Outdoor Power Equipment and Small Engines - Removing Carb Throttle Bushings

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View Full Version : Removing Carb Throttle Bushings


cando
12-03-04, 07:00 PM
I am overhauling the carb (392587) from a 10Hp B&S engine. The bushings on each end of the throttle shaft are obviously worn and should be replaced. I have the throttle shaft removed. Is there a special tool or technique for removing the bushings? They bottom out in the holes from each side so I see no way to drive them out with normal punches. Any help would be appreciated. Thanks


TheKneebiter
12-03-04, 07:36 PM
i would use a dental pick to pry it out. if you do not have one then go to your local auto parts store and purchase a set. they are great for things like you are talking about.

cando
12-03-04, 07:41 PM
These bushings appear to be pressed in and I don't see how a dental pick will be strong enough to remove them. Have you used these tools to do this job?
Thanks.


cheese
12-04-04, 12:20 AM
A dental pick won't do it on a carb. I'm not sure if a bushing kit is still available for those. One thing that works...find an O-ring that fits the shaft snugly but not so tight that it won't turn freely on the shaft, then find a drill bit the size of the outside diameter of the O-ring and drill into the carb bushing just far enough for the O-ring to fit flush with the outside of the carb body. Install the shaft with the O-ring in place of the bushing. It works well.

cando
12-04-04, 07:23 PM
I have already ordered the bushings. If I can't get the old ones out I may try your suggestion. It seems that the o-ring(s) would tend to walk out of the holes as the throttle shaft moves. Not so?? I guess a person could stack small washers outside the o-ring and against the throttle shaft end fittings to hold the o-rings. I am considering drilling (or grinding) a small hole through the pot metal inside the throttle throat where the old bushing is now seated. That material is less than 1/16 of an inch thick there. If I could get access to even one point on the inside / end circumference of the bushing it seems I should be able to get the bushing started out with a punch inserted through the opposite side bushing. Does that sound feasable? This would disturb the normal throat geometry but if the point was below the throttle shaft it doesn't seem like it would foul the mixture flow much. Another thought I had was to start an "Easy Out" into the old bushing and maybe draw it out that way. I'm just not sure how hard the bushing material is and whether I risk cracking the surounding pot metal housing when the Easy Out trys to expand it. I really thought the pros must have some tried and true way to remove the bushings. Maybe someone else will have the solution before the new bushings arrive. Thanks for both of your responses.

cheese
12-05-04, 01:37 AM
Use a 1/4-20 tap to thread the bushing. You may be able to pull the bushing out with the tap (hold the tap with a vise and pull on the carb). If not, use a screw with a nut and oversized washers as a puller to pull the bushing out. I wasn't sure if those bushings were still available. Good to know they still are. It's been a long time since I had to worry about bushings in a carb. An easy out also works.

cando
12-05-04, 12:12 PM
Cheese,
Pretty funny because I woke up this morning with the same solution in my head. My plan was to tap the bushing, install a screw (about 1/8 inch) and then I can either drive or press the bushing out with a punch through the opposite side bushing. I'm not going to exercise the process untill the parts are "In Hand" just in case they don't show. I'm glad I thought about this problem for a few days while waiting for parts or I may have really messed things up. Thanks for your input too, it validates my delayed realization of the smart way to do it. Getting inputs on this site just kind of fertilizes the thought process some times too. :)

jughead
12-05-04, 12:23 PM
Yea, I used to replace oilite bushings on the old mechanical printers back in the early 70's. I had service contracts and would replace bearings one a regular basis as part of a service routine. There was a little tool I used that was real simple. The basic thing was to draw the bearing into a pocket using a quarter twenty screw and a small wrench. Using a pile of washers would effectively be the same thing. It would be quick - easy - and cheap, and you wouldn't have to pick just two.

cando
12-05-04, 12:45 PM
Jughead,
It sounds like you are describing a way to "Install" the new bushings which is needed also. It sounds like essentially creating a "mini press" which uses the screw w/washers to pull the bushing into place. I can use that process when I install the new bushings. Thanks.

jughead
12-05-04, 07:49 PM
Yep, it was just a minpress. Mine would work for installing or removing the bearing. It was all in how you applied the tool to the bearing. The most basic of all tools, a circular incline in the form of a screw turning rotary motion into linear motion.