- Thread starter DennisCA
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You can buy machineable ceramics - maybe you can make your own ceramic sleeve?
www.ortechceramics.com
Macor Glass Ceramic- Machining Information
Macor® is a machinable glass ceramic material that posses outstanding engineering properties. Unlike other ceramics, Macor can be machined with ordinary met
www.ortechceramics.com
carbon
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Some pumps have ceramic piston’s of 28mm and 36mm diameter I’ve found one that is 32mm x 63 but not sure I’d want to buy four to modify that pump as the cost would be prohibitive especially if you managed to crack one installing it.
Another option would be to not use the cylinder with the bad piston by not connecting it into the inlet or outlet pipework. You will lose 25% of the flow but with the correct jetting you could maintain the pressure.
Every quality pump I've ever worked on, including CAT, Karcher, KEW, WAP, Interpump, Speck, Kranzle, etc all use a fibre reinforced hard rubber/plastic hp seal. The only ones that use a non reinforced rubber seal are the cheap domestic washers.
Every quality pump I've ever worked on, including CAT, Karcher, KEW, WAP, Interpump, Speck, Kranzle, etc all use a fibre reinforced hard rubber/plastic hp seal. The only ones that use a non reinforced rubber seal are the cheap domestic washers.
DennisCA
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I can find softer and harder seals, doesn't say anything about fiber though. The harder seal says it will not bend while a softer will be able to be folded into the slot.
BTW, upon inspection of all the other seals they all look whole and intact, though hey are very hard and likely brittle enough that trying to remove them would break them. Even the seal around cylinder 1 with the worst corrosion looks fine surprisingly. It's only the seal of cylinder 2 that looks bad, which ironically has the least corrosion.
BTW, upon inspection of all the other seals they all look whole and intact, though hey are very hard and likely brittle enough that trying to remove them would break them. Even the seal around cylinder 1 with the worst corrosion looks fine surprisingly. It's only the seal of cylinder 2 that looks bad, which ironically has the least corrosion.
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DennisCA
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Mostly been working on disassembling the pump fully. It's full of debris of some kind. I dunno if it's rust or something else. I broke my 3 jaw bearing puller three times getting the adapter that fits on to the bottom bearing off. Had to resort to a propane torch and heat cycle it a few times. Also rewelded the puller a few times. It's not very beefy but the only I got that fit in there.
Big gear came off with a lot of resistance too, but I had a big bearing puller to use at least.
This I think is the last bit keeping everything together. Once that is gone the shaft should fall out and the pistons should be removable.
The pump housing is actually aluminum, so I wonder what all this brown crap is. Is it rust? It looks like it, but also doesn't exactly feel like it.
Big gear came off with a lot of resistance too, but I had a big bearing puller to use at least.
This I think is the last bit keeping everything together. Once that is gone the shaft should fall out and the pistons should be removable.
The pump housing is actually aluminum, so I wonder what all this brown crap is. Is it rust? It looks like it, but also doesn't exactly feel like it.
DennisCA
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The pistons are double sealed though, behind the water seal there is a space that is open to the air via two holes, I think it's a sort of compartment to prevent the two from leaking into each other. After the compartment the oil facing part has it's own seal (they all look to be whole) and PTFE gaskets. I guess it's still possible for water to make it's way in there, but then oil should also be coming out of the housing if water was coming in there.
carbon
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I see this when the water seals fail, even when there is an open space between the water seal and oil seal water still manages to pass past the oil seal and contaminate the oil. The oil seal will only stop the oil coming out of the pump it won’t stop water getting in. I think in the last 40 years I’ve only seen one pump that had two oil seals fitted per cylinder with the outer one reversed in an attempt it stop water getting in. Even that wasn’t very successful and water still managed to contaminate the oil and damage the bearings inside.
DennisCA
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WNMG inserts work well on machining away the hard chrome. After I used the angle grinder anyway to lob off the corroded end.
