Leaking 3Z180

by Jesse
(Austin, TX (more or less))

1Z721 with 3Z180 pump

1Z721 with 3Z180 pump

1Z721 with 3Z180 pump
3Z180 Motor + Pump
3Z180 Pump
Pump ID Tag (faded)

Hi Bill,
Tks for creating a great online resource.

Have had several compressors over the years. Last week I came by this not-so-pretty 1973 Speedaire 1Z721 upright compressor set with 3Z180 2-stage pump,Dayton 5K483-J 110v/220V motor, and 80gal Bell & Gossett tank at a very reasonable price.

It had not been run for a couple years so inspected tank, replaced belts, fittings & wiring, ran it up to working pressure a couple times (in increments of 25psi) before changing oil.

Motor and compressor run smooth and quiet, system pumps to 150psi in about 20 minutes before cutting off and unloading as designed. With full tank and all valves closed (2x 3/4", 1x 1/4"), the pressure switch kicks in @ 75psi after about 4 days.

Question 1: A full, unused tank will leak down to 75psi in about 4 days. Is this normal?

Question 2: I noticed a bit of air coming from the Unloader Muffler Assembly when running. The systems unloads when it cuts off at 150psi and I don't hear/feel anything else (assume unloader working correctly). Is this normal?

Question 2a: Unloader Muffler Assembly (part #Z4593) is missing packing and appears to be an open fitting. Pics of available replacements look like the fitting includes a packing. Will this cause a problem?

Your post stated you needed pics of the 3Z180. Apologies for photo quality and system appearance. Although previous owners had it under cover, the paint and decals are a bit weathered from Texas sun. Won't be insulted if you opt to not post pics and will be happy to oblige if you want specific pics or descriptions.

Comments for Leaking 3Z180

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Jul 27, 2017
good copy
by: o.p.

tks for feedback.
upon further inspection, determined it's the check valve.
good copy on the unloader comment.

Jul 26, 2017
Leaking #1
by: Doug in s.d.ca.

Additionally, that tank doesn't look great, so you might have a leak at one of the plugs, drain valve, or even a pinhole or three...

Jul 25, 2017
Leaking 3Z180
by: Bill

You are most welcome, and no worries about photos. Bad ones are better than no photos, though yours are just fine.

#1) Not normal. If pipe to discharge coupler doesn't leak, coupler itself doesn't leak, no downstream fittings or hose leaks, then the only place the air could be leaking from is the tank and out through the open unloader, meaning the tank check valve isn't seating securely and slowly bleeding air.

#2) An unloader valve that is leaking while the compressor is running is one that isn't working properly. The unloader valve should not bleed air while the compressor is running.

#3) Unloader packing is what I would consider a muffler, yes? If so, the absence of it would mean that the expulsion of air when the compressor unloads would be louder than expected. If I'm out of line with this, please start another thread, upload closeup photos of the unloader mechanism with one overview showing where it is, and in the title of the new submission put For Leaking 3Z180, and I'll combine the two.

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