How to Replace the Slave Cylinder in a '95 Isuzu Rodeo 3.2L

When the clutch pedal in your 1995 Isuzu Rodeo 3.2L falls to the floor chances are highest that your clutch slave cylinder has failed. The clutch system is hydraulic. There is a master cylinder that holds the fluid reservoir and takes input from the pedal, and a slave cylinder that boosts the pressure up to the point where it can engage and disengage the clutch. If your clutch pedal is spongy, or sinks to the floor, or takes pumping to engage, your problem is most likely in this hydraulic system, and most likely the slave cylinder.

I searched the Internet for hours looking for information on the slave cylinder...there's almost nothing. Oh, there's plenty of information on how to buy one, but next to nothing on how to replace it! Because I didn't know any better, I decided to take a 50/50 approach to the system. I chose to replace the master cylinder. It's cheaper and easier to find!

The master cylinder is on the firewall on the driver's side, outboard of the brake booster. It was less than half the cost of the slave cylinder, and easier to reach, so I replaced mine. It had zero effect on the pedal problem. I talked to an Isuzu factory guy who told me it's always the slave cylinder. He actually said "it's always the slave cylinder." Oops.

The factory guy I talked to was at www.RepairPal.com. I'm not a big fan of paying money for stuff you should be able to figure out on your own, but these guys were really, really helpful. The guy I spoke with used to work for Isuzu, and had tons of information. I highly, highly recommend their service. It's worth the $20 for the live chat.

I got both the master and slave cylinders from Napa Auto Parts. They have a cool online shopping system that lets you print out a shopping list to take with you to the store if you can't wait for the delivery of an online purchase. My local Pep Boys store told me each part was "special order", but I found both at my local Napa store. Actually, the guy in the store said he'd have to special order the slave cylinder..."can you come back in about an hour?" Uh, sure!

Going after the slave cylinder, once you know it's underneath the exhaust system and does not see the light of day, can take some courage. Once you get to it, though, you'll find that it's not hard. It is gaining access to the cylinder that makes the job tough.

You'll have to raise your Rodeo to give yourself access. I bought a pair of plastic ramps from Pep Boys that work great. I found that laying flattened cardboard boxes on the ground under the Rodeo made it easier to work and kept my driveway cleaner. Bring a shop light and a flashlight with you under the Rodeo- you'll need both. Your work is going to be above you, so here's what you'll need in addition to the two lights: bandaids (just kidding), sockets in 10mm and 14mm, a 17mm socket, open end wrenches in those sizes, a box end wrench in 9mm, extension bars for your ratchet, and rags. I found this really cool foldable socket wrench at Harbor Tools for twelve bucks...it really came in handy, too.

The hardest part of this job...well, there are two hard parts. The first hard part is in locating the slave cylinder itself. You'll find it about six inches behind the trailing edge of the driver's side front wheel, on the side of the transmission bell housing, above and behind the exhaust pipe, and behind a small rhomboidal shroud. You'll find a thick, almost braided-looking hose leading to it. From under the Rodeo, look up the firewall under the driver's side and you'll find that the steel hydraulic line coming from the clutch master cylinder terminates in a small junction, out of which runs the thicker hydraulic line. If you follow this thicker line down the firewall you'll see that it passes under a small shroud, emerges about four inches back, and then curves up and disappears under another shroud. If you remove that second shroud you'll find the slave cylinder.

I found it easiest to remove the big armor piece that attaches to the first frame crossmember. While not critical to the operation, it does help in giving your hands some clearance. You'll see that there is a small rhomboidal shroud up behind the exhaust pipe held on with two bolts. Those two bolts go into the holes on the side of the slave cylinder. Removing these 10mm bolts allows you access to the cylinder.

The hydraulic line is held onto the end of the slave cylinder with a 17mm bolt. Be ready to get a bath as you turn this bolt...all of the brake fluid remaining in the system will run over your hand. Remove the bolt and push the hydraulic hose out of the way. The slave cylinder is held in place by a pair of 14mm bolts. Once you remove those it literally pops out.

When you install the new cylinder you will find that it can happily be installed in only one way. The pushrod goes into transmission, the bleeder valve points up and to the right, and the two small bolt holes point down and to the left.

