Edwards E2M12 vacuum pump rebuild / overhaul / cleanup .....
Many pumps are very similar, including other brands, so this will cover many makes\models. Pardon my rambling, I ramble better then write.
Link to pictures of a different model (same design) pump I rebuilt...
http://s852.photobucket.com/user/pcmeiners/library/Edwards%20E2M2%20Vacuum%20Pump%20overhaul?sort=3&page=1Task difficultly..
Once past your own fears, which is the most difficult part of the project (or life), overhauling one of these pumps was surprisingly simple, yet detailed as to cleanliness. The engineering of these pumps is very good. Parts are few and most only fit one obvious way; that is not the norm as of late. As a perspective, overhauling a pump like this is slightly more involved then doing a automobile disc brake job involving replacing the rotors and a hydraulic cylinder. If you done this, you can rebuild a vacuum pump; this is also a lot more fun then a brake job.
In the following, part numbers and descriptions are as referred to from the Edwards parts list PDF.
My pump's background.....
From it appearance the pump had been used very little, I speculate it failed within very low hours of use. After preliminary cleaning and flushing the pump failed to produce any appreciable vacuum, I purchased a major maintenance kit (all seals/o-rings/vanes). Little did I know, I could have gotten the minor kit, same components of the major kit without the vanes ( a good bit cheaper), because the original vanes were in good shape.
Likely issues with my pump were partially seized vanes, possible worn shaft seals and a spring support (part 47) which was totally loose, worn/destroyed from wobbling.
Purchased a major clean and overhaul kit (37001800) from A&J Vacuum Service, one of the lowest priced dealers, delivered it quickly. Prices for minor/major repair kits vary tremendously, from reasonable to ridiculous. For the major kit, on the low end $ 200, high end $800 (same exact kit). Minor kit $65 to $300. P.T. Barnum could have take a lesson from some of parts dealers out there..
Lower priced parts dealers...
http://www.ajvs.com/http://www.capvac.com/If you intend to reuse the seals/O-Rings/gaskets be very care as to solvent used for cleaning, paint thinner is safe, carburetor spray maybe safe but there was a warning as to seals and O-ring being affected by certain solvents. I had one of the old seals and O-rings soaking in carburetor cleaner, seemed to have no affect. I highly recommend purchasing the minor maintenance kit at minimum, it has all the seals, o-rings, gaskets, springs, filters etc. Vanes can be purchased separately if needed.
If you have another make/model which has ball bearings which are sealed or shielded , do not use any solvent near them. My unit just has solid bearing surfaces, no ball bearing to worry about. I am in the habit of replacing ball bearings automatically if the equipment has been well used, has vibration issues or has been contaminated for any length of time. It is not necessary to get the exact bearing brand, but get the same size/type. The bearing info will most likely be stamped on the bearings. Make sure you get the same clearance, most likely "C3", as heat is involved in vacuum pumps. SKF or Japanese brands are good bearings, do not use no-name or Chinese brands. It is not necessary to get them via a vacuum parts supplier, unless you enjoy premium prices, I get most of my bearings off Ebay.
Tools needed...
hex keys
paper towels, 1 roll
dental pick if you have one
tweezers
Locktite 242 blue for the Allen bolts, sold at Autozone
Permatex Threadlocker green ( Locktite 290), only for one of the shaft seals, AutoZone
Wet/dry 1500 sand paper, 1 full sheet minimum, small piece of 2000, AutoZone.
1 gallon paint thinner ( if you pump is really dirty), 2 qt minimum, Home Depot .
1 qt Lacquer thinner, a more aggressive cleaner, Home Depot.
2 14-16 oz spray cans Carburetor cleaner, AutoZone
An old 6203 bearing would be handy to remove/install the outer pump seals, but not required.
Snap ring pliers, a must have tool, as the snap ring in this pump is large/stiff.
A low height plastic container to soak parts.
I skipped gloves, but if your pump is contaminated use them.
Safety glasses due to the carburetor cleaner spray and or contamination.
Download your pump's manual and expanded parts list, both are necessary.
Overhaul kit, either minor for the seals, O-rings, gasket, springs or major with the vanes.
Plastic hammer, a must have tool
Tooth brush (but not the wife's)
Very thin plastic bristle brush to get into small orifices. Pipe cleaners leave lint .
