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trouts2
09-20-2010, 06:47 AM
On small hp Tecusmeh carbs (3-12hp) there is a tube parallel at the side of the main jet tube that has a steel ball at the end. Some carb have one tube some have two.

Sometimes a ball shows at the end of the tube. Sometimes there is something down in there further.

The balls seem to be fixed in there. I've never seen one that would move.

What is/are the tube(s) for? What is taking place in there and for what reason?

dutch1
09-20-2010, 08:49 AM
To the best of my knowledge,the carb that has a tapered idle adjustment screw will have a ball in the idle air bleed tube. If cannot hear the ball move when you turn the carb upside down it will likely be locked up by varnish or corrosion. You will find it quite difficult to free up if corrosion is the problem. Soaking in a carb cleaner can free it up but that often is not successful. If you find that the engine will not idle, either on the lean or rich side or idles erratically, or hesitates, a stuck ball in the tube is likely the problem. In the barrel of the carb, you will find a port that is opposite the lead ball plug in the tube, that must be clear. You can use a welding tip cleaner with a short 90 degree bend to clear that port.

Typically, carbs that have the square shouldered(with a point) idle needle will not have a ball in the tube.

If a carb has a second tube, I believe that to be the main nozzle air bleed and to be honest I haven't seen many of them.

Other techs may have additional opinions and are free to contradict what I have offered.

trouts2
09-20-2010, 09:16 AM
Dutch1:
The carbs I work on are mostly from winter engine Tecumseh engines so I don’t have much experience with other versions of Tecumseh carbs.

I have read a number of places that mention the ball rattle. I’ve cleaned many carbs but never heard a ball rattle with these carbs which puzzles me.

To the best of my knowledge,the carb that has a tapered idle adjustment screw will have a ball in the idle air bleed tube.

I’ll have to check for this. They generally end in a long taper or are stepped.

Typically, carbs that have the square shouldered(with a point) idle needle will not have a ball in the tube.

If a carb has a second tube, I believe that to be the main nozzle air bleed and to be honest I haven't seen many of them.

The ones with second tubes seemed to be on newer carbs so probably a design enhancement. Looking onto those holes there were plugs down in further.

Intersting post. I'll now check on each carb for the idle screw type and ball plug type.

Restrorob
09-20-2010, 09:36 AM
Here's a small How too on this style carb.....

As Dutch mentioned it depends on the series carb if it has the check ball or not and he's right on with it near impossible to free a stuck ball.

After going into these carbs multiple times trying to get them to run properly I no longer bother, For the parts and labor cost to go into one a new carb can be purchased and the job done.....

http://outdoorpowerinfo.com/repairs/tecumseh_carb_640017.asp

trouts2
09-20-2010, 10:02 AM
Restrorob
Great link. I've always wondered what was going on with that pedistal. thanks.

I’m not arguing here just trying to figure out what is going on.

When the ball is a plug it should probably not move. I’ve never had one where the ball was on the end and moved.

The carbs I see are mostly of this type where the ball is fixed and won’t move. They have all been rebuildable and work.

For posts that have mentioned the rattle I’ve never seen a description of what was rattling other than a ball but no description of what the function was. Are the ball rattle types rattling for this ball or some other internal ball. If anyone knows why the ball moves please let me know.

It seems then there could be designs with a fixed ball and hole in the tube it sits in and designs where there is no ball and I assume no hole for gas draw into the tube. Maybe they just make one type of carb body and use it for many variations as it’s cheaper.

StihlMechanic
09-20-2010, 02:08 PM
Here's a small How too on this style carb.....

As Dutch mentioned it depends on the series carb if it has the check ball or not and he's right on with it near impossible to free a stuck ball.

After going into these carbs multiple times trying to get them to run properly I no longer bother, For the parts and labor cost to go into one a new carb can be purchased and the job done.....

http://outdoorpowerinfo.com/repairs/tecumseh_carb_640017.asp

agreed, those carbs are junk.

Restrorob
09-20-2010, 04:51 PM
Are the ball rattle types rattling for this ball or some other internal ball.


There's another smaller ball inside that orifice under the stationary ball plug.

dutch1
09-20-2010, 06:52 PM
I have an old Tecumseh carb trouble shooting guide which contains a cross section which does show the air bleed tubes but I don't remember seeing any reference to the ball in either tube. What I am fairly sure of is that the ball in the idle bleed tube sits above the taper of idle needle as I experienced problems turning in the idle needle when the carb was in the upright position--it had tobe turned upside down to do so. I'm thinking that the passage that the ball sits in is also tapered and as you turn the idle needle in, the taper of the needle raises the ball permitting more air to pass by the ball into the idle circuit, thereby leaning out the mixture.

I have no idea how the ball in the short pedestal functions without a true cross section that would show the orientation.

I do know that when faced with a Tecumseh carb that had this problem, our shop didn't make any excess profit with the price of a carb rebuild being $48 plus parts but that is close to 10 years ago now. Toward the end of my days in the shop we were doing what Rob suggested, install a new one and move on.

I'm not a fan of any of the Tecumseh carbs but the Vector carb with the machined aluminum body and plastic bowl, was absolute junk.

BigFish
09-20-2010, 08:10 PM
Here's a Tecumseh carb manual :
Ok, maybe not!!

Got it saved as a pdf, cant get it into here.

Anybody know how?

Restrorob
09-20-2010, 08:41 PM
Anybody know how?


You can't upload PDF files from your computer to a message board.

Go to your user control panel then click on "edit options", Scroll down and click on the box next to "enable private messaging" then a couple boxes down click "Show New Private Message Notification Pop-up". I then can send you a message explaining a way to get it on here.


Dutch, That's twice now we've posted at the same time..... Either your getting faster or I'm getting slower !!! LOL

dutch1
09-20-2010, 08:41 PM
Here's a link to the dual pedestal(bleed off tubes) Tecumseh Series 11. This likely the one you are describing.

http://outdoorpowerinfo.com/repairs/tecumseh_series_11.asp

Restrorob
09-20-2010, 09:35 PM
Originally Posted by BigFish


Anybody know how?

You can't upload PDF files from your computer to a message board.

Go to your user control panel then click on "edit options", Scroll down and click on the box next to "enable private messaging" then a couple boxes down click "Show New Private Message Notification Pop-up". I then can send you a message explaining a way to get it on here.

BigFish
09-23-2010, 11:59 AM
You can't upload PDF files from your computer to a message board.

Go to your user control panel then click on "edit options", Scroll down and click on the box next to "enable private messaging" then a couple boxes down click "Show New Private Message Notification Pop-up". I then can send you a message explaining a way to get it on here.

Did it, gimme a shout.
Thanks