Mechanics

CLUTCH PRESSURE

1991 Nissan 240SX

Engine Mechanical problem
1991 Nissan 240SX 4 cyl Two Wheel Drive Manual 148300 miles

HI, MY PROBLEM STARTED LIKE 1 1/2 YEARS AGO WHEN I REPLACED BOTH CLUTCH MASTER AND SLAVE CYLINDER. EVERSINCE THAT DAY I COULDN'T GET STABLE PRESSURE ON MY CLUTCH WHEN YOU DEPRESS IT. I KEEP GOING BACK TO THE MECHANIC TO BLEED IT AGAIN & AGAIN BUT STILL THE SAME RESULT. I KEEP DRIVING MY CAR WITH THAT CLUTCH CONDITION FOR 1 1/2 YEARS THEN ABOUT 2 MONTHS AGO MY CLUTH FAILED TOTALLY SO WE REPLACED THE WHOLE SET. THEN AFTER A WHILE I FELT A DIFFERENT CLUTH PRESSURE EVERYTIME I USE MY CAR. THEN ABOUT 2 WEEKS AGO ON MY WAY TO WORK I KNEW SOMETHING IS TERRIBLY WRONG BECAUSE DEPRESSING THE CLUTCH PEDAL IS REALLY A BATTLE. IT GETS REALLY HARD TO DEPRESS. ALSO I NOTICED THAT AT THE 4TH SPEED I COULDN'T GET ANY FASTER THAN 40MPH. IT FEELS LIKE THE CLUTCH IS ENGAGE BUT THEN IT'S NOT. YOU KNOW. IT FEELS LIKE TRYING TO SPEED UP YOUR CAR ON NEUTRAL. THEN I SMELL THIS BURNING SMELL. SO I GOT TO WORK OK. BUT WHEN IT'S TIME TO GO HOME I FOUND THAT I HAVE NO PRESSURE ON MY CLUTCH AT ALL. I TRIED TO PUMP IT BUT TO NO AVAIL. SO I HAD IT TOWED THEN THE MECHANIC ( DIFFERENT FROM THE FIRST ONE) REPLACED BOTH MASTER AND SLAVE CYLINDER. WELL, IT TURN OUT OK FOR A WHILE THEN I STARTED FEELING DIFFERENT CLUTCH PRESSURE AGAIN EVERYTIME I DRIVE MY CAR. THERE ARE TIMES WHERE I FEEL A FREE PLAY ON THE CLUTCH PEDAL AND SOMETIMES NONE AT ALL. I DONT REALLY KNOW WHAT'S GOING ON. PLEASE GIVE ME SOME ADVISE ON WHAT TO DO AND WHAT TO CHECK. THANKS IN ADVANCE.
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NELSON SAMSON
July 3, 2008.



Hi NELSON SAMSON,

Probable cause : fluid not returning causing self clutch when fluid heats up.

Check if the master cylinder is faulty whereby the relief hole for fluid return is blocked, could be manufacturing defect.

If you drive with one foot resting on the clutch pedal, it would definitely cause it.

Check if the pedal to master cylinder free play is sufficient and if the pedal return spring is broken or weak.
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KHLow2008
Jul 8, 2008.
THANKS KHLow2008!

Where to find that relief hole for fluid return?

When I checked the owner's manual regarding the clutch pedal, it is mentioning about a free play. It used to be like that before both the master and slave cylinder was replaced. ANd one more thing that I noticed is that (it might sound weird) during early morining the clutch pressure feel fine and there's a free play on the clutch pedal. But when when I start my car, say after it has been under the sun for most of day, I felt a different pressure. Does it make sense? I already ask 3 mechanics and they said just ignored it. BUt I just can't because I know it's not normal for the pressure to be like that. I know something is wrong. Please I need more help. Again, thanks in advance.

Tiny
NELSON SAMSON
Jul 16, 2008.
Hi NELSON SAMSON,

Return/relief hole is inside the master cylinder.

Since the master cylinder have been replaced recently, I would suggest checking the push rod clearance. The push rod should be able to move slightly without any resistance when the pedal is free.

If not, adjust it shorter after releasing the locking nut and turning it anticlockwise from the pedal side.

Remember to lock the locking nut back.

KHLow2008
Jul 16, 2008.
Hi KHLow2008,

How would you check if the master cylinder relief hole is the problem. Can you see it right away or you have to remove the master cylinder and check visually?
About the push rod, that's what i've been doing all this days. Adjust. Adjust. Adjust. And even if I leave a clearance, at the end of the long drive the pressure will build up again. It happened while I was on the freeway 2 days ago and all of a sudden I cant go above 60mph on 5th gear, so I had to pull over and adjust the push rod. Pretty much that's what I do every couple of days, adjusting, coz I can't afford not to have a car, you know tried to work two jobs so I can go back to school. And considering the more than $1000 I already spend when I replaced the clutch and the cylinders. Also, when the pressure get really high, at neutral when I pressed the gas, I can't go past 3000rpm. It feels like something is holding it. Please need more help. Thanks in advance.

Tiny
NELSON SAMSON
Aug 20, 2008.

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