Soft Clutch, Won't shift into gear, full resevoir

[RYNOEagle]

1982 SX4 with T5 4.2L

Drove nicely all day, then I had hard shifting on the way home. By the time I got home, it wouldnt go into gear at all if the engine was on. If the engine isnt running, it'll shift in just fine.

Clutch had less resistance behind it, and felt a little short, and got worse as I pumped and pumped it.

Got under the car with someone pumping for me. The master cylinder moves the fork in and out, and is totally dry, so I know it's not leaking. Plus it's been installed under 6 months.

The master cylinder also shows no signs of leaking that I can tell. Dry under the dash, and as far as I can see under the brake booster, it's not leaking there either. But then again, maybe it had already purged everything in it.

The only curious thing is that the resevoir is still totally full, and not moving at all when the pedal is pushed. No bubbles or ripples or anything. I dunno if that's normal, but if there's a leak, it should be going down.

it may be worth noting that the fluid became brown since I filled it.

Could it be an internal transmission problem? Is there any way of looking at the master cylinder better without needing to bleed my brakes afterwards? thanks.

[Amc1320]

Have  you checked the slave cylinder ? If you replaced the master the slave usually goes soon afterward

Good news is they are cheaper, available and MUCH easier to get to

[RYNOEagle]

Wouldn't it leak if it were bad?

[RYNOEagle]

Wow,I just realized I mixed them up. The SLAVE cylinder was just replaced, the MASTER cylinder under the brake booster is the one that wasn't. But the thing is. But like I said before, wouldnt it leak if it were bad?

[eagleman]

Not if its leaking out of the back and into the booster itself. If that's the case be prepared to change the booster too as the brake fluid will destroy the boosters diaphragm if it has not already.

[RYNOEagle]

I dont believe my clutch master cyl. has a booster

[RYNOEagle]

Does the Master Cyl. have an adjuster or self-adjuster?

The throwout bearing is definitely being pushed into the clutch, the fork still moves a good 3 inches or so. and like I said, neither are leaking externally. I also realized that I still have pressure, it's just alot shorter, and seems maybe a little less. But it is still there.

[Amc1320]

You are right, the clutch master cylinder does not have a booster

I would bleed it first to make sure you haven't picked up an air pocket in there somewhere

Another possibility is the hose from the master to the slave sometimes becomes weak and will expand and lose pressure

[eagleman]

My bad. I thought you were asking about the brake master cylinder leaking. No the clutch master cylinder does not have a booster. Sorry if I confused things for ya.

[RYNOEagle]

at this point, i think its either the clutch, or the throwout bearing. i suppose it could still also be internal bleeding within the master cyl. but unlikely.

looks like ill be pulling the engine/tranny soon.

[RYNOEagle]

ill try this procedure tomorroew though, and see how it goes.

Step 1: Make sure that screwed up tube AMC called a master resevoir is full.
2) Get under the car...use a broomstick, pipe or other device to SLOWLY push the clutch fork (and in turn, the slave cyl piston) forward, so the slave piston bottoms in it's bore.  Hold it there, using the stick, pipe, etc to brace against the floor or x-member.
3) (this step requires an octopus, or 2-3 people-your choice) while under the car, open the bleeder on the slave cyl, then have assistant 1 SLOWLY push the clutch pedal down.  The location of the bleeder seems to resist getting all the air out any other way....once the pedal is down fully, close the bleeder.
4) Before assistant 1 releases pedal, either come up, or have assistant 2 monitor the fluid level in the "reservoir" as assistant 1 releases the pedal.  That tube won't have enough fluid to refill the bore of the master & slave, so you've gotta fill it as the pedal is released.  ALSO, remove the brace you shoved up against the fork...again, monitor the fluid level, cause it's gonna drop as the piston is allowed to travel outward....

[captspillane]

I'm willing to bet your master cylinder is bad. When they go bad they just stop pumping or applying pressure. When you replace the master cylinder I highly suggest putting in a different resevoir. The tubes typically crack at the base and leave you stranded. If you can't get a factory style reservoir I have some ideas on making one.

I bleed them differently than that. I use a ratchet strap to pull the fork and compress the slave cylinder in. It doesn't compress it much but it is more there to make sure that it can't extend. I then bleed the fluid while the strap holds it in place and an assistant gently pumps twice per purge.

Keeping the slave from extending increases the back pressure in the line and the air quickly bleeds out without a hassle. If you let the slave extend as the master is pumped you'll be there all day and not get anywhere.

If you are working on it yourself I suggest putting hose clamps around the hex heads of the two bolts on the master cylinder. It works well to keep them from spinning while you're inside tightening the nuts.

[carnuck]

Bent fork?

[RYNOEagle]

The fork is good, no bends.

Can the master cylinder be bad without leaking? The metal all under the master cyl. is dry and the resevoir is still full.

Not having to replace the clutch yet would be huge, so I hope it's that. Even though it'd still be a hassle because of the awful placement.

[RYNOEagle]

Also, the fork still pushes the throw out bearing into the clutch, so would it be that the system still has enough force to push the fork, but not enough to actually move anything once it hits that resistance? Because it goes all the way until it hits, then stops. I'm not too sure how it looks when it's operational, so I don't know what's different now.