Tire o-ring replacement for leak.

[ldmack3]

Disassembled wheel, cleaned and replaced o-ring using HG silicone. Big leak, 20 lbs lost overnight. When standing on tread with valve stem at the bottom lots of bubbles around the stem, but not coming from the stem where it attaches. Disassembled again, found some questionable areas on o-ring seat. Cleaned and smoothed. Before I go through this again is there any problem using some silicone RTV to help seal the o-ring?

 

[simp5782]

Disassembled wheel, cleaned and replaced o-ring using HG silicone. Big leak, 20 lbs lost overnight. When standing on tread with valve stem at the bottom lots of bubbles around the stem, but not coming from the stem where it attaches. Disassembled again, found some questionable areas on o-ring seat. Cleaned and smoothed. Before I go through this again is there any problem using some silicone RTV to help seal the o-ring?

Yes. Don't use it. Use super 77 adhesive spray.

Why don't you just get new O rings? They aren't but a few dollars.

 

[ldmack3]

This is with a new o-ring. Should have said installed new..

 

[simp5782]

This is with a new o-ring. Should have said installed new..

Use super 77

 

[Floridianson]

Murphy's tire soap on O ring and valve stem rubber is all I use. Never had a problem but I also use two non distorted nuts to pull the ring down even and tight. Then put on all distorted nuts tight and replace the two first nuts with distorted.

 

[frank8003]

Yes. Don't use it. Use super 77 adhesive spray.

Why don't you just get new O rings? They aren't but a few dollars.

I don't find an application specific sheet for wheel o-rings with nomenclature and NSN/part numbers.
Does that exist anywhere inside SS website?

 

[ldmack3]

TM just says to lube the oring. Doesn't say with what. HD silicone was not enough or I have bigger problems.

I'll clean it up again and redo.

 

[simp5782]

TM just says to lube the oring. Doesn't say with what. HD silicone was not enough or I have bigger problems.

I'll clean it up again and redo.

Did the wheel hit anything? Doesn't take much to bend it and throw it off.

 

[simp5782]

It

I don't find an application specific sheet for wheel o-rings with nomenclature and NSN/part numbers.
Does that exist anywhere inside SS website?

Varies on wheel types some are 1/4 some are 3/8 some are silicone some are rubber

 

[ldmack3]

I've never hit anything nor does it look bent. O-Ring is 1/4" actually 3/16". The oring I used was one that came with the truck in the spare parts. I have 4 new ones from Big Mike. They actually measured .010 larger so I'll try one of those this time. The new ones were harder to get to stay on so i suspect the other had stretched.

I'll build it up tonight and check it again tomorrow.

Thanks everyone.

 

[HDN]

What rims are you working on? The regular lock ring rims or A3 bolt-together rims?

 

[simp5782]

What rims are you working on? The regular lock ring rims or A3 bolt-together rims?

Lock rings don't require an o ring they have a tube in them instead.

 

[HDN]

Lock rings don't require an o ring they have a tube in them instead.

Thanks for that. For some reason I thought there was a lock ring design that used an O-ring, but thinking about it now I don't know how it wouldn't leak barring real tight tolerances or a really tight ring

If you're working on a bolt-together rim, make sure the clamp ring nuts are tight enough. M35A3 rims for example need 425-475 ft-lbs for each nut.

 

[Floridianson]

TM just says to lube the oring. Doesn't say with what. HD silicone was not enough or I have bigger problems.

I'll clean it up again and redo.

When dealing with any other O rings I use a non-petroleum base O ring lube. As said tires, O rings and valve stem rubber Murry's tire soap in solid form not turned into a liquid. Also makes it easer when you have to change the tire in the future. Jtm Products Inc F1.0003 $28.26 8Lb Pail Murphys Original Tire Paste #2000 | Zoro.com

 

[Floridianson]

I ordered some O rings and use the Accurite # that was stamped into my wheel. If you are having trouble getting the correct o ring to seal then something is wrong or you are doing it wrong. Bad edge on outer ring or O ring groove on wheel damage or not cleaned out right. O ring lube or tire soap is all that is needed in my .02. O rings (militarytrucks.com)

 

[HDN]

I used Oatey plumbing silicone grease on my o-rings. It's the stuff from Lowes, non-petroleum.

I also wire brushed and painted the sealing surfaces. During assembly I made sure the o-ring was seated correctly on the rim with a hand and a clean paint stick. Then I seated the clamp ring and alternately tightened the clamp ring nuts.

Are you sure it's an o-ring leak and not the turret valve or its grommet? Those can fail too. Why did you disassemble the wheel in the first place?

 

[ldmack3]

Still tight this AM.
Tire has been leaking down since I got it, about 20 psi a week. After the first go-round I found some rough areas on the rim I had missed before. I cleaned them up very good, rechecked the valve stem and re assembled. This morning no air loss. Will give it another day before mounting back on truck.
Repacking bearings and changing wheel cylinder in the meantime.

RH aft tire also ha a leak, but not as bad. My next victim!

Appreciate all the info!

 

[HDN]

I've learned that even with the wheel not leaking while dismounted, it may still leak when mounted due to the truck's weight squishing the tire. Soapy water in a spray bottle quickly became my friend I discovered a few air leaks at brass fittings this way after noticing enough of a tire pressure drop to know it wasn't affected by ambient temperature. I had to jack up a couple wheels after mounting them to deflate, reseal threads, and retighten (or further tighten) elbows and bushings to prevent leaks.

 

[ldmack3]

Mine doesn't have CTIS (A2 with A3 wheels) so I'm hoping I'm good. I always recheck the torque after mounting and adjust the cold pressure.

Where do you usually see the leaks (using soapy water, which I do) if the oring seal is leaking?

 

[HDN]

Where do you usually see the leaks (using soapy water, which I do) if the oring seal is leaking?

I'd think that O-ring leaks would be hard to detect when the tire is mounted because the only place the tire would be leaking from the O-ring would be from the gap between the inside edge of the clamp ring and the rim. You'd need a lot of soapy water for any leak there to make bubbles.

Check and double-check your fittings to your Schrader/tank valve, as I found most of my post-installation leaks at the elbow and the bushings screwed into the elbow. @Floridianson also suggested to make sure the valve core is screwed in tight enough so that air isn't leaking past it. Take care to not overtighten otherwise you'll shear the nubs on the valve core and have to get a new Schrader valve if you ever want to deflate your tire easily again - ask me how I know

I included a picture of one of my wheels with the potential leak zones highlighted. Provided your O-ring sealing surfaces were thoroughly wire-wheeled and painted, I doubt your leak is there unless your clamp ring just isn't tight enough. The torque required for tightening the A3 clamp ring is ridiculous, and twice that required for the M939A1 rims.