Mk 25 honking/ howling noise from 1st stage help

[Couv]

Most likely the piston shaft or piston head o-rings are damaged. The shaft o-ring can easily get damaged if a piston bullet is not used when the piston is installed.

 

[Stayingfrosty]

Yes I did submerge it the air was coming out of the ambient chamber holes as suspected. I checked the ip and it was right at 125psi and locked up tight. However I was starting to do the tear down and I noticed that the chamber body was very loose. So loose in fact that I was able to get almost 4 full turns on it. I thought this might have contributed to the issue but it did not fix it. So I repacked the the two O-rings in the pack and it did not fix the issue. I am starting to lean toward the high pressure oring as the possible culprit.

 

[Stayingfrosty]

Also @couv, thanks the diagram helped.

 

[Couv]

the chamber body was very loose.

I was able to get almost 4 full turns on it.

‽‽‽

Here is the manual and an annotated file.

 

[michael-fisch]

Scubapro piston regs have had a tendency to honk at least since I bought my first Mk10 back in 1988.
If it honks - it's a Scubapro.
But, the damn things always work, which is usually more important than the stealth qualities of the reg.
Fortunately, the 9 Mk20s that I have don't honk.

Michael

 

[rhwestfall]

My MK-17 never honked....

 

[lexvil]

My MK-17 never honked....

Yep neither have any MK 25’s I’ve had, MK 10 and 15 were better honkers than the MK 7 which was designed to honk.

 

[Stayingfrosty]

@couv you hit the nail on the head it was indeed the piston shaft oring. A big thanks to you and everyone else for all of the pointers and help.

 

[rhwestfall]

@couv - where did you get that colored image?

 

[Couv]

@couv - where did you get that colored image?

I don't remember. I've had it a while.