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My Eagle kit came with a never opened, never used Christen 844 wobble pump. I had heard that when they were built, they were lubed quite well and may work as is, even though it had sat for 35+ years. So, I installed mine as is, and I tried it out after I got the fuel system installed. Unfortunately, it leaked around the fuel valve selector shaft. I started to send it off for overhaul, but I just couldn't resist this opportunity to learn something, even though I might learn it the hard way. I'm kind of dumb like that sometimes, but I figured, how hard could it be? Its just a pump and a valve...
Anyway, below is a brief description of what I learned. In the end, it ended up working great. No more leaks.
I do have to put in a disclaimer here. This is the first wobble pump that I've resealed. I am not an expert on these things. Use this information at your own risk. And remember, this info is worth exactly what you paid for it....
With all that out of the way, here we go.
Here is a list of O-rings that I used. I don't remember the exact quantities. I just recommend getting bags of 50 or 100 from Mcmaster Carr. Use Buna A70 Durometer Orings. These are the most common.
004
010
012
014
019
027
040
.070" Diameter Buna N Cord 1'
I also used Parker Super O Lube for reassembly
First, give the exterior a good cleaning. Remove all of the fittings that might be installed (I didn't do this, but I figured out later that I should have). Remove the filter housing and the filter.
Next, remove the wobble pump handle. To do this, simply loosen the set screw enough to slide the handle, then slide it in so that you can remove the "C" clip. Then slide it out.
Next, remove the fuel selector handle, its cover, and then knock out the roll pins that hold the detent plate down. You can now pull the valve selector shaft out.
Next, remove the main cover. Take your time here. Mine was a little stubborn, but I managed to remove it without scarring up the mating surfaces. After you get the cover off, pull the main pump shaft out.
Next, remove the black plastic fuel outlet pickup. It is only held in place by the spring and friction between the O-ring and its bore. I simply rotated it about 90 degrees in its bore, then I was able to rotate it back and forth a little while pulling to remove it.
Now, remove the screws that secure the casting that contains the pressure relief valve and the pump's check valves. There are 4 of them. Note that these are special screws that have an O-ring groove machined into the bottom side of the screw head. Don't get them mixed up with the other screws. After the screws are removed the casting should come right out. In the 3rd pic below, ignore the black plastic outlet pickup tube. My life would have been much easier had I removed it first.
After you get the casting out, you should be able to remove the pressure relief valve piston, its spring, and its shaft. If your relief pressure is set correctly, don't touch the set screw.
Next, remove the snap rings that are on both sides of the valve. This will allow you to remove the aluminum plugs. Removing the aluminum plugs will take some patience. I had to use an "L" shaped piece of wire that I snaked back through the inlet ports (this is where I realized that I had to remove the fittings) to push the plugs out. They are spring loaded, but they get hung up if you don't push them straight out. Once you get them situated just right, the spring will send them flying across the shop....I found this out the hard way. Use your hand to to cover them up so that you can prevent this.
I also removed the O-rings, and the internal snap rings (sorry no pic). I tried to remove the main fuel valve, but I never figured out how to do it. I chickened out here and just left it alone.
Before reassembly, clean everything real good. You should be able to figure out what O-ring goes where by just comparing the old and the new. There are a couple of exceptions to this. On the black plastic fuel outlet pickup tube, I used a 010 O-ring. It looks to be closer to a 012, but the 012 is too big to allow it to fit back in its bore. The 010 stretches out, and thins out allowing to go back in properly. I couldn't find an exact match to the O-rings that are under the casting's screws. I used 004 O-rings here. They seemed to work fine. The .070" Buna N cord is used to replace the straight "O-rings". Simply cut it the same length as the old.
I used Parker Super O Lube for assembly lubrication.
Keep in mind here that I was working with a new, never used pump. An old, worn out pump probably won't be this easy. I'm guessing that the delrin or nylon or UHMW (I don't know which one) pump "paddle" will wear over time. I think you could machine a new one easy enough, but it will take a little finess to get it to fit right. I don't know if the plastic check valves wear or not, but they would be harder to replace. I'm not sure about the selector valve either.
Anyway, below is a brief description of what I learned. In the end, it ended up working great. No more leaks.
I do have to put in a disclaimer here. This is the first wobble pump that I've resealed. I am not an expert on these things. Use this information at your own risk. And remember, this info is worth exactly what you paid for it....
With all that out of the way, here we go.
Here is a list of O-rings that I used. I don't remember the exact quantities. I just recommend getting bags of 50 or 100 from Mcmaster Carr. Use Buna A70 Durometer Orings. These are the most common.
004
010
012
014
019
027
040
.070" Diameter Buna N Cord 1'
I also used Parker Super O Lube for reassembly
First, give the exterior a good cleaning. Remove all of the fittings that might be installed (I didn't do this, but I figured out later that I should have). Remove the filter housing and the filter.
Next, remove the wobble pump handle. To do this, simply loosen the set screw enough to slide the handle, then slide it in so that you can remove the "C" clip. Then slide it out.
Next, remove the fuel selector handle, its cover, and then knock out the roll pins that hold the detent plate down. You can now pull the valve selector shaft out.
Next, remove the main cover. Take your time here. Mine was a little stubborn, but I managed to remove it without scarring up the mating surfaces. After you get the cover off, pull the main pump shaft out.
Next, remove the black plastic fuel outlet pickup. It is only held in place by the spring and friction between the O-ring and its bore. I simply rotated it about 90 degrees in its bore, then I was able to rotate it back and forth a little while pulling to remove it.
Now, remove the screws that secure the casting that contains the pressure relief valve and the pump's check valves. There are 4 of them. Note that these are special screws that have an O-ring groove machined into the bottom side of the screw head. Don't get them mixed up with the other screws. After the screws are removed the casting should come right out. In the 3rd pic below, ignore the black plastic outlet pickup tube. My life would have been much easier had I removed it first.
After you get the casting out, you should be able to remove the pressure relief valve piston, its spring, and its shaft. If your relief pressure is set correctly, don't touch the set screw.
Next, remove the snap rings that are on both sides of the valve. This will allow you to remove the aluminum plugs. Removing the aluminum plugs will take some patience. I had to use an "L" shaped piece of wire that I snaked back through the inlet ports (this is where I realized that I had to remove the fittings) to push the plugs out. They are spring loaded, but they get hung up if you don't push them straight out. Once you get them situated just right, the spring will send them flying across the shop....I found this out the hard way. Use your hand to to cover them up so that you can prevent this.
I also removed the O-rings, and the internal snap rings (sorry no pic). I tried to remove the main fuel valve, but I never figured out how to do it. I chickened out here and just left it alone.
Before reassembly, clean everything real good. You should be able to figure out what O-ring goes where by just comparing the old and the new. There are a couple of exceptions to this. On the black plastic fuel outlet pickup tube, I used a 010 O-ring. It looks to be closer to a 012, but the 012 is too big to allow it to fit back in its bore. The 010 stretches out, and thins out allowing to go back in properly. I couldn't find an exact match to the O-rings that are under the casting's screws. I used 004 O-rings here. They seemed to work fine. The .070" Buna N cord is used to replace the straight "O-rings". Simply cut it the same length as the old.
I used Parker Super O Lube for assembly lubrication.
Keep in mind here that I was working with a new, never used pump. An old, worn out pump probably won't be this easy. I'm guessing that the delrin or nylon or UHMW (I don't know which one) pump "paddle" will wear over time. I think you could machine a new one easy enough, but it will take a little finess to get it to fit right. I don't know if the plastic check valves wear or not, but they would be harder to replace. I'm not sure about the selector valve either.
