Magnet oil filter- DIY style -updated

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Brucey
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Magnet oil filter- DIY style -updated

Post by Brucey »

'Turn a curse into a blessing' they say.

Well, all that was far from my mind as I contemplated my wrecked auxiliary cooling fan motor. I was instead thinking more of the alleged 175 quid it'd take to pry a new fan out of the hands of my local dealer.

The magnets had come loose inside the motor, resulting in total inertia... I noticed they were curved, an unusual shape for a magnet, and this set a little germ of an idea off in my mind. A few minutes later and I was convinced; I'd be able to make a 'magnet oil filter' from these magnets.

A what?

Well, you may have seen old-style sump plugs with magnets in them (I wonder why they stopped doing it, it seemed like a great idea to me). You can also buy a 'filtermag' gadget that straps on to a canister-type oil filter. It is a good idea, but quite pricey (about sixty quid IIRC). Here's how I made my own version.

The filtermag blurb says that most oil filters are rated to about 25 microns, and that they will let fine wear debris through them. Of the fine wear debris, a significant portion of it is iron. The filtermag picks this up and stops your engine wearing out so fast. Simple.

Well, maybe, maybe not. IIRC most modern oil filters are rated closer to ten microns. Any sump plug magnet I'd ever seen would be covered in a 'little tree' of wear debris; but I had no idea what size range this debris might cover. However, given that typical shell bearing running clearances are nearer three microns than ten, anything that removes even very tiny iron particles from the oil can't be a bad thing.

I fabricated a steel strap with a recessed pocket for the magnet. The magnet was bonded into the pocket with epoxy, using an old filter as a jig. If the filter housing is steel, it is VITAL that the magnet very powerful AND is a very tight fit onto the OD. This is because the field hates to run through air (so a gap is bad) and then would prefer to run in steel than in the oil on the other side. If the magnet isn't strong enough to 'saturate' the thin steel canister, there will be insufficient leakage field on the inside, and particles won't be taken from the oil. An added potential problem is thermal stability; most common magnets just start to die once they get above about 150 degrees C; I hope my oil never gets that hot...

The acid test was to fit my prototype onto my Landy for several thousand miles. When I opened the filter canister up (carefully, to avoid making extra debris) there was no obvious 'little tree' of debris poking out of the oil; I wondered if it had worked properly. After leaving it to drain for several days, I could clearly see an area of debris caught on the surface. So the good news is that my 15-year-old landy engine doesn't seem to be wearing out at any great speed (there really wasn't much debris) and the gadget seems to work.

I have yet to examine the debris under a microscope, but I'm pretty sure a lot of it IS very small particles that might pass through a filter. At worst, a gadget of this type falls into the 'won't do any harm, might do some good' category. I believe that it is better than that, but by how much I don't know.

I have made a similar item for my 6er. Because the oil filter canister is aluminium, the magnet doesn't need to be so powerful, or to fit perfectly on the outside (a good thing, it is a smaller diameter and kinda lumpy to boot). I'm glad I didn't spend a total of 120 quid or so on two genuine filtermags, simply because I don't think they would have fitted very easily to either vehicle. On the landy, there is no room to fit it in situ; yet if fitted, there is then no access for a filter removal tool. Likewise on the 6er the clearance is very tight to the back of the alternator. My version is much slimmer, and fits both vehicles without any problems. I can leave it in place on the landy and still fit a filter wrench on OK.

So, what do you guys think? Have I been wasting my time (again) or have I been doing some good?

cheers
Attachments
and here's one I made earlier....
and here's one I made earlier....
Magnet filterv2.jpg (89.29 KiB) Viewed 13882 times
Last edited by Brucey on Sun Dec 10, 2006 3:09 pm, edited 1 time in total.
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Mauicruizer

Post by Mauicruizer »

Cool idea. I'm no expert but that must be helping.

Are you going to mass produce and sell on eBay?
Finally6

Post by Finally6 »

excellent idea, with the aluminum canister that is on the sixes is the strap all the way around the canister?
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Post by sharkfan »

Brucey,

Great idea - I can remember a magnetic sump plug on my old 2002tii and I was always a little shocked at the debris picked up.

I do however feel ashamed that I recently chucked away a cooling fan without much thought to it's possible salvage value :oops: :(

And yes, you do have a little too much time on your hands :wink: but at least you pop out with good ideas.

Cheers,

Sharkfan
Drew

Post by Drew »

I think most alts have cylindrical magnets, no? how about strapping a couple of these around the exterior of the filter housing using a couple of those huge jubilee clips you get on the AFM/ intake?

not sure how you'd liberate them from the alt though!!

beautiful concept Brucey, time well spent I say :P
boa

Post by boa »

What a great idea.

