Clutch pressure - Good to losing pedal and then back to good

[99RangerKrazy]

Hey all,

I searched and didn't find anyone with this particular problem.

Truck is a 99 Mazda B2500. 146k miles. Unsure if clutch assembly (slave, master, clutch assembly) has been replaced.

When I first leave my house, the clutch pressure is great, a nice full pedal. After driving for a bit (a few miles/several shifts), I lose about an inch or so of pedal travel, but I can still shift just find with no grinding or anything. However, the disengagement point does move a bit. But then again, after driving a bit further (a few miles/many shifts), the pedal pressure builds back up to normal and all is well again.

Sign of a master cylinder on its way out? I was thinking slave, but it doesn't make sense that it would build up the pressure again. I would think that it would just slowly lose pedal pressure all the way to the floor and couldn't be built back up again.

Anyways, just hoping for some thoughts before I start throwing a whole new clutch assembly at it, though it may need it anyways.

Thanks.

 

[Explorin94]

It does sound like your slave may be weak ot internally leaking by. Try to bleed it first and go from there. If you do decide to change it out do the whole clutch assembly with it. It sucks doing the same job twice within a short period of time.

 

[99RangerKrazy]

Yeah I was hoping to put this off til next spring, shoot. I guess another thing worth mentioning is the clutch system isn't losing any fluid. Probably still a weak slave.

 

[alwaysFlOoReD]

Way back when I first started working these newer to me trucks I checked the master and saw that fluid was needed. I topped it off not realizing that there was a rubber expansion sleeve in the master. Needless to say I had a hell of a time trying to bleed the system out until I realized a few hours later what I'd done wrong, oops.
Just be sure that you've checked properly.
Good luck,

Richard

 

[Explorin94]

Another thing to check is the clutch master. It could be your culprit and not your slave. That is alot easier to change.

 

[99RangerKrazy]

Yeah I'm going to start with the master and go from there...good starting point anyways. Thanks for all the replies.

 

[99RangerKrazy]

Well I bled the system this evening and so far the problem hasn't returned. Maybe it just had a little air in the line...I'll check it again in the morn.