Now, here is where you can take a gamble. The pushrod must rest against a fork inside the transmission. When you stick it in the hole, it will meet solid resistance if it's too high. It will meet zero resistance if it's too low. It feels like you're pressing it into a spring if it's just right, because that means it's pressing against the end of spring-loaded fork in the clutch. Here's the gamble part: If you feel confident that the springiness is correct, bolt the cylinder in place and move on.

But, if you want to make doubly-doubly sure that you've mounted the cylinder correctly, here's the way to check: Forward on the bell housing you'll see another rhomboidal shroud, a little larger than the one you removed to get to the cylinder. This one is held in place by three 10mm bolts, two down low, and one way up there, in back of the exhaust. Those two lower bolts come out quite easily, but that upper third one takes the fingers of a spider monkey and the strength of an orangutan to get off (fortunately, I seem to have both). Removing this shroud gives you access to an oval shaped inspection cover, held in place by two more 10mm bolts. Pull these bolts off and shine your flashlight in the hole. You'll see the end of the pushrod shoved through the hole in the end of the clutch fork. Now you may rest assured that you did it right. Now you can replace the inspection cover and replace the shroud. The shroud's position is counter-intuitive, with the "L" shaped tab going down, not up.

I installed my slave cylinder without removing this inspection cover. I bolted the cylinder to the transmission and checked the pedal for signs of life, but it still rested on the floor. I panicked and pulled the shroud and inspection cover and found that I'd done it right. I panicked for nothing: the pedal rests on the floor because there's still no fluid in the system. Duh.

Before you reinstall the hydraulic line, open the bleeder valve on the cylinder with your 9mm box end wrench. It'll make things easier if you do it now. Now you can pull the little plastic plug out of the end of the new cylinder...that's where the hydraulic line goes. When you reinstall the hydraulic line don't forget that there's a brass washer that goes on first. Torque this bolt down mightily...you don't want it to leak.

Now you must bleed the air from the system. If you go check the clutch pedal right now, you'll see that it's resting on the floor. No, you didn't screw it up...there's just air in the system. Refill the master cylinder and climb back under the Rodeo. You' may see that the bleeder valve is weeping a little. Don't worry.

Here's how the bleeding process should work: first, fill the master cylinder. Second, open the bleed valve. Third, have a companion pump the clutch pedal until a solid spray of brake fluids squirts from the bleeder valve. It can take as many as a gazillion pumps, and there will most likely be zero pressure on the pedal for quite a while. The valve will spit air for quite a while. Eventually, however, you'll feel nothing but a fine spray coming out. Fourth, close the bleeder valve again. Fifth, refill the master cylinder. Repeat steps 2-5 until nothing but fluid squirts from the valve. Once the air is out, you'll see that the clutch pedal is nice and stiff again. When all you get is fluid out of the bleeder valve, don't forget to lock it down with the 9mm wrench. The Isuzu guy I talked with said the easy part was replacing the cylinder; the hard part was bleeding the system.

It's very important to do the bleeding correctly. Make sure and keep the master cylinder full of fluid. If you let it drain dry and then pump the pedal, you'll pump air in the system. Air in the hydraulic system will make the pedal feel spongy, which is what this repair is supposed to fix in the first place. You'll find yourself in a vicious and time-consuming circle that will make you tear your hair out! Please, for your own sake, take your time in bleeding the system. Check the master cylinder frequently. My wife helped me, and we had the system fully bled in about ten minutes.

At first I made a bunch of snide comments about how the bleeder valve was positioned to squirt brake fluid all over my transmission. But then I realized I'd rather have that than have it squirting in my face! Thank you, unknown Isuzu engineer!

Now you can replace the smaller rhomboidal shroud. It, too, is counter-intuitive...the broad piece reaches outboard, not underneath. Replace the armor plate and go wash your hands.

Road test your Rodeo thoroughly. If the clutch works at all, you did everything right! Your clutch should feel much stiffer. If it's still spongy, make the master cylinder is full. Sponginess could be the result of either low fluid or air in the system. You should probably bleed it again.

That's it. I found that the hardest part, beyond getting that bolt off of the inspection plate shroud, was actually finding the darn cylinder in the first place!

After all the swearing and grease and catastrophic blood loss, I am again impressed at the robust, thoughtful engineering that went into this vehicle. You may feel confident that you've made a good choice in purchasing your Isuzu Rodeo!