DIN Retainer stuck...and i mean really stuck !

[Shugrnutz]

Having been a certified welder for half my life, you need heat. Use a small torch and heat it until the metal starts to discolour, quickly quench it with cold water, and it should spin right out.

 

[halocline]

Don't use a hammer, and don't use a torch. This is not auto mechanics.....

The torque spec for this retainer is around 22 ftlbs, meaning not very tight. Unless the tech who worked on it is a real idiot (and there's plenty out there) there's no loctite involved. Probably it's just dried salt water that has crudded things up. That's because, as awap pointed out, the o-ring is on the end of the retainer deep in the reg body, leaving the threads unprotected. With every dive, water gets in those threads. This is exactly why it's important to soak, not just dunk, regulators in fresh water after diving. There are unprotected threads somewhere on most of them.

 

[kwinter]

Heat in the oven is the answer if someone used Loctite on it, as I suspect might be the case. Otherwise if you think it is just salt deposits, you might try some Salt-X. But a lot of fresh soaking and repeated hot/cold water changes should otherwise do it eventually.

 

[ams511]

If you have access to a pressure cooker, I wonder how that would work? I don't think there's anything in there that would get ruined by boiling water.

A pressure cooker requires liquid to work, so nothing will get ruined by boiling water.

 

[tbone1004]

Don't use a hammer, and don't use a torch. This is not auto mechanics.....

The torque spec for this retainer is around 22 ftlbs, meaning not very tight. Unless the tech who worked on it is a real idiot (and there's plenty out there) there's no loctite involved. Probably it's just dried salt water that has crudded things up. That's because, as awap pointed out, the o-ring is on the end of the retainer deep in the reg body, leaving the threads unprotected. With every dive, water gets in those threads. This is exactly why it's important to soak, not just dunk, regulators in fresh water after diving. There are unprotected threads somewhere on most of them.

why no hammer? It is better for the reg than putting an allen key on there and pulling as hard as you can. Actually it's much better for the reg.... I agree on no heat other than the oven though. The oven at 300F isn't going to hurt anything that's in there, but it's important to cool it before you try to move anything.

 

[luscioman]

Could you please post a picture of it. I have some ideas but want to see what it looks like.

 

[redacted]

While I'm sure the expansion from heat and contraction from subsequent cooling will help, using hot and cold at the same time to expand the area of the seized threads should be faster and more effective. The heated body and the cooled retainer will produce a void in the threads and solvent (water) will be pulled into that void. High turning force may cause damage so keep the turning forces just a bit over the range of the recommended torque. While a light tap on the wrench may help, I would not overdo it. Holding the reg body in your hand a tap the wrench should be enough. I do like the idea of tapping in both a tightening and loosening direction to break up the deposits that are holding it. You might even try a light blow ont the end of the retainer, perhaps against a piece of wood to avoid damaging the retainer. That would work counter to the direction of the torque and not involve any stress on the hex fitting.

I can't imagine the idiot that would use loctite on that connection, but if heat/cold and soaking does not do the trick in a couple weeks; that may be why.

I'm not sure what a picture could possibly reveal since the threads are internal. It will just look like a Mk20/25 din 1st stage. How about this:

 

[Jim Lapenta]

I have had this issue on some DIN retainers and metal enviro caps where people cranked them down too tight or never bothered to clean the threads after a saltwater dive outing. What has worked everytime so far is submerging the offending part, not the whole reg, in my ultrasonic with 50/50 vinegar and water with the heat on and left it there for a few hours. I cannot guarantee it won't discolor the metal but on the ones I've done so far it has not. Then while it's still warm taking the proper tools (1st stage handle and proper wrench), secure it on a pad, and apply EVEN steady pressure. Except for one that the owner left so long that it was welded and required cutting the cap to get it off, it has worked. That one required replacing the top end of the reg. I keep that on hand for reg repair and equipment care courses to show what neglect can result in.

 

[RobinC.]

I can not take off the plastic saddle and the knob so i will not stick it in the oven for the moment even if i thought about it.
I do not think than brass will love to be heaten by a proper torch either so i'll keep this solution for last resort too.

Why would someone use loctite on threads ?????

Anyway i will continue the Hot / Cold treatment as awap adviced me for a while, lets say two weeks. I'll keep you posted on this. And then if nothing moved i will start to think about more hardcore treatment.

Thank you dark siders for all your insights on this issue !

Here are some pictures if you think it can help.

 

[NotSure]

If the DIN bolt was over tightened and then slightly corroded you may end up having to destroy your DIN bolt to remove it. You just can't apply enough torque to beak it loose with an allen wrench. I would give it a couple of weeks trying the methods AWAP suggested, but after that I think a vise and a pair of vise grips may be your only choice. If you do end up with a damaged DIN bolt it is not necessary to buy a whole new kit, the MK20 DIN update comes with just the universal DIN bolt and I'm sure someone would list one on that large auction site for you if needed.