Tecumseh 3.5 hp carburetor leaking help

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  #1  
Old 12-09-05, 01:48 PM
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Tecumseh 3.5 hp carburetor leaking help

Hello, I just finished rebuilding my carburetor on my 10+ year old 2-stage Ariens snow blower equipped with HS-35 Tecumseh engine using part no. 22-10103 (replaces Tecumseh 631029). Before the rebuild, my engine would only run for about a minute before shutting down. Now the engine is running fine in idle and fast modes and the snow blower is working good under load. MY PROBLEM IS: the bottom ajustment needle valve screw under carburetor bowl is leaking gas at a rate of 2 drops per minute from the screw threads. I installed new float needle valve and seat, new slow and fast needle value ajustment screws, also new o-rings and backup washers on ajustments screws, new upper bowl rubber gasket, new fiber gasket on lower bowl retainer. No float setting ajustments were made during rebuild. Holding the carb up side down and viewing the float position, the float is closer to carb body on the unhinged side by about 1/8 of a inch. The bowl is installed with the deep side across from the bowl hinge pin. Can anyone offer some help? Thanks, swissbob
 

Last edited by swissbob; 12-10-05 at 06:36 AM.
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  #2  
Old 12-09-05, 09:02 PM
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leaking from the bowl nut/adjustment screw? its possible one of the gaskets got damaged, its good and tight ain't it? the carb doesn't flood out does it? anyway, float should be parallel to the carb body
 
  #3  
Old 12-10-05, 06:01 AM
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Thanks for the tip on the float ajustment. The gas is leaking from around the needle valve ajustment screw. The large bowl attachment nut is not leaking, I will check the o-ring seal for damage when I ajust the float setting. swissbob
 
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Old 12-10-05, 06:22 AM
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Originally Posted by v8driver
leaking from the bowl nut/adjustment screw? its possible one of the gaskets got damaged, its good and tight ain't it? the carb doesn't flood out does it? anyway, float should be parallel to the carb body
The fuel is leaking around the threads of the adjustment screw. I will check the o-ring seal when I correct the float setting to parallel. thanks for the advice.
 
  #5  
Old 12-12-05, 07:05 PM
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swissbob
Looking at the float setting guide in the manual, Tecumseh now recommends using an 11/64 bit for setting the float height. The float should just touch the bit when the carb is turned upside down and the bit will be directly opposite and parallel to the float hinge. Bend the tab on the float if it is either too high or too low.

snoman
 
  #6  
Old 12-13-05, 03:04 AM
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It appears you have installed an aftermarket carb kit and it could be that this is to blame - tolerances, specs, etc. - may not be on the money. Particularly the o-ring as sno mentioned that is on the adjusting needle.
 
  #7  
Old 12-13-05, 12:25 PM
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Originally Posted by puey61
It appears you have installed an aftermarket carb kit and it could be that this is to blame - tolerances, specs, etc. - may not be on the money. Particularly the o-ring as sno mentioned that is on the adjusting needle.
I ordered the carb kit over the internet, and the kit was made in brasil. I check the parts and they looked real good. The oring supplied for the lower bowl ajustment screw turn out to be to large and didn't make contact with the treads. I replaced it with the old seal to see the effects on the leakage problem. NOW THE LEAK IS LESS about 1 drop in 2 minutes vs. 2 drops per min. I will have to get a new oring for that lower ajustment screw of the correct size.
Do you know if this item is available by itself??
I am planning on making a couple of calls to some repair parts dealers in my area to see if they sell this item by itself. Thanks for the help, swissbob
 
  #8  
Old 12-13-05, 12:33 PM
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Originally Posted by snoman
swissbob
Looking at the float setting guide in the manual, Tecumseh now recommends using an 11/64 bit for setting the float height. The float should just touch the bit when the carb is turned upside down and the bit will be directly opposite and parallel to the float hinge. Bend the tab on the float if it is either too high or too low.

