MK5 HP Seat

[boat sju]

As an experiment could I flip over a conical seat? It may not seal but I don't think it would damage anything. But is that a bad assumption????????

 

[p_kos]

As an experiment could I flip over a conical seat? It may not seal but I don't think it would damage anything. But is that a bad assumption????????

IP might be lower than right side up but could work (as long as the “+/-l/-ll” marking fits inside the piston bore fully).

 

[happy-diver]

Shave the conical protrusions off first

 

[boat sju]

IP might be lower than right side up but could work (as long as the “+/-l/-ll” marking fits inside the piston bore fully).

The thing is, neither of the white seats I have left have any markings on them (they're both the same size anyway). I did have a gray SP seat that was marked +. I put that in the reg and it fixed what was a relatively slow recovery but then the IP still crept up to about 170. Bottom line is, I'm sure I'm learning something from playing around with the reg but I need to buy a service kit and do this right.

 

[James79]

The thing is, neither of the white seats I have left have any markings on them (they're both the same size anyway). I did have a gray SP seat that was marked +. I put that in the reg and it fixed what was a relatively slow recovery but then the IP still crept up to about 170. Bottom line is, I'm sure I'm learning something from playing around with the reg but I need to buy a service kit and do this right.

If a new seat is still giving a slow creep to a much higher IP, I would suspect damage to the piston knife edge. Look with a magnifier to see if there are any tiny nicks (doesn't take much at all)... If so, refer to @rsingler 's wonderful explanation of knife edge piston repair:

How to restore a Knife Edge Piston

About four months ago, I posted a thread on How to restore a Piston Regulator that has IP creep . In probably excessive detail, we walked through how to restore a piston regulator with a blunt-end piston. Most newer pistons have switched from knife-edge pistons to blunt pistons with a cone...

scubaboard.com

 

[boat sju]

James, I'm hoping I don't have to get into that. I've been learning on some old regs I got off of ebay, etc. I've been waiting to work on this MK9 as it's my primary reg that I purchased "new". So I left servicing it until last as I gained confidence. I hope to tear it apart soon, but apparently my wife thinks its more important that I fix the snowblower first .

 

[James79]

James, I'm hoping I don't have to get into that. I've been learning on some old regs I got off of ebay, etc. I've been waiting to work on this MK9 as it's my primary reg that I purchased "new". So I left servicing it until last as I gained confidence. I hope to tear it apart soon, but apparently my wife thinks its more important that I fix the snowblower first .

Is it the Mk5 or the Mk9 that you have the IP creep to 170? Either way, if you diagnose it as a flawed knife edge, I probably have an old 5 or 10 that I can trade you pistons out of (partly because I want to take a crack at Robs piston edge restoration method!).

 

[boat sju]

James, thanks for the offer. It's the MK9. I may take you up on it but I want to try the rebuild first. I need to order a kit from VDH and that will probably take two or three weeks. (Bryan is busy with work.)

 

[boat sju]

Just realized we had an unused otoscope tucked away. Seems to work better than a phone app? I know, not the best video.

mk5 piston.mp4

 

[rsingler]

Oof! Those are two large dings on the wrong side of the knife edge. Especially #2. That's a big restoration project, @James79 ! I'm guessing IP will go up 10-15 psi after you get to the bottom of those. Still, fun to see it work, given enough time and effort.