Installation and replacement instructions

Pump seal · Marlex pump coupler · Compressor drive assembly

The water pump seal must be replaced if water is observed leaking between the engine and pump adapter or around the engine shaft,. To replace a seal or to install a compressor drive assembly (engine shaft pulley and drive belt), the pump must first be removed from the engine.

INSTRUCTIONS TO REMOVE THE PUMP FROM THE ENGINE:

1. Note: If the pump has been in use for a year or more, we suggest that you apply a penetrant such as "Blaster" to the engine shaft threads and allow it to penetrate the threads of the engine shaft. Saturate for 24 hours before attempting to remove the impeller from the engine shaft!
   
2. Remove the four housing bolts and remove the pump housing. If the housing does not pull off easily, gently pry it off with a screwdriver. Inspect the housing gasket and replace if necessary.
   
3. The impeller is directly mounted to the engine shaft and will unscrew in a counter clockwise direction. Before attempting to remove the impeller the engine shaft must be locked in a fixed position to prevent it from turning. A simple way of locking the shaft is to insert a pointed tool such as a screwdriver or an awl through one of the many holes in the starter assembly and turning the engine over until the tool is firmly locked in place by the starter housing cover.
   

IMPORTANT: Always disconnect the spark plug wire before attempting any repairs or service on your pump or engine. Once the engine shaft is locked into position, there are two methods that can be used to remove the impeller.

Methods of removal:

1. Use a block of wood, such as a 2x4 and place one corner of it into one of the impeller vanes on the left side of the impeller and strike the block of wood sharply with a hammer. This should loosen the impeller and enable it to be unscrewed in a counter clock-wise direction.
   
2. If the above is not successful, use a thin breaker bar or a heavy duty screw driver. Insert the blade into one of the impeller vanes towards the left side and try to unscrew the impeller by applying a downward pressure. If this still does not work carefully strike the end of the bar with a hammer until the impeller loosens from the shaft. If this still does not work, strike gently with a hammer. This method may cause a chip in the vane of the impeller. Depending on the size break of the corner of the impeller, it may or may not have adverse effects on the performance of the pump. So be careful!

SEAL REMOVAL AND INSTALLATION:

1. All of our pumps use a two piece seal assembly, with the exception of some older models (P-50 and P-60). One half of the seal located in the backside of the impeller is called the "seat", or ceramic portion. The other side of the seal is shrouded in a brass encasement, encasing a hardened material that rests against the ceramic portion of the seal. Always replace both sides of the seal. Remove the ceramic portion with a sharp object similar to a screwdriver and press the new seat into place by hand. Always inspect the seal to note that it is not cracked. Always place the smooth surface of the seal to the outside.
   
2. Remove the pump adapter from the engine and press the brass portion of the seal towards the outside from the back of the adapter. If it cannot be pressed out easily, place a screwdriver handle on the seal and gently tap it out. When replacing, it is suggested that a small amount of silicone sealant be placed on the brass portion that fits into the adapter to ensure that it will not leak. Be careful not to get any sealant on the face of the seal. Position the seal in the center of the hole and press gently by hand into the cavity as far as possible. Use a screwdriver or a blunt instrument and tap the seal gently around the edge of the seal in a circular motion until the seal is firmly fitted into place. Wipe off seal facing with a clean cloth before reassembling.
   
3. After both sides of the seals is installed, replace the pump adapter onto the engine and carefully tighten. Thread the impeller onto the engine shaft until the impeller is hand tight. Install the housing and use care not to over tighten the bolts to avoid stripping the threads as they are a soft alloy aluminum.

HOW TO INSTALL THE HOSE ADAPTOR PUMP INTAKE COUPLER:
  (For all models except the P-50 and P-300 Series).

The tolerance of the Hose Adapter is critical for proper pump performance. The hose Adapter should be installed as close as possible to the intake portion of the impeller. Center the adapter into the housing opening and press in by hand to locate it into place and place a wooden block against the outside of the adapter and gently tap until the adapter is firmly seated against the face of the impeller. Pull the starter rope until the engine turns. When the coupler is properly seated, the engine should be somewhat difficult to turn over, making sure that the adapter is against the face of the impeller.

COMPRESSOR DRIVE INSTALLATION:

To install the shaft pulley and belt for a compressor adaptation, the pump must be completely removed from the engine. For larger engines to include the 8 HP through 18 HP engines, slide the pulley to the back of the engine shaft and tighten the set screw. To install the engine pulley on smaller engines to include the 3HP to 5HP Engines, the furnished bushing should be pressed onto the pulley at the factory to ensure proper alignment and spacing. If you choose to install it yourself, this can be accomplished by placing the pulley on a flat surface, center the bushing in the hole of the pulley and gently drive it through by tapping it with a hammer taking care not to damage the bushing. The bushing should be pressed or driven through the pulley, in a flush position to the other side of the pulley. It should not extend though the other side. Then install the V Belt before placing the pulley and bushing over the engine shaft. After the pump is installed and secured, mount the compressor and compressor pulley. Install the V Belt to compressor and make sure that the alignment is correct. You can compensate for some misalignment by adjusting the compressor pulley on the compressor shaft. Tighten firmly the set screw and all bolt and check for any misalignment before starting.