White cloth, old white sheet to work on, to keep dropped parts visible.
Seal removing tool for the smaller inner shaft seal, about $20, PepBoys , or make it
Downloads sources....
http://www.gasflovac.com/GASFLO_DOWNLOADS.htmExploded Parts diagrams
http://www.idealvac.com/downloads/explodedviews/Edwards_E2M2_to_E2M12_Exploded_Views.pdfE2m12 Manual...
http://www.ajvs.com/technical_library.php?tlcPath=0_34&man=7Empty the oil into a low pan, I used a large tray which had a 1" lip. Tilt the pump with a block of wood or similar item under the motor to drain the oil remnants, I let it drain overnight.
I used paint thinner to flush out the remaining oil which makes it much easier to work on the pump. This pump does not have sealed ball bearing which could be affected by solvents, if your pump has sealed bearings, do not flush the pump with solvent. On the other hand if your pump has open bearing (no covers or contained grease), you can flush as described below.
Flushing...
Reinstall the oil plug, fill the pump with paint thinner, 3/4 full, and added some to the inlet port of the pump, I turned on the pump for 4 seconds only. With the pump off, rock the pump sided to side to get the solvent around the inside, let it sit for a while, turn the pump on again for 3 seconds; if you have the time, let it sit over night. Empty the paint thinner/oil solution into a container. Turn on the pump for 1 second only to clear the pump stages; in all this basically cleans out approx. 98 % of the oil. You will get a 1/4 cup of pure oil from the area of the main pump seal (closest to motor area) upon dis-assembly, so be prepared with paper towels. Without using paint thinner to solvent out the oil, overhauling is one messy procedure.
Do yourself a favor, remove the motor from the pump body first. On my pump, I needed to remove the plastic side covers, loosen the Allen set screw from the motor coupler, then remove 4 Allen bolts. Be careful the motor does not drop, as it could damage the plastic fan blade; I removed the two bottom bolts first, wedged my sneakers to support the motor , then removed the top two bolts, slowly backing out the motor. With the motor removed the pump assembly weighs little; trust me with the motor in place working on the pump is a tough. Remove the motor shaft key if it does not stay with the motor coupler.
To make it even easier remove the base plate (part 14), 4 Allen bolts. This way the pump is light and the pump body can be rested standing vertically, much easier to disassemble/ assemble, and can be easily worked on in any position. In the vertical position, o-ring will remain in place during assembly.
Next remove the main pump housing cover (oil box assembly, part 90), 4 Allen bolts. Clean up the oil box interior of metal particles/gunk.
Remove the exhaust baffle (part 108), remove clamp (part 48).
Remove the plate which covers the first pump section, referred to as the rear cover (part 94). Remove gas ballast tube assembly (part 5) by gently but firmly pulling up, while twisting slightly after the bolts are removed from the end plate, and plate is lowered by about 1".
Remove the LV vanes . The vanes in my pump are phenolic material, rather hard material but do not even think of using anything near these which could scratch their smooth surfaces.
To get these out of the LV stage, I could not grip them with my fingers as the space is confined, I used a dental pick (sharp angular point) to grab them on the surface which does not need to be perfect, where the vane springs are, they slid out easily; you could use a small hook tool to hook around the springs if you are using an overhaul kit, as the springs will be replaced. A sharpened piece of thin hard plastic could be used as a wedge between the stator wall and vane. Do not use a screw driver, pliers etc, you could damage the vans or pump walls. Both the LV and HV vanes have a tendency to fly across the room if you do not hold them, I had a set fly 10 feet, finding the springs and pins was loads of fun, especially on a dark floor.
Another method, Loosen the bolts connecting the LV stage to the HV stator, as described in the next paragraph. Once the LV stator has a separation of approx 1/2" from the HV stator, carefully push or tap the LV stator back to it's original position. The vanes will likely not go back to their original position, at this point you should be able to pull them out with you fingers.
Another method but untried. Cut two strips of wet/dry sand paper, 1"x6", oil the back of the paper. Push a vane in with you finger nail or a thin wedge, slip the sand paper under the vane, abrasive side towards the vane, do the other side. Now pull both pieces of paper at the same time.
