MJ mods-Is anyones actually working?

[Mdwannabe]

Gflat:
I would have to agree, if they work correctly out of the water, then we shorted you on the inlet cuts. We did a lot of mod's in a very short time, so inlet cut's being too small is a valid possibility.
Just try opening up the inlet cuts on one pump and see if it solves the problem. My 900 double prop mod's are still working fine.
JMTCW, Chris, you may want to give you're input.

Rick

 

[dhnguyen]

Here's how I do my housing if it helps.

total length of housing 2.25"

Starting from the bottom where the flanged groove is go 1/2" then I start measuring and mark every 1/4" for 6 slots total

Each mark is where the inlet slot will be cut.


The rigid tubing is 1.25" in length.


D.

 

[c_stowers]

Thanks for the numbers D.. I will have to check mine when I get home.

 

[gflat65]

My housing is 2" instead of 2 1/8" and there were only five cuts, but they look like they are the width of three blade passes. I cut the lower slot out on both sides of one and it is still changing directions constantly... Let me go get some pics...

 

[gflat65]

Finally. Here are some pics. I measured one of the rigid tubes at 1.1875". Could a short shaft be the problem (no more from the peanut gallery)?

I opened one of the shrouds up (removed the lower most divider on both sides of the pump) and got the same reaction. I have one that has been working since I replaced the flex tubing with a more rigid flex tubing (1/4" RO type tubing). Another one ran through the night with no problems, then somehow knocked the center brace off. I reglued it and reassembled, but to no avail... Any ideas?

 

[dhnguyen]

That rigid tubing looks to be a lot longer than 1.1875" almost looks like 1.75" from the start of the propeller to where it connects to the magnet. I would suggest cutting that down some still. Cut it down to 1.25" in length from the tip of the propeller to where it connects to the magnet.


D.

 

[gflat65]

I obviously can't read a tape... I don't know how I got 1.1875"... I thought you were seeing a trick of angles and perception, but I remeasured one on mine and one of the spares and the rigid tubing is 1.6875"... I'll cut mine down and see how that works...

 

[gflat65]

Forgot to add...

Thanks D.

 

[Mdwannabe]

Mine are still working fine (900 double props x2).

Thank's D for the input, maybe we missed something simple in the 60+ mod's we did, at least I hope it is simple. Seem's the 1200 mod's are our biggest problem.

Sorry for the problems folks, but I'm sure we can work it out, especially with "D" monitoring the post's.

Again THANKS "D"

Rick

 

[rcmike]

I checked mine today and it is doing just like rsteagalls is doing. It has wallowed out the hole in the acrylic piece and is wearing a grove in the plastic part of the stopper. I looked at the Seio I have and it has a ceramic part on the end and the middle of the impeller magnet is ceramic as well. We need some sort of washer that can stand up to the abuse. Anyone ever seen a small ceramic washer?

 

[dhnguyen]

Hmm... Do this for a quick and dirty washer. Take a rigid tubing and cut a small sliver of it and use that as a washer of sorts. Should hold for a while and be cheap to replace at any rate.

I've been running mine since July or August of last year 24/7 and have not had this wearing problem.



D.

 

[rcmike]

I have some plastic/nylon type servo horns from R/C servos that I may cut some washers out of. I think they would hold up better than airline tubing. I had some nylon washers somewhere but I can't find them.

 

[Mdwannabe]

Well...I'll keep you updated on my mod's. As I said, they are still running fine.

Have them pointed up at about a 40 degree angle, not sure if this matters, but that's where mine are and they still work fine.

Rick

 

[gflat65]

I shortened the rigid tubing to 1.25". One of them is working. I had to put a spacer above the prop on one of them and it will now only turn backwards (blows out rather than in). The other one has popped the center brace off within 30 seconds of being turned on three times... This is frustrating. At least one is going for now. I've had luck with one out of three running for up to three days with no issues on several occasions in the past... I'll relax a little and try again on the one that keeps popping off the center brace. Maybe the 900's are better off.

 

[dhnguyen]

<a href=showthread.php?s=&postid=7137979#post7137979 target=_blank>Originally posted</a> by gflat65
I shortened the rigid tubing to 1.25". One of them is working. I had to put a spacer above the prop on one of them and it will now only turn backwards (blows out rather than in). The other one has popped the center brace off within 30 seconds of being turned on three times... This is frustrating. At least one is going for now. I've had luck with one out of three running for up to three days with no issues on several occasions in the past... I'll relax a little and try again on the one that keeps popping off the center brace. Maybe the 900's are better off.

Let me guess. That one that keeps popping off the center brace is the larger 1.75" Dumas prop on a MJ1200 right? What you need to do is notch out a little groove in the housing where the brace is glued into, that will make it much stronger to be able to withstand the force of the 1.75" Dumas propeller. This is from experience


D.

 

[gflat65]

Ahhh. I'll give it a shot. A dremel really earns its keep around a reef addicts house. I'll need to either shorten the shaft or push the bushing out a little from the shroud if I do this, since the center brace will be a bit lower in the shroud, right. I'm thinking the bushing relocation will be the better fix, as it can be adjusted.

 

[Mdwannabe]

On-going update. Both my 900 double prop mod's are working fine. Could angle of discharge be a consideration "D"?
Just wondering.

Rick

 

[dhnguyen]

<a href=showthread.php?s=&postid=7139042#post7139042 target=_blank>Originally posted</a> by Mdwannabe
...Could angle of discharge be a consideration "D"?
Just wondering.

Rick

Possibly but only if you're pointing downward where the force of gravity may push the magnet out and causes problem. I have mine pointed straight horizontally and there're no problems at all.

 

[rcmike]

I put a nylon washer I made in mine and it is working fine now. I think the force of the 1200 with the big prop is just a little too much for the plastic base of the impeller shaft. The 900 probably doesn't have that problem as much since it isn't pushing as hard back into the pump.

 

[rsteagall]

rcmike, i have yet to get or use any kind of washer on mine. But my double prop 900 defintely pushes back into the pump and has made indentions on the plastic base of the impeller shaft. I need to go to Lowes today. If I can, I'm going to get a SS one.