Clutch Master not pumping

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The Neck
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Clutch Master not pumping

Post by The Neck »

Hi everyone,

I'm taking a little break from the engine tonight since it's a bit too late to be making a bunch of noise and decided to flush and bleed the clutch. I have a new slave, rubber line, and hard line, and removed and cleaned up the master cylinder.

As I started to bench bleed and then install on the actual line, I noticed I was having fluid push back into the reservoir when I pressed the clutch pedal. I am able to flush the line, however there doesn't seem to be any actual pressure building up in the line itself. Every time I push the clutch pedal/arm, fluid immediately goes back into the res.

I pulled the cylinder apart, cleaned it out a little, and it's still doing this. Would this mean the actual seals on the piston are shot? I can only assume so since the fluid isn't going where it should.

Mike
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Nissanman
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Re: Clutch Master not pumping

Post by Nissanman »

I would advise putting a recon kit through the master, especially if you have fitted a new slave.
Also check for any scratches or corrosion in the M/C bore.
Anything that your finger nail catches on requires replacement/repair.
Nissanman, just trying to help.
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bossbob
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Re: Clutch Master not pumping

Post by bossbob »

Your fluid pressure is bypassing the seals. New seal kit as above if your cylinder is good, or new replacement. I did both the mc and slave at the same time.
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The Neck
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Re: Clutch Master not pumping

Post by The Neck »

That's what I was thinking, thanks for verifying!
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zippy67roadster
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Re: Clutch Master not pumping

Post by zippy67roadster »

I sell a rebuild kit for the clutch master but you need to make sure the cylinder walls are not pitted as the seals will just fail again. The kit is located here: http://sincitydatsuns.com/store/p121/Af ... inder.html
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mraitch
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Re: Clutch Master not pumping

Post by mraitch »

a) Just to reiterate, unlike the brakes, clutch is merely 'gravity' filled.

b) I had similar problem - Skip said just tap the cylinder - all went away.

c) follow instructions below about rebuilding.

Good luck.
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Re: Clutch Master not pumping

Post by The Neck »

mraitch wrote: Tue Aug 13, 2019 11:28 am a) Just to reiterate, unlike the brakes, clutch is merely 'gravity' filled.

b) I had similar problem - Skip said just tap the cylinder - all went away.

c) follow instructions below about rebuilding.

Good luck.
a) Please elaborate on gravity filled versus the brakes. Do you mean the bleeding procedure is different?

b) What do you mean by tap the cylinder?

c) rebuild kit is ordered and should be all back together soon.
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mraitch
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Re: Clutch Master not pumping

Post by mraitch »

a) just fill the reservoir, let some fluid drain out to remove water, then tighten and fill up to line - there is not the same pressure needed as with the brakes

b) apparently there is something inside that gets stuck - some sort of valave - happened to Dave Emsley as well. Tapping the cylinder freed it up.

c) have fyn
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gnoplos
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Re: Clutch Master not pumping

Post by gnoplos »

I had the exact same problem just a bit ago. There was a spare M/C in the trunk as well as a "new" one installed. Both did exactly what you're talking about. I was skeptical since both appeared to be doing the exact same thing but a new master fixed it right up!
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Re: Clutch Master not pumping

Post by The Neck »

I got the rebuild kit installed today and bled the clutch. Works absolutely perfectly, and bleeding it was very easy. I basically cracked the bleeder screw, let it flow, and gave it a few solid pumps once the fluid was consistent. Getting great engagement with the slave now and the clutch pedal feels great.

As I was getting the pedal buttoned back up I noticed brake fluid coming form the brake master now.... Ha ha ha ha oh boy.... Time to rebuild that guy now too, as well as the rear cylinder that's got a real slow leak with it.
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Re: Clutch Master not pumping

Post by DAC21 »

Saw this thread when researching for Clutch rebuild kits. I know after market New Clutch Masters can be had for $30 for the 1965-1967, but I'm going to try and keep my OEM Master which will require a hone at a minimum and a Karps insert being more likely. So I'm Ok with about $110 all in worst case. Not sure if the Brake master will be as economically as friendly as I guess the Brake master cylinder valve can be a crap shoot if it's still good after sitting for 40 years. It dramatically adds to the cost to a rebuild kit from what kits I could find.

Anyway I believe you can still get a Clutch rebuild kit from Nissan, but I'm not sure how complete it is. After tax and shipping you are in for $40 or so. I found this on eBay, I think DATSON may have hurt his sales. I even offered him less and he went for it. Looks to be as complete a kits as possible sans the corroded washer. Hopefully the seals have life in them. Just thought I'd pass that along if others were in the same boat.

https://www.ebay.com/itm/381432492669
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