Jump to content

Nominations for Tractor of the Month
Garden Tractors and Parts on eBay



Photo
- - - - -

Sears Sst16


  • Please log in to reply
12 replies to this topic

#1 Jazz OFFLINE  

Jazz
  • Senior Member
  • Member No: 62028
  • 1,438 Thanks
  • 949 posts
  • Location: Thunder Bay Ontario

Posted September 30, 2014 - 02:32 PM

 
My '73 sears tractor I recently purchased runs however I have to keep the choke out about halfway to keep engine running. Adjusting the fuel flow did not help.  Any suggestions as to what to look for. I likely have to remove carb. I did put some Seafoam in gas tank although it does look clean in tank.  Since getting the tractor home I changed oil in crankcase as well as transmission and repaired the hood. The fibreglass was broken at the hinge so that has been taken care of.  Then engine is a ONAN,

thanks

 

Attached Thumbnails

  • IMG_1158.JPG

Edited by Jazz, September 30, 2014 - 02:33 PM.


#2 Auburn David OFFLINE  

Auburn David
  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 61865
  • 2,754 Thanks
  • 1,962 posts
  • Location: Alabama

Posted September 30, 2014 - 02:42 PM

you either have trash in the carb..or a leaking base gasket I would think..


  • MountainMichael said thank you

#3 Jazz OFFLINE  

Jazz
  • Senior Member
  • Member No: 62028
  • 1,438 Thanks
  • 949 posts
  • Location: Thunder Bay Ontario

Posted September 30, 2014 - 04:06 PM

 

I have also sprayed carb cleaner down throat ,,,lots and it still won't clear. I know the base gasket was changed but I guess it could be damaged or loose. Removing the carb will be the next step. The engine starts right up but now is missin' 'n fartin and there looks to be a significant amount of fuel be sprayed in carb for such a small engine,,,that is just a observation as I can only compare it to a truck carb. 

 

Edited by Jazz, September 30, 2014 - 04:07 PM.


#4 motobreeder OFFLINE  

motobreeder

    Member

  • Senior Member
  • Contributor
  • Member No: 3989
  • 425 Thanks
  • 611 posts
  • Location: Eastern Ontario

Posted September 30, 2014 - 10:56 PM

I've heard the intake tube has a seam on the bottom that can open and allow air in.


  • Alc said thank you

#5 TAHOE ONLINE  

TAHOE
  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 24522
  • 6,482 Thanks
  • 4,943 posts
  • Location: "Hamiltucky" Ohio

Posted October 01, 2014 - 09:04 AM

Sounss like the typical it sat with bad gas and has a port clogged up. You can remove just the top of the carb while it's on intake and run a very small piece of copper wire through the little tubes/ orifices in the carb body and top and spray down them with carb cleaner. That might be enough to clear out any debris.

The intake runner are two halves, they do have a history of separating. I've seen guys just glob on some RTV along seam while others have drilled out where the bosses are on the sides, separate, clean, the light bead of RTV and bolt back together.

 

While it's running you can spray some brake cleaner down intake seams and base of carb, if the rpm changes, that will indicate an air leak in that area which could cause you half choke syndrome.


  • MH81 said thank you

#6 Jazz OFFLINE  

Jazz
  • Senior Member
  • Member No: 62028
  • 1,438 Thanks
  • 949 posts
  • Location: Thunder Bay Ontario

Posted October 10, 2014 - 07:22 PM

 

Finally went to remove carb and found  one of the carb screws loose. Tightened that up and engine smoothed out for a bit then #1 son noticed the screw for fuel mixture was unscrewing itself while engine was running, as well fuel was leaking from the fuel mixture screw,,not a lot but noticeable,,,,so the threads are worn in carb.  I can't really see trying to repair threads unless anyone else has a solution. 

 

Edited by Jazz, October 10, 2014 - 07:24 PM.

