Clutch Slave Cylinder Losing Pressure

I have a 03 Tacoma 5 spd trans with the same issue(s). The place that replaced my master and slave did not replace with Aisin / Denso parts. Hence 6 months down the road issues popped up. I took it back 2 times and they bled and bled and tightened everything. Worked a couple weeks and started again. I replaced both Master & Slave (non Aisin/Denso) myself this time using a vacuum bleeder. It worked! BUT after install I read that it must have Aisin or Denso parts OR the issues will happen again. Now after 8 months I took a long drive in heat and it starts to make it hard to put in first gear. I now have the Denso/Aisin M&S cylinders at the ready. Just waiting for a cool spell.
Went to the repair company and I asked why they DIDN'T use recommended Aisin or Denso parts. I found out that the repair company used is directed to obtain cheap parts.
My issues started with a pinhole leak in the flexible hose that goes from the fire wall clutch Master line to the Slave connection line.
Good luck and hope it works out for you.

 

Did you ever figure out the issue.
I've the same but intermittent.

 

Parabellum : I went thru the same exact issues. I bled the brakes, tightened connections, replaced master and slave with Aisin/Denso parts it worked okay for about a day. Finally found the problem because I had to find out what it was. Transmission pulled and found cracks in the Clutch Release Fork. That made it so that the clutch was not engaging or releasing all the way. Welded the cracked area and re-enforced that area, installed to spec and BAM! it is doing what it is supposed to. Been months Now with no issues. Costly to pull that 4x4 trans but inspection showed everything else in good shape.
Side note: it's very hard to spot the hairline fracture in that Clutch Release Arm. I would just replace it if you have the money. At the time I didn't.

 

I just replaced the master clutch reservoir with new fluid ( sucked out the old with a baster pump) it was brown for a long time. I went to loosen the slave bleeder and no fluid came out whatsoever, I backed the entire bleeder screw out and the inner tip was dry. Truck has been hard to get into first gear for a while so maybe I should get that pump from Harbor Freight as from the thread is sounds like there is air bubbles in the system… Advice?