Brucey would it make the magnets more powerful if a electric current
was conected.
and if so What....? Amps....Volts....
Please advise.

thanks boa.
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Brucey
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Post by Brucey »

well chaps, here is the 6er version.

Re your comments;

Alternators don't have permanent magnets in them. (old style dynamos did though)

As you can see there is a strap right round the canister on both the Landy and 6er versions.

An electromagnet for this field strength would be a more complex solution; I think there are enough wires, fuses etc on a 6er already.....

I'm not planning on manufacturing these items; this is more to spur you blokes on....

cheers
Attachments
well I think it even looks half decent, what are the chances??
well I think it even looks half decent, what are the chances??
DSCF0944v3.jpg (65.95 KiB) Viewed 13756 times
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horsetan

Post by horsetan »

I think I'd want to get the suspension conversion work finished, and then finally get to relieve Brucey of that Pioneer CD-changer/cassette set.....
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Magnet filter update - debris analysis.

Post by Brucey »

I just cranked up the microscope, and took a look at the dark-coloured debris that was attracted to the oil filter magnet in my Landy (see pictures above).

Before, I explained the theory that particles in the ~3-10 micron range are likely the ones that will damage hydrodynamic bearings (mains, big ends, little ends, piston-to-bore, etc etc). Note also that 'boundary lubricated' parts (cam followers, ANY bearing on a cold start etc) will suffer with particles of any size.

I kind of assumed that many of the iron particles trapped by the magnet would be larger than ~10 microns, and that they would have been caught by the normal oil filter anyway.

Well, I was in for a BIG surprise.

The pictures below tell the story; the upper one shows particle clusters. The particles are clustered because they are magnetised and are slightly attracted to one another. Each cluster appears to comprise tens or hundreds of individual smaller particles. Far from there being few particles smaller than 10 microns or so, there seem to be few (if any) that are larger than this. However, from this image alone, it is not possible to to say that all the particles seen are iron.

The lower image shows what happens when a magnetic field is applied. The clusters are aligned with the field, into 'whiskers' of aligned particles. Pretty much all the particles are iron, and follow the magnetic field. I estimate the thinnest of the whiskers to be less than one micron in width.

The conclusion that I draw from this is that the normal filter is probably removing particles ten microns and up quite efficiently. Remember I added the magnet late on in the life of this lot of good quality semi-synthetic oil; it'd done ~3000 miles before the magnet was added, and about 3000 miles after. I suspect that much of the material trapped by the magnet had passed THROUGH the ordinary filter (and the bearings, ... ouch!) many times already.

It seems very likely that the magnet filter is trapping particles which are exactly in the 'dangerous' range for the bearings. Obviously I don't know how efficiently it is doing this; to determine this, I shall have to sample 'filtered' oil and see what debris lurks in that, untrapped by any filter. I'll do that on the next oil change. However I would say that the removal of the iron debris seen in the pictures can only be 'a very very good thing'.

I'm not sure I shall drive any of my vehicles without a magnet oil filter of some kind on ever again.

What do you chaps think?

cheers
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well, it surprised me....
well, it surprised me....
magnet filter debris v2.jpg (114.08 KiB) Viewed 13655 times
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Finally6

Post by Finally6 »

I've got a spare cooling fan lying about, I am going to follow your design and build one asap. I am only about 300 miles into my oil, so it's a good starting point.
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another update

Post by Brucey »

I changed the oil in the Landy again recently and once more opened up the filter canister to view what I'd collected with the magnet.

I was pleased to see a little less debris than last time right next to the magnet but I did notice that there was some magnetic material deposited all over the inside of the filter canister. Presumably the entire steel canister becomes weakly magnetised and attracts fine debris.

When I checked the valve clearances they were all up about 0.002" after 25000 miles since the last check. This can only really occur by wear in the valve train and I think this is where most of the steel and iron debris comes from. If you wanted to simulate this amount of wear debris I think you would have to take (say) a small hard steel washer, grind it to dust and then throw it into your engine. Pretty ugly, huh?

Nearly all engines have their highest contact loads in the valve train and therefore generate hard wear debris in a similar way. I expect to find a similar story when I change the oil in the 6er (due soon) which will be the first time with the magnet installed on it.

Anyone else had a go at this yet?

cheers
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magnet filter lr oct 2007v2.jpg
magnet filter lr oct 2007v2.jpg (56.85 KiB) Viewed 12685 times
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Drew

Post by Drew »

would like to do this but I have no spare fan motors lying about, actaully I just replaced the starter motor on the VW didn't I!! silly me

I reckon that'll have some good magnets knocking about, now where did I put it?? I think it did have curved magnets but with a smaller radius than the oil filter canister on the sixer, hmmm
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Re: another update

Post by sharkfan »

Brucey wrote:Anyone else had a go at this yet?

cheers
I remembered the posting when yet another TVR cooling fan threw it's legs in the air and so kept the magnets but with imminent fatherhood on the way I'm pretty busy doing all the household DIY jobs that I should have done over the last few years :oops:

The strap fabrication looks a little time consuming - is there a quicker/simpler/easier way?

