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Quincy 325 compressor rebuild


Sep 9, 2021
I purchased a seized Quincy 325 pump from the original owner, randomly found the ad. Said it would not turn on one day, it has lived in an outbuilding next to a wood working shop/barn. He purchased a new pump and did not want to throw it in the recycle.

Could not get the flywheel to turn at all. Thought it may be a parts machine or repairable, but I have wanted one of these for a while. This line of pumps were way way outside my budget when I purchased my QT5 years ago.

Funny, most of the semi local shops I called pushed the new random brand pump they are currently selling, saying it would cost less.

I have found some excellent YouTube videos from Rotarycomptech, just outstanding work and stumbled across his videos years ago and this likely gave me the courage to give this project a go.
Also some more recent content from a compressor shop channel called The Compressor Guru. Nice rebuild series on an IR, the 325 series were rushed and I hope another 325 rebuild makes the channel. The practical machinist and GJ have good threads, but many details are missing. A lot of content is a fresh beautiful coat of paint, but I need to go further (plus paint).

Will share some pictures of the partial disassembled 40+ yr old pump. I think this one is starting to look rebuildable, but needs a lot of inspections, cleaning and new parts.

Would normally use only OEM parts especially since the original parts have lasted so long. One of the rebuild threads showed factory OEM parts with overseas sourced bearings vs the Timken USA made bearings.

Would like to rebuild so it last longer before the next rebuild.

So I need help with who currently makes the really good parts for a 900 rpm pump, many of the good companies of yesterday have sold and the parts are relabeled using global components. But are the parts still a premium line or not so great. Just because it says made in the USA, if current quality is horrible it should be avoided.
Piston rings, rod bearings, wrist pin bronze sleeves and other small pieces, such as the crank seal. I will track down some new or nos timken USA bearing if they are needed, those are good stuff imo.(car projects+), also, the org ones seem to spin really nice so maybe leave alone if they check out.

Would appreciate tips on how to rebuild this better than when it was first manufactured and keep me from messing up.

You can see lots of carbon, wonder what caused this or due to an extended period of no cleaning? Could not remove one of the 3/8 hex thread locks, actually split my 3/8 socket in half. Hoping a long soak in pb blaster and heat will free it.


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Sep 9, 2021
More pictures

Soaked with ATF, finally got it to move using a hammer, brass punch and a block of wood. Removed the connecting rod bolts. So far the bolts are easy to remove other on the set screws on the head.
At this point, looks like the high side piston was the issue. The high pressure piston wrist pin was not centered and rubbed the cylinder wall at some point, they have bumpers with aluminum or lead, so the cylinder was not scratched.


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Sep 9, 2021

The crank journals look amazing. The crank easily spins and this is where I have stopped.
I am looking to source some made in USA parts. The piston rings, checking to see if a set of Hastings or others are available. If anyone has recently sourced USA rings feel free to post the part # and share if you changed any rings to the 2 piece style to reduce blow by.


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Hot Rolled
Aug 5, 2014
Wisconsin Rapids WI
I don't remember when I redid my QR but I thought Quincy sold rebuild kits. Rings, gaskets, etc are disposable so as long as they fit the ROC it shouldn't matter where they were made. Pistons are different but most parts needing replacement are pretty generic. I put the valves in Evaporust and used a die grinder to clean and sandpaper to lap them. Getting the shims right is most important to longevity but the QR run pretty much forever if not stored in the rain barrel. DaveDSCN3747.jpgDSCN3754.jpg


Sep 9, 2021
Quincy sell parts, but seems to gone to the lowest price source, just like others have done. These parts in my machine appear to be original, way over built. Trying to source the best that is current available. If you like new rings made in Germany, because the metal is a superior alloy or a mfg that uses two rings on the second grove 180 degrees apart if it noticeably improves volume by lower blow by. I may choose that brand. Mentioned hasting and others due a long track record and not trying to save a few dollars on parts for my rebuild. Appreciate the tip on the valves. You have some beautiful compressors!


Congrats on becoming a member of the QR club! They may look similar to other compressors, but only those in the know, know.
I recently rebuilt a little 210 after it served me for 34 years. Bought the parts on EBAY and they seem fine. With minimal care, any model QR pump with a fresh rebuild will be on it's way of outlasting it's current owner. PS, I've got a QR325 waiting for a rebuild as well.


Oct 10, 2009
Where do you get the idea that stuff made in USA is better than stuff made anywhere else? I don't think this is realistic.

I would buy the updated ring packs from whomever you like and put it together correctly.

I patched up a 350 a few months ago that has run 10 hours a day since the mid 70's. It lost a high pressure valve on one of those 116 degree days we had this summer.

If you have a bit of an engineering background and look at the Quincy QR design as you get intimate with it you can't help but realize they are designed to be field repairable with a crescent wrench and a hammer.

That QR350 I patched up was a time sensitive deal. I made all the gaskets from the thick paper backing from a notepad and a bit of grease.