Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

One of my neighbours just gave me his lightly used Sears 10/28 snowblower. He is physically unable to use it any more and was having problems with it for the last couple of years. I suspect the main problem was lack of use and old gas. The machine looks practically new and is very clean. Its in better overall shape than my machine. The only two things I've found missing are the knob on the gear shift and the bolt that holds the top of the tube that the oil dip stick goes into. The engine would not start when I got it.

I took the cowling off and low and behold, the end of the tube from the primer bulb was frayed at the carburetor end. I cut off about 1/4" and put it back on. I've bought a new tube and will replace the old one as soon as it stops snowing and the sun comes out.

The engine starts up but now surges. I've put some Sea Foam into the gas and let it run for about 10 minutes. The engine is running better and does perform better under load. It still needs work.

According to what I've read from searches on this forum and on the Tecumseh Technician's Handbook for 3 to 11HP L-Head Engines the next thing is to take apart the carburetor and clean it. I've never done a carburetor disassembly, cleaning, rebuild before so any advice on cleaning agents, things to watch out for, errors in the handbook or any other advice people would care to offer would be appreciated. I will be getting a carburetor kit from the local L&G since I'm positive gaskets and O-rings need to be replaced.

I don't have the engine serial number but will post it once the snow stops ( Thursday morning is the current prediction).

If I still have a problem then it will be time to look at the governor.

If I were you, I wouldn't be jumping in too deep right off.  First thing to do is to ensure you gave a good clean unobstructed fuel supply to the carb.  If that is good,  I would pull the float bowl off, clean out any dirt/water or ice that might be in it.  Gently take the float off and inspect the float needle and float needle seat for debris and varnish.  You can use a paper clip or straight pin to clean the fuel inlet hole in the float needle seat and blow air into the fuel line inlet.  That will ensure you have good fuel supply into the carb.    If there is a screw on the bottom of the float bowl, it can be adjusted to eliminate surging.  Give that a shot and let us know how it goes.

if the carb is adjustable, idle mixture as well as high speed, i would go ahead and throw in a kit.   if the "adjustments" are fixed remove both screws and shoot some carb cleaner in there and blow with compressed air.  remove bowl nut and do same.   1 thing though DO NOT remove inlet seat.   if it not leaking do not mess with that.

mech12 wrote:

What's an "inlet seat"?  Would it be what I think is the float needle seat?

While fiddling to get the engine running I removed the main adjustment screw and drained the bowl. The top of the screw is a needle and is what adjusts the fuel flow into the main nozzle. It had a varnish like deposit on it which I cleaned off by scraping and using a plastic scrubbing pad. I noticed the O-Ring was stiff and cracked. I've fiddled with it a fair amount and while I can improve the sound of the engine while it is running it still surges. According to the book there are some gaskets and O-rings that should be replaced when there are signs of deterioration.

The float controls how much gas comes into the bowl by opening and closing a valve that is formed from an inlet needle and an inlet valve seat. The valve seat is pressed into the passageway that leads to the inlet fitting. The inlet fitting is what the fuel line is attached to.

There is a diagram on page 10 of the manual and a description of the process on page 22.

I will take the bowl apart and clean it out as recommended but I have a hunch I'm going to have replace all the rubber seals ( o-rings and gaskets) The book also has a few other service recommendations. I need to make space on my bench.

the rebuild kit is around 20 bucks,it is pretty simple,the little clip for the needle goes a certain way,the book tells you,and the little o ring with a groove on it,that also goes in a certain way,when you take off the needle and clip,there is a little o ring in there,when you get that out and cleaned the carb real good,put the new o ring in so the groove is going in so you can not see it.then re assemble,set your float 11/64ths,set the screws,1 turn out on the side,1 and a half turns out for the bottom.good luck.

Thanks for the info, any recommendations for carburetor cleaner?

nibbler wrote:

There is no substitution for physically removing the dirt.  I'm rebuilding/modifying two Mikuni VM28 carbs for my 1976 Yamaha RD400.  I soaked both carbs in low odor varsol for two days then began to disassemble and clean.  The grime on the exterior came off good but the contaminants on the inside were considerably more stubborn.  When I drifted out the needle jets, I was surprised with how much contamination there was on them.  Fortunately, I'm replacing  the needle jets, the air jets and pilot jets as part of the modification.  The best way to really clean the carb is to tear it down as much as you can, clean orifices and passages with a thin flexible wire, blow WD40 through as many orifices and passages as possible then finish off with compressed air. 

gumout works really well,but any carb cleaner is fine,like borat said,get a thin wire to get at the holes and blow air.hope this helps

OK sounds like I just need to dig out some thin copper wire and the big magnifying glass. Should be fun. Hopefully at the end of it I'll here the screaming roar of a big snow machine ( apologies to Snoopy vs the Red Baron).

Thanks

I just finished cleaning and rebuilding my two Mikunis.  Lots of little parts to clean and replace (in this case).  One picture shows the shiny new replacement parts and the not so clean original parts.  The other shot is of the 32 year old carbs all cleaned up, re-assembled and pretty much ready to go..