Here are my thoughts for what they are worth:
when is the opportune time to install the Magnefine Filter? When the fluid is being changed at the pan?
Anytime - You just cut a piece out of the inbound (to the trans cooler in front of the radiator) rubber hose the same length as the filter - you will lose a little bit of fluid but you can just top up - make sure the filter is pointed the right way and you are cutting the right hose. It's the one nearest the right front wheel on the Tundra.
To install that filter, do I need any special tools, like a pipe/tubing cutter?
You will need a sharp knife to cut the rubber hose and a screwdriver to tighten the hose clamps.
When you say "get the 3/8 fittings," you mean the "smart fittings?"
No 'smart fittings', just order the Magnefine with the 3/8" ends to fit the rubber hose. Hose clamps are included.
am I correct to assume the replacement fluid goes down the A/T fluid level pipe inside the engine compartment?
Yes, use a funnel with plastic accordion hose attached - available at any autoparts store for a couple of bucks.
Would it be smart to measure exactly how much comes out from the pan, and replace an equal amount? What happens if I put in too little or too much?
My experience is almost exactly 4 quarts will drain - buy five to be sure. I use an empty 5 quart Mobil 1 jug (buy at wallmart) to measure what comes out just to be sure. Immediately check the dipstick after the drain and refill with the truck running in Park and after shifting through all the gears, P, R, N, D, 2 and L. Get the fluid level between the 'cold' notches on the stick - not enough? add more (carefully) too much - you get to use the drain plug again! You want the level between the notches - check again when hot - fluid should be between the 'hot' notches.
BTW, my parts supplier-- http://www.rockauto.com-- lists a transmission gasket for my Sequoia: Fel-Pro, 19 holes, #TOS18685, measuring 15-15/16 by 10-1/16. Clearly this is for the transmission oil pan, no?
That would be my guess - but if it's my truck I buy a factory gasket - Rock Auto are good people - I would just go factory. But then I wouldn't choose to drop the pan and change the filter or the gasket until the truck has high mileage - We just did this to my son's Corolla at 76,000 miles and there was very little debris in the screen. Didn't need doing IMO...
if I install the Magnefine filter, would it not be smart to drop the transmission oil pan and clean the metal screen first?
Not in my opinion...leak potential is very high if not properly resealed
Here is a photo with the trans pan off:
http://www.tundrasolutions.com/photo...cat/all/page/2
Here are some pix I just took of the install on my truck:
http://www.tundrasolutions.com/photo...at/6223/page/1 http://www.tundrasolutions.com/photo...at/6223/page/1 http://www.tundrasolutions.com/photo...at/6223/page/1
Hope all that helps!
Cheers,
Brad