Do you ever service your SPG?

[Bob DBF]

They're mostly not servicable.

You can change the o-rings in the spool, but if it's been leaking sticking or is significantly out of calibration, about all you can do it toss it.

Some of the oil filled SPGs could be refilled, but it's not really a permanent fix for anything.

I've tried to repair the old SPG's, but the seals must have been proprietary as I haven't found a replacement for them yet. I test them in fresh water so the mechanism is fine and works well but it floods. I'll probably give it a go again when I'm bored, I would like matching gauges for vintage gear.



Bob
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You only need two tools in life – WD40 and Duct Tape. If it doesn't move and should, use the WD40. If it shouldn't move and does, use the Duct Tape.

 

[Texasguy]

For auto applications they have a specific caulk that allows you to create your own custom seals from a paste. Maybe worth exploring?

 

[FinnMom]

What everyone else said about replacing: o-rings or the whole deal.

 

[Lost down under]

Only had one brake on me, as I pressured it up the dial fell off. Managed to open it up, fix and dive it out of sheer curiosity but obviously wouldn't recommend it, after my "I bet I can dive it" the SPG now lives under the sofa with other bits of unwanted kit!

 

[buddhasummer]

I replace spool annually regardless. I do periodically check reading against another gauge to check for "accuracy". Other than that there's nothing else you can really do. In over 15 years of diving I've only had one gauge actually die, it started giving strange readings, I threw it out. It was a plastic oceanic one. I've never had any issues with brass and glass ones, spools yes, but gauge no.

 

[miketsp]

I had one that was sticking so I bought a new one to replace it. I then opened it up just to see and it turned out to be easily repairable. There was a brass pinion gear that turned the pointer and this was operated by a toothed quadrant attached to the expansion tube. The pinion teeth were worn at the point of contact with the quadrant causing it to jam. I just bent the quadrant slightly to make contact with a new region on the pinion. It then worked as good as new.
So I have a spare SPG in my save-a-dive kit. This repair could have been repeated once more by bending the quadrant in the other direction. So in practice it would have been possible to triple the life of the SPG before really putting it in the garbage.

 

[scorman]

Got a quick qs:
Was diving a few weeks ago, and at end of one dive, noted bubbles coming from console, so went back to room and noted that it did not rotate smoothly. Removed spool and noted one o-ring frayed. No problem changing both o-rings, but noted that the housing on the Sherwood SPG was brass, not chromed, and there was salt and green crud on the exterior. The spool itself was clean and shinny when removed, but the port into the SPG did not feel smooth as it should, so I reamed it out with a cloth and looked down the barrel and did not note any pitting. The new well greased o-ring went in smoothly and console rotated smoothly ....next dives were fine, problem solved.

Home now and planning on rebuilding everything on three reg/BCD setups. I will buy a pair of replacement spools to keep greased in a zip lock. For the hp spool, if there is no visual pitting of inner surface, is it advisable to use some 800 wet/dry sandpaper rolled into a cylinder to "polish" the bore hole of the SPG? I was also thinking of dipping into vinegar to clean up exterior and swabbing with plumbers waterproof valve stem grease as a coating.

Slightly OT ...Heard of several stories about power inflator sticking "on" ....some have recommended replacing the entire BCD inflator assembly for $14.95 instead of taking apart and replacing rings:
https://www.divegearexpress.com/bcs/bcdparts.shtml
...admittedly, salt water stays there long time, but rings I could replace every season and examine the guts inside, so how often would you replace the whole assembly??

TIA for any suggestions,
Stew

 

[Ricky B]

For the hp spool, if there is no visual pitting of inner surface, is it advisable to use some 800 wet/dry sandpaper rolled into a cylinder to "polish" the bore hole of the SPG?

If there is no pitting, what is to be gained?

If you polish the bore of the SPG and the polishing is not perfectly concentric, might you not provide an escape route for the gas?

 

[g1138]

Got a quick qs:
Home now and planning on rebuilding everything on three reg/BCD setups. I will buy a pair of replacement spools to keep greased in a zip lock. For the hp spool, if there is no visual pitting of inner surface, is it advisable to use some 800 wet/dry sandpaper rolled into a cylinder to "polish" the bore hole of the SPG? I was also thinking of dipping into vinegar to clean up exterior and swabbing with plumbers waterproof valve stem grease as a coating.

Slightly OT ...Heard of several stories about power inflator sticking "on" ....some have recommended replacing the entire BCD inflator assembly for $14.95 instead of taking apart and replacing rings:
https://www.divegearexpress.com/bcs/bcdparts.shtml
...admittedly, salt water stays there long time, but rings I could replace every season and examine the guts inside, so how often would you replace the whole assembly??

TIA for any suggestions,
Stew

You should keep those spools dry till you need them. Grease gets crummy when overtime after it's applied.
You should also only use a brass wire brush on your brass-chrome parts, less you want to introduce an imperfection for air leakage.
Don't use that plumbers stuff, there's no benefit for what you're intending to do. Parts that are supposed to stay dry, stay dry with air pressure. Parts that get wet will wash away any coating over time. So any extra coating you try to do, say like greasing threads, greasing body. It provides no benefit but makes a mess for the next person who decides to service it.

Use a 50-50 distilled white vinegar & water mix to get rid of corrosion and rinse with fresh water after application and scrubbing. Be sure not to get any in the SPG. That would entail dipping the wire brush.
Best to air dry every part with a blow whip from a clean air source. IE use a scuba tank not an industrial air compressor from the construction yard.

For the BC, just rinse it religiously, which includes shake-tapping the corrugate hose to get rid of water that collects there.

 

[scorman]

If there is no pitting, what is to be gained?

If you polish the bore of the SPG and the polishing is not perfectly concentric, might you not provide an escape route for the gas?

Ricky,
There is a difference between polishing and reaming ....800 w/d couldn't take off more than .01 mil (10 millionth of an inch), so NO, concentric bore diameter is not an issue. I had also thought of using a plastic toothpick as a probe.
If my observation is correct, the hp spool slides back and forth inside the bore a small amount, but salt water is exposed to the center of the shaft between the o-rings. Since it doesn't really get flushed inside the console, salts and corrosion crystals could accumulate there and that is what I believe caused the "roughness" after years of exposure ( just got into this refurb concept).


G1138 ...thanks for the tip to use brass brush and your other thoughtful advise.

You should keep those spools dry till you need them. Grease gets crummy when overtime after it's applied.

some vendors are shipping the hp spool w/ o-rings w/grease ..but your point is taken
I have new o-ring sets, but people talk about old rings "drying out"...odd since that usually occurs upon exposure to UV.
Some think that packing in silicone grease would prevent this??
I keep my o-rings dry in a ziplock.
Do you refurb or replace the inflator assembly?? How often would you take it apart?

Stew