Magnet Pre-filters Myth or Fact?

[_RaT_]

I just did the 400 hour hydraulic fluid change. My hydraulic filter has a magnet as the picture showed. My new filter is identical but was about $8 cheaper. I yank the magnet out of the older one, clean it and pop it on the new filter. Very little on the magnet on the 400 hour change compared to the 200 hour or the 50 hour. Next change is 600 hours. I like the magnet. What it does not trap, I'm confident the filter will.

 

[KennedyDiesel]

To add to this, most filters do not go very low on a micron scale. a magnet does not care how large it is.

Even with the ring magnet in my Allison filter I get a lot of crap.

Fuel filter too...

 

[Charolais]

I ask when buying any filter what the micron rating is. The tractors I've owned, I never had a hydraulic filter below 25 micron. Some as high as 32 micron. Hydraulic filters on the suction side have to be this way for the pump to pull enough fluid. When you look at industrial hydraulic systems most or many use the filter on the pressure side and can use a much lower micron. There may be some tractors with filters on the pressure side but I've never seen one.

Although I've never used a filter magnet it sure wouldn't hurt to have one. And on another note. With standard hy/trans oil for tractors I always had build up on the magnet plugs at oil change time. The synthetic hy/trans oil has reduced this to almost nothing.

I still haven't gotten back to my portable filter system for the pressure side on the farm tractors. Just need to finish the mounting. Hope to do that soon. But with this system I can filter down to 3 micron. Not continuos but will use it about every 20 hours.

 

[awlchu]

I have done some research on the effects of magnets since my first post.

It is a well known fact that a particle <10u is the leading source for wear in engines. This average diameter is much smaller than the pores in your oil filter. The efficiency of the filter at removing these small particles is so small they will normally be passed through the element.

If I recall correctly good oil will leave a film of about 10u between mating surfaces in your engine. This leaves plenty of room for smaller particles to pass through.

On a more scientific review, there are documented studies of used oil showing the average particle count (dia <20u) being significantly reduced (looks to be 10x average) between magnet and non-magnet filtered systems. This to me is a significant advantage for such a simple design change that I can do.

Also, I'm not worried about the Fe 'paste' falling into the oil stream from the side of the can. The velocity of the oil at the inner surface of the oil filter can is almost zero. There is no kinetic energy to be transferred to the mass of the Fe.

dino vs syth
mag vs non-mag
Green vs Orange
Paper vs Plastic

oh! /forums/images/graemlins/tongue.gif

 

[KennedyDiesel]

Here's a pic of the sludge inside my Allison filter. This one also had the ring magnet on the outside of the end plate. The magnet has been moved around a bunch making the patterns goofy, but you get the idea....

 

[slowrev]

I am with you Soundguy, Catch all the devris you can even if it is not all. Many Automatic transmissions have magnets in the pan to catch ferrous metals.
Ben