O-rings

[William Fissell]

Hi,

does anyone know the correct size and O-ring material for the fuel tank shutoff and or carb mixture valves on hundred series tractors? Hate to replace a whole part just for an o ring.

thanks in dvance

Bilkl

 

[Hemmjo]

I do, but the valve is not close, I will get back to you!!

 

[Btzj02]

I recently started using Viton O rings. According to the literature I found Viton is good for gasoline service both static and dynamic sealing. I did not write down the size of the O rings but I did match the Diameter of the old O rings.
If it means anything, Google says Viton O rings are made of: hexafluoropropylene (HFP) and vinylidene fluoride (VF₂).

 

[Hobo,NC]

-009 for the stem and valve to tank -115. A 70 are 90 will do the job.

 

[Hobo,NC]

-009 for the stem and valve to tank -115. A 70 are 90 will do the job.

For the record A 1000 series uses a -110 .

 

[Hemmjo]

I have not found mine yet. But, I highly suggest you use "HNBR" or "HSN" orings (two names, same material). Nitrile and Vitron, both swell in contact with gasoline

The fuel valve under the tank on these tractors is a very harsh environment. ESPECIALLY if you run out of fuel while working. I believe this is the reason for most failures. Fuel flowing through the valve helps to keep it cool. When the tanks runs dry, the residual heat in the engine bakes the valves, forces the gasoline out of the orings, they shrink and harden. Then they leak.

I got mine here https://www.theoringstore.com/store/index.php?main_page=index&cPath=367_123

They do have a minimum order so that jacks the price up a bit. I bought extras to meet the minimum order. I have no problem sending you a pair... IF I can find them. I did notice that Harbor Freight has an assortment of HSN. I cannot verify their quality, but they have some.

From their site;

HNBR O-Rings (HSN) Hydrogenated Nitrile Green/Black​

Hydrogenated Nitrile O-Rings manufacturing process results in the superior heat, ozone, chemical resistance and mechanical characteristics of HNBR over standard Nitrile. Standard HNBRs typically have 36% ACN content which iimproves fuels and polar lubricants resistance. HNBR O-Rings are available in 70 durometer, 80 durometer, and 90 durometer.

HNBR O-Rings are preferable for use with petroleum-based oils and fuels, aliphatic hydrocarbons, vegetable oils, silicone oils and greases, ethylene glycol, water and steam (up to 300ºF), and diluted acids, bases, and salt solutions.

HNBR o-rings are not preferable for use with chlorinated hydrocarbons, ketones, ethers, esters, and strong acids.

 

[Hobo,NC]

I use buna-n so far so good. Most all across the board other than ac orings buna-n have served me well. Im' not again better

 

[Hemmjo]

Found my drawing of the fuel shutoff stems in my 860. I have 3 valves, the original, one I got from another supplier and the one I got from that supplier to replace the one that leaked after 6 months. When the second replacement valve leaked, I began my investigation. The two new valves I got have different stem designs. The original is like the "older" one shown in the drawing below, bt the nose is rounded, rather than stepped like the older replacement valve stem.

I highly recommend anyone having trouble with a leaky valve to do some research in regard to o'ring materials. This is one of the best sources for information regarding materials.

O-Ring Compound Selections : The O-Ring Store LLC, We make getting O-Rings easy!

The O-Ring Store LLC : O-Ring Compound Selections - O-Ring Cord Stock | Buna-N, Viton, EPDM, Silicone OSK™ O-Ring Service Kits OSK™ O-Ring Repair Kits OSK™ Hydraulic Cylinder Seal Kits OSK™ Air Nailer O-Ring Kits OSK™ Sanitary & Brewery Gaskets O-Ring Lubricants | FN Lube & FN Lube Plus Olypsys®...

www.theoringstore.com

There are 3 important factors in selecting o'rings. Chemical resistance, Operating temperature, and abrasion resistance IF the o'ring is in a dynamic (moving) application. In a static application abrasion resistance is not so much a factor..

As mentioned before, I have found HNBR/ HSN to be the best for this application.

