I'm bleeding my brakes and find a leak in one of the rear calipers right at the adjuster screw on the outer piston. I pull the caliper off and take it apart and find that there is no o-ring, gasket or other means of sealing the adjuster screw. It's simply a metal to metal fit and I can't imagine that that's enough to seal.

I've got a rebuild kit and there isn't a seal included for that adjuster screw. There is one for the other piston. So what am I missing here? Is there supposed to be an o-ring or something else to seal that screw? Thanks.

Tom

Nope, no o-ring. Just get it tight and not cross threaded.

Great! So the reason it was leaking is because it wasn't tightened down? DOH!

Most likely.

I guess that's better than a rebuild. Thanks a bunch!

Tom

Tom, forgive my retardation.

I reread your post and see where you are talking about. This is not the screw I was thinking you were talking about. Please take a picture of the area and post it. There should not be anything leaking there.

Maybe Eric will chime in.

Oh darn, here I thought it was solved. I'll take a shot and post it here tomorrow.

OK, here's some pics of the adjuster screw in question.

Click to view attachment
There's a boss machined into the caliper body where the flange of the screw goes (2nd picture), but there is not a recess for an o-ring. You could put an o-ring in there but it would simply smash down and be destroyed as soon as you tightened the screw down. I don't see any other sealing method. It's not like the o-ring setup on the inner side of the caliper.
Click to view attachment

I'm going to cut a gasket to fit the boss and put it all back together again with a very tight locking screw. I'll check back tonight and let you know how it goes and listen to all the suggestions as to how I REALLY should have done it. Thanks guys.

Tom

When I replaced the rear pads/rotors a while back I encountered the same leak but found the leak only happened when I was backing the adjuster out. When I would start to turn it in to set the venting clearance the leak would stop. It concerned me a bit so I kept my eye on it over the next couple of days and drives but it has never leaked again. Oddly enough this only happened on the right rear. The left one didn't have this leak.

Derpy-Derr.



Double Derpy-Derr!!



It will... soon.

There's an o-ring on that shaft. I can see it from that bad picture (Is that a "Big Red?)

This happens often and when it does, it means you have a hardened, crusty seal. Your seal is old and compressed. It has hardened and will probably come out in pieces. It probably looks almost like part of the shaft at this point. It resides where you see this shiney seal in this picture:

Click to view attachment

You need to use a dental pick and get that old, bad seal off that shaft. Then, if you have one, it's best to use a 8x1.25 die to chase the threads, Your 13mm nut likes to get hung up on the clip galley:



Once that's done, you need to walk a new seal down the shaft and into the seal galley. Kinda like a "Holla-Hoop" falling to your ankles (or a prom dress). Keep the dental pick in there and walk it down:



Then pop it back in the bore:



No more weaping from you or your caliper.

If you're "really" a cheapskate (or a cheapsnake), you can try to spray a little PB Blaster on it "WHILE IT IS IN THE CALIPER BODY". If you look at the side of the PB Blaster can you'll see they bill it as a "Seal Reconditioner". It's actually just a petroleum based "Seal Sweller" (which is why you want that seal installed before or very shortly after you spray the PB Blaster on it). Your seal will loosen and swell and should stop leaking (for now). By the time it leaks again, it will be the other owners problem. Then we can start a DAPO thread.

On the bright side... it's only your brakes we're talking about. Might as well experiment with them a bit.

I learned the hard way. Mine was leaking, bought some rebuild kit off evil bay, before I knew about pmb. They didn't come with the orings, and leaked right away. Needless to say when I did my fronts,Eric got the order !

I just had to know Eric would chime in here and ruin my day. Anyway, I went ahead and cut me a gasket and it seems to have worked, no leak. Despite this small victory, the worst thing about this is the fact that I completely missed the o-ring on the shaft. DOH!

So now I can be the DAPO for a change.

Tom

Huh?

Happy to help!

Hey, I said I was retarded.

These cell phones just don't have the writing big enough.