Replacing tire valve stem - size?

[DrT]

So my old MF188 has a tire valve stem problem - it's leaking! I think I have found a way to replace the stem without breaking the tire bead and losing the ballast by using the Colby XL valve stems (https://colby-valve.myshopify.com/products/xl-emergency-valve). I have already ordered two via Amazon but I was wondering if anyone knows the diameter of the valve stem hole in an old MF wheel?
I've had the tractor for coming on 20 years now and I wouldn't be surprised if the valve stems are the factory originals!
Thanks for reading and taking the time to answer if you do.

 

[Jim.ME]

So my old MF188 has a tire valve stem problem - it's leaking! I think I have found a way to replace the stem without breaking the tire bead and losing the ballast by using the Colby XL valve stems (https://colby-valve.myshopify.com/products/xl-emergency-valve). I have already ordered two via Amazon but I was wondering if anyone knows the diameter of the valve stem hole in an old MF wheel?
I've had the tractor for coming on 20 years now and I wouldn't be surprised if the valve stems are the factory originals!
Thanks for reading and taking the time to answer if you do.

Are you sure it has tubeless tires? I believe your 188 has tube type tires. If so, the fix is a tube replacement. How about a picture of the stem currently in the rim? There may be a simple fix you can try, but I need to see what you have. What is your general location in this wide world?

 

[DrT]

Hey there, thanks for replying! I'm down in New Zealand on the lower South Island too far away from a tractor tyre service place to drive it there to get sorted and can't afford to call in a mobile tractor tyre service. Besides, I usually find a way to get done what I need done.
Anyway, the tyres are definitely tubeless, or at least I reckon they must be because I've plugged more than one puncture with a tubeless tyre repair kit. They wheels may not be factory stock as they have the ability to be made wider or narrower and even have duals attached.
Here are some photos anyway of the side that's not leaking. The valve stem is missing the countersunk thumbscrew which pulls the stem into the rim because I lost the one on the leaky side and had to use the one from the good side to effect a temporary repair. You can see the stems can take a liquid ballast fitting which the Colby stems do not have so I'll have to add ballast through the smaller stem hole.

 

[Jim.ME]

Those look like the common power adjust rims.

If that is a tubeless stem held in by a thumb screw, I admit it is not like any I have seen. How about a picture of the one with the thumbscrew on it?

What I see in your picture looks like the stem that would be on an inner tube here. The rubber around the metal stem protrudes out of the rim. The stem is held from dropping back into the rim when deflated by a round nut, usually plastic these days. Our tubeless stems have metal washers and hex nuts on the outside to compress the rubber seal in the rim hole. The common TR218A and TR618A type stems here fit a 5/8" hole, which is what the rear rims of my tractors (MF, JD, AC) all have. You should be able to get a very close measurement with a caliper from what I see in your picture. Here are pictures of our common tube and tubeless stems.



I have seen plugs seal a leak in tires with tubes in them, if the tire beads had sealed to the rims and the tube and stem had bonded to the rim.

Good luck.

 

[DrT]

I think you are right, the valve assembly looks like the tube patch one on the left! And I guess I just got lucky with the tyre plugs I've put in that tyre like you mentioned!
I may cancel that Amazon order and take some time to re-think this. In the meantime I have slowed the leak enough to use the tractor by using a bit of an old rubber chainsaw vibration damper cut to fit, slathered with rubber cement and tightened down onto the rim with the rim nut from the other side, gotta make do with whatever shade tree engineering I can come up with!
Thanks for your help in clarifying the mysteries of tractor tyres and tubes, I've got lots of experience with car, motorcycle and bicycle tyres but this is my first major dealing with tractor tyres, old ones at that!

 

[Jim.ME]

I think you are right, the valve assembly looks like the tube patch one on the left! And I guess I just got lucky with the tyre plugs I've put in that tyre like you mentioned!
I may cancel that Amazon order and take some time to re-think this. In the meantime I have slowed the leak enough to use the tractor by using a bit of an old rubber chainsaw vibration damper cut to fit, slathered with rubber cement and tightened down onto the rim with the rim nut from the other side, gotta make do with whatever shade tree engineering I can come up with!
Thanks for your help in clarifying the mysteries of tractor tyres and tubes, I've got lots of experience with car, motorcycle and bicycle tyres but this is my first major dealing with tractor tyres, old ones at that!

If your tires have a calcium chloride solution in them the longer you delay a proper fix, the more the rim will be damaged by corrosion.

I think you will find this picture of the stem of a tube removed from a MF255 is similar to what you have.

 

[DrT]

Bingo! You're on to it! That particular rim has had so many leaks there's a bit of corrosion on it already, possibly worse on the inside. It leaked nearly all of whatever solution was in it a few years ago and I re-filled it with left over radiator coolant mixture from when I rebuilt the engine from fan to throw-out bearing, figuring it wouldn't harm the rubber and provide some corrosion resistance to the metal and it's what I had. The guys at the local tractor place suggested methylated spirits (denatured alcohol) as a tyre ballast anti-freeze as that's what they use.
I wasn't able to cancel the Amazon order for the Colby valves so I'll flog them off I guess.
I'll have to figure out if I can get the wheel off and haul it somewhere for a new tube someday. But that could take years if my field repair holds, I've got field repairs still holding up after a decade waiting for enough roundtoits in the bank to fix properly.

 

[Ray,IN]

The go-to liquid ballast is Calcium Chloride solution that rusts metal. Once the rim is coated inside with calcuim chloride it will continue rusting until the rim fails or is removed and washed thoroughly.
That happened to my 1972 MF 135 rear rims. Went to get on the tractor one day and the bead of one rim was split off for about a foot. Bought new rims, tires and tubes, and had them filled with Beet Juice.
It that tire is tubed, a new valve stem can be installed, they screw-in, which is how they can be filled with liquid ballast.
This is the ballast gun my local tractor tire service truck uses: https://www.haltec.com/pc/Valve-Adapter-Gun-p808.htm

 

[keljan11]

When the rim on my 265 finally gave up, I removed the tire and took it to a tire shop to remove the rubber from the rim. Located another rusted out rim that a welder cut out and welded in (tire shop wouldn't replace the tube and fill it if weld repair wasn't done by a certified welder). Long story short, it's back on my tractor, refilled with calcium chloride. Attached you will see what eventually happens if it is ignored and not repaired