1995 Mazda Truck clutch

Tiny
DLEVE
  • MEMBER
  • 1995 MAZDA TRUCK
  • 4 CYL
  • 2WD
  • MANUAL
  • 140,000 MILES
My b2300 pickup's clutch fails to engage when hot. When I depress the pedal when I come to a stop (or just shiftiing at other times) the hydraulic system seems to bind. The pedal returns to the normal position but the clutch remains dissengaged when pressing the pedal again it has a lot of resistance (I can shift through the gears but all I get is revving when I apply the gas and then it may engage suddenly). The hydraulic resevoir is at the proper fluid level, when the clutch works, it is smooth. If I open the fluid resevoir when the clutch is stuck like this it sometimes solves thi problem but only until you push the clutch again. I am baffled and do not want to overhaul the entire system if it is not necessary. Any help with this will be appreciated! Sorry I had a brain hiccup and poste the truck as a ;97 when it is a '95. Does this make a difference?
Wednesday, July 8th, 2009 AT 9:29 AM

7 Replies

Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Hi dleve,

Thank you for the donation.

From the symptom description, the problem could be due to insufficient pedal pushrod to master cylinder clearance. Check if you have sufficient pedal free travel.

Next to check would be the master cylinder cap. It might be clogged and not venting.

If both above are correct. The master cylinder seal could be bad and blocking the fluid return hole in the master cylinder to reservoir.

All the above would result in the fluid heating up and self applying resulting in the clutch slipping.
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Wednesday, July 8th, 2009 AT 11:00 AM
Tiny
DLEVE
  • MEMBER
  • 4 POSTS
Thanks for your response. How do you measure the pedal pushrod to master cylinder clearance. Also, if the seal on the master cylinder is bad (I will check that next) can you buy a repair kit with the seals etc. Without replacing the entire master cylinder?
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Thursday, July 9th, 2009 AT 9:37 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
The easiest way to test the clutch pedal clearance is to push at the push rod pin attached to pedal. It should move freely if the pedal is depressed just enough to move it. If there is insufficient clearance, the pin would be stiff and you would encounter resistance.

Repair kits are available but you need to check the condition of the cylinder bore, if it is not in good condition, repairing with the repair kit would not last.

Seals seldom causes such faults unless the clutch fluid is contaminated with oil which would cause the seal to expand and this usually causes the clutch pressure to fail, which is not happening in your case.
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+1
Friday, July 10th, 2009 AT 8:39 AM
Tiny
DLEVE
  • MEMBER
  • 4 POSTS
I just replaced the master cylinder and it did not fix the problem. Guess I will drop the tranny and inspect the rest of the system!
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Saturday, June 26th, 2010 AT 3:01 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
After replacement of the master cylinder, did you check/adjust the push rod to master clearance?

Improper adjustment would cause that.
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Sunday, June 27th, 2010 AT 2:50 AM
Tiny
DLEVE
  • MEMBER
  • 4 POSTS
After I installed and bled the master cylinder I test drove the truck and everything seemed fine until I had driven a mile or two and shifted several times then I pressed the clutch pedal, shifted into first gear to start off, released the pedal and the clutch remained engaged. When I attempted to depress the pedal again it was very stiff and had no effect. After a few seconds the clutch disengaged and the truck lurched forward and stalled. Same old problem. I see no way to adjust the pushrod clearance-the pushrod attached to the master cylinder and to a stud on the clutch pedal no way to lengthen or shorten it if that is what you mean.
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Friday, July 2nd, 2010 AT 10:31 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Repairs to the slave cylinder requires removal of the transmission so I guess the problem could be there. Did you check the clutch release bearing free travel and check for hydraulic leakages there?

You mentioned removing the reservoir cap sometimes works. Did you check if the cap bleeder is clogged? That can cause a vacumn in the reservoir and cause problems with the hydraulics.
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Saturday, July 3rd, 2010 AT 6:27 AM

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