Bonaro
Hero Member
- Aug 9, 2004
- 977
- 2,213
- Detector(s) used
- Minelab Xterra 70, Minelab SD 2200d, 2.5", 3", 4"and several Keene 5" production dredges, Knelson Centrifuge, Gold screw automatic panner
- Primary Interest:
- Prospecting
MY compressor drive belt is slipping a bit and the compressor is at the end of its adjustment so I thougt I would shoot a few pics of how to take a dredge pump apart.
This is a standard Keene 3x4 450 gpm pump driven by a 11hp honda with a Gast compressor.
To begin, get the beast up on a bench where you can work on it
Locate 4 1/2" bolts on the back side of the pump housing (volute) and remove
Tap on the volute with a rubber mallet and it should pop off exposing the impeller. Note there is a big O-ring behind it, just leave the O-ring alone unless its damaged. A full seal kit will have a new O-ring.
Now you have to remove the impeller. My impeller has a center bolt that holds the impeller on a smooth keyed shaft. Yours may have a threaded shaft in which case you would still follow these instruction except you would unscrew the impeller.
i removed the center bolt and then loosened the small set screw in the back that fits into the keyed shaft. The impeller just pulls off at that point. I used a Vise-grip chain clamp to hold the impeller while I removed the center bolt. Another good way to keep the shaft from turning is to remove the spark plug and push a couple feet of starter rope into the cylinder, this will lock the crank.
This is the ceramic part of the seal and it's pressed into the back of the impeller. You should not allow grease or dirt to contact the seal face, dont even touch it. If it's dirty then wipe it with a soft dry cloth.
Next, remove 4 1/2" bolts that hold to pump base to the motor. Notice how the drive belt is woven thru the pump base.
If you need to replace the seal, Keene can sell you this nifty installation tool with the seal kit. You can also drive it in with a punch and hammer f you are handy.
Find a suitable spacer so you can use a pry bar against the compressor to tighten the belt.
Reverse the order to reassemble.
Note: The bolts dont need to be tightened excessively, just good and snug.
Total time spent - about 1hour
This is a standard Keene 3x4 450 gpm pump driven by a 11hp honda with a Gast compressor.
To begin, get the beast up on a bench where you can work on it
Locate 4 1/2" bolts on the back side of the pump housing (volute) and remove
Tap on the volute with a rubber mallet and it should pop off exposing the impeller. Note there is a big O-ring behind it, just leave the O-ring alone unless its damaged. A full seal kit will have a new O-ring.
Now you have to remove the impeller. My impeller has a center bolt that holds the impeller on a smooth keyed shaft. Yours may have a threaded shaft in which case you would still follow these instruction except you would unscrew the impeller.
i removed the center bolt and then loosened the small set screw in the back that fits into the keyed shaft. The impeller just pulls off at that point. I used a Vise-grip chain clamp to hold the impeller while I removed the center bolt. Another good way to keep the shaft from turning is to remove the spark plug and push a couple feet of starter rope into the cylinder, this will lock the crank.
This is the ceramic part of the seal and it's pressed into the back of the impeller. You should not allow grease or dirt to contact the seal face, dont even touch it. If it's dirty then wipe it with a soft dry cloth.
Next, remove 4 1/2" bolts that hold to pump base to the motor. Notice how the drive belt is woven thru the pump base.
If you need to replace the seal, Keene can sell you this nifty installation tool with the seal kit. You can also drive it in with a punch and hammer f you are handy.
Find a suitable spacer so you can use a pry bar against the compressor to tighten the belt.
Reverse the order to reassemble.
Note: The bolts dont need to be tightened excessively, just good and snug.
Total time spent - about 1hour
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