Loosen the Allen bolts from this pump stage (LV stator, part 20) a few turns (1/4"). If your lucky, by tapping around the LV stator (plasic hammer), the stator will loosen from the next pump stage (HV stator part 9) easily. Go slow here, the matting of parts here are very close tolerance, especially the shaft to stator clearances; so tight they provide a partial seal between the LV and HV pumps. The are two small détentes where you could tap a hard plastic, wood, or aluminum wedge, to separate the stator (on the sides of pump stages), DO NOT use a steel screw driver, a sharpened wood wedge or a piece of sharpened aluminum is soft enough to use. The stator must separate from the next stage evenly,. Once you see a separation develop, keep tapping with the plastic hammer evenly around the separation ( top, side, bottom, side of the LV stator). Once it is loosened, remove the Allen bolts, very carefully pull the LV stator off, do not pivot the LV stator or it will jam due to the close tolerances; do not use excessive force, it is not required. Do not use a metal hammer on any part, all parts in the pump are hardened but very little.
Once the LV stator is removed, the next stage's internals are visible (HV stator), again you will need to remove a set of pump vanes. On the e2m12, you need to carefully remove the entire pump rotor assembly (Part 113), which is now free, slowly pulling forward with the fingers; if a bit tight, lightly tap the shaft from where the motor connects to the pump with a plastic or rubber hammer; this should require very little force . Go slow as the vanes have springs which will shoot the vane assembly across the room if you are not compressing them together as the shaft is removed. Make sure the shaft key was removed previously before removing.
Be extremely careful with all these machined parts; drop them or knock them together producing a dent and your in trouble; seriously dent a bearing surface and the part is lost and VERY expensive.
Next, remove the Allen bolts which hold the HV stator to the pump body rear plate (part 6 adapter? (where the outer seal resides)) . As the stator comes off, there is about 1/4 cup of pure oil between it and the rear seal , no appreciable amount of solvent could get in here, so have paper towels handy.
There is a pressed in solid metal bearing in the E2M12's LV stator, leave it be. I do not see a number for it so if damaged I assume you would need to purchase the entire stator body. Likely it was milled once it was press installed in the stator.
Cleanup time. If you plan on reusing the seals, use a non aggressive solvent. My advice is at least get new seals/O-Rings (available kits); after all this work, you do not want to pull the pump apart once reassembled to reseal.
If you get a kit, then use paint thinner first then Carburetor cleaner or even more aggressive solvents to initially clean the parts (Lacquer thinner works great). You will need to clean all surfaces a number of times. Initially soak everything in paint thinner, cleaning everything with a tooth brush and pipe cleaners (skip the Q-tips). For the final cleaning, with new seals and gaskets in place, play it safe and use a mild solvent such as paint thinner What you are after most is the microscopic metal particles, secondly the gunk.
The following is NOT recommended by vacuum pump manufacturers. Personally I somewhat polished the LV and HV stator surfaces which the vanes contact. With 1500 wet/dry ( with some oil on it), on a hard rubber backing pad I sanded the surfaces lightly. Mine had a couple tiny metal flecks embedded in the surface, just enough to be felt on the finger tips. I sanded enough to smooth the surfaces slightly, but not enough to create a polished surface. Lastly I used a PVC 3/4" pipe wrapped with 1500 to sand, so the sanding marks were perpendicular to the vanes, as were the original milling marks. I did not want to polish the surfaces, so surfaces absorbed oil better; if the surfaces are highly polished, oil will not cling as much. Hard to explain, I was looking to knock of very rough areas, making it all consistent . With 1500-2000 grit you can get a fairly high polish, as in you can see details of your face, this was not what I wanted. I spend roughly 20 minutes sanding total on both stages, this included cleaning often, and feeling the surfaces with my finger tips, and I was not moving fast...basically not a terrible amount of sanding. Sand with oil or paint thinner or the 1500 paper does not cut. Personally I would not use a courser paper, it would cut to much. If the stators have scoring, it is not possible to remove it by sanding without negatively affecting the pumps vacuum ability, leave scoring alone.
I also sanded the matting surfaces where the pumps stages come together (flat surfaces) by placing 1500 paper on a perfectly flat surface and rubbing the matting surfaces on it, again you need liquid on the paper, again do not sand a great deal.
