Vacuum bleed destroyed master/slave??

[jdnsx]

At 69,000 miles my clutch master was showing the fluid trickle and hard shift into 1st without pumping so I replaced the master and slave and flushed the system with new DOT 3 brake fluid. I was by myself when I did it so I used a vacuum bleeder and all worked fine and I drove every day for a week with no problems.

My car then sat for a week and when I got back in to start it the clutch would not disengage even with the pedal to the floor. I pumped it many times and got the clutch to disengage. Obviously I thought I had air in the system so I hooked up the vacuum bleeder and bled again and all was fine for 2-3 more days.

The car sat for another week and would not disengage the clutch no mater how many times I pumped so I tried to vacuum bleed one more time. After bleeding when I pushed on the pedal the motion was rough and there was a metallic ping coming from the slave and the clutch would not disengage. The slave pushrod was moving but I do not know if it was going all the way.

The car sat like this for 2 days while I waited on a speed bleeder so I could pressure bleed the system but now it will not build any pressure at all even with everything closed. It is not leaking any fluid at all but it is obviously not moving any fluid.

Did I somehow destroy the master or the slave or both?

 

[Thunder]

DOT 3? you made an error, I think that the good oil of brake is DOT 4 or DOT 5.1

 

[ftuhy]

Per the factory shop manual, for the clutch use only US DOT 3 or DOT4 brake fluid.

 

[jdnsx]

So it's not the fluid...any ideas on what happend?

 

[ralph cerbone]

So it's not the fluid...any ideas on what happend?

maybe ? did you use a bleeder like a Mighty Vac hand held vacuum pump,if so you must first remove the bleeder on the slave cyl. then wrap the threads of the bleeder with teflon tape ,pull a light vacuum (maybe 10 in.) and just crack the fitting open and watch fluid run clear. what happens if you pull too much of a vacuum (25inches) and then crack the fittings the air you see being drawn is actually the air coming in from the threads, this is a common complaint from guys that have problems with mighty vac., Idont know if this your problem just food for thought
Ralph

 

[jdnsx]

You are correct about the teflon tape on the fitting and I did do this. I don't think air in the system is the problem now like it was at first. It is so bad now I think there is a failed component??

 

[EdinKali]

Sounds like one of your components is defective or you have a leak at one of the line fittings.

 

[pgilliam1]

Put the car on a level surface. Take the cap off the clutch master cylinder reservoir, then open the clutch slave cylinder bleeder (attach a clear tube to the bleeder if you have one). You should see a steady stream of fluid slowly come out of the bleeder (gravity does this for you without any pressure applied to the system). Watch for pockets of air in the tube. Good Luck and let us know what you find. Happy Motoring!

 

[angus]

I have found the NSX to be particularly difficult to bleed the clutch, mostly due to the long run of lines. Best thing is to manually bleed it with two people old school way.

Yours does sound like you may have a defective component though.

 

[NSXclear]

Forget about the vacuum method. Just ask a friend or neighbor to help and just the bleed it the 2 person method.

That way you can at least isolate or rule out what is wrong.

 

[OLDMNSX]

Did you use a new OEM master and slave? Did you get all of the fittings and clamps tight?

I use my home made vacuum bleeder and have never had a problem. Just make sure that the master reservoir does not run dry.

I DO NOT use teflon tape on the bleeder. I expect to have small air bubbles in the fluid catch container (Mason Jar).

The gravity method is great for draining fluid, but I don't depend on it to get all of the air out of the system.

Brad

 

[Aluminsx]

I just bled the clutch on my NSX with a Mityvac and all is well so far. It scares me that your symptoms started after the car sat for a couple of days. I'll have to go check mine out. I'm not a mechanic but it sounds like you did not bleed the lines completely or one of the components is bad. I suppose the cheapest way to diagnose the problem would be to redo the bleed and see what happens. It maybe just as simple as having a rouge air bubble in the line. Good luck.

At 69,000 miles my clutch master was showing the fluid trickle and hard shift into 1st without pumping so I replaced the master and slave and flushed the system with new DOT 3 brake fluid. I was by myself when I did it so I used a vacuum bleeder and all worked fine and I drove every day for a week with no problems.

My car then sat for a week and when I got back in to start it the clutch would not disengage even with the pedal to the floor. I pumped it many times and got the clutch to disengage. Obviously I thought I had air in the system so I hooked up the vacuum bleeder and bled again and all was fine for 2-3 more days.

The car sat for another week and would not disengage the clutch no mater how many times I pumped so I tried to vacuum bleed one more time. After bleeding when I pushed on the pedal the motion was rough and there was a metallic ping coming from the slave and the clutch would not disengage. The slave pushrod was moving but I do not know if it was going all the way.

The car sat like this for 2 days while I waited on a speed bleeder so I could pressure bleed the system but now it will not build any pressure at all even with everything closed. It is not leaking any fluid at all but it is obviously not moving any fluid.

Did I somehow destroy the master or the slave or both?

 

[ftuhy]

I had an air bubble problem the first time I flushed my clutch master/slave, but with persistence the 2-person method resolved it after some time.

Subsequently, I have used the Shooter brand pressure bleeder. That still requires 2 people - one to open the fitting on the slave and one to hold the rubber-tipped tube from the Shooter in the clutch master. But, it really flushes out the system (I send about 8 oz through) and takes just seconds. I've never had a soft clutch pedal after that.