Sharkfan
Drew

Re: another update

Post by Drew »

sharkfan wrote:
The strap fabrication looks a little time consuming - is there a quicker/simpler/easier way?

Sharkfan
I think Brucey has gone for a lovely bit of engineering here, I think my solution would be a bit more wallace & grommit, not sellotape but maybe an elastic band :lol:
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Re: another update

Post by sharkfan »

Drew wrote:
sharkfan wrote:
The strap fabrication looks a little time consuming - is there a quicker/simpler/easier way?

Sharkfan
I think Brucey has gone for a lovely bit of engineering here, I think my solution would be a bit more wallace & grommit, not sellotape but maybe an elastic band :lol:
Yep, I'm with you on this - although maybe we should push the budget to a pair of monster jubilee clips - eh? :wink:

Sharkfan
87M6chris

magnets for oil filter

Post by 87M6chris »

Brucey, you might also want to try rare earth manets. They are 10 X the
strength of regular magnets. I get them for free from my local computer repair shop, there are two in every hard drive. I ask them for the old hard drives that have died then take them apart. I just use a tie wrap to keep them on the aluminum oil filter housing but now seeing your clamp solution I think I'll build something like that instead.
Thanks,
Chris
TheMonkey

Post by TheMonkey »

just thought i'd share an experience with a magnet on the filter. i bought one of those red ones from filtermag. yes, it was expensive, but remarkable how powerful the magnets are. requires both hands and some leverage to get it off the canister.

i recently built a bottoms up traditional pushrod large displacement American V8 motor. here is a picture from a filter after initial break-in to seat the rings and 7 dyno pulls to read power and optimize timing. the ribs you see going up and down are the different magnets. i'll change the oil again after 500 miles, it will be interesting to see what it grabs at that point.

this motor has hydraulic roller lifters, full roller rockers, and was graded an A+ on the health check. from what i understand, this is a pretty normal sight if using a magnet on break-in. i can't believe these magnets are not standard operating procedure.

Image
GWL

Post by GWL »

TheMonkey wrote:just thought i'd share an experience with a magnet on the filter. i bought one of those red ones from filtermag. yes, it was expensive, but remarkable how powerful the magnets are. requires both hands and some leverage to get it off the canister.

i recently built a bottoms up traditional pushrod large displacement American V8 motor. here is a picture from a filter after initial break-in to seat the rings and 7 dyno pulls to read power and optimize timing. the ribs you see going up and down are the different magnets. i'll change the oil again after 500 miles, it will be interesting to see what it grabs at that point.

this motor has hydraulic roller lifters, full roller rockers, and was graded an A+ on the health check. from what i understand, this is a pretty normal sight if using a magnet on break-in. i can't believe these magnets are not standard operating procedure.

Image
Interesting, but I would be more concerned with the tiny filings small enough to go through the filter. Maybe I am mistaken, but I believe that the oil flows from the outside of the filter to the central chamber, so the magnet picks up pre-filtered oil. Those tiny sub micron bits of metal picked up by the magnets are more important than the larger bits that will be filtered by the filter media.
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Post by Brucey »

chaps, thanks for the feedback, most interesting; I shall have to take apart a hard drive or two!

Incidentally I agree with GWL; most magnets on filters pick up pre-filtered oil so it is the very small pieces that are the biggest worry (although it is somewhat disturbing to see all the larger bits even on a supposedly 100% clean rebuilt engine, I suppose there are bound to be some...)

Hence the microscope pictures I posted earlier; these showed me that there is a lot of small stuff in there......

cheers
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6er filter results, at last!

Post by Brucey »

Due to a combination of sloth, few miles, and one or two other things, I've not changed the oil in my '87 635 for several years (slap on wrist due...). I didn't worry too much because the oil looked pretty good, and I'd used a good quality semi-synthetic when I last changed it. This oil has done 6000 miles, about 50:50 between 15-mile trips and much longer runs. The oil service light finally told me to get on and do something, and when it blinked on, I slavishly changed it. Pavlov's mechanic, or something.....

About 4000 miles ago I built my magnet device and fitted it. I'd been curious to see what I'd caught with it. I left the magnet on the filter housing when I drained the oil, and sure enough, there was a load of black stuff on the inside of the housing nearest the magnet. I scooped up most of it using another magnet and put it into an old film container.

