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HelicopterEngines Plugs Mufflers Fuel › YS engines : muffler get loose
04-28-2002 12:35 PM  15 years agoPost 1
RemiEpron

rrNovice

France

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Hi,

I noticed that on YS engine, the muffler mounting screws get loose sometimes. It happenned twice on my YS80 and I saw that many times on some others helis equipped with YS engines.

I know the crankcase was used to be tapped in 3.5 mm and is now in 4mm. So there is no mixing-up between diameters.
Mine has 4mm bolt in a 4mm tapped crankcase.

I would like to stick onto YS engines, but I need a real fix to that problem as I don't want to see the muffler falling into the rotordisc during an inverted hovering!

Did someone experienced the same problems ad founded a fix?

Thanks,

Remi

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04-28-2002 01:07 PM  15 years agoPost 2
z11355

rrMaster

New England

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what muffler are you using?

I have one YS61 w/ a Zimmermann 1piece muffler and use
the Swedish 'Nordlock' washers and it hold perfectly.

If you have a 2 piece, that would require something different.

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04-28-2002 03:32 PM  15 years agoPost 3
rickc

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Creve Coeur IL. (Peoria Area)

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I found out that I could use about 3 mm longer bolts. I measured the depth of the tapped crankcase and it was like 12 mm deep. I then measured the thickness of the muffler flange and decided I could use a 4x16 mm bolt. It's been sometime and I 'm not positive of the size I ended up with but I do remember going to the hardware store and buying longer bolts and also used lockwashers. Having longer bolts, it gives more surface area for the bolt to hold on the engine. I have not hade a screw come loose since.

Rick

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04-28-2002 03:48 PM  15 years agoPost 4
Andy17

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Ellijay, GA

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Do you use red locktite? I do and it works good and still comes off when I need it to. I think the instructions tell you to use red now.

Andy

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04-28-2002 04:13 PM  15 years agoPost 5
crash-

rrVeteran

Ca

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I found after you run the engine to temp
land the heli and tighting the bolts
when engine and exhaust sys hot

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04-28-2002 05:32 PM  15 years agoPost 6
Twobeers

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Toronto, Canada

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100% fix.

Use red locktite.
Insure that the mate between the muffler and exhaust port are perfect. Carefully file it flat if necessary with a large sized fine pitched file.
Don't use a gasket.
Coat a very thin film of red locktite on the muffler and the exhaust port of the engine.
Place a small drop, just a pin pricks worth on the tip of the bolts.
Assemble and tighten.
Set the heli aside and don't touch, don't breathe on the heli for 24hrs.
Once you have done this don't ever touch the bolts again, don't turn them with a wrench or allen key to check their tightness, ever. Unless you want to remove the muffler.
Turning or attempting to turn the bolts will break the locktite bond.

If the need arrises that you have to disassemble the muffler. Place something against the bolt heads and give it a sharp but gentle rap with a hard object to break the locktite bond. Remove the bolts. Rap the muffler as close as possible to the joining point with a shearing motion. Presto the muffler will go flying off, so make sure you're ready to catch it.

Using this technique which has been used by plank fliers for decades will ensure that the muffler will never come loose on its own & will never leak at the junction point to the engine.

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04-28-2002 05:48 PM  15 years agoPost 7
RemiEpron

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France

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YS & Muffler

Hi guys,

z11355 : BTW I'm using a Hatori one piece (the fat one)

crash- : I'm a bit afraid of over tightening in a warm-up aluminum

thanks for the tips, I 'm gonna try longer bolts , washers and a clean red loctite application.

Remi

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04-28-2002 07:51 PM  15 years agoPost 8
z11355

rrMaster

New England

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You should really try the Nordlock washers.

They are absolutely foolproof and instantly removable.

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04-29-2002 12:14 AM  15 years agoPost 9
z11355

rrMaster

New England

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I was referring to the Zimm.

Can't do it on the two piece Hatori units as you noted the
recesses preclude it.

