i can just run the engine with the muffler bolt loose and see if it loosens up but i draw the line at running the engine with the prop not secured. The prop is on there so well that i cannot find any kind of way to get it off.
Any ideas

What I do to get the prop off is.. I will take off the head and put a small pic of rope in there and put the head back on. The rope will stop the eng so you can tern the prop. The rope will not hurt the eng.

Go get a nut cracker at the hardware store and use it to crack the hub of the prop into two pieces.

Even though rope is soft, it eventually totally compresses. The torque necessary to remove the prop could bend the crankpin or the connecting rod. I'd rather sacrifice a prop. Just my $.02.

Every time I hear of a heli person using a piston stop to tighten up the clutch assembly, I cringe. I tighten them as far as I can without locking the piston in place, but I use lots of blue Loctite, or equivalent thread locker, instead of massive amounts of torque being applied to a locked up engine. None of mine have come loose yet. It only takes a little heat to get it apart when the time comes.


Ed Cregger

Loosen muffler clamp bolt and nut. If your in a hurry take a flat blade screwdriver and spread the muffler in between the slit . Not in hurry spray a little penitrating oil and the next day heat flange with heat gun or torch and it will twist off . Use gloves...........

Ed is right on locking the piton thing DO NOt you can also use a dremel. coping saw or anything else to saw the hub of the prop on mine the muffler is the econony one pc conventional not the 2 pc with the stack it either gauls and sticks or falls off
my guess is they did that hugh thing to comply with noise levels in Europe and England martin

Thanks everyone.
At the moment i don't really need to get the prop off so i will leave it on.

I have used a pair of vice grip pliers on the thrust wash assembly and hefty wrench on the nut to loosen a few props (or pieces of prop hubs). If there is still enough prop blade left, it hold on to it to counter the torque needed to remove the nut.

Cheers,

Chip

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And you are right about the prop removal. Nut cracker? What was I thinking? Hmm, now if someone made....


Ed Cregger

I read somewhere that problem with the ST manifold joint is caused by the metal of the two parts fusing together. Whether or not this true, I know they can be a SOB to separate.

Anyway, to prevent it happening again, you need to use some kind of grease (I use copper grease) in the joint. And if either of the parts has become nicked, take some time with very fine sandpaper to smooth the metal, as it only takes a tiny bump to bring everything to a halt.

Matthew

Ed nut cracker?? are you hitting the egg nog again?? on a serious note I really think that ST muffler should be rethought every one else uses a convential design of course use can use an after market pitts type and drop 40 bucks the ST 40 mounting bolts are pretty widly spaced so tower or an OS spaced bolt pattern will not work martin

I've got a Tower 46 muffler on my G51. It seemed to fit well, so I used it, so I didn't have to use that stupid ST header. Glen

The muffler on my ST-40 also stuck on break-in. After a lot of working back and forth to get apart Ifound the metal galled together. I lightly filed the header til a slip fit was obtained again and reassembled it with anti-seize. So far so good, but am going to replace it with a Macs as soon as I can. It is also too heavy! Great engine though!

thank you glenn-- I stand corrected I had picked up the wrong engine an MVVS 40 to compare the spacing is indeed the same as my
OSAX46 martin

You'll need to use a wide bladed screwdriver in the muffler slot to expand it out enough to break it free. There really should be a note in the instruction manual warning against fitting the muffler dry onto the stub because alloy against alloy like that will weld itself together. Take it apart, polish both surfaces then use a copper based anti seize paste from an auto parts store.

For the prop, the problem is that although the threads are 1/4x28 the machined area behind it is 7mm which is slightly larger than 1/4" (6.35mm). Try taking off the prop washer then use two propnuts as locking nuts (with a bit of clearance from the prop of course). Hold the outer nut with a spanner and then try turning the prop to get it to break free.

Downdunder, i was thinking of that, and it just might work. I will try this weekend and keep you posted. At the moment, the engine is going into my dads tower 40 trainer. I am corssing my fingers to see if the muffler clears the fuse.

You would think ST would sell more engines if they pushed the economy muffler rather than the silent muffler. The economy is lighter by about 100 grams and smaller like an OS or Magnum. I've got both and don't notice the sound difference much. Maybe the DB meter does.