(NOTE this kit will not fit any 71R6 models).  The 71R6 model requires the K634 KIT in our store categories of Rebuild Kits to the left **
  

Condition:  This is a NEW Aftermarket Kit that
Includes: Gaskets, cups, o rings, Sleeves, and will restore the compressor to proper working PSI or HG / VAC Specs.

Fits Gast Models:

Universal 1975-K557D Gast Repair Kit is a replacement part for Universal Gast Compressor (71R642)

71R642-P112-D501X

71R645-P112-D303X

71R645-P112D-D402CX

71R645-V114-D303X

71R647-P112-D401X

71R655-P112-D304X

71R655-V114-D304X

*****    DOES NOT fit the 72R models - we have those available in our store as well.  They have different dimensions but look the same.

If we are accepting returns on an item, it must be returned in its original box, unused, NEW, with all packing materials. If it is factory sealed, it must be returned factory sealed. 

Universal COMPRESSOR SERVICE KIT Instructions

 WARNING: Unplug the compressor before beginning disassembly.

NOTE: All parts in kit may not apply to your specific model.

NOTE: Before you begin, read these instructions thoroughly and assemble the necessary tools. You will typically the following tools:

1/4” Hex Socket attachment for torque wrench

Torx T-27, Philips, etc for attachment for torque wrench (for retainer screws)

Torx T-25, Allen wrench, Philips, etc for attachment for torque wrench (for head screws)

5/32” Allen® wrench for torque wrench (eccentric screw)

Flat Screwdriver (2)

DISASSEMBLY

NOTE: To avoid confusion, service one end of the compressor at a time if applicable.

STEP 2. Loosen the head screws (1) and remove the compressor head (2). Note orientation of head and valve plates for reassembly (very important). Mark with a sharpie.

STEP 3. Carefully remove the valve plates (4) from the bottom of the head, or cylinder sleeves.

STEP 4. Remove the head gaskets if replacing (3). Turn the valve plates over. Remove the valve plate O-rings if replacing (5). Note orientation for reassembly.

STEP 5. Remove the intake valve flapper (1), keeper (2), restraint (3) if replacing, and screw. Clean the bottom of the plate with a clean, soft cloth. Install the new intake valve flapper, restraint, if one was removed, and keeper. The valve keeper should be placed on top of the flapper so that the word “UP” is visible.

NOTE: Pay close attention to valve assembly.

STEP 6. Install the new O-ring gaskets if replacing, seating it firmly into the groove with your finger or blunt object.

STEP 7. Only remove the exhaust valve flapper (1), restraint (2) and valve keeper (3) from the top of the valve plate and discard them if you are replacing these. Clean the top of the plate with a clean, soft cloth. Install the new exhaust valve flapper, restraint and keeper. 

Helpful Tips:  Reed Valve / Flapper Valve Installation:

To install flapper valves and the retainer on top is generally done by holding the 2 pieces with needle nose pliers and tightening.

STEP 8. If replacing, install the new head gasket, seating it firmly into the groove with your finger or blunt object. Set aside. Repeat steps 5 thru 8 to service the other end of the compressor.

STEP 9. Remove the fan guard by depressing the 4 tabs on the side of the housing or unscrewing for some models.

Cup Seal Removal:

Write a line across the retainer with a sharpie in correlation to another part of the permanent housing prior to removal.

Most screws that hold the retainer on will have Loctite previously installed.  It is recommended to heat the retainer up with a torch for a minute or two to loosen this. NOT doing so may cause the screw to strip and in some cases the whole pump must be replaced.  ** Especially on Gast models.

***NOTE orientation of the reed valve with the pump – most retainers have a protruding set pin underneath that MUST be reinstalled exactly, or it will hit the head or valve plate when running, causing noise, and eventually breaking your connecting rod. GSE ZW280 models have these, Thomas 2660, 2680, 2685, and others. The retainer must be aligned to fit in the connecting rod with this set PIN.  

     Cup Seal Installation:  

The easiest way to reinstall the CUP seal onto the connecting rod is to rotate the connecting rod to the top of the sleeve with the fan blades on the side. Place the new cylinder sleeve in the pump around the connecting rod loosely.  HOLD the fan blade in place with your fingers (or have another person hold it still) with the connecting rod at the top of the sleeve while placing the cup seal evenly on the rod on top of the sleeve, place the retainer on top of the cup seal - screw in place while holding the rod by the cooling fan in place.  Rotate this completed side to the bottom of the cylinder sleeve and perform the same thing on the other side of the pump if you have a double head pump.  IF the set pin does not seem aligned – gently loosen the screws and press the retainer around until there is no movement and the set pin feels in place. Tighten down again.

** YES the cup seal is rigid and will fit very tight. That is how it creates compression.

****  On some models, it is easier to have the cylinder sleeve lying flat on a work bench.  Place the cup seal on top of the sleeve, place the retainer on top of the cup seal and with even pressure by your palm push the retainer and cup seal gently into the sleeve.  IF it is bent, crooked, or deformed after this then you would need to remove and try again.  

Then you can place this on the connecting rod and screw it down.

Typically only works on Gast models.

Trouble installing the cup seal??   

IF you cannot seat the cup seal on the piston inside the pump then proceed to step 10 which allows you to remove the whole connecting rod assembly and install the cup seal outside of the compressor.  Otherwise – skip to step 16.

STEP 10. Remove the fan by using two flat blade screwdrivers to pry off, making sure screwdriver contact is made with hub back, and not the fan blades. Note fan orientation for reassembly.

STEP 11. Insert the 5/32” allen wrench (may vary from model you have) into the access hole in the compressor housing on the sides. Loosen the set screw 1/4 turn. Rotate the connecting rod to the top dead center (180°) and slide the connecting rod/eccentric assembly off the shaft and through the opening in the housing.

STEP 12. Secure the rod assembly in a fixture. Remove the sleeve from the connecting rod. Remove the screw from the cup retainer. Remove the piston cup and wipe debris from the top of the connecting rod and retainer with a clean cloth.

STEP 13. Carefully place the new sleeve over the connecting rod top. Place a new cup in the center of the connecting rod top. Do not damage the cup. Place retainer on top of cup (counterbore up – curved side UP), making sure that the cup inside diameter is seated properly over the retaining boss. Note that the retainer has a locating boss (set pin on some models) that must be inserted into the rod top pilot. Tighten the retainer screw. Carefully push the sleeve up around the cup forming the cup.  DO NOT deform, cause sharp bends, or tear the cup. YES, it is a tight fit. This is what causes compression. Stop pushing the cylinder sleeve up when the piston cup is positioned midway inside the sleeve.

STEP 14. Rotate the rotor shaft so that flat faces up (12:00). Position cup at bottom dead center of cylinder sleeve.

STEP 15. Slide the connecting rod assembly onto the shaft until the eccentric face positively stops against the bearing. Align the eccentric setscrew with the flat of the shaft. Rotate the eccentric and shaft 90 degrees so the set screw is visible through the access hole in the housing and tighten set screw.

STEP 16. Align the flat on the fan with the flat on the motor shaft and slide the fan back onto the motor shaft, making sure you position the fan clip in the same orientation as it was before you removed it. Incorrect orientation of the fan will not provide adequate cooling of the compressor.

CHECK OPERATION

Hold the sleeve down against the housing with one hand, and slowly rotate the fan with the other hand to ensure all components are lined up properly. As the piston travels up and down it will also rock from side to side. This is a feature of the WOB-L Piston. Repeat steps 9-16 on the other side of the compressor.