Opening the transmission thermostat bypass during filter change?

I am looking into replacing the transmission filter in a '14 Tundra and I've seen some videos where they put a pin in the thermostat housing to allow coolant to flow through the cooler for a full fluid swap.
I don't plan to do a full fluid swap, but I am going to replace the filter inside the transmission. Do I need to open that thermostat if I drain the fluid, swap the filter, and refill the fluid? I am aware of the proper temp the fluid needs to be and how to check when it's full, but I'm not finding any info on just replacing the fluid that comes out during a filter replacement.

 

You have to open the thermostat to check if it’s properly filled. Some people weigh the drained fluid and replace that way. When I drain/filled I checked mine and noticed it was slightly on the low side from factory. Most people don’t change there filters due to it being basically a screen. Also you’re almost certainly going to break a pan bolt and will have to drill and tap.

 

I second what @JeffMac said. I just did a drain/fill after extensive research on the procedure. There are so many damn opinions on this, but all in all, I went with a drain of 3 quarts, then fill of the same. Breaking of the pan bolts is very common.

 

Just to make sure I understand, if I'm not going to do the full fluid flush, I still need to open that valve for the cooler because it will affect my "full" level when I go to replace the fluid?

Do you have a little more on the part where people don't seem to bother with the filter? I see that it's a large mesh screen and not a familiar design like common oil filters, but are you finding that people don't seem to need to replace these things?

I got a little heart burn when you said I'll likely break a pan bolt. Is there a way to do a little work "up front" so I don't break a bolt?

 

The filter is called a screen, but it's it's fiber type media. Don't change it, it's not clogged, mine had 173k on it when I changed it. I split the filter open and there was virtually nothing inside of it.

Do a full fluid exchange through the cooler line for best results.

This is the filter when split open, 173k miles maybe more, but somewhere around there

 

You need the fluid to be warmed up to the proper temp and circulating to ensure its filled correctly.

I drain/fill mine every 30k miles. I takes me about 30 min. I attached the how to pdf.

@Sumo91 is the one who cut his open above.

edit: Before I did mine I was going to replace my filter and called 3 dealers and they told me they don’t replace the filters and it would be a special order. The filter was intended to last the life of the vehicle.

 

You guys are awesome, thank you for the heads up.

I already purchased the filter and gasket, but it's only money, so I guess it can sit on the shelf.

Jeff, thank you for the PDF, I was looking for something like that and I have been piecing together bit of instructions from various places, it's nice to have it all in one doc.

I purchased 6 qts, for the drain and fill, but if I do a flush, roughly how much more fluid show I get? I'm not in a position to go get more fluid during the flush, so I need to have it all here for the work.

 

No problem. It’s around 12.5 qts. I’d probably get 14 incase any gets spilt.

 

But you only have a thermostat if you have a trans cooler, correct?

 

I have no clue on that. Someone with a 2019+ would have to answer that for you.

 

Inside of my filter at 121K. Pretty much spotless minus a few small metal particles (probably from the break in process) . The only reason I changed mine was because I was pulling my valve body and figured I wouldn’t be in there for another 100k.

 

Thanks for showing this. What is wrong with the valve body?

 

I though I had a piece of trash in my accumulator but it ended up being clean. While I had it split open I went ahead and put in a sonnex valve body rebuild kit.