Is it possible to put the prop in the wrong way? My MJ mod keeps spinning backwards forcing the water out of the slits on the back of the shroud. Is the new prop assembly too tight...or did i put the prop on wrong...or what else could it be? What am i doing wrong?
MJ mod spins backwards
- Thread starter zenn
- Start date
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Ed Hahn
Life is A Highway...
Hello Zen,
Sometimes they start back wards. You just unplug it and try it again until it goes the right direction. It should fix itself pretty quick. Good luck.
Sometimes they start back wards. You just unplug it and try it again until it goes the right direction. It should fix itself pretty quick. Good luck.
james734
Well-known member
Not uncommon. Mine will do the same. I just unplug and replug it in until it starts to spin the correct way and let it be. You can place a piece of acrylic rod in there that the prop will hit and correct the direction.
Pic 6 on this page shows it.
http://www.mjmods.com/index.php?main_page=page_2&zenid=a3a68f9923cb9a2cfc993cae96ffc61a
The MJ pump can spin in either direction, which is not a problem one a unmodified MJ.
Pic 6 on this page shows it.
http://www.mjmods.com/index.php?main_page=page_2&zenid=a3a68f9923cb9a2cfc993cae96ffc61a
The MJ pump can spin in either direction, which is not a problem one a unmodified MJ.
james734
Well-known member
so it's impossible to put the prop on backwards right?
cause i tried starting and stopping it and it keeps going the wrong way
This problem can also be caused by prop placement. How far out is the prop. IE: can you see the prop through the shroud when looking at the side.
FYI: I place the prop on there with the notches down/toward the pump end and not out.
Post a few pics of it and I might be able to see the problem. Assemebled/unassembled
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i got it to work. Not sure why it wasn't working at first but it's spinning the right way the last few times i tried it. I just freaked out there a bit. Sorry.
HOLY MOWLY!!! Does this thing whip up the water! I'm building a diy sea swirl as we speak for it. THis is going to be night to just have one powerhead in the tank and not 3-4 all over the back wall.
HOLY MOWLY!!! Does this thing whip up the water! I'm building a diy sea swirl as we speak for it. THis is going to be night to just have one powerhead in the tank and not 3-4 all over the back wall.
brianblack
Well-known member
Yes they do move some water. I built the big 1200 with the Dumas 3004 I think it was and was too much for my tank so I built the MJ900 with the smaller prop and seems it will be OK and I am gonna do the swirl mod - gonna order motors tonight!
lizardarm
Reptilian Disco Biscuit
yeah, that's why the mjmods kit comes with the acrylic rod to put in. so that it'll bounce the prop off if it starts backwards and moves forward. it took me a while to figure out what the heck they were talking about, but it all makes sense in the end.
Ed Hahn
Life is A Highway...
Houston, we have lift off! Congradulations Buddy! Please keep us posted on your progress on Swirler Stein. I want one too.
forgive me but i still don't know how this acrylic rod helps the prop right itself. Do you have any pics or other info on what exactly it looks like and how it works?
james734
Well-known member
Basically what happens is the rod is placed in the shroud far enough out so when the prop is spinning in the correct way it will not hit it. With the prop spinning the correct way it will forces it back into the MJ. But if it spinning in reverse it will try and pull it's self out of the MJ. When it does this it should hit the 1/4 rod and force the prop to spin in the other direction.
Look in Pics 6&7 of in this link.. It shows it.
http://www.mjmods.com/index.php?main_page=page_2&zenid=a3a68f9923cb9a2cfc993cae96ffc61a
Look in Pics 6&7 of in this link.. It shows it.
http://www.mjmods.com/index.php?main_page=page_2&zenid=a3a68f9923cb9a2cfc993cae96ffc61a
i'm still having problems with my mj mod. Things have gotten worse. The pump worked for about a week without any problems. Then this week, it just reversed itself. I thought maybe it was a fluke...but no. In the last 3 days, it's just getting worse. It will run for an hour and then reverse itself, or run for a day and reverse itself. The only way i can get it to spin the right direction is if i start it up and blow air underneath the shroud with a turket baster. Then sometimes it will start in the right direction. But not till after 4-10 trys.
I'm thinking prop placement might be a factor. The Dumas 3004 prop sits litterally a quarter inch or less away from the centering cap. So it's pushed almost as far out as it will go without rubbing on the centering cap. Would it help if i pushed it backwards?
I am also considering going with a smaller prop and moving it back as well. But i dont' want to sacrifice too much just because of this current situation and then wish i'd have more flow out of it. Thanks for the help in advance.
