Devilbiss 342 says 10wt oil on tag.

by gary
(washington state)

Have an old old devilibiss 342 that says 10wt oil on the metal tag located on block. It runs at 600 rpm and located outside winter and summer. OIl is still clean and hasnt been changed in 15 years of light use.......figure its about due.

1----Should I stay with 10wt non detergent, or is there a modern 30wt or synthetic subsitute that would work better for my application?

2----anyone know how much oil the crankcase holds?

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Nov 29, 2016
still going strong
by: gary

I think this old devilibiss might make another 65 years.

Its a 2 stage pump, 2 cyl, rated at 175psi at 700 rpm max.....Minimum rpm is 300. Pretty quiet old monster.

It has an old old us electric motor that seems to be older than everyone I've showed a picture of it to. The frame is a 254-4. It is gray, about 26" long, 12" wide, and has a cast iron rounded plate that 2 bolts onto back of motor. THe frame looks like its at least 1/4 cast all the way around. If it ever goes bad, I will have to hire 2 strong guys just to lift the motor off..

Greased both grease fittings on each end of motor and still purring away.

I put on a new pressure switch rated at 175psi but turned it down 3 turns and now shuts off at 135psi. Its a 100 gal tank which takes 10 min to fill from empty to 135 PSI, at 600 rpm.

I figured with that volume and what little I do in shop, that should fit all my needs and not have the compressor work any more than necessary. I think before it always cut out at 150 psi.

I was seriously thinking about buying a new 60 gallon vertical compressor for shop, but the quality of most for $600-700 didnt seem to come close to what I already have. IMO

Anyway I think I'll just let the old monster keep going and have a happy death, hopefully decades from now. I wonder which will last longer, the pump or the motor?

Nov 29, 2016
Devilbiss 342
by: Doug in

I think you're right about the low rpm.

And I'm sure the iso32 will be fine.

Thanks for the update.

Nov 29, 2016
decided on hyd oil
by: gary

Its 2 quart capacity. I think about 1950 year.

Tag says below 32 = sae 10wt
32-100 =10wt
above 100 =20wt.........

It sits outside, We get all 4 easons here...0 to 100 degrees.

Cant find 10wt oil, so bought some hydraulic oil ISO32 = 10wt. Will run and drain it several times and call it good. Read lots of posts on internet where guys have always used hydraulic oil in these old compressors with no problems.....

Called an air compressor shop, and guy told me to just use iso 32 hydraulic oil if I cant find any 10wt non detergent.

. I wondered why the outside of compressor over the last 15-20 years seemed to get darker and darker. When I drained oil yesterday, it was really dark. I think my dad must have put motor oil in it 15 years ago??? OIl level was down about 1/2 quart.

Still runs good. Maybe the low 600 rpm helped over the years.

Nov 27, 2016
Devilbiss 342 says 10wt oil
by: Doug in

Does the tag say 10w - 10 10 ?

Then for your area, I'd say stick with sae 10, either dino or syn.

Don't know capacity, but looks like probably a quart or maybe two.

I'd further say, if the oil feels smooth on your fingers, and there's no water, let be, especially if you can't find sae 10.

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Devilbiss 342 pressure relief valve needed

by roger
(watervliet, michigan U.S.A.)

I'm looking for a pressure relief valve that's made of brass and screws into the centrifugal unloader that is mounted on the opposite side of the crankcase from the sheave.

The part number which also serves the 432 pump as well is: 330-430-3.

If anyone has one please post.

Thanks guys.


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Feb 11, 2016
by: Doug in

Have you tried getting a quote from any of the several potential sources shown by google for 330-430-3?

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