[bikeman1]

I had recently serviced my Rockshox Monarch RT3 shock - just inspection/clean/oil/grease. However, after installing I noticed it was stuck down halfway. Figured some air got in the negative chamber so removed the air from the valve and then went to remove the aircan. There was a super loud pop when removing this - I hope this hasn't damaged the shock...

I reassembled and pumped up to 200psi in increments. The shock holds air but fully compresses and bottoms out regardless of pressure. The lockout actually works and restricts movement but when it's open it fully compresses.

I disassembled the shock again and found that one of the seals under the aircan had a very small chip in it - would this be enough to cause the above issue?

 

[nice one]

Hi, did you find out what was causing the issue?

 

[eshew]

I had a similar issue happen to me.

Put on new air can, added some air can oil, a few drops below the seals, a few more on top. I also greased the air shaft seals with Slickoleum.

Apparently the grease blocked the equalization dimple & caused the stuck down issue I ran into.... OR I added to much air can fluid.

What I think happened is although merely 5-10 drops of oil was used, it caused a hydrolock condition that forced the oil passed the seals permanently deforming the white seals on the piston.

Less oil & grease & new seals solved the issue, but it seams these RS shocks are a little more fragile than their fox counterparts in terms of seals.

And a bad seal can certainly cause a stuck down situation.

 

[nice one]

Thanks, do you mean the white glide rings, had a similar issue myself, also used slickoleum instead of the recommended grease and was being a bit cheap not replacing the seals, so wanted to make sure this was the issue before I replaced them and did a 'proper' air can service.

 

[eshew]

Yes the white glide rings were the ones that looked smashed when I inspected the shock.

Not sure what the cause was, perhaps to much oil between the upper & lower seals caused it to hydrolock and blew out the lower seals. That's about the only think I would guess, I was running the shock pretty hard just after the new air can & it was leaking oil pretty badly passed the dust seals.

 

[nice one]

I will take a closer look at mine, that's good to know, cant harm to put some new seals and o rings in and see if it helps.

 

[eshew]

Yeah That will probably get you going again. Just go a little light on the oil.

Was thinking about it & too much air can oil might fill the equalization port and eventually transport that oil to the negative chamber & fill it with oil & blow the seals.

Just a guess, but if it can transport air, I'm sure it can do the same with oil.

 

[eshew]

Ha! I can confirm that too much oil was my issue.... Rather than 5ml of oil it should be .5ml above & .5ml below the main piston.


Just for reference thats only about 5 drops of oil above and 5 drops below the main piston. Not much at all.

Which means these air cans should probably be serviced quite often as there is not a lot of lube.

Apparently 5X more is not 5x better.

 

[bikeman1]

I ended up taking mine into the shop.

It needed new seals, fresh oil and grease. Now works like new. I'd recommend buying new seals as they seem to stretch and fail after removing them once or twice.