What kind of carb on 620

Also, remember that the gasket goes inside the fuel bowl, and not outside between the bowl and nut (although I normally put one in both places).

A. FUEL SHUT OFF PROBLEMS ALLOWING GAS TO CONTINUE TO THE CARB

They have a flat o ring/washer on the bottom of the little center vertical shut off plunger that is up (when no oil pressure) and oil presuure (tractor running) pushes down a rubber diaphragm lowering it to allow gas to enter and fill the glass sediment bowl. If the bowl is clean and clear you can look in its top center and see it lower when tractor is startred but raise and close off when no oil pressure there when the tractor is off. If you loosen the top center knurled nut you can manually push it down to see if it works.

If you remove the glass bowl with the tractor not running, if the pluinger is up and no gas is dripping out, shes doing her job. If gas still runs out there, the o ring/washer may need replaced or crud removed around where it seals. That o ring/washer and all the shut off sediment bowl diaphragms can be purchased from John Deere. Just remoive the glass bowl and you can see if its sealing off gas or not as its supposed to.

Also, with the carbs lower bowl drain cock/plug removed and tractor not running, gas should drain out until the bowl empties, but then no more should run out if the shut off is working. If its leaky, gas will continue to drip out there however.

B. CARB FLOAT/NEEDLE/SEAT PROBLEMS ALLOWING GAS TO OVER FILL THE BOWL AND LEAK OUT

You may also have a problem in the carbs needle valve and seat assembly. Even if the shut off above did not work, when the carbs bowl fills gas to the proper float level, the needle should raise into the seat and seal so no more gas can enter the carb and raise its level. If gas raises above the float level and leaks over the top and/or renters the manifold and engine, the needle and seat may be bad or have dirt in it or be gummed and varnished up or the float could be bad. If the needle and seat and float all worked, gas shouldnt over fill the bowl and leak out the top regardless. The needle and seat might possiblt just need cleaned out or it may need replaced. Also, if the float leaked, it cant raise to shut the needle/seat off and gas would again over fill the bowl and leak out. However, if she starts n runs okay over long periods, I suspect the float may be okay BUTTTTT T if settign she over fills the bowl and leaks out there are 2 problems:

1) The shut off sediment bowl isnt working, its allowong gas to still flow even if tractor is off.

PLUS

2) The carbs needle valve and seat isnt working, maybe dirty or sticking or gummed or varnished up and/or the float may be bad.

You can but the carb gaskets from Roberts Carb repair or John Deere and Deere also has the shut off assembly parts including that o ring/washer you mentioned. Its also possible if the rubber diaphragms are leaking, gas could leak out and get into the oil plus it not work right. If you get the JD repair kit, be sure you replace all in the same orientation it came apart, and make sure the new plunger o ring/washer seal is clean and works okay.

I hope this helps and hopefully others can provide additional opinions concernign your possible problems. Post back ir e mail [email protected] any questions.

Good Luck n God Bless

John T PS was yours the gas carb that Duane and I mentioned????? or was it an all fuel???

~If you send me your E-Mail address I can send you a carb breakdown showing all the gaskets & Deere part numbers.. That way you can call the dealer & ask if they stock the parts you need.

~On your auto shut-off leaking,, that's possible.. Pull the fuel line loose at the carb & put a pan under that line.. If it�s leaking it won't take long to verify that. Your fuel leak out of the carb could just be the "O" ring around the load needle & that will leak for a long time on just the fuel that's in the carb bowl & strainer assembly [common problem]..

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~There is another possibility & that is at one time someone installed a universal replacement carb I believe that's a DLTX 109 or 109U..

~In any case most of the gaskets & other standard replacement parts are the same for all the carbs.

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Serial Number 6200001 and up GAS used a Marvel-Schebler DLTX-94 Carb.

Serial Number 6200001 and up ALL FUEL used a Marvel-Schebler DLTX-97 Carb.

So is yours a gas or an all fuel tractor??? Most were gas only. The All Fuels would have had one small gasoline tank used for starting and another main large tank for Distillate or Drip Fuel similar to todays Kerosene. Plus, the All Fuels would have had a valve used to switch tanks to supply gas (starting) or fuel (running after warmed up) to the carb. If yours dont have any of that stuff, then its a gas tractor and uses the carb shown above from what I looked up. Ive never seen a 620 All Fuel??? my guess is that would be rare. By the time they (620's)were made, gas was the prefered fuel, you could run higher compression that way and they wouldnt spark knock pre ignite on it like they would have on the lower octane distillate fuels used in prior years.

That what you were looking for??

Good Luck n God Bless

John T