Your problem sounds weird in that it takes a day or two to appear. I have to agree it sounds like a defective part or a leaky fitting. Also, I've not had to remove the slave on mine, but the metallic ping from the slave sounds like the pushrod may not have been properly engaged upon slave installation. Anyone have insight on that?

 

[jdnsx]

All parts were OEM from Ray Laks but I think they are out of business now. I have Vacuum bled, speed bled, gravity bled and old fashion 2 person bled. The fluid is full and everything is closed yet I can not get ANY pressure to build at all. This is what leads me to believe either the master or slave has completely failed.

I am thinking of taking the hose off the slave, putting my thumb over the line and pumping the master to see if there is any pressure. This should tell me if the master is working...correct???

BTW... I am a decent mechanic having built motors, a supercharger system, installed clutches, etc. However I think one of the hardest diagnoses to make is when a brand new component has failed in some way because you are just not expecting it.

Please remember the car worked fine for a week then worked fine for 2-3 more days after second bleed and has progressively gotten worse now to the point of not working at all. This is why I thought I might have damaged a seal or something.

 

[Aluminsx]

Keep us posted if you are able to find out what the root cause is. I'm curious.

 

[Larry Bastanza]

I have found the NSX to be particularly difficult to bleed the clutch, mostly due to the long run of lines. Best thing is to manually bleed it with two people old school way.

Funny you say this because I have had the same experience. I now use a check valve on a hose then pump by hand slowly and evening. I typically go 75-100 pumps, but I have a bottle that feeds the reservoir with a qt. of brake fluid in it. The reservoir only allows for 5 pumps or so as is, so if you do not have a large supply you need to check it every 4-5 pumps of the pedal.

Now to jd:

Is there fluid leaking?

You mention a mechanical sound. Time to remove the slave and inspect. Also carefully inspect the clutch fork. It may be out of place. I hate to ask, but tell me about your clutch: type, age, miles.

Keep us posted...

Regards,
LarryB

 

[jdnsx]

No fluid leaking anywhere.

The slave is properly seated in the fork and the slave pushrod is not and will not extend.

Now the part you'll love Larry, I have the first 6 speed SPEC clutch ever made.(your favorite):wink: It has 30,000 miles and I have never had any problems.

My question is, if this were a clutch issue wouldn't the slave still be moving??

 

[ralph cerbone]

No fluid leaking anywhere.

The slave is properly seated in the fork and the slave pushrod is not and will not extend.

Now the part you'll love Larry, I have the first 6 speed SPEC clutch ever made.(your favorite):wink: It has 30,000 miles and I have never had any problems.

My question is, if this were a clutch issue wouldn't the slave still be moving??

it should ,make sure you have enough play in the clutch master cyl push rod, everthing is new ,it should work , could you have a defective m/c yes , but unlikely , there are specific dimensions in the manual , when i did mine i left it i left it a hair loose ( more freeplay) hope this helps

 

[Larry Bastanza]

If the slave will not push the fork, either there is still air or some issue has occured with the pressure plate, or the fork is not seated on the pivot pin correctly(or it may be broken).

So you are saying you can pull the boot back and have someone press the clutch pedal and the fork does not move?

And then after a while of you pressing it, it starts to work?

And if it sits for weeks this typically happens?

LMK,

Regards,
LarryB

 

[NONSENSE]

I had some problems with my clutch a couple of months ago, and tried vacuum bleeding and the traditional method. Neither worked. I searched the "internets" and found another method. It WORKS, period. For whatever reason, bleeding a hydraulic clutch and bleeding brakes are different, and a different method was employed.

You're going to need a couple of plastic syringes, get the luer-lok kind that you can put a needle on (although you will not be needing a needle). I used a 60 ml at the slave cylinder and a 30 ml at the master. You can use a "catheter tip" at the master cylinder (it may be easier, you're just sucking out fluid), but you're going to need the luer-lok at the back. You're also going to need a short section of tubing to go between the syringe and the bleeder nipple on the slave cylinder.

Essentially, you're going to be flushing the system from the slave to the master, not the other way around like the other methods. Use the "master" syringe to remove as much fluid from the clutch master cylinder as possible. Fill the slave cylinder syringe with clean, new fluid by sucking it up into the syringe from the brake fluid bottle. Push the short section of tubing onto the syringe (it has to be tight). Place a 10 mm box end wrench over the bleed nipple on the slave cylinder, then push the other end of the tubing onto the slave cylinder nipple (again, tight fit). Open the the slave cylinder bleed nipple a quarter-turn, the slowly push the fluid in the "slave" syringe through the tubing and into the slave cylinder. Of course, this forces fluid all the way through the system and out the master cylinder, so what goes in has to come out by using the master cylinder syringe to suck out the fluid before the clutch master cylinder overfills.

When you've pushed all the fluid from the "slave" syringe simply close the clutch slave bleeder nipple, remove the slave syringe, refill and repeat as necessary. Take care not to push any air into the system, which is easy if you keep the syringe vertical with the outlet down toward the clutch slave cylinder). Makes sense, works like a charm, and you're flushing the system with clean fluid as you go.