Have any of you guys ever encountered a set up on a meritor axle where the s cam seals have the lips facing each other and you have to install a grease pressure relief valve to service the s cam grease? I have one no matter what i do you cannot grease the s cam without blowing out the seals. Even if you put the seals in normally with the lips pointing to the slack adjuster it just blows the seal. I have a publication that comes with the meritor s cam bushing kit and it says to use a service kit to service the s cam grease which basically comes with a zerk, a pressure relief valve and a sticker to tell future techs its something different. There is two spots in th s cam tube that is threaded. One has the grease zerk and the other has a plug. I really need to find where i can get the relief valve. You can find them online under a manufacturer name alemite. They come in several different pressure ranges and have no idea which one to order. Meritor is zero help. They gave me a meritor part number for the valve but that number does not come up in any parts systems.
I converted one 3 axle lowboy to that setup. A) hand grease gun only. II) remove vent when greasing. 3) alternately put fitting in each hole (other empty) when greasing. In hindsight, the cams don't last any longer.
Oh, and McMaster Carr has them. 1 psi is sufficient.
I think the idea was for longer service intervals. The two fatal flaws i see in the idea is that anything it gets servicedno one knows its a special procedure and just pump er up and blow the seals. Second flaw is with the seal lip next to the slack adjuster pointed in it allows water to get in when pressure washing but you now have no wat to purge it out via greasing. My suspicion on that is confirmed by the heavily rusted and pitted journals on the s cam! I wonder what psi range meritor is putting in thier service kit?
On those-I shim the area behind slack adjuster so there is very little play inboard/outboard on the S-cam. I use the hose reel gun and grease them. Haven't blown any seals out but grease goes past. Also I don't try to grease till it's pushed out a blob either.
No matter what I try I cannot get grease to go past the seal without blowing the seal out on the outside s cam lobe! I put a pressure gauge on the second threaded hole in the tube and i can go up to 100psi before it pushes the seal out. Think im going to order the pressure relief valves that have a 45-80 psi pressure range.
Well here's another side to that-stop at 80. The cavity is filled the air pushed out and after x amount of miles the grease will work past the seal. Once the S-cam bushing gets slightly worn grease will go past, those bushing don't stay tight very long. But do what you think is best.