Why is my hydro clutch such a PITA

[csdineley]

Ok guys about a year ago I swapped in a sm465. I got all new parts

Flywheel, Clutch, PP, throw out bearing, and fork
Master and Slave cylinders, hoses, syn brake fluid
I used the proper hydro pedals

And everything was fine for a few months. Then it started to act like it was losing pressure if I held the pedal down. So I talked a mechanic friend who said it was a bad master cyl. So I replaced it. Once again everything was good. For a few months. Now it stated doing it again, yesterday. So today I pulled the slave to check for any leaking. Nothing but I did notice the push rod was worn down where it contacts the fork. There was no point on the end at all. So I thought maybe that was the problem all a long. Maybe the part store units are using cheap push rods??? And now it just cant move far enough. So I went to a different store and got another slave. Put it on today and now the master feels like the piston is sticking and doesn't hold any pressure?

HELP Please any advise or suggestions?

And yes I've bleed the hell out of it. Using every method I could find on the internet.

[silverbear]

You may have already looked at this but if the pushrod on the slave cylinder was wore down, look at the dimple in the clutch fork. If is worn through the pushrod can't push the fork out far enough to release the clutch. I ran into this on mySM465 and spent countless hours troubleshooting and replacing everything like you have. I felt like an idiot when I finally discovered the hole in the clutch fork.

[csdineley]

Thanks, the fork still looks new except for some surface rust starting to form. Seems to me to be losing pressure. When I have my wife push and hold the pedal down. The Slave pushes the fork back like normal. Then it slowly returns, with her still holding the pedal down. I took the entire system out as in one piece and bench bleed it again. Re installed it and still doing the same thing.

[86c20]

then its a bad master
it is that simple it should hold no matter what.

also beanch beed it. dont do it in the truck..........ever. it dont work.

[csdineley]

Guess I'll stop tomorrow and get my third master cylinder. I really hope this is the last time I have to mess with this setup. With my 71 MGB I've only replaced the master and slave once in 43 years. It's probably the only part of that car I haven't had to mess with.

[Tucson38]

I had a recent hydro clutch problem also, the new master cylinder pushrod immediately bent into an "S" shape, shortening the throw considerably. Push rod just couldn't handle the pressure of doing its job.

[silverbear]

Originally Posted by Tucson38

I had a recent hydro clutch problem also, the new master cylinder pushrod immediately bent into an "S" shape, shortening the throw considerably. Push rod just couldn't handle the pressure of doing its job.

I had the same thing happen to my first replacement master cylinder while trying to bleed the system. The auto parts store where I purchased it from "warrantied" the first one and the replacement they gave me had a larger diameter pushrod. This one has worked flawlessly so far.

[csdineley]

Had to wait a day for them to get another master cylinder in. But it's in now and all seems to be working. But I'm still worried how long this set will last.

[86c20]

where dou get them from?

[csdineley]

The first one: I got was from Amazon (ACDelco 385344) on 9-7-13
Second one: was from Autozone (Duralast 12176 ) on 7/25/14
Third one: I just used the lifetime warranty on the Autozone one (Duralast 12176 ) Today 9/12/14

[csdineley]

That was for the Master cylinders

The Slave Cylinders have come from Rockauto and Advance auto.

[86c20]

all mine have come form autozone. but that was a few years ago. never had a problem. wonder if they cheapned them up.