  • Auburn David said thank you

#7 Auburn David OFFLINE  

Auburn David
  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 61865
  • 2,754 Thanks
  • 1,962 posts
  • Location: Alabama

Posted October 10, 2014 - 07:36 PM

 

 

Finally went to remove carb and found  one of the carb screws loose. Tightened that up and engine smoothed out for a bit then #1 son noticed the screw for fuel mixture was unscrewing itself while engine was running, as well fuel was leaking from the fuel mixture screw,,not a lot but noticeable,,,,so the threads are worn in carb.  I can't really see trying to repair threads unless anyone else has a solution. 

 

 

Lock tight or blue glue work well for that..



#8 Auburn David OFFLINE  

Auburn David
  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 61865
  • 2,754 Thanks
  • 1,962 posts
  • Location: Alabama

Posted October 10, 2014 - 07:38 PM

l fuel was leaking from the fuel mixture screw should never happen.



#9 MH81 ONLINE  

MH81

    Proud to be Deplorable

  • Staff Admin
  • Staff
  • -GTt Supporter-
  • Contributor
  • Member No: 802
  • 27,280 Thanks
  • 28,615 posts
  • Location: N. W. PA

Posted October 10, 2014 - 07:41 PM

Finally went to remove carb and found  one of the carb screws loose. Tightened that up and engine smoothed out for a bit then #1 son noticed the screw for fuel mixture was unscrewing itself while engine was running, as well fuel was leaking from the fuel mixture screw,,not a lot but noticeable,,,,so the threads are worn in carb.  I can't really see trying to repair threads unless anyone else has a solution.


Which screw was moving and which was leaking?
A lot of mixture screws are supposed to have a spring to keep them from turning.

#10 MNGB ONLINE  

MNGB
  • Senior Member
  • Member No: 62466
  • 1,001 Thanks
  • 829 posts
  • Location: Minnesota

Posted October 10, 2014 - 07:41 PM

Hi the main fuel mixture screw has an "O" ring in the head of the screw that maybe be missing or damaged if you can find an "O" ring to fit I would bet the leak wil stop and the screw will stay in place.

GB in MN


  • MH81 said thank you

#11 MH81 ONLINE  

MH81

    Proud to be Deplorable

  • Staff Admin
  • Staff
  • -GTt Supporter-
  • Contributor
  • Member No: 802
  • 27,280 Thanks
  • 28,615 posts
  • Location: N. W. PA

Posted October 10, 2014 - 07:56 PM

Hi the main fuel mixture screw has an "O" ring in the head of the screw that maybe be missing or damaged if you can find an "O" ring to fit I would bet the leak wil stop and the screw will stay in place.
GB in MN


Good catch, I forgot this was an Onan. :thumbs:
If the gas was leaking out, I wonder if its possible that the float is sinking or at least not floating like it should.

#12 Jazz OFFLINE  

Jazz
  • Senior Member
  • Member No: 62028
  • 1,438 Thanks
  • 949 posts
  • Location: Thunder Bay Ontario

Posted October 10, 2014 - 08:41 PM

 

Hi the main fuel mixture screw has an "O" ring in the head of the screw that maybe be missing or damaged if you can find an "O" ring to fit I would bet the leak wil stop and the screw will stay in place.

GB in MN

 

I think that is the culprit...i will check tomorrow as shortly after posting I saw a picture of one  of these mixture screws with the o-ring on it. So the o-ring also keeps the screw snug? 

Edited by Jazz, October 10, 2014 - 08:43 PM.


#13 Jazz OFFLINE  

Jazz
  • Senior Member
  • Member No: 62028
  • 1,438 Thanks
  • 949 posts
  • Location: Thunder Bay Ontario

Posted October 11, 2014 - 03:56 PM

 

I removed needle and the o-ring was petrified.  The o-ring must be a oddball size as the ones that fit snug on needle would not go into carb,,I don't want to pound it in and pushing was not successful. I found new needle with o-ring on ebay so for $12.00 i will get  new one instead of driving around looking for o-ring @ $1.35 a litre for gasoline up here. Thanks all for your help

 

Edited by Jazz, October 11, 2014 - 03:57 PM.

  • MH81 said thank you




Top