W59 transmission breather questions: fitment and filtering

Hello --

I use the LC Engineering short shift kit on my W59 transmission which came stock on my standard cab 1997 Tacoma 4x4 2.7L.

Recently, and as an experiment based on a theory (which I outline in bullet point number two), I removed the transmission breather plug, added some 3/8" fuel line to the open plug, ran that fuel line up high into my engine bay, and, using a brass barb, attached a small

$30 K&N Vent Air Filter/Breather: High Performance, Premium, Washable, Replacement Engine Filter: Flange Diameter: 0.3125 in, Filter Height: 1.125 in, Flange Length: 0.4375 in, Shape: Breather, 62-2470

K&N air filter pod instead of a breather plug to the end of the fuel line.

My questions are as follows:

• Is an air filter pod OK for transmission breathing, or would a breather plug be better? Another way of framing this question might be: does a manual transmission such as the W59 sometimes need vacuum pressure? We know that transmissions must relieve pressure but if a manual transmission also sometimes needs vacuum pressure then, obviously, a breather plug is better than a filter. Thoughts?
• The LCE short shift kit raises the shifter assembly about one inch. As many of us know, this kit makes installation and removal difficult due to fitment. Relatedly, the space between the breather plug and rubber shifter housing is quite small. So small, actually, that I worry the breather plug might be depressed by the little tab on the bottom of the rubber shifter housing, causing pressure to accumulate in the transmission. The whole reason I installed the 3/8" inch fuel line was not to drive through deep water but actually to relieve pressure. Ironically, though, the raised height of the short shift kit also means the 3/8" fuel line must bend. The bend is not so dramatic that it kinks (closes); however, I think this is nevertheless a real concern, as well as an ironic twist of fate.

This is my first post.

Thank you all in advance.

 

Can't speak to the specifics, but if pressure is escaping when hot, then naturally it's going to want to pull back in once it cools, so it's bidirectional. You may see residue on the filter over time due to this "breathing"

 

Interesting. These cotton filter pods can be cleaned and recharged; however, I wonder if they are appropriate for this application after all. I see many guys use filter pods for manual transmissions but those tend to be for drag and racing applications.

I have a big road trip end of month. I will keep the filter pod installed for now. However, I will bring an OEM breather plug with me just in case.

I will monitor this filter pod and report back to you all my thoughts.