Check the shaft surfaces where the oil seals contacted it. I polished this area slightly with 2000 wet/dry paper. If you have considerable wear/pitting on the shaft due to the seals, you are suppose to use a spacer shim washer, so the seal contacts the shaft in a different area.
After sanding, clean everything again . Every orifice needs to be cleaned out.
The are two shaft seal to be replaced, remember the direction they are installed; the Edwards parts pictorial is not that clear. I will not go into great detail but what ever tools/method used to remove/replace the seals do not scratch the surfaces they go into; your vacuum/oil depends on those surfaces. The inside oil seal (part 55) is a royal pain to get out, I had to create a tool to pull the old seal out. If you have a metal shop, you could easily make a tool for it. I made one from a 3/16 bolt, creating a hook on the end of it by hammering the tip to flatten it, bending the flattened tip >90 degrees, sharpening on a grinding wheel; a Dremel rotary tool would do it. After the fact, I found a seal puller at Pepboys, shaped like the letter J with a small bent up hook.
Installing the replacement seal part 55, you need something close to the outside diameter of the seal to push it into place. I used a common washer, slightly larger then the seal's OD. I sprayed the seal and the housing with Teflon spray ( Borden's Teflon Spray or Remington's (dry powder)) before pressing the seals into the housing; aligns flush with the back of the stator body, do not push further or leave seal a bit above the surface; when you install the rotor, a couple of light taps to the rotor end will seat the seal at proper depth, which is VERY IMPORTANT.
I used a bit of Locktite 290 on the outer seal, after it was installed, as it is very easy to remove/install. On the outer seal I used an old, clean 6203 bearing to push out the old seal and install the new one (with a bit of grease on it); this seal should be easy enough to remove and replace without the bearing; perhaps a properly sized large metal washer would be a help.
Refer to the parts list and disassemble the distributor valve assembly (part 14), clean or replace the distributor rubber (part 40), clean all parts, reassemble.
Cleanup the vanes, spring, pins, if to be reused. If the vanes are very lightly scored. sand with 1500 paper on all side. If highly scored, chipped or worn. replace them. The minor/major kits have new vane springs/pins.
Do a final cleaning, When your parts are clean enough, your solvent soaked white paper towel will remain white after wiping parts; I spent more time cleaning then disassembling/reassembling. Remember, go after the gunk in the pump ports and orifices.
Reassemble in the reverse order, referring to the downloaded parts list, ensuring all O-rings, springs, button valves etc are replaced, oiling all parts before assembly, including the shaft seals. During the reassembly, check the main shaft turns during each stage of assembly. Turning the shaft gets a bit tough after both stages are assembled with the vanes in place.
As far as torque on the Allen bolts... snug fit seems to be OK, do not super tighten. Personally I used a small amount of Locktite 242 for each Allen bolt (let fully cure), I would not full coat the bolts with Locktite, they are rather long, longer then necessary (over engineered), so using a full coat just makes it more work for the next person working on the pump. Locktite 242 releases with normal tools, it is medium strength; DO NOT use a high strength Locktite (such as Locktite red 271), under any circumstances. High strength Loctite requires high temperatures to release which would affect metal hardness, no less even with heat it is difficult to disassemble parts assembled with 271; basically you will ruin your pump.
I have super magnets from computer hard drive activator arms; really strong magnets. I placed one on the bottom portion of the oil box upon reassembly to catch metal particles suspended in the oil.
The glass oil site area had aluminum/steel particles in the area where you view the oil level, it was difficult to see the level. Snaked a pipe cleaner between the stainless back plate and the glass, with paint thinner to clean the glass.
Replace the oil box gasket, I used a lacquer base spray to tack hold the cork gasket to one of the mating surfaces. Bolt up the oil box, again not super tight, replace the base plate. Bolt the motor on, make sure the key-way key is in place, tighten the Allen bolt holding the shaft to the motor fairly tight, but remember your going into aluminum, which does not withstand high torque .
Fill with oil to just below proper level, add some oil to the pump intake . Turn on the pump for a couple seconds, check the oil level, add oil if necessary. Turn on the pump for a few seconds, check for unusual noises.
If the pump has no unusual noise or vibration, let the pump break in by letting it run for hours without attachments.