Clutch Slave Cylinder Replacement

APPLICATION: All 2WD gasoline engine Vanagons. It may apply also to diesels but I don't know for sure. I also don't know if it applies to Syncros.

SITUATION: Your clutch slave cylinder is spewing brake fluid out when you push on the clutch.

This is a fairly simple procedure, though it can be frustrating. You will also need a helper to help you bleed the clutch when you are done unless you have a one-man bleeder kit. Before you start, go get a new slave cylinder and don't forget the supplies for your brake/clutch bleeder kit -- a section of clear hose that will fit snugly over the bleeder valve, a glass jar to catch brake fluid, and plenty of fresh unused brake fluid.

OK, first remove the hubcap from the left rear wheel and then break the lug nuts loose. Now jack up the rear of the van and support it on jackstands. Remove the lug nuts and then remove the left rear wheel. Look in through the left rear wheel well and you can see and reach the slave cylinder. You will see that there is a hydraulic connection to the front (front is front) of the cylinder and there are two bolts with nuts that hold the slave cylinder to its mounting bracket, which is apparently bolted to the transmission case. Additionally, you will see that the pushrod of the slave cylinder pushes directly on the clutch release lever arm.

NOTE: Someone has told me that the slave cylinder bracket does in fact bolt to the transmission case. Since that's the case, it would undoubtedly be easier to undo the bracket from the case and replace the slave cylinder that way. Since I was unaware that the bracket was separate from the case, I will tell you how to do it the way I did it.

First, take a pair of locking pliers and clamp them firmly on the rubber portion of the clutch fluid supply line, near the front of the transmission. This will keep brake fluid from siphoning out when you undo the hydraulic fitting from the slave cylinder.

Now take your 12mm wrench and undo the hydraulic fitting from the slave cylinder. Go counterclockwise to loosen. Once it is free, take your 13mm wrench and undo the two nuts that hold the slave cylinder to the bracket. The nuts are accessible at the top of the bracket, and the bolt heads will probably have to be held from under the bracket to keep them from turning. This may be a three-handed job. It helps to have someone below to hold the bolts from turning, especially the rearmost bolt since it is hidden behind the slave cylinder pushrod and is very hard to reach.

Once you have the nuts off, put them in a safe place and withdraw the slave cylinder from its bracket. Get the new one and prepare to install it. This is where the second person laying underneath the car really helps. You need him/her to help hold the bolts in place while you mount the slave cylinder, make sure the socket on the pushrod aligns with the ball on the clutch release lever arm, align the holes on the cylinder with the bolts, and push down against clutch spring pressure so you can thread the nuts on the bolts. Yes, it's difficult. It will take some time, so be patient. Swearing helps.

Once you get the nuts threaded a bit onto the bolts, start tightening them down. You will not be able to attach the hydraulic fitting until the nuts are tightened pretty much all the way down because the pressure from the clutch lever arm pushes the whole cylinder upward. Tighten the nuts down and when they are tightened, attach the hydraulic fitting. Be careful to get the fitting threaded into the hole on the cylinder straight or it won't start on the threads. Once you've got it started, tighten it down. Then do a final tightening of the mounting nuts and you're set.

Remove the locking pliers from the rubber fluid supply line and have your helper go up front and sit in the driver's seat with a can of brake fluid. Have him/her top up the reservoir and be sure to tell him/her not to allow the fluid level to drop below the take-off point for the clutch system (the thick fabric-covered hose that attaches to the side of the reservoir).

Now get your 7mm wrench ready and attach your bleeder hose to the bleeder valve on top of the slave cylinder, after removing the dust cap. Have your helper pump the clutch pedal a few times, then have him/her hold the clutch pedal down steadily while you open the bleeder valve. Then close the bleeder valve and tell your helper to let up on the clutch and pump it some more. Tell your helper NOT to let up on the clutch until you close the bleeder valve. Communication is important here. Repeat this procedure until you are getting clean clear fluid from the bleeder with NO bubbles visible. Bubbles indicate air trapped in the system and this will give you a spongy pedal and may cause hard shifting.

Once you are finished bleeding the system, have your helper top off the brake fluid reservoir to the "max" line. Now you can replace the dust cap on the bleeder valve, remove your equipment, replace the wheel and lug nuts, lower the car and torque the lug nuts to 125 foot-pounds. Of course put the cap back on the brake fluid reservoir and put the lid back on. Put the hub cap back on, put all your stuff away and dispose of the brake fluid properly. If you got brake fluid on anything painted, wash it off immediately with cold water. Also wash your hands.

You are done. The clutch should feel firm and shifting should be smooth. If not, you probably did not bleed the system properly.

Sean Bartnik
April 19, 1998

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