Originally Posted By: spasm3
Originally Posted By: Ducked
Originally Posted By: demarpaint
I caught a lot of flack some time ago for posting something I read about oil filter magnets, and shared it here. It might have even been posted here several years ago. This coincides with what Ducked said about magnetic drain plugs. I read there is a risk of magnetizing ferrous metal and it escaping from the magnet, magnetized, and attaching itself to the crank shaft, cam shaft or other part made of ferrous metal causing damage until it gets freed and trapped by the magnet, or a filter. That had me wondering about using filter magnets and magnet drain plugs. I haven't given it much thought again until now.
I've posted this a few times. It's the only mention I've seen in print of the potential problem of magnetised wear particles. Hard to tell how big a problem it is, but I'd guess magnetic removal is probably a net gain.
I'd think its potentially more of a problem with the magnets inside the filter, and to a lesser extend drain plugs and pan magnets, and less of a problem with the oil filter external bandoliers.
http://www.machinerylubrication.com/Read/781/particle-contamination
"Magnetic Susceptibility. Permanent magnets are used in some filters and online wear particle sensors. Particles of iron or steel that are attracted to a magnetic field are preferentially separated from the oil by these devices. Later, any particles that may have sloughed off these separators and sensors (due to shock or surge flow conditions) are often left magnetized. They can then magnetically grip onto steel orifices, glands and oilways restricting flow or simply interfering with machine part movement. Additionally, directional control and servo valves commonly used in hydraulic systems deploy the use of electro magnets in their solenoids. The actuation of these valves can be adversely affected by the magnetic susceptibility of iron and steel particles that are attracted by the solenoid."
I could see that in a transmission, where the filtration is not as good. But transmissions have had magnets for decades.
Which proves nothing either way, unless you've seen the results of tests validating the practice.
Originally Posted By: spasm3
With an oil pan bolt magnet, any magnetized particles should adhere to the pan itself, or be caught by the oil filter.
Yeh, might be a non-issue, dunno
However, there's no "should". A magnetised particle will stick to anything ferrous that it comes close enough to where the flow is insufficient to dislodge it. Could be the sump, but could be elsewhere, though hopefully oil flow will keep critical areas "swept".
Re "caught by the oil filter" part of the attraction (fnar fnar, geddit) of magnetic removal is that, unlike standard filters, there's no lower size limit on removal, so a lot of the particles are going to be below the filtration limit. I suppose they might clump bigger though.
