Vintage Double Hose

Hi,

Recently went diving with a new MK7 honker, breaths fine, however, there was no 'honk' even when breath till 40psi. I was wondering if I bought a service kit from Bryan and service it myself, will that solve this problem? or do it require a separate kit altogether? Thanks!

Jonathan

A cleaning and lube might help. Make sure the two o-rings on the oscillator are in good shape. Finally, you may be breathing so lightly that the oscillator is not doing its think, so try a bit more demand once supply pressure gets down to about 400 psi. Once the tank pressure falls below IP the oscillator should stop working and the primary should stop delivering enough gas to breath comfortably. With your pressure having dropped to 40 psi, I suspect you need to replace a a few o-rings or you might even have a problem with the supply pressure stem not withdrawing. In any case, inspect, clean and lube as a first step.

....and make sure you have the second stage hose installed into the correct port-unlike a twit I know who thought he had the same problem.

awap and couv, nice to see you guy here.

Thanks Herman.

@ the OP. Did you resolve the issue with your Honker? If so, what was the problem.

Cheers,

Couv

I'd also like to know if the audible reserve 'honker' has been resolved and the 'fix'. I have two MK7's one purchased when I started diving in 1973 and another one purchased in 1981. The 1973 was warranty repaired at the factory in 1982 with a minor first-stage leak. Both MK7's are still working great.

TheHonker O ring White around the edge is not to be lubricated per Scubapro.I own a few and have rebuilt per my classes from scubapro.
Jl

Hi Mk7 Experts,

This is another potential 'honker' issue but I'll post it here as it may be related to the problem with the OP. I serviced my MK7 with kit and tools obtained here. I submerged the first stage and there were no bubbles-so far so good. The low-pressure honk seems to have changed a bit. My testing was performed out of the water.

At 3000 psi there is now a subtle high-pitched note like the one made by a modern atomic when breathing from the 2nd stage while out of the water. With the tank valve off, breathing forcefully the honk is observed briefly at the beginning of the last breath. This seems different than before but may still be within the scope of normal operation. Also, with the tank valve off, when purging the second stage the usual 'honk' is not always audible. Interestingly, this seems to be related to the 'tightness' of the 2nd stage poppet spring.

I was just wondering if I am making any rookie mistakes.

Thanks,

Ken

Here is what it says in the Scubapro Service schematic:

Flow through piston designs will under some conditions make a whistling noise during flow. To alleviate , replace Item #15 HP seat, and heavily
lubricate Item #25, 01-050-137 o-ring.

Remember, this is Scubapro saying to lubricate o-ring #25. I was rebuilding one last month and took this statement to heart. I replaced the seat as well. After I reassembled the unit, it purred like a kitten and started honking at about 400 psi. Lube that o-ring!

Bronze06 wrote:Here is what it says in the Scubapro Service schematic:

Flow through piston designs will under some conditions make a whistling noise during flow. To alleviate , replace Item #15 HP seat, and heavily
lubricate Item #25, 01-050-137 o-ring.

Remember, this is Scubapro saying to lubricate o-ring #25. I was rebuilding one last month and took this statement to heart. I replaced the seat as well. After I reassembled the unit, it purred like a kitten and started honking at about 400 psi. Lube that o-ring!

Hi Russ,

Just to be clear, item 25 is the piston stem o-ring. Yes, it should be heavily lubricated. The HP seat (item 15) was originally a flat seat and due to air flow and harmonics sometimes caused an odd humming in the first stage. This is not part of the aural warning system used to indicate low air pressure.

The black/white o-ring mentioned in the post above is item 7 and fits in the oscillator groove.

BTW: the note you quote in your post also applies to other flow through piston regulators such as the MK5 and MK10.

Cheers,

Couv

Flat hp seats must be few and far between these days.

Hey Couv,

God, we all seem to really love the "Honker". I guess it appeals to our sense of primitive brute force engineering. That and they are cosmetically unique, big, clunky and fun to rebuild.
I understand what you meant about the audio system, but sometimes you will hear a high pitch on not only this reg but others due to a HP seat not opening up or sealing up quite fast enough, thus causing a shrill tone that can be heard as you breath. Sometimes called "piston squeak". This is independent of the audio oscillator on the Mark 7 and the noise can be carried through the LP line to the 2nd stage and is audible in the water as well. It can be confused with the audio system at times.
With regards to HP seats, what I have done on occasion if in need of a seat is to just flip the old HP seat over and use the un-marred other side and on most occasions it does just great. You just have to take a good look at the seat and ensure that it is not damaged. Of course you must do your regular service checks in all other areas but in a pinch this works.
As per lube, I not only lube this seal, as Couv says on the MKs 5,7 and 10 but also on my MK 2s of which I have 4 ( 1967-1999) and you will definitely get a better breathing 1st stage. Granted, the o-ring is held in place differently in the MK 2 but the principle is the same.

Thanks

A video showing what the "Honker" does at 400 psi or below.
https://youtu.be/z3gNLTk3nto

Well done. ..Honk. ...........Honk

Thanks for the video. It has been decades since I have heard the honker.