G50 clutch slave cylinder: why you need to flush

[jlex]

Bled the brakes on my '88 last fall: no big surprises as the calipers had been replaced, but I was suspicious the PO didn't make sure the clutch slave cylinder was flushed at the same time. Here are pix of the old (probably original) fluid after flushing it with one liter of fresh fluid. Although the clutch operated well beforehand and the flush made no change in its operation, I feel better about it using fresh fluid.

[bigel]

Was it a complex undertaking to flush the slave cylinder??

[DRACO A5OG]

Getting the clutch bleeder to break open with out rounding it off is the biggest thing, so be prepared to buy a replacement.

[bigel]

When I get around to doing the job I'll have a spare on hand just in case...that will ensure that it won't round off, right?!

Originally Posted by DRACO A5OG

Getting the clutch bleeder to break open with out rounding it off is the biggest thing, so be prepared to buy a replacement.

[jlex]

Originally Posted by bigel

Was it a complex undertaking to flush the slave cylinder??

No. Actually, it was pretty simple & not nearly a pain in the neck as doing a valve adjustment is.
Remove the LR tire after putting both rear wheels on jack stands (don't forget to chock the front wheels). Get a good visual on where the bleeder valve is, then slip your box end wrench over it (I believe it's 7mm). You will next want to place a piece of clear plastic tubing over the valve that just as you would do if bleeding the brakes. Place the other end of the hose into the waste bottle (keep it in a small box or something so it won't tip over).
I used the Motive power bleeder for the operation. Put a fresh liter of brake fluid into the bottle, make sure the overflow hose is pinched off, then pressurize the bottle. From there, while you're flat on your back & can't see anything, it's a matter of reaching up to the pre-positioned 7mm box end wrench & opening the bleeder valve about 1/4 turn. Pressure from the motive bleeder will force new fluid in and old fluid out. Keep checking on the fluid level in the Motive bottle.
Note that I did not pump the clutch as this is not a bleeding operation, just a flush to replace the old fluid with new. If the master or slave cylinder had just been replaced, then you'd be looking to evacuate air as well as old fluid so a pump or two on the clutch may be in order.
From reading prior posts, I was a bit concerned about rounding the bleeder valve, but with only 36,200 miles on my car, I wasn't expecting it to give much of a struggle. I will have to say, though, that the bleeder valve itself is a bit long, so you want to make sure the box end wrench is centered on the shoulders of the valve before you try to open it. I suspect (since you can't see what you're doing & have to go by feel) that people allow the wrench to ride too far down on the valve toward the body & end up unwittingly rounding off the corners. Just center the wrench before you open it & you should be okay. This job should only take about 1.5 hrs. from start to finish.
If you don't have a Motive bleeder, I assume it would be just like bleeding brakes: get a helper to push the clutch pedal in while you open the valve, then you'd tighten the valve before the pedal returns to it's original position, making sure that the hose was submerged in fluid to keep out air & also making sure the reservoir didn't go down too far and admit air. I haven't done it that way, so I can't guarantee that's the way to do it w/o a Motive.

[ganun]

Yeah on mine it took over a liter before it came out clear. It had only been 3 yrs since the a new master and slave .... I figured it must be the hose going up by the tranny going south, bought another but haven't put it in. Gets a lot darker faster than the calipers ?????

[DRACO A5OG]

Originally Posted by jlex

(I believe it's 7mm).

Yes, it is , Helped buddy with his, he had a horrible time, could not break that sucka loose, once he did, he rounded it off :-(. Lucky he had a spare to complete the job.

[stephen1070]

would using a six point flare nut wrench on the slave fitting reduce the chances of rounding it off?

[spyerx]

I use a 7mm flare. It's just really thought access.

My fluid looked worse. Brakes clearly bled and looked pretty good but the clutch...

https://instagram.com/p/5TtU9WrnrW/

[DRACO A5OG]

^^^, Whoa, that is pretty fowl.

[jlex]

Originally Posted by stephen1070

would using a six point flare nut wrench on the slave fitting reduce the chances of rounding it off?

I believe a flare nut wrench is opened at one part so it can be used on a nut when there's a line connected to it (like a brake line). You don't have the problem with the bleeder valve, because you're attaching the line after you've placed the closed, boxed end wrench on the bleeder. I'd use the box end wrench as it gives an additional side to grab the nut with. The box end grabs it on all sides, 360 degrees....

[JasonAndreas]

Use a deep six-sided 7mm socket to loosen the bleeder valve, then a (regular/flare/whatever) wrench to open the valve with a small clear tube attached and more than likely you won't round it off.

[sugarwood]

Can someone explain what bleeding the clutch means? I thought these cars have mechanical clutch. I only have ever heard about bleeding brakes, not slave clutches.

[$ Short]

Your 86 is mechanical.
87 on went to hydraulic with the G50

[Jcslocum]

Originally Posted by sugarwood

Can someone explain what bleeding the clutch means? I thought these cars have mechanical clutch. I only have ever heard about bleeding brakes, not slave clutches.

Sugar, (I usually get slapped or the dirty look when using that term) it's the bleeding of your hands and forearms from reaching up into that deep dark area to work the bleeder screw hidden up there. And the wrench only goes about 6 degrees per turn until you cut it down to about 2" long. It can be a real PIA!!

[jlex]

Originally Posted by JasonAndreas

Use a deep six-sided 7mm socket to loosen the bleeder valve, then a (regular/flare/whatever) wrench to open the valve with a small clear tube attached and more than likely you won't round it off.

That's probably a good suggestion; you wouldn't have to worry about centering the wrench on the bleeder valve to initially crack it open. Hopefully, there's enough room up there for a deep socket/wrench. For the ultra cautious, a drop or two of PB Blaster before you started couldn't hurt either.

[froggert]

Originally Posted by Jcslocum

Sugar, (I usually get slapped or the dirty look when using that term) it's the bleeding of your hands and forearms from reaching up into that deep dark area to work the bleeder screw hidden up there. And the wrench only goes about 6 degrees per turn until you cut it down to about 2" long. It can be a real PIA!!

Good thing you have a minion with double jointed pipe cleaners for arms!!

[jlex]

Originally Posted by froggert

Good thing you have a minion with double jointed pipe cleaners for arms!!

Hey, I'd rather do a clutch slave flush any day over adjusting the valves. I'd rate it at only 20% of the PITA of doing a valve adjust. No real reason to delay on it & chance having to replace the master or slave cylinders later due to rust. The only downside is you don't get the reward of a performance boost that a valve adjustment offers... just peace of mind.