3MSHY carburetor throttle plate stuck

[mrlnavykorea]

The 3MSHY carburetor throttle plate is stuck. I have disassembled the carburetor down to its basic parts and I can get access to all the parts for cleaning or replacement except the throttle plate in the carburetor main body.Superficial inspection shows the rod to which the throttle plate is attached to be bright and it doesn't appear to be corroded or worn. Tried WD-40 and carburetor cleaner but no luck. Anybody know any other method of freeing the brass rod to which the throttle plate is attached ?

[99yam40]

heated ultrasonic bath/cleaner may do the trick

[TownsendsFJR1300]

I had the EXACT same thing many years ago on a generator carb (10HP Briggs and Stratton).

I mean it was like welded solid. WD40, for your issue is useless.

Get either PB Blaster or Liquid Wrench PENETRATING oil (PB is preferred).

Set the carb on it side (each side but of course only one side at a time).

Soak the area where the shaft goes thru the carb body both internally and on the outside and let it soak overnight. Flip it over and repat to the other side and let soak.

GENTLY lean on the throttle "arm", perhaps a little heat with a hair drier but it should break loose before that. DO NOT FORCE IT or count on buying a new carb, it WILL come loose..

I was impatient, and did the above all inside maybe 3 hours. It was a bitch but did loosen up and works as new. Its my current back up generator for the house.

Please post back how it goes..

[mrlnavykorea]

Trying it now

Doing exactly what you suggested with liquid wrench. One side has been left all night. Doing the other side now. There is a huge temptation to force it

[TownsendsFJR1300]

Oh yea, there's temptation but let the lube do its job. Some LIGHT PRESSURE is ok, but give it time to work.

Tomorrow, start trying to work it and adding a little heat (hair drier should be plenty) aimed at the aluminum body and spray as well while doing so.

If you can, secure the carb CAREFULLY in a vise so you have a nice steady platform once you do start trying to work it. You don't want to be working against your other hand and loosing any torque working it..

It'll break loose, just be patient another day.

[mrlnavykorea]

Thanks to all for the suggestions.Have tried Liquid wrench and the got a can of PB blaster (boy does that stuff stink). Twice soaked it well and left. I think I can occasionally detect a very small movement. I used a drift pin punch with a very light jeweler's hammer to tap on either end of the rod that carries the plate. One end is peened over to secure the rod, and the other has what looks like a tiny snap ring. I have thought about removing the ring and attempting to drive the rod, but If the ring gets damaged i'm not sure there is a replacement part. The suggestion of securing the body in a vise is helpful. I do think I really haven't really exerted torque-I've only been holding the body in my hand. I will be careful. this is really frustrating. If I can get this loose I'm on the way to replacing the worn parts and repairing the carburetor. Hair dryer next with the vise.

[TownsendsFJR1300]

If you got a slight amount of movement, that's great. Spray some more and secure it in a vise.

Slight tapping as you did is also god to loosen things up...

Besides "leaning" on the outside throttle plate(where the linkages attach), you may be able to sneak you finger (or something blunt) on the butterfly itself to help spread some of the load. Of course, DON'T bugger up that plate, its pretty fragile...

Soak, secure, add some heat and start working it. Fingers crossed..

[rodbolt17]

the hair dryer or heat lamp is a good thing.
with that you cannot damage it.
set the heat on it and let it rip.
the AL carb body will expand much greater than the SS shaft.
be patient.
DO NOT force it.

[TownsendsFJR1300]

Any updates?

Does it run??

[mrlnavykorea]

Tried heat from a hair dryer. got the body quite hot. Besides the previous days PB blaster I added some more while the body was warm. Tapped the rod ends some more. No movement. Body was in a vise where I will keep it while working on it. Made a a small set of custom wooden vise jaw covers so as not to mar the body. Bad news is the small movement I experienced is a tiny bit of slack between the throttle arm and the rod through the body. There has got to be some secret to this thing. When I inspect the throttle plate , as with the rest of the body, doesn't look corroded or anything. The plate itself and as far as I can see the pivot rod looks clean, the plate itself is clean. Some of this wrench and blaster liquid certainly should penetrate. The choke plate at the other side of the body looks clear and functions just fine. I wonder is there anything I can soak it in for a couple of days? There has to be some way to free this throttle rod!!

[TownsendsFJR1300]

I know Yamaha makes some carb cleaner (expensive but I've never used it) that you soak the carb in.

I don't know if that would work.

At this point, I would probably remove all the rubber parts(needle seat if rubber), float,etc and take a heat gun to the body.

The heat gun is probably 20x hotter on max and I would think would do it. I wouldn't go full temp hot, but enough where you cannot touch the carb. Spray as you did with LW or PB Blaster.

You won't melt the aluminum or brass shaft but anything else will likely get cooked/ distorted.

Your on the right track, its just froze really bad....

**I just got a HF cheapo heat gun for about $25 and that will flat burn paint off a surface.

[99yam40]

thinking a heated ultrasonic cleaner might do some good.
all that vibrating may loosen things up

[mrlnavykorea]

A little research says that a 50/50 mixture of acetone and transmission fluid may make a good penetrating soak to loosen a stuck shaft. Lots of suggestions about using heat guns and heat of some kind. Just for the record all the other parts of the body have been removed. Someone even suggested putting it in a plastic bag and freezing to get a temperature differential. At this point I will try anything. Lots of suggestions about heating things and banging with a hammer-not feasible here!

[TownsendsFJR1300]

Never heard of that mix but I guess it can't hurt.

What year is the engine so I can look up the carb parts diagram?


This 3 HP doesn't even show the shaft and butterfly...:
http://www.boats.net/parts/search/Ya...AKE/parts.html

[mrlnavykorea]

3MSHY-year is 2000 Look under the "intake" section and there is a clear expanded diagram of the carburetor.