Flushing Gast 0523 vacuum pump?

[Alan Heffernan]

I am putting together a vacuum chucking system and have acquired a Gast model 0523 vacuum pump via ebay. It appears to be in good shape but I want to flush it out before I assemble my vacuum chucking system and put it into service.

I have spoken to Gast and they said to use electrical contact cleaner or brake part aerosol cleaner for the flush. They said to remove the muffler plenum and then run the pump while spraying the cleaner into the suction port and let it throw it out the pressure side. This frees up the vanes so they slide easier in their slots and of course it also removes any carbon dust and/or paste that has built up. Gast told me they will paste up if run in high humidity environments and the flush will clear that out.

Please share any personal experience you have in flushing one out.

[Dwight Rutherford]

I have had a Gast vaccum pump for 10+ years. Have never "flushed" it out. Pulls the same vaccum as when new.

[Jeffrey J Smith]

I'm in the same camp as Dwight - never had a reason to flush after several years of use. It still pegs the gauge. That said, it's good to know how to flush it and free up the vanes. I'd guess that, as long as you didn't make a weekly habit of it, a little preventive maintenance is a good thing.

[Alan Heffernan]

My pump is used, perhaps yours was new when you got it. Glad you haven't felt the need to do so.

The specs on the model I have (Gast 0523) will not peg the needle out of the box new since its spec is 26" Hg. However it will pump a relatively large flow rate and that is what makes it great for a vacuum chuck in that it can keep up with a small leak.

I am going to flush it before I put it into service so looking for someone here who's done it.

[Tom Albrecht]

I am a Gast user as well. I'm not sure what more you will learn from "someone here who's done it". The folks at Gast who recommended it have surely done it.

Aerosol brake cleaner is good for lot's of cleanup jobs. I'd probably recommend that you do it outside though.

[Alan Heffernan]

I am a Gast user as well. I'm not sure what more you will learn from "someone here who's done it". The folks at Gast who recommended it have surely done it.

Aerosol brake cleaner is good for lot's of cleanup jobs. I'd probably recommend that you do it outside though.
Example, the Gast flushing cleaner is 60 to 70 bucks per can. I am trying to get some insights as to which brake cleaner and/or contact cleaner to use in lieu of that. The Gast person simply said brake cleaner or contact cleaner. I did not get a specific recommendation because they primarily recommend their flush. I have been digging through safety data sheets to find something equivalent. Perhaps someone here has done that research already and could share it.

Another insight I would be interested in would be whether or not the muffler plenum gasket comes apart when you disassemble it. From what I have discovered thus far, you can only buy them 10 at a time from from Gast or get one in the 70 dollar kit for a complete rebuild. Hopefully the plenum comes off without destroying the gasket but I do not know since I have not done one. Of course the option is to make one if needed since it is not a clearance gasket and thickness is somewhat irrelevant.+

Edit: Meant to also say that the brake cleaner would need to a chlorinated cleaner, the non-chlorinated ones are very flammable and dangerous for this application.

[Don Kondra]

Ah, preventive maintenance !

I used the Gast flushing/cleaner on my 25 + years old 1550 V16D (which has a syphon oiler).

My pump used to hit it's rated 25", it now runs @ 23.5", sigh...

Cheers, Don

[Charles Drake]

Why not just remove the head and clean the vanes with almost any solvent. Super easy to disassemble and reassemble. Many youtube videos.

[Alan Heffernan]

Why not just remove the head and clean the vanes with almost any solvent. Super easy to disassemble and reassemble. Many youtube videos.
Yes, I have seen the videos. The one that pops up first is of a brand new pump so the gaskets are fresh and aren't destroyed. My reluctance is destruction of the gaskets by taking it apart. So has anyone taken one apart without destroying the gaskets? The Gast representative believed the gaskets would be destroyed on a 9 1/2 year old pump.

Here's the youtube: https://www.youtube.com/watch?v=1h6pj4wrJIU

[Alan Heffernan]

Ah, preventive maintenance !

I used the Gast flushing/cleaner on my 25 + years old 1550 V16D (which has a syphon oiler).

My pump used to hit it's rated 25", it now runs @ 23.5", sigh...

Cheers, Don
Sorry Don that it didn't work on yours. I am not familiar with your pump but the 0523 is not oiled. It is a dry vane pump so I think it is a different animal than yours.

[Paul Gilbert]

I was once ran a lab that used a Gast pump to pull a vacuum on a manifold of filters. It had a 5 gal reservoir to catch the filtrate which often contained acids. When someone forgot to empty the liquid trap the pump would waterlog and the vanes would gum up. I took that pump apart for cleaning about once a month. I never changed a gasket, and infact, I don't recall any gaskets being installed. The clearance between the rotating disk and the inside and outside face of the pump is very small and I doubt that gaskets would have close enough tolerances to allow the pump to pull a good vacuum if gaskets were used.

