Auxiliary ATF filter; bypass or full flow?

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gofastman

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My old man has a '06 Acura MDX. They have notoriously problematic transmissions I gather. So far no issues, but I want to install a filter and I'm just wondering if it would be more beneficial to use a full flow system or a bypass type.
The transmission doesn't have a true filter from the factory, it's more of a mesh strainer.
I was leaning towards the bypass type due to the fact it's more or less a sealed system ant the only thing that needs to be filtered out is very fine metal particles and some clutch material.
 
I imagine any type of filter would be good. In my opinion, an auxiliary cooler and regular fluid changes are most helpful. The MDX's transmission is noted to be very good from about mid-2004 onward. Prior to about mid-2004, they had very poor durability.

Our 2005's has been perfect so far. 130k miles. About a third of which were being towed behind my folks' motorhome, so it's had some "unconventional" use as well.
 
A Magnefine is 15 minutes and under $20. 30 micron filter and a magnet the ATF flows past.

A spin on is probably $75 for filter and mount, at least 1 hour, 10 micron (or so) and no magnet.

Once installed the spin on is under $10 per change while the Magnefine is another under $20.
 
Originally Posted By: Greasymechtech
Start by servicing the stock filter.


It's an internal screen, and not serviceable by the user. GM's 4T80-E is like that, as well -- an internal mesh instead of an external filter. I think many transmissions use this type of design.

I personally like how Saturn and, I think, Subaru offer the spin-on filter. Others may use factory spin-ons, as well.
 
Honda's and Acura's usually have an inline ATF filter. Some are replaceable cartridges and others look like a generic Magnefine.
Finding it is a little difficult, usually removing battery and or airbox/plumbing and following the ATF cooler lines.
And, ALL dealer parts department, that I've dealt with, were clueless to the replaceable filter. Research at the Honda/Acura Pilot/MDX/Ridgeline/Odyssey fanboy forums for location and filter PN's.
 
I've been using external mounts/ spin-on full flow filters (3/4-16) thread size on the automatic transmissions of my plow trucks and personal cars for years (even have several remote mounts/filters for the power steering fluid mounted). Never had any problems. I change out the remote transmission filters every 6,000-8,000 miles and do a line flush with fresh transmission fluid every 25,000-30,000 miles. Maybe I've been lucky, but so far I have had minimal transmission issues.
 
AFAIK trans coolers are bypass anyway. A low pressure capillary from the pump that gets cooled and dumps back into the pan. I would use a spin on remote filter plummed into the cooler line.
 
Last edited:
Originally Posted By: asand1
AFAIK trans coolers are bypass anyway. A low pressure capillary from the pump that gets cooled and dumps back into the pan. I would use a spin on remote filter plummed into the cooler line.


Not how the cooler works on any trans I know of. Most take fluid from the hottest part of the trans at the torque converter output (not sure if it's just some or all), run it through the cooler and then return to pan. I don't know of any that feed the cooler directly off the pump.
 
Negative. The fact that the torque converter feeds directly to the cooler is exactly why a cooler line flush works. If it we're a bypass, you would get constant fluid mixing, but instead I get perfectly clear fluid right about the point where I have emptied the listed capacity of the transmission.

I'm certain there are exceptions somewhere, but not too many.
 
Originally Posted By: Donald
A Magnefine is 15 minutes and under $20. 30 micron filter and a magnet the ATF flows past.

A spin on is probably $75 for filter and mount, at least 1 hour, 10 micron (or so) and no magnet.

Once installed the spin on is under $10 per change while the Magnefine is another under $20.

I was thinking it might be a good idea to have a magnefine before the bypass filter. Idk, perhaps that is overkill.
 
Filters on automatic transmissions are essentially a waste. Since an automatic transmission is a closed system, the inside stays clean. Automatic transmissions don't burn fuel or suck in large amounts of air so external contaminants are not being introduced. An automatic transmission's worst enemy is heat, keep the fluid cool and change it per manufacturer's recommendation.
 
Autos definitely produce contaminants in the form of clutch material. However, they don't produce it at a terribly fast rate, so it's not terribly hard to filter out. Having some kind of filtration is a good idea, but going from the in pan rock catcher and a Magnefine to a 0.1 micron bypass setup isn't going to produce a meaningful increase in trans or fluid lifespan, IMO.
 
Originally Posted By: stchman
Filters on automatic transmissions are essentially a waste. Since an automatic transmission is a closed system, the inside stays clean. Automatic transmissions don't burn fuel or suck in large amounts of air so external contaminants are not being introduced. An automatic transmission's worst enemy is heat, keep the fluid cool and change it per manufacturer's recommendation.


The system is capable of building up solid contaminants from the clutches. Changing the fluid actually increases these contaminants significantly, which is why a fluid change is the perfect time to install a filter.
 
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