Clutch getting soft

[Tim Kay]

New development yesterday, clutch pedal got real soft. I can get presure back by pumping the pedal but has to be done between each shift.

I flushed new fluid through the lines and bleed the line. Worked well for about 3 miles then became soft again. BTW, no leaking fluid anywhere.

Is this an indication of a master cylinder going bad or a slave cylinder or what?

 

[Lynn Larsen]

Tim,

It could be either. Master could just be bypassing most of the fluid rather than pumping it. Slave, depending on type and location could be leaking into the bell housing and hasn't filled up the reservoir catching it enough to leak out yet. Given that the slave requires several more coincidental actions or features, the master is the more likely candidate.

Regards,
Lynn

 

[Tim Kay]

Thanks Lynn,

I did go back and re-bleed the systems and all is fine, for now. Go figure!

Can't seem to figure why out of the blue it went soft. I guess it just needs to "develope" a little more! Per your suggestion, I will keep my eye on the fluid possibly leaking from the bell housing. Although, as I think here, the fluid level in the master cylinder has not dropped at any point since the intial accurance. Even at the first visual, fluid level was high. And subsequent bleeds the fluid level remained at the same filled level /ubbthreads/images/graemlins/confused.gif

Anyway, I'll let you know if it rears it's head again. To busy loving the drive to let a little clutch problem keep me from the open road /ubbthreads/images/graemlins/grin.gif

 

[Frank Catt]

TIM, If the fluid in the master cylinder reservoir is changing color and going very black, this indicates wear on the master cylinder rubber seals and will eventually fail if not replaced, Frank

 

[Simon]

Tim,

Good advice from Frank there. I had the same EXACTLY the same problem. New seals in the slave cylinder cured it straight away. New seals both ends are cheap and (fairly) simple to do.
Simon

 

[Eric A.]

I have had this problem on other cars with a hydraulic clutch and it has turned out to be the master cylinder leaking back the fluid. I would replace the cylinder or the seals and you should be fine. Eric A.

 

[Lynn Larsen]

Depending on the path your lines take, air can be a pesky bugger to get out completely. Sometimes it takes several bleedings, over time, of 2x to 3x of the total amount of fluid the system holds to get it all. If you have any rubber in the plumbing, I would replace it with all teflon lined SS lines and AN fittings. Moisture can pass through rubber lines, believe it or not, over time of course. (Same is true of brakes as I learned the hard way in my failed attempt to use a silicone fluid: big mistake.) Unless you are running carbon discs on a hard core racer, Ford High Performance (DOT 3 I believe) brake fluid is what most of the more casual racers and performance minded people in the know run after having tried all of the other gimmicks. Unless your components were designed for something else, I would think this would be optimal in your clutch lines as well.

PS: I think the brake and clutch lines should be completely flushed once a year or every other year at a max. I just thought of something, you aren't using one of those plastic hand pumps on this are you? If they had a good solution to air leaking around the threads of bleeders they would be OK. But, no matter what I have tried, I have not been able to guarantee that this doesn't occur. Backwards pressure fill is the only other method, besides the tried and true fill the reservoir and have a buddy pump, that I know works, period. Indeed in some systems, this is the only way you can fill it and be sure of not getting air into the lines; motorcycles are famous for this. I have seen where guys use air pressure to assist the tried and true method. If you have time to make the a sealing pressure cap for the reservoir or can buy one, I don't see this as a problem either. Just make sure you don't let the reservoir go dry, of course Speed bleeders DO work also and make the tried and true method a lot easier.

Regards,
Lynn

(Tim, don't take this the wrong way. My descriptions may seem like you don't know most of this already, but they are meant more for the nubee who is reading this sometime down the road. My wife let me know the other day that it is sometimes taken as condescending and that is the last thing I want to do.)

 

[Tim Kay]

Great advice guys. Thanks.

Lynn, it's always good to go back to basics. Often times, with me, it's the simple things I over look /ubbthreads/images/graemlins/crazy.gif