Does anyone know what this is?

It's this black puck thing sitting in the clutch slave cylinder reservoir.

 

I have one in there too. Looks like one of those vanilla cookies, but black.

 

Looks like a float of some sort...or toyotanation says surface area for preventing absorption of moisture.

 

Whatever it is, don't play with it.

 

This. It is a float designed to minimize the surface area of brake fluid exposed when you open the reservoir cap. The less area exposed, the less airborne moisture can be absorbed by the fluid.

 

Even with the asterisks I think the use of the word is a bit much here.

 

He meant nilla, calm down.

 

So did I?

 

That's not what he meant. He was referring to the color of the black puck. Highly offensive, if you have ever been called that word. I have and its not funny.

 

Wafer?

 

All I'm saying is I literally got banned for posting a meme with the "friendly" version in it.

 

My apologies to those I have offended. Took the post down.

I think the answer "it keeps water vapor from contacting the brake fluid" is probably the best assumption. That's what most other folks online have been saying too, but no one is really 100% sure. Very strange that this is in the clutch resi but they didn't include anything like that in the brake resi, maybe the brake resi is sealed better?

 

It's suppose to be there. Leave it alone

 

interesting mine was gone when I bought the truck so I was curious what it was .

Not sure what it really does .

Then the fluid gets changed every year when the slave cylinder gets changed

 

You put a new slave cylinder in your truck every year?

 

pretty much the liquid brine gets up there and just about eats the bleeder valve and hard line off .

Pits the rod allowing the liquid brine past the rubber boot

After having the line fail once it is just easier to change them out .

I would rather change them on my time not when it fails

 

Might also be there to prevent fluid splashing/foaming. Some motorcycles have foam floaters in the brake/clutch reservoirs for this purpose.

 

Or eat it...

 

This is my guess also.