MW 2250 PISTON MECHANICAL PROBLEM
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bloke
- Mid South Music
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Re: MW 2250 PISTON MECHANICAL PROBLEM
Before attempting to figure out if there's something weird causing that phenomenon (such as an imperfect casing or piston) I would do these things:
- clean the bottom cap interior
- clean the ports going in and out of that valve casing. (This is not nearly as easy as typing these words about doing it, even some so-called "techs" don't do a complete and thorough job of this.)
- completely dry out that valve casing and piston, and carefully examine their surfaces fpr scale. Use your flashlight or your phone light to reveal this. Scale is either white or greenish white. For a piston to ride nicely inside a casing with both of them coated with scale is basically expecting them to ride nicely against each other with a very thin coating of limestone rock on both of them.)
- This one requires finesse and care: Gingerly run a very small very sharp tipped object down the valve guide track in each corner, and check for built up scale, trash, or imperfections.
- check the valve guide itself.
As a repair guy, the first thing I would do - after having done all of those - would be too run the piston in the casing up and down by hand and see if I can detect any friction points with my fingers. If I felt such places and before doing something more radical - particularly if I felt one friction point at the port which connects the mouthpipe to the first valve casing - and check for tension that might be able to be released from from heating the solder at that connection just enough to allow it to shift, but not enough to allow it to make a horrible mess.
You might want to just take it to someone who has a really good reputation for messing with stuff like this - stuff which can easily be messed up by someone who really doesn't know what they're doing. It might be worth driving a few hours to reach someone like that. The idea/goal is to do as little as possible - beyond the cleaning steps outlined, and I didn't discuss how to remove scale - to make it work properly.
Realize that the piston and casing were originally manufactured with very sophisticated tools, and some people tend to use some pretty hillbilly types of tools to try to make them work as they did before. That usually doesn't turn out well.
- clean the bottom cap interior
- clean the ports going in and out of that valve casing. (This is not nearly as easy as typing these words about doing it, even some so-called "techs" don't do a complete and thorough job of this.)
- completely dry out that valve casing and piston, and carefully examine their surfaces fpr scale. Use your flashlight or your phone light to reveal this. Scale is either white or greenish white. For a piston to ride nicely inside a casing with both of them coated with scale is basically expecting them to ride nicely against each other with a very thin coating of limestone rock on both of them.)
- This one requires finesse and care: Gingerly run a very small very sharp tipped object down the valve guide track in each corner, and check for built up scale, trash, or imperfections.
- check the valve guide itself.
As a repair guy, the first thing I would do - after having done all of those - would be too run the piston in the casing up and down by hand and see if I can detect any friction points with my fingers. If I felt such places and before doing something more radical - particularly if I felt one friction point at the port which connects the mouthpipe to the first valve casing - and check for tension that might be able to be released from from heating the solder at that connection just enough to allow it to shift, but not enough to allow it to make a horrible mess.
You might want to just take it to someone who has a really good reputation for messing with stuff like this - stuff which can easily be messed up by someone who really doesn't know what they're doing. It might be worth driving a few hours to reach someone like that. The idea/goal is to do as little as possible - beyond the cleaning steps outlined, and I didn't discuss how to remove scale - to make it work properly.
Realize that the piston and casing were originally manufactured with very sophisticated tools, and some people tend to use some pretty hillbilly types of tools to try to make them work as they did before. That usually doesn't turn out well.
- These users thanked the author bloke for the post (total 2):
- Ace (Sun Aug 27, 2023 10:09 am) • TheBerlinerTuba (Sun Aug 27, 2023 4:32 pm)
Re: MW 2250 PISTON MECHANICAL PROBLEM
Thanks a lot for ur advice! its really worked!!! When I encountered this problem (the first piston rebounds slowly), someone told me that is a defect of MW2250.I mean, his words tend to make me belive that all 2250 have such problem, beg me pardon,sir, have u ever heard of something similar? To be honest, I just got this instrument for nearly 2 month, so it's horrible to enconted any problems on it now. One more thing, could u please tell me something more about instrument maintenance? I would be appreciate if u do that! Anyway, thank you very much!!!
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bloke
- Mid South Music
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Re: MW 2250 PISTON MECHANICAL PROBLEM
If it's new, you're going to need to be OILING it a tremendous amount.
The shiny-brass valve casings are tarnishing (turning from yellow-brass to brown-brass) and tarnish does NOT form as if a smooth coating of paint.
Tarnish forms ROUGH, and needs to be scuffed SMOOTH (by the pistons) and OIL takes away the rough brown tarnish.
...Let casings turn brown and STAY brown, but OIL the pistons a TREMENDOUS amount - so that the forming tarnish is polished smooth by the pistons.
This is a "years" (not weeks) thing.
I oil the valves in my (NOT new) instruments every time I play them. It puzzles me that so many do not. Oil for valves is VERY thin, and there's nothing to keep it in place (and is mostly evaporates).
I also use VERY inexpensive oil, but everyone else is sick of hearing about it...
The shiny-brass valve casings are tarnishing (turning from yellow-brass to brown-brass) and tarnish does NOT form as if a smooth coating of paint.
Tarnish forms ROUGH, and needs to be scuffed SMOOTH (by the pistons) and OIL takes away the rough brown tarnish.
...Let casings turn brown and STAY brown, but OIL the pistons a TREMENDOUS amount - so that the forming tarnish is polished smooth by the pistons.
This is a "years" (not weeks) thing.
I oil the valves in my (NOT new) instruments every time I play them. It puzzles me that so many do not. Oil for valves is VERY thin, and there's nothing to keep it in place (and is mostly evaporates).
I also use VERY inexpensive oil, but everyone else is sick of hearing about it...
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bloke
- Mid South Music
- Posts: 19412
- Joined: Thu Aug 13, 2020 8:55 am
- Location: western Tennessee - near Memphis
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Re: MW 2250 PISTON MECHANICAL PROBLEM
If you were talking to me, I suppose.. but sometimes I don't even notice friend requests because don't check them very often. You can always ask me stuff here. If I'm going to accept a friend request on facebook, I need to know what your name is, and if you don't want to put it here you can private message it to me. If your last name is the same as this k word, then I should be able to find it.