MP40 with Swollen Magnet

[redfishbluefish]

I need to take a break from MP40’s for a while! (And I’ll include MP10’s as well because I have three of those.)

I just discovered a second MP40 wetside with a crack magnet case with a swollen magnet. The first one occurred about a year ago or so and I assumed it was a one time fluke. Well I guess not!

I have a history with swollen magnets with MP40’s that I blamed on acetic acid…vinegar that is. I documented my experiences here where I lost all the original wetsides on my 2005-2007 MP40’s (four of them):

Beware of Vinegar - The Pump Killer


At the time I ended up buying five new wetsides over about 2 years to replace the ruined ones, with one being a spare.

Well, after my discovery today, I’m not so sure vinegar is the culprit. I’m also not sure I wish to spend another 90 bucks to once again replace the wetside….180 if I replace the spare that crapped out a year ago or so.

After thinking vinegar was the problem with swelling magnets, I switched to citric acid. I also greatly reduced the number of times I was cleaning the wetsides….maybe four times a year. Well reduced cleaning and using citric acid didn’t help me. Here’s what I found today while cleaning the wetsides.

Some might say I can’t complain….these wetsides were purchased between 2016 and 2018, so I got 5 - 7 years out of them. Well I pampered these wetsides and only ran them at about half speed. I’m not a happy camper.

So right now I’m pulling out one of my MP40’s that sits towards the back of the tank and replacing it with a big Jebao I have….shouldn’t be too noticeable.

 

[vtecintegra]

Design flaw in my opinion. The plastic fails to keep water out of the magnet, which then rust. Has been happening for a long time, myself included.

 

[Sisterlimonpot]

I had a hypothesis about this a 3+ years ago. Right around when the vinegar thread became popular.

I never cleaned with vinegar, always with hydrochloric acid because I have a pool and is always on hand.

When I was cleaning the magnet I accidentally set it down onto the corner of my sink that must have ferrous metal behind it because it slammed hard onto the surface.

That action got me thinking that these neodymium magnets are definitely fragile and if slamming it down onto the sink caused a fracture that can also create a stress crack in the plastic.

It led me to consider that maybe we're blaming this on the manufacturer, when it very well might be user error.

Just something to think about...

I started cleaning my wetsides in a laundry room plastic sink and consciously make the effort to prevent it from crashing into anything ferrous.

My findings at this point are strictly anecdotal, but since I've made this change, I've yet to have another swollen magnet.