Help please with Scubapro MK25 service

[Dive_Gypsy]

I am doing a service of my DIN MK25 A700. I am trying to loosen the filter retainer with a 6mm hex wrench per the manual. The 6mm hex wrench is just loose enough when placed into the retainer that it does not engage. Another copy of the manual says to use a 5/32 hex wrench. Visual examination of the interior of the filter retainer shows it as rounded. Any ideas or suggestions?

 

[halocline]

Should be 4 mm for the filter retainer, not 6 mm. 6 is for the larger DIN retainer fitting found when you remove the filter retainer. 5/32" and 4mm are just about the same size, also used for port plugs. If you already know this and are saying that the small hex fitting for the filter retainer is stripped, try a good long soak in mild acid (ultrasonic cleaner would be best) to remove the verdigris, and get a 4.5 mm or 3/16 hex wrench, maybe file it a bit, try to jam it in and remove the filter retainer, then you'll need a new one.

 

[Dive_Gypsy]

Thanks. I did realize that the 4mm hex wrench is for the stub and 6mm to remove the DIN fitting. At this point, I will have to hold off until I can get access to a new filter retainer.

 

[axxel57]

Unfortunately it is quite common that the filter retaining screw is over-torqued.

Ultrasonic cleaning usually doesn't help too much, because the threads of the retainer are pretty fine and the acidic liquid does not enter them.

I use liquid silicone around the screw and use a small hammer (carefully) to hit on the retainer. Wait and repeat.
By the vibration you loose a bit the threads and give space to let the silicone (which I think has less liquid tension than the acid) to enter the threads . It raises the chances that you can loosen the screw with an Alan key a bit bigger than the 4mm key, as Halo mentioned.

If you can loosen it and change the filter, you might be able to reuse it, because the recommended torque is only 4 Newton-meter, which is surprisingly little torque for this retainer.

 

[JohnN]

If you can loosen it and change the filter, you might be able to reuse it, because the recommended torque is only 4 Newton-meter, which is surprisingly little torque for this retainer.

Yousa,

For those of us that still think in furlongs per fortnight, my handy converter says ~35 inch-pounds. That is just finger-tight