I've now done the same thing several times with my Land Rover which has seen many more miles in recent years. Each successive time I've changed the oil in the landy there has been much less stuff stuck to the magnet. Now, it is possible that the magnet is losing strength as time goes on, but I suspect that I'm gradually removing whatever stuff is sloshing around in the oil and doesn't come out in the filter or the oil when it is changed. As a consequence of this, as time goes on, I'm hopefully creating less and less debris because the oil is cleaner. Well that is the theory, anyway. When I checked the valve clearances on the landy's diesel engine, they had all opened up through cam follower/valve train wear, by about 0.001" to 0.002" over about 20000 miles. I would describe this as a 'very low wear rate'. Not bad when you think they are not exactly expensive parts in this motor; I replaced some pushrods about six years ago and they cost ?1.58 each or something ridiculous like that....

Now I've looked under the microscope at the stuff that came out of the 6er filter. I reckon there was about four times as much stuff as I've seen in my landy. I was expecting this to some extent, since I know the valve train is more highly loaded in the M30 engine, and this is the first place to exhibit obvious wear in these engines should there be any problem with the oil feed system. Using a magnet on several M30 engines, I've fished out quite substantial quantities of steel fragments out of the little 'trough' that holds oil for the camchain tensioner damper, for example.

Although many of the particles were clustered because they are now magnetised, I was able to separate some of them which you can see in parts of the attached picture. I reckon there are very many particles in the range 1 to 5 um and this is somewhat disturbing; it is particles in this range which are going to pass through the oil filter some of the time at least, but be of a size that will easily cause wear even in well-lubricated bearings.

If my experience with the landy motor is anything to go by, I'll see less of this stuff next time I do the oil on the 635. However this will be a while yet, despite now reverting to the 'Dino oil every 4000 miles' strategy (although I have carefully selected CF rated stuff which should have good ZDP levels).

Before I looked at this magnet debris I would have categorised the use of a magnet on an M30 as ' won't do any harm, might do some good'. I will now revise this view; ' I'm never going to run my M30s without one again'.

As suggested by another board member, I may try using the much stronger magnets out of old computer hard drives for this task in the future.

Anyone else had a go?

cheers
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eeeek!
eeeek!
400um field of view 635 aug 2010v2.jpg (66.9 KiB) Viewed 8824 times
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sixpack

Post by sixpack »

Very interesting stuff Brucey.
Drew

Post by Drew »

sixpack wrote:Very interesting stuff Brucey.
+1

a different car I know but my 993 had some very furry magnets in the sump for it's auto box transmissions when I had it apart (filter and fluid renewal). So much so that I fear this service job had mean much neglected for much of the car's life. A partial fluid change (only about 50% comes out even with a drop of the sump as so much stays inside the cooler and torque converter) is due every 30k.

Anyway, based on the furryness results I decided to do four changes in quick sucession as that would give about 85% ATF renewal. I also bought some neodymium magnets from ebay to supplement the magnets in the sump from the factory. These new magenets are quite fierce!! I haven't seen what they've picked up yet as they've only been in for a hundred miles or so.

I don't have Brucey's super microscope to hand!! but will get some furry photos up.... um
dividedbydrew

Post by dividedbydrew »

I'm looking into buying some RE magnets right now before I do my next oil change. It appears that amazon sells them fairly inexpensively (~$11) for packs of 10-50 depending on the size and shape you want. Now, what size and shape DO I want???
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Post by Brucey »

actually the computer hard drive route is excellent, as the magnets come out with a backing piece that has holes in, meaning that the thing can be simply wired into position without too much difficulty.

The curved magnets I used are important for a steel filter housing, but much less so for a RE magnet on a 6er Aluminium housing. Pretty much any shape will work OK, I reckon.

And the RE magnets are SO powerful that I think flat ones will work OK on a thin curved steel filter cartridge, even. I will try this and see how it works.

cheers
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Post by Brucey »

Drew wrote:
sixpack wrote:Very interesting stuff Brucey.
+1

a different car I know but my 993 had some very furry magnets in the sump for it's auto box transmissions when I had it apart (filter and fluid renewal). So much so that I fear this service job had mean much neglected for much of the car's life. A partial fluid change (only about 50% comes out even with a drop of the sump as so much stays inside the cooler and torque converter) is due every 30k.

Anyway, based on the furryness results I decided to do four changes in quick sucession as that would give about 85% ATF renewal. I also bought some neodymium magnets from ebay to supplement the magnets in the sump from the factory. These new magenets are quite fierce!! I haven't seen what they've picked up yet as they've only been in for a hundred miles or so.

I don't have Brucey's super microscope to hand!! but will get some furry photos up.... um
don't fret at autobox magnet furryness! This is normal! The reason is that the friction plates contain steel and are designed to wear. The magnets are supplied OE and are designed to soak up a LOT of iron debris from the friction plates. Eventually the filter may block from the organic material from the plates; this is a bigger worry normally, leastways on most autoboxes.....

cheers
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