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Wetsuit
Diver
Posts: 18
Joined: Mon Jul 10, 2017 9:42 am
First Name: Dave
Location: Hamilton, Ont

Mistral O’ring removal

Sat Feb 15, 2020 9:51 am

Hello,

Not sure if I asked this before or if anyone else has, but does anyone have any tips or tricks on how to get the o’ring out of the body without causing unnecessary damage?

Thanks

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Herman
VDH Moderator
Posts: 1280
Joined: Thu Oct 25, 2007 1:45 pm
Location: Raleigh NC

Re: Mistral O’ring removal

Sat Feb 15, 2020 10:32 am

It's a pain in the rear, I use a sharp dental pick to stab it. I know that is not the recommended way but some times you have to do what you have to do. On the up side, that oring is more of a guide than a seal so damaging the seating area is not the big deal as it is other places. I am not saying be careless but it's also not as critical if you do scratch something. Yes it seals some but unlike other orings it is not really a pressure boundary, it just keeps excess flow from going around the stem which in turn keeps the venturi working properly. If you look, you will see a small vent hole beside the pin which already flows some air past that oring
Herman

swimjim
Master Diver
Posts: 1621
Joined: Thu Mar 23, 2006 12:28 am
First Name: Jim
Location: Belgium WI

Re: Mistral O’ring removal

Sat Feb 15, 2020 1:08 pm

Bryan has a video on the Mistral somewhere and he deals with the o ring in it. Can't seem to locate it right now though

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Greg Barlow
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First Name: Greg
Location: SW Ohio

Re: Mistral O’ring removal

Sat Feb 15, 2020 8:27 pm

I typically use a safety pin to “spear” the cross section. Be prepared, as many of them have become brittle over the decades, and break into pieces.

Greg Barlow
Greg Barlow
PADI Assistant Instructor
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Wetsuit
Diver
Posts: 18
Joined: Mon Jul 10, 2017 9:42 am
First Name: Dave
Location: Hamilton, Ont

Re: Mistral O’ring removal

Sun Feb 16, 2020 11:08 am

Thanks everybody,

I was able to remove the o’ring and replace it with minimal effort and what I think and hope was minimal damage.

Now my second question I still have air escaping from the hp seat, it’s not very much so i was wondering if it was normal? Or if the body, seat, or pin might need replacement, or just needs a really good cleaning?

Thanks again

Dave

swimjim
Master Diver
Posts: 1621
Joined: Thu Mar 23, 2006 12:28 am
First Name: Jim
Location: Belgium WI

Re: Mistral O’ring removal

Sun Feb 16, 2020 4:12 pm

swimjim wrote:
Sat Feb 15, 2020 1:08 pm
Bryan has a video on the Mistral somewhere and he deals with the o ring in it. Can't seem to locate it right now though
[/quote

A little late but found the video. It's in the files and catalog section under onestagers wmv.

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Herman
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Posts: 1280
Joined: Thu Oct 25, 2007 1:45 pm
Location: Raleigh NC

Re: Mistral O’ring removal

Sun Feb 16, 2020 4:29 pm

Wetsuit wrote:
Sun Feb 16, 2020 11:08 am
Thanks everybody,

I was able to remove the o’ring and replace it with minimal effort and what I think and hope was minimal damage.

Now my second question I still have air escaping from the hp seat, it’s not very much so i was wondering if it was normal? Or if the body, seat, or pin might need replacement, or just needs a really good cleaning?

Thanks again

Dave
A leak is not normal esp at higher tank pressures. Hard to say what the issue is without it in my hands but there are several possible problems. A defective HP seat or defective orifice is possible . HP seats take a set (groove in them) and do not like being reinstalled in a different orientation, this is the most likely problem. Look very closely at the soft part of the seat, if you see overlapping rings in it, which is what different orientations cause, that is your issue. You have 2 options, CAREFULLY sand the seat back flat or replace it.
Herman

Vancetp
Master Diver
Posts: 305
Joined: Tue Oct 04, 2016 7:26 pm
First Name: Phillip
Location: Belmont CA

Re: Mistral O’ring removal

Mon Feb 17, 2020 10:42 pm

I have NOS seats if you need one. $20 shipped.

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simonbeans
VDH Moderator
Posts: 979
Joined: Sat Jun 25, 2005 2:00 pm
First Name: Allan
Location: Rochester NY

Re: Mistral O’ring removal

Tue Feb 18, 2020 10:24 am

And Bryan here at VDH has new made seats.
Check out my website: www.vintagescubastuff.com

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Wetsuit
Diver
Posts: 18
Joined: Mon Jul 10, 2017 9:42 am
First Name: Dave
Location: Hamilton, Ont

Re: Mistral O’ring removal

Sat Feb 22, 2020 10:38 am

Thanks everyone for the advice and help, I just ordered a replacement hp seat and then figured it out
Thanks

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