Magnets and Hot Motor Oil

[amgine]

Thanks for the prompt reply, Flux.

Alnico is what I have.

Wondering if the negative effect of temperature on Neod is instantaneous, or cumulative ?

A motor only does about 10 or 15 hours at full operating temperature between oil changes ( 750 to 1,000 kms )

Naturally I want the strongest possible magnet in there, and if it takes a longer time for a Neod to decay at 100 + degrees C then that's fine as I can well afford to replace at each oil change.

Surely some experiments have been done on heat degredation vs temp, just I can't seem to find such info.

amgine

[amgine]

NOW I can see how to post a Comment - for some reason my last Posting didn't give me an option to Post a Comment, spent quite some time looking to see how - sorry for wasting bandwidth :-)

amgine

[Flux]

Information is contradictory so I am reluctant to comment.You are well below curie temperature but there are certain instabilities in the material that start to show above 80 deg C for some grades. The best grades on the face of things should be ok to a temperature of 110 deg with no demagnetising field.

I boiled a neo magnet at 100 deg with no loss at all, I did this after advising someone here to boil a magnet rotor to break the glue to remove them. He managed to remove them but claimed to have seriously lost field. I do wonder if the problem was direct transfer of heat through the saucepan raising the temperature above 100 c.

I believe the later neo magnets are more stable than the earlier ones due to continual improvements in the manufacturing process.

Personally I think you will get away with running them at 110C for fairly long periods in your application but don't blame me if they fail.

Flux

[amgine]

Thanks again.

Of course a magnet sitting on the bottom of a saucepan could get to well above boiling point - doh !

Looks like I'll have to do some experimentation.

Will try suspending some in hot oil for a while and see what happens,

I'll report back to you with the results, and if I burn the house down, don't worry, I won't blame you :-)

amgine

[Flux]

Have a look at

http://www.magnetweb.com/

There is obviously problems above 60 dec c if you take the magnet back along the third quadrant but without any reverse field you should be safe to about 120deg.

Fairly closed magnetic circuits should be able to manage nearer 140 deg C but your magnetic circuit will not be particularly good and you will have some self demagnetising field but 110 should be possible.

If you can find magnets with H or SH after the grade number I believe these are the high temperature ones and will do it easily.

Good luck.

Flux

[wooferhound]

I tried to post a comment on here earlier and Comments were disabled somehow.

What I was gonna suggest is to place the magnet outside of the motor. I have had many friends say that they just stuck a really strong magnet onto the bottom of the oilpan under the motor on thier car. The magnetic field will go through and attract the metal bits that you may be speaking about. I don't know much about motorcycles, but there should be some area like a rubber hose or some area close to where the oil is running or sitting where you could attach a magnet.

Just a side note, many motorcycle blocks are made of aluminum, if this is the case on your motorbike then the magnet will not remove those bits from the oil.

I have heard of people doing this to motors since I was very young in the 60's, but I've never heard of anybody saying that it really worked. Has anybody else here tried this magnet motor thing ?

[maker of toys]

it was/is quite common to do this sort of thing with air-cooled VW bug engines. there you're not so concerned with aluminum; all the bearings were shell-type so aluminum wear particles big enough to cause trouble were rare.  (you'd get a little from piston scuff when the engine was cold, but that's about it)

you could tell how your engine was doing by the amount of swarf accumulated on the plug. if the magnet was completely obscured, you were due for an overhaul, as you'd overstressed the thing somehow.  Long 4th gear climbs out of death valley in the summer will thin your oil pretty effectively. . .<G>   (my '64 Bug had/has close to 600K on the clock, and it's spent about 20 years of its life up on blocks waiting for inspiration to strike. )

I also ran a magnetic plug on both the engine and transaxle of my X1/9-  I was always a little concerned at the amount of steel that accumulated on the transaxle plug. The engine plug stayed pretty clean; I guess the oil filter was doing its job.

it is not uncommon to include a magnet on the drain plug of aircraft, heavy equipment and stationary gear-reduction units.  IIRC, all the plugs I have were off-the-shelf units with magnetized tool steel pressed into a mild-steel or aluminum plug, and I never had a problem with flux loss.