I think the one piece Hatori's are similar to the Zimm's, (no recess).

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04-29-2002 09:21 PM  15 years agoPost 10
a_korandr

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Chicago, IL

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i have ys80 and 2-piece hatory, secured with green locktide. no problem at all.

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04-30-2002 02:58 AM  15 years agoPost 11
Dirty

rrApprentice

Des Moines, Iowa, USA

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YS80, Hatori 2 piece muffler, blue loctite, 10 gallons of fuel = never a problem....don't know what you are talking about with the loose muffler issue.

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04-30-2002 02:26 PM  15 years agoPost 12
spincycl

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Marietta, GA

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my solution

I got some 20mm long screws. I put a drop of red locktite, and tighten the screws at room temp. Any more locktitle makes it really hard to remove them.

I think that the extra threads in the engine makes a big difference.

What happened before I did this was, the first screw came out in flight, and it was holding with one of the screws, and finally that screw was fatigued enough and it broke. Fortuantely my ez-out managed to get the screw tip out of the engine.

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04-30-2002 09:01 PM  15 years agoPost 13
steve9534

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yakima, wa.

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Loose bolts

I tried red Loctite and had the bolt break off right at the case when I tried to unscrew it, effectively ruining the case. This was with an older 61, but I would be most anxious about using the red Loctite again, it was really designed for permanent applications that won't be disassembled. Steve.

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05-13-2002 12:57 PM  15 years agoPost 14
jetranger

rrVeteran

PERHAM M.E.

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bolts

If your bolts are comming loose it is because when the engine comes up to tempature the alu. in the motor will expand before the steel bolt does and the bolt vibrates loose. Use good alu. bolts and this does not happen they are very hard to find I got mine a long time ago I think from a mail order catalog Mico Mart ? When I'm out I use blue loctite and a lockwasher. On one muffler where bolts go through muffler and engine used locknuts never came loose.

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05-13-2002 04:23 PM  15 years agoPost 15
Futurac

rrKey Veteran

Belgium , Europe

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Loose Muffler

Remi

it is very recommended to use longer bolts, with Nyloc nuts, (the nut with some plastic inside)
i am putting on top also loctite(blue)
Ys known as a little vibration producer, because of the torque,(moment)
So its normal to see the muffler loosen if you dont secure it.
Put some larger washers from all sides, and a soft gasket, with RTV,
and you can a little overtight the muffler, again, with sence.
It should solve your problem.

as a Zimmermann distributor, i advised that way to people, and they were happy with the combination

Alex (Formerly Known as RCMarket )

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05-13-2002 07:45 PM  15 years agoPost 16
miataguy

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Santa Barbara, CA

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I use Alex's method and haven't a problem since going to the longer bolts with nylocs.

Official RunRyder Googlewhacker!

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05-14-2002 12:59 AM  15 years agoPost 17
Julius

rrNovice

Tracy CA

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loose muffler

A few years ago I saw Wayne Mann install a muffler on his YS without using locktite. The secret is to clean the holes and the bolts thoroughly, no gasket either. After the engine is warm, tighten again but just slightly.

After a couple of years I've had no leaks and no loose mufflers.

julius

ps: this also works well for tightening the compressor fan onto the muffler bearing.

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05-16-2002 03:04 AM  15 years agoPost 18
steve9534

rrKey Veteran

yakima, wa.

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answers

Interesting to read the responses in this thread. Futurac has recommended longer bolts with Nylock nuts. Unfortunately the YS motor doesn't use any nuts to hold the muffler as the screws thread directly into the case, and the motor's crankcase is effectively the "nut". How one could incorporate a Nylock nut is something of a mystery to me, but nevertheless Miataguy reports having tried them and they worked well. Where exactly did you put them? Am I missing something here, or can I presume that you maybe didn't really try your method with this motor? Steve.

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HelicopterEngines Plugs Mufflers Fuel › YS engines : muffler get loose
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