Magnetic Oil Drain Plugs? The good/bad/ugly?

[Denwa]

I think they're a good idea. If you want one, spend 10 minutes with a drill press, then insert a rare earth magnet from Lee Valley, etc. It isn't like it's going to come loose and get into anything.

Chilly

I will be stopping by Radio Shack ASAP for my rare earth magnet buy.
Thanks y'all for all the input and ideas. Drill press (got it), glue (got it),
magnets (shopping list).

Having mag drain plugs will tell a lot and likely save from a lot of potential
problems by trapping small debris.

Regards,
Dennis

 

[Baby Grand]

Denwa-

Sounds like you have all the gear to do the tight press fit plug.

If you decide to go the loose fit & epoxy route you will need to "vent" the hole. One way is to use a syringe to put the expoy mix only at the bottom of the hole so the air can escape around the magnet as you insert it. If you don't get the air our the magnet will keep popping out of the hole.

-Jim

 

[Chilly807]

You can glue it in if you want, but from my past experience with rare earth magnets, you won't have to.. try sticking it in the new hole first, if you can get it back out it may need glue, if not it's there for good.

Mag drain plugs are good for getting fine particles out of suspension, and they'll tell you if you're starting to get rapid wear in the gear train, etc. More of a comparative tool than anything else, if the first two oil changes show minor buildup then on the third trip it shows a lot more debris, something is going on.

Chilly

 

[Baby Grand]

You can glue it in if you want, but from my past experience with rare earth magnets, you won't have to.. try sticking it in the new hole first, if you can get it back out it may need glue, if not it's there for good.

I would pot it with epoxy, but not to keep it from falling out. As Chilly correctly states, it won't. I would pot it to keep it from fretting due to minute shifting from all the vibration going on all around it. I know, it sort of a belt and suspenders thing, but I'd pot it.

My reasoning: If the fit is loose by .0005" and it sticks to the cylindrical surface of the hole, then it will have only line contact (underconstrained). It's center of mass will be a proportionately large distance from the line of contact with very little preventing it from revolving around the hole in an eccentric path. If it sticks to the cone from the drill point, then it will be making circular line contact (better), but still with it's center of mass removed from the contact, so still underconstrained. It will want to tip and make contact with the cylindrical bore surface. Then it will have 2 point contact - even less constrained. Potting will overconstrain it like a telephone pole in the dirt.

This is why my wife never asks me to do anything around the house [8^).

-Jim

 

[638]

And you are saying that the magnet will wear out ???? Perhaps the oil around the magnet will lubricate it enough to prevent it from wearing out in my lifetime.

 

[Baby Grand]

And you are saying that the magnet will wear out ???? Perhaps the oil around the magnet will lubricate it enough to prevent it from wearing out in my lifetime.

No argument from me about that.

I'm just compulsive about addressing the "perhapses" of anything I design. In my day job I design bearing compartments for aircraft engines, and I don't like fretting. Fretting is bad - I have seen the results.

I'm also not really familiar with the mechanical and physical properties of rare earth magnets. What happens to one if you slowly erode it into wear particles? Are the particles oxides? Will they be ferromagnetic & remain stuck to, or will they separate from the magnet an go wherever? Will they be abrasive? Do I want them circulating around in my engine or gearbox?

I know - it's just a tractor, not an airliner or fighter jet, but I would beat myself up thinking about that, late at night, so I use the epoxy and sleep well. Somehow, my wife puts up with this nonsense.

-Jim

 

[jlrsn]

I'm just compulsive about addressing the "perhapses" of anything I design.
-Jim

I fully understand you Jim, My "What Ifs?" have kept me alive in many an emergency!!
Jim

 

[Denwa]

No argument from me about that.

I'm just compulsive about addressing the "perhapses" of anything I design. In my day job I design bearing compartments for aircraft engines, and I don't like fretting. Fretting is bad - I have seen the results.

I'm also not really familiar with the mechanical and physical properties of rare earth magnets. What happens to one if you slowly erode it into wear particles? Are the particles oxides? Will they be ferromagnetic & remain stuck to, or will they separate from the magnet an go wherever? Will they be abrasive? Do I want them circulating around in my engine or gearbox?

I know - it's just a tractor, not an airliner or fighter jet, but I would beat myself up thinking about that, late at night, so I use the epoxy and sleep well. Somehow, my wife puts up with this nonsense.

-Jim

Well gents, I went to Radio Shack today to procure some rare earth magnets. Lo and behold, Radio Shack has only one size and type available. It's a tad smaller than a 81mg low dose aspirin, and about the same shape only with sharp edges. I checked on line when I got home, and the web site shows the same. Launch Google....

These are the size and shape that look appropriate for the job.

Rod Magnets


This a quite educational site on the "rare earth" subject.

Rare-earth magnet - Wikipedia, the free encyclopedia

Jim,
And, these two pages will likely answer most of your unknowns, Though I certainly don't know how to drive all those charts. If you can deduce anything useful and interpret it for us non engineering types that would be appreciated.

Technical Specifications
Rod Magnet Pull Force Calculator

Jim, your concern with the fretting things is of course well founded in
experience and professional intuition. And, I would say very correct by what the Wiki info has to offer.
Logic would dictate that if particles of the fragile magnet were to get loose in the oil they would likely stick to the closest ferrous object, likely the plug itself. But if they DID go adrift they COULD end up in the gears, or bearings which would not be good. The transmission case on my B20 is aluminum, so if the particles weren't attracted to drain plug or a shaft, then
life could be less good on the farm. Epoxy, definitely epoxy.....


Thanks for the thoughts,
Dennis

 

[Denwa]

Here's another link for rod magnets, right from the TBN page...
Has great size comparative photos.

K&J Magnetics - Products

Dennis

 

[NIXON]

I've always thought that magnetic plugs are somewhat of a waste . In My 22 years of working on acft , every mag plug that read continuity ( fouled ) was just pulled and then wiped off by the engine techs . If You are truly concerned about the metal floating around in the sump ,do a UAO . It'll give You a better idea of what's going on in Your machine .