I have a 89 comanchee, and over the past 2 years i've replaced the cluch master cylinder 3 times and the slave once. It's been about 6 months to a year since i last replaced it and now  the system is haveing trouble again. You  know, pressing the pedal and nothing happens. Well, i also have a buddy who has a 91 YJ and withen 6 months he too will have replaced the master  twice. Is there something i'm missing here? Why do they keep going out?  Is there a good quality part that i should be using to get more than a years use out of the cylinders?  Thanks for your help  

Hi

I have a 1980 CJ5 with the hydro clutch master and slave and had to replace it twice, then a Jeep buddy of mine told me to use ONLY repeat ONLY Castrol heavy duty brake fluid DOT 3, the Girling hydro clutch parts are kinda picky about fluid type for some reason they like the Castorl stuff however, and also never buy a rebuilt master or slave only use new parts something about a coating on the inside where the piston goes, and when it gets rebuilt they tend to leak, don't know if this is true but I followed his advise and so far after 5 years the thing is working fine, I also bleed the system once a year and put in fresh Castrol dot 3, hope this helps. and just in case you were wondering no we don't work for Castrol, we just work alot on Jeeps ours and everybody elses, and you kinda pick up this stuff after a lot of late night pizza, beer and jeep wrenching hope this helps

Mark

I agree with Mark.  Rebuilt cylinders, when honed take off the finish which actually causes the seals to wear down at an accelerated rate.  Also, brake fluid is hydroscopic ( it attracts an absorbs water).  Without the finish coat on the cylinder it could rust and wear faster still.