I was thinking of threading the replacement rod in place, and maybe using a carefully turned shoulder to make sure it's aligned. I don't really have the ability to do any further turning once I fit the pieces together, then it has to be on and be concentric.
Also I don't know what purpose if any the hole in the center of the piston played, I had not planned on replicating that feature. Actually I do, but as a threaded hole to fit a stainless face cover.
I was thinking of threading the replacement rod in place, and maybe using a carefully turned shoulder to make sure it's aligned. I don't really have the ability to do any further turning once I fit the pieces together, then it has to be on and be concentric.
Also I don't know what purpose if any the hole in the center of the piston played, I had not planned on replicating that feature. Actually I do, but as a threaded hole to fit a stainless face cover.
DennisCA
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The thing I have not yet ordered are new seals for the cylinders. I am unsure what to get. I decided to get more info on my hands on more data. The thing I was more worried over was the speed the pistons would work at, secondly the hardness of the seals. They can't be too hard or you cannot get them into the turned slot they fit into, so they need to deform a little for installation.
For the matter of speed I looked for stats on what speeds PU seals work at found a maximum speed of .5m/s. Then I went and measure the cam action of the pump and found it has about a 10mm stroke, possibly a little longer. The motor is a 1435 rpm motor, using that I get a piston speed of .473m/s
So great! I look to be inside specs. It seems the pump runs even slower than the motor, since the pulley ratio has the motor pulley as the smaller one. I have not counted the actual ratio but I don't care, it's only in my favour regardless of what it is. I feel I can with a good degree of certainly order PU U-seals.
I suppose this is indicative of how an older pump differs from a modern pump. Lower RPM, but displaced volume per stroke is greater.
For the matter of speed I looked for stats on what speeds PU seals work at found a maximum speed of .5m/s. Then I went and measure the cam action of the pump and found it has about a 10mm stroke, possibly a little longer. The motor is a 1435 rpm motor, using that I get a piston speed of .473m/s
So great! I look to be inside specs. It seems the pump runs even slower than the motor, since the pulley ratio has the motor pulley as the smaller one. I have not counted the actual ratio but I don't care, it's only in my favour regardless of what it is. I feel I can with a good degree of certainly order PU U-seals.
I suppose this is indicative of how an older pump differs from a modern pump. Lower RPM, but displaced volume per stroke is greater.
Gareth J
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I know it's a bit dull, but might be worth checking to see if you can find, and the cost of, a new hollow shaft pump from the likes of interpump. Before spending too much time and cash on odd sized seals and pistons. Just to compare.
You might find a new pump, using your existing motor, frame and bypass plumbing, doesn't work out that expensive. And spares will be obtainable.
You might find a new pump, using your existing motor, frame and bypass plumbing, doesn't work out that expensive. And spares will be obtainable.
DennisCA
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Quick look for interpump prices on ebay, 300-800 euros depending on model.
Price for new shafting material and seals, in the order of 70 euros. I ordered the new shafting last week for 50 euros shipped. So to me this still looks like the cheapest option.
Price for new shafting material and seals, in the order of 70 euros. I ordered the new shafting last week for 50 euros shipped. So to me this still looks like the cheapest option.
To install the seals make a brass collar with an internal taper going from the seals outer dia to the inner diameter of the slot they go into. Make it as long as possible to make it easier to get the seal in.
To push the seal you can make up a plastic mandrel with the end profiled to suit the shape of the seal & a bit sticking out the same dia as the internal seal dia.
To push the seal you can make up a plastic mandrel with the end profiled to suit the shape of the seal & a bit sticking out the same dia as the internal seal dia.
DennisCA
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Well I drawed up the pistons in cad. I find doing that helps me consider just how to go about it and also making sure everything will end up the right size. So this is how I planned to do it. Use a matching taper instead to align the new piston part, and use a bolt, hex bolt most likely to screw it in place. Then cap that with a stainless top face. I was wondering if I should use an o-ring to seal the face, but I think a flat face will work, a slight countersink near the threads though. Then use a gasket ot something like Hylomar to seal it up.