[ghurd]

Toyota puts 3 magnets each in the oil pan and transmission pan, so say the aftermarket repair manuals.  I never had to go in and see them.

G-

[maker of toys]

come to think on it, Fiat puts a ceramic donut magnet in the transaxle. . . it's about a 20mm x 5mm unit with stamped steel pole pieces of about 30mm x 3mm. I broke mine (dropped it while cleaning it); that's why I got swarf on the plug after that, I guess.

(that, and the fact that I tore a boot and got sand in the thing once. . . even after the rebuild I got lots of swarf.  Maybe had something to do with the new cogs and syncros wearing in?)

[MattB]

I've always recommended against magnets on the outside of the motor... should the magnet accumulate bits, then get knocked off by a rock or what have you, all collected bits get released and could cause damage. If you got one stuck to the oil pan, you gotta remove said pan to collect the bits. Go for something removable...drain plug, oil filter...etc.

We've had customers using neodymium magnets inside oil pans of racing motorcycles (shared oil with transmission, and frequent tear-downs), with no ill effects from heat. Not to say it won't be an issue in some cases.

-Matt

[Gagster]

My '99 Trans Am had a magnet in the rear end straight from the factory.  When I shredded a bearing and started chewing up gears, all the metal bits stuck to the magnet and didn't do further damage inside the case.  Pain in the.... Real hard to get all the metal bits off before reassembly, but well worth it.  As for aluminum engines, it's not the case you're worried about.  It's the bearings, rings, piston pins, camshaft, valvetrain, and cylinder sleves that are all steel and are wear surfaces.

[amgine]

Yes, yes and yes, thanks gentlemen, saved me a lotta typing.

All I'll add is that very few mosickles have oilpans, a teardown involves

splitting the motor in half, OK for racing machines which must have severely stressed internals inspected/replaced almost daily.

I could buy several tidy cars for the cost of a motor rebuild for my babe  http://www.machinerycleanery.com/GtPanorama.htm

 - 12 months ago I rebuilt it for the 3rd time. If Neods cost me a thousand bucks each it would be worth every cent :-)

What's this about polarity ? Do steel particles prefer sticking to the North or the South ?

Because my first post got deleted here's the pic again of the drain plug with the magnet I inserted. Cutting up the magnet to fit was one helluva task. I got the cutting swarf off by putting body filler all around then breaking it off, not that a piece was gonna go anywher, that just me tho.

http://www.machinerycleanery.com/OilDrainPlugMagnet.jpg

BTW, these original drain plugs themselves are now hen's teeth, or unobtainium ,

there's a logo on the outside. Some people would have me shot for drilling the holes to insert the holding pin :-)

amgine

[maker of toys]

MMmm.. tape works well for getting swarf and magnet chips off magnets.

you can solvent-clean the plug, then drop a little blob of JB weld into the recess, then bed the magnet into that.  saves drilling; and modifying the magnet.

I don't think steel has a preference for one pole or the other.

[maker of toys]

Shifter on the right?  Huh.  I thought lefty shifting was the standard.

Apparently, the Italians didn't get that memo.

Nice Duc.  I'm jelous.

-dan

[wdyasq]

no standard for shifters until the Japs flooded the market - Original Brittish, German, Italian and Spanish bikes were right shift - IIRC.

Owned a few Manx, Inters, GoldStars, Triumpth 500 sinlgles, cubs and Norton juniors years back... and one Ariel.

Ron

[amgine]

Did an oil change just now, practically zilch on the magnet, just some extremely fine powdery stuff. From a rough test it seems the magnet has lost a little pull, but it's back in there now and won't be touched til next oil change, by then I'll have bought a variety of mags and will have boiled them up to see what happens.

Thanks again for all the advice.

Two Einstein's I love -

Einstein's mother must have been one heck of a physicist.

" I know not the weapons to be used in WW3 but WW4 will be fought with sticks and stones " AE

amgine