When I got my used Gast pump the first thing I did was disassemble it and clean up the vanes. Mine has carbon vanes and there was a good bit of carbon dust in the pump. It is a simple job to take the pump apart and clean it.

The outside ring comes off, but as I remember it isn't absolutely necessary to remove it. The gap between the outside ring and the rotor is critical. Too big a gap and you will have low vacuum. If the rotor rubs against the outer ring it will score the ring and the ring will require replacement. (DAMHIK) I used the cellophane wrapper of a cigarette pack to set this gap.

[Dwight Rutherford]

My experience with my Gast pump is the same as Paul's. When I took it apart there was no gasket just two machined surfaces. I would recommend getting the rebuild kit. New vanes and filters restored mine to pull 25# at sea level.

[Alan Heffernan]

Paul and Dwight, is there no gasket between the muffler plenum and the pump? What seals the rotor cover to the housing? The youtube looks like a sealant or mylar film.

Thanks for the feedback!

[Mike Goetzke]

Paul and Dwight, is there no gasket between the muffler plenum and the pump? What seals the rotor cover to the housing? The youtube looks like a sealant or mylar film.

Thanks for the feedback!

Alan - I bought a Oneway system used from a guy retiring from turning. I was thinking about tearing into the Gast pump like you but I took the advice of others to block of the inlet to see how much suction it could develop. Mine was at close to 25" of Hg which is right where its supposed to be. Maybe get yourself a Vacuum gauge and check the pressure.

Mike

[Dwight Rutherford]

I stand corrected, there is in fact a gasket between the muffler box (plenum) and the pump. You can go to the Gast website and view a video on how to install a repair kit. I also agree with the comment above, before any attempt to flush or repair, turn the pump on attach a vacuum gauge and see what the reading is. If you are at sea level or close and the pump is pulling 25# or close, then leave well enough alone and finish your vacuum system. Enjoy

[Alan Heffernan]

Yeap agree on checking performance and I did when I got it. It pulls 23.5. BTW, I live at a very high altitude of about 60 ft above sea level!

[Dwight Rutherford]

23.5 isn't too bad. Suggest you pull the two filters out, replace the plugs and briefly run the pump, check if the vacuum gauge gives a better reading. Could be dirty filters. My pump was also used and would only pull 18#. Replaced the filters and saw 25#.

[Alan Heffernan]

23.5 isn't too bad. Suggest you pull the two filters out, replace the plugs and briefly run the pump, check if the vacuum gauge gives a better reading. Could be dirty filters. My pump was also used and would only pull 18#. Replaced the filters and saw 25#.
Dwight, I put the gauge directly on the plenum and dead headed the pump. Not sure how the filters would have any impact when there's essentially no flow. BTW, my son suggested the same based on experience he had. I'll give it a shot. Problem is it will be several days before I can get to it due to other priorities.

[Alan Heffernan]

Finally back to my shop after a long trip.

As suggested here and elsewhere, I tested the pump without the filters/felts and the snubber installed and no real change with the best it would do was to be near 24".

So I decided to pull the plenum off to see what it looked like and it didn't look that dirty so I gave up the idea of a flush. By the way, the plenum gasket is tough as nails and wasn't destroyed in the process.

I then decided to pull the cover off the vane cavity. Turns out the that the carbon blades are worn beyond the minimum length spec that the Gast representative gave me so it's time for new ones. In addition to the vanes being too short in length, there is also significant wear on their face where they move in their slides. This flat face wear is too be expected of course but I do not have a spec. on that from Gast.

I recognize that 24" is adequate for the job but I am betting there's an impact on flow rate due the worn vanes. The 24" performance was with the pump deadheaded and of course there is no way that I can test or estimate flow without a lot of trouble.

So with the carbon vanes beyond their useful life per the Gast advice, I ordered a rebuild kit. When I get the kit and the new carbon vanes in it I will report back.

[Dwight Rutherford]

Alan,
Thanks for the update. When I replaced the vanes in my Gast 3 years ago I had an increase of 5" of mercury which still holds today. Bet you have a similar result.

[Alan Heffernan]

Put the new vanes in and it works very well. I am now getting well in excess of 26" hg.

The old vanes were even more worn than I thought when I pulled them out and inspected them. Too short and curved from wear.

[Alan Heffernan]

Had difficulty with my Windows 10 update but here's the proof now of the better performance.