I'm thinking prop placement might be a factor. The Dumas 3004 prop sits litterally a quarter inch or less away from the centering cap. So it's pushed almost as far out as it will go without rubbing on the centering cap. Would it help if i pushed it backwards?
I am also considering going with a smaller prop and moving it back as well. But i dont' want to sacrifice too much just because of this current situation and then wish i'd have more flow out of it. Thanks for the help in advance.
Cut your impeller to its final size . for the large shroud with the dumas 3004 that is between 4 1/8†and 4 ¼†depending on how high you put the stopper. The idea is unplugged the prop should be about 1/8†under the stopper and running it should be about ¼†( you can simulate it running by sticking your finger in the shroud and pushing the impeller down) the length for the larger octura props will be different . I am unable to give you an exact size for the small shrouds because they are hand made and each one is a slightly different size but use the information above so the prop runs about ¼†below the stopper.
That's from the instructions on the mjmod.com website. It says the length of the impeller should be between 4 1/8 and 4 1/4. Mine is exactly 4 inches long. I don't think i could make it too much long though as it's already touching the centering cap pretty much.
I'm starting to think I'm just unlucky.
That's from the instructions on the mjmod.com website. It says the length of the impeller should be between 4 1/8 and 4 1/4. Mine is exactly 4 inches long. I don't think i could make it too much long though as it's already touching the centering cap pretty much.
I'm starting to think I'm just unlucky.
brianblack
Well-known member
Everything looks good except the shroud seems to be missing the 3/16 acrylic rod at the end by the output cap. This rod should stick in about 3/4 inch or maybe was the overall length. I think the hole should be drilled about a 1/16 or so from the end of the shroud and the rod glued in there. this is what the impeller will hit when starting backwards - rebound and change direction to spin forward. I will have to find my camera and show ya mine. I have built a 1200 with the Dumas and a 900 with the octura. Both run fine so far. I have the 1200 in my salt mixing container - too much power for the 75. The 900 is waiting for me to build the swirl mod. Another thing is how much movement do you have or space from the end cap to the 3/16 tube the prop is mounted on. There needs to be a little movement there so it can hit the acrylic rod. AC motors like this can move the magnet either way on startup. That is why the original impeller blades are not angled like the prop.
Best to show you mine
Best to show you mine
brianblack
Well-known member
No not unlucky - I thought the directions were a bit vague for someone who is not used to tinkering. I made all my stuff - just bought the props and rods from them. Photoshopping pics now
The first pic is my 1200 inside the shroud. The Acrylic pin is coming up from the bottom almost to center.
The second and third are where I put the pin in the shroud
The fourth(900) and fifth(1200) is the space on the shaft from the end to the 3/16 tube
Hope this helps
The first pic is my 1200 inside the shroud. The Acrylic pin is coming up from the bottom almost to center.
The second and third are where I put the pin in the shroud
The fourth(900) and fifth(1200) is the space on the shaft from the end to the 3/16 tube
Hope this helps
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brianblack
Well-known member
Sorry missed this key piece of info. your prop tube needs some movement on the inner shaft. ie when it starts up backward it pulls the prop to the front of the housing where it will hit the acrylic rod and bounce back and change direction forward forcing the prop back into the shroud. That is the whole idea for the acrylic rod to work so your water blaster will always run forward. So putting in the rod and cutting some off the front of the 3/16 tube enough to allow the prop to hit the acrylic rod on the forward movement and clear on the reverse movement (pretty much when you assemble it it should be in the 'running position' since the motor sucks the magnet all the way back) and it should work well. The prop needs to hit the rod for it to work properly. Hope this helps
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yeah that helps. I didn't understand the stopper until just now. I didn't get an acrylic rod and don't know where to find one. Where can you get them (preferably not online either unless I have to)?
I'm thinking the Dumas 3004 might be too much power for my 75g anyways. I think i'll order a smaller octura just so the flow isn't blowing sand all over the place and whatnot. Plus, a smaller prop probably wouldn't spin backwards as much. Eitherway, i'll need to put in that stopper.
I'm thinking the Dumas 3004 might be too much power for my 75g anyways. I think i'll order a smaller octura just so the flow isn't blowing sand all over the place and whatnot. Plus, a smaller prop probably wouldn't spin backwards as much. Eitherway, i'll need to put in that stopper.
actually, i'm thinking i could just widdle down the prop i've already got on there a bit to make it smaller/easier to turn. Then i could cut the impeller a little bit to give it some play like you said. I don't have any acrylic rods laying around but i do have some acrylic. Why couldn't I just superglue a small piece of acrylic onto the center brace/side of the shroud to act like an acrylic rod? wouldn't that be pretty much the same thing?