snoman
Thanks for your comment on the float setting specs. I did reajust the float setting so the float was parelell to the carb body on sunday. The engine runs good except for the fuel leak. The new float setting didn't seem to change anything, the fuel leak is much less since I reinstalled to old oring on the lower ajustment screw. swissbob
 
  #9  
Old 12-13-05, 01:04 PM
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Smile

Originally Posted by swissbob
I ordered the carb kit over the internet, and the kit was made in brasil. I check the parts and they looked real good. The oring supplied for the lower bowl ajustment screw turn out to be to large and didn't make contact with the treads. I replaced it with the old seal to see the effects on the leakage problem. NOW THE LEAK IS LESS about 1 drop in 2 minutes vs. 2 drops per min. I will have to get a new oring for that lower ajustment screw of the correct size.
Do you know if this item is available by itself??
I am planning on making a couple of calls to some repair parts dealers in my area to see if they sell this item by itself. Thanks for the help, swissbob
HELLO AGAIN TO ALL : I JUST GOT A PART NO. 630740 O-RING SEAL and plan to purchase it yet today. I will let you all know the results of my leak problem soon. Thanks again, swissbob
 
  #10  
Old 12-13-05, 03:19 PM
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Originally Posted by swissbob
HELLO AGAIN TO ALL : I JUST GOT A PART NO. 630740 O-RING SEAL and plan to purchase it yet today. I will let you all know the results of my leak problem soon. Thanks again, swissbob

I picked up 2 new o-rings from the locate parts dealer and installed one. This o-ring fits tight on the ajustment screw threads, BUT it still leaks 1 drop per minute. The fast run(bottom of carb bowl) ajustment screw does not have a machined surface for o-ring to seal on. The slow speed ajustment screw has a machined surface(located on the upper body of the carb)for the o-ring to seal on! Both the old and new fast run ajustment screws have all threads. and the parts guy told me that the seal should work on the threads.
MY NEXT STEP:: is to check the machined surface with a magnifing glass on the lower bowl retaining bushing for sealing surface defects.
Thanks to all again, swissbob
 
  #11  
Old 12-13-05, 09:17 PM
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Does the spring between the head of the screw and the backup washer have tension on it pushing the backup washer against the bowl nut?
 
  #12  
Old 12-14-05, 05:56 AM
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Originally Posted by cheese
Does the spring between the head of the screw and the backup washer have tension on it pushing the backup washer against the bowl nut?
Yes there is tension, the screw is only out about 1 turn. Thats a good tip and I will compair the old and new springs for lenght and compression force when I check the bowl retaining nut for defects on the sealing surface area.
Thanks, swissbob
 
  #13  
Old 01-01-06, 12:42 PM
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Leak Problem Is Solved!!!

Originally Posted by cheese
Does the spring between the head of the screw and the backup washer have tension on it pushing the backup washer against the bowl nut?
LEAK PROBLEM IS SOLVED: I removed the replacement bowl nut and did a comparision to the old one.
The sealing surface for the bowl fiber washer looked marginal at best. The threads were machined all the way to the hex nut sealing surface(OLD BOWL NUT HAS A STEP FLANGE FOR CENTERING FIBER WASHER AND A LARGER FLANGE AREA FOR FIBER WASHER TO SEAL ON+NO THREADS).
I noticed that the new o-ring that I installed on the bowl nut needle valve (between spring on thethreaded needle valve and bowl nut) had swelled up a bit and was not fitting tightly around the needle valve threads. I installed a 2nd new o-ring on ajustment screw assembly(screw, spring, and brass backup washer) and reassemble to the carbrator. The leak is gone and the engine still runs fine using the old bowl nut.
Thanks to all on your help and suggestions and Happy New Year 2006!!
 
  #14  
Old 01-05-06, 01:08 AM
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Glad you got it! Thanks for keeping us updated. Happy New Year!
 
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