Buna-N Nitrile (NBR) will work but they are less resistant to abrasion and the upper temperature range is lower which can be problem give the location of the valve above the engine and in relatively close proximity to the muffler.

Vitron has a higher upper temperature limit 482F, but the lower limit -8F is often reached here in Ohio. It s not as abrasion resistant as the HSN,

Still have not found my stash of extra o'rings, but still looking.

 

[Hobo,NC]

Nice post we need more of this instead of the normal Pick one up from the dealer. I'm not arguing your point other than what are you increasing the life span from. My take from 50 to an upgrade of 100 years. I know what I most comely use if I need to make a order I may step my selection up. The price of o-rings are not gonna break me.

 

[Check Break]

I have not found mine yet. But, I highly suggest you use "HNBR" or "HSN" orings (two names, same material). Nitrile and Vitron, both swell in contact with gasoline

The fuel valve under the tank on these tractors is a very harsh environment. ESPECIALLY if you run out of fuel while working. I believe this is the reason for most failures. Fuel flowing through the valve helps to keep it cool. When the tanks runs dry, the residual heat in the engine bakes the valves, forces the gasoline out of the orings, they shrink and harden. Then they leak.

To each their own but compared to Viton, HNBR is not the best choice for this application. It has a cheaper up front cost and will definitely handle the new fuels, but Viton is the superior material. Ultimately, the oring that eliminates leaks for the longest period of time is the cheapest solution in terms of less labor, lost fuel, ruined engine oil and engine damage.

 

[Btzj02]

Found my drawing of the fuel shutoff stems in my 860. I have 3 valves, the original, one I got from another supplier and the one I got from that supplier to replace the one that leaked after 6 months. When the second replacement valve leaked, I began my investigation. The two new valves I got have different stem designs. The original is like the "older" one shown in the drawing below, bt the nose is rounded, rather than stepped like the older replacement valve stem.

I highly recommend anyone having trouble with a leaky valve to do some research in regard to o'ring materials. This is one of the best sources for information regarding materials.

O-Ring Compound Selections : The O-Ring Store LLC, We make getting O-Rings easy!

The O-Ring Store LLC : O-Ring Compound Selections - O-Ring Cord Stock | Buna-N, Viton, EPDM, Silicone OSK™ O-Ring Service Kits OSK™ O-Ring Repair Kits OSK™ Hydraulic Cylinder Seal Kits OSK™ Air Nailer O-Ring Kits OSK™ Sanitary & Brewery Gaskets O-Ring Lubricants | FN Lube & FN Lube Plus Olypsys®...

www.theoringstore.com

There are 3 important factors in selecting o'rings. Chemical resistance, Operating temperature, and abrasion resistance IF the o'ring is in a dynamic (moving) application. In a static application abrasion resistance is not so much a factor..

As mentioned before, I have found HNBR/ HSN to be the best for this application.

Buna-N Nitrile (NBR) will work but they are less resistant to abrasion and the upper temperature range is lower which can be problem give the location of the valve above the engine and in relatively close proximity to the muffler.

Vitron has a higher upper temperature limit 482F, but the lower limit -8F is often reached here in Ohio. It s not as abrasion resistant as the HSN,

Still have not found my stash of extra o'rings, but still looking.



View attachment 88525

Yesterday my neighbor came over with a fuel shut off valve, we have both been experimenting with rebuilding these valves, and in his hand he had the newer design valve you posted above. He was frustrated because it would not leak through the stem but it would not shut off the gas to the carburetor either. Interestingly the O ring that was there was green but there was not an o ring on the end to shut off the fuel to the carburetor. I went to my box of O rings and slipped a little one on the end and told him that that should do it. He was impressed that I knew that an O ring was missing. I did give you credit for posting the picture otherwise I would havemhad no idea. Interesting to note he had two brand new valves from TSC and one was the newer design above and the other was the older design with a metal seat to shut off the gas to the carburetor. Packaging was identical, nothing indicating what you were getting. Thanks again for posting the above.