Clutch not engaging

[SupraTrbo89]

A few days ago I was driving my 89 turbo 7mgte 5 speed (R154). In mid drive I went to shift from 2nd to 3rd and it wouldn't go into gear. I pulled over and the car would no longer go into any gears. I popped the hood and checked the master cylinder fluid level, and it was down about 2/3rds of the way. Not low enough to suck air into the system. I have owned this car for 20 years and never noticed the fluid level being low. It must be leaking from somewhere and I figured maybe air got in the system that way preventing the clutch from engaging. I checked under my carpet and also followed the lines from the master to the tranny and do not see any leaks. Any ideas where to go from here?

Also, the car goes into all gears fine with the car not running. One additional item, the prior own installed an ACT stage 1 clutch so I am assuming a stock clutch but slightly upgraded pressure plate. Don't think this really matters though b/c its been perfect for the past 20 years. The car is not a daily, just a weekend ride.

 

[Bru]

If the clutch master cylinder is leaking internally you should see fluid draining out the back into the driver's compartment. Try bleeding the system at the slave cylinder with fresh fluid. I like Valvoline synthetic DOT 3 & 4. Get a one-man check valve bleeder, or attach a tight fitting clear hose at the bleeding nipple and get another person to operate the pedal. Catch the expelled fluid in a jar or bottle. Open the bleeder, depress the pedal to the floor (the spring should keep it there), close the bleeder then raise the pedal and repeat until no bubbles are present in the hose. Be sure to keep topping off the reservoir to prevent air getting into into the system. Another possibility is that the slave cylinder is leaking, but you should see fluid dripping from the access ports on the transmission. You can remove that left side access port and make an inspection. After bleeding, the pedal should feel stiff again and not be stuck at the bottom when depressed. With someone in the car pressing and releasing the pedal, you can observe the action of the slave cylinder pushing against the fork moving it. There is also the matter of clutch pedal adjustment. The push rod pushing against the back of the master cylinder needs a tiny amount of clearance so that it's not pressing all the time. The method is in the online manual.. You'll need 2 wrenches, one to hold the clevis and the other to loosen or tighten the lock nut. Once the lock nut is loose, the push rod screws in and out to adjust clearance. If you can wiggle it slightly, that's enough. Lock it down and recheck. Rock Auto is a place to look for parts. The LUK brand master cylinder they sell is not a OEM AISIN part, even though the photo graph would lead you to believe that. The one I sent back was made in Taiwan. If the clevis pin is overly worn, you can obtain a new one from the Toyota dealer. Part number is: 90240-08006. There's also a plastic bushing that fits over the pin but many times pedal has worn through the bushing and into the surrounding metal. I plan on mending mine with some JB weld and let it set up overnight, if the hole is out of round there when I put the bushing in. The plastic bushing part number is: 90386-08010. The bushing ($8) costs more than the clevis pin ($2), go figure. In the Toyota parts diagram they call it a pin with a hole. Put a small amount of grease at the clevis pin. If you plan on loosening any of the hydraulic lines, use a flare nut wrench to minimize the chance of rounding the flare nut over. It looks like a closed end wrench with a slot cut in it to get over the hydraulic line.

 

[eraezer]

Does the pedal feel spongy? This is what usually happens when you have air in the system.

If you put your car on jackstands, remove the service covers from the bellhousing of the gearbox and look at the movement of the clutch while someone is depressing the clutch pedal. Does it move? Does it look like it's moving enough? You might be able to tell by looking on the shaft that it's moving along.

 

[SupraTrbo89]

Thanks, this is all useful info. I did try and bleed the system already however I was treating it like bleeding the brakes. Press on the brake pedal and then crack the bleeder nut loose. I guess you are saying to crack the slave nut loose and then press the pedal?

Also, I was planning on installing a new slave, master and get the DM clutch line that replaces the hardline and then the small rubber section just in case there is a small leak there I am not seeing. There is fluid / wetness on the bottom of the tranny but its not enough to drip. Could be the slave leaking as you noted above.

 

[Bru]

Thanks, this is all useful info. I did try and bleed the system already however I was treating it like bleeding the brakes. Press on the brake pedal and then crack the bleeder nut loose. I guess you are saying to crack the slave nut loose and then press the pedal?

Also, I was planning on installing a new slave, master and get the DM clutch line that replaces the hardline and then the small rubber section just in case there is a small leak there I am not seeing. There is fluid / wetness on the bottom of the tranny but its not enough to drip. Could be the slave leaking as you noted above.

Slightly open the bleeder nut when the pedal is up. Push the pedal to the floor. Close the bleeder nut then raise the pedal back up and repeat until no bubbles are present in the hose and the fluid color is clear. Its the same procedure for brakes and clutch. Always be careful not to run dry at the reservoir.

Rock Auto has an original equipment AISIN slave cylinder for $20.79 Click here to go there.
The LUK (LMC278) clutch master they sell cylinder looks like a OEM Aisin part, but the one I received was made in Taiwan and is not what was pictured.
If you ever need a brake master cylinder Rock Auto sells an OE unit made by ADVICS (BMT-360 with anti-lock brakes) with all of the original markings even Toyota on the reservoir for $86.79. Click here to go there. Sometimes RA runs a 10% off sale for this brand and also you can look online for a discount code to use at check out. You can pick up the paper gasket that goes between the master cylinder and brake booster at the dealer. The part number is: 47275-24010. There is an alignment procedure when installing a new brake master cylinder so that there is zero clearance between the back of the master cylinder plunger and the rod that sticks out of the brake booster. You can pick up a cheap alignment tool on eBay, or cook up something of your own. Here's the online manual illustration and procedure. Click here to go there.

 

[SupraTrbo89]

Thanks all. I purchased a new slave off of Rock Auto and it's coming tomorrow. I will install it this weekend and see what happens. There are no leaks behind the carpet so I don't think it's the master. I did notice some fluid on the bottom of the tranny so I'm guessing it's the slave. Any special procedures for installing? Seems like a simple part to install, 2 bolts and then the hard line.

 

[Bru]

Put a little dab of hi temp bearing grease where the tip of the plunger contacts the fork. You could also pull the fork out and grease its points as described in the manual. The fork is held in lightly by spring tension. Use a flare nut wrench if possible, when disconnecting / connecting the hydraulic line. Click here to go there.

 

[SupraTrbo89]

I installed the new slave and bled the system and still the same result. I got the car moved into my garage so I can now take my time with it. My next step will be to pull the inspection cover and have someone push the clutch so I can see what's going on.

 

[Asterix]

Here's another idea I got from bleeding the clutch in my '04 350Z after I replaced both cylinders. Try as I did, I could not get all the air out of that system doing my usual routine using a Speed Bleeder. What I ended up doing is this with the stock bleed nipple:
1. close the nipple
2. depress the clutch pedal and hold it (with a stick or a 2nd person)
3. open the nipple quickly to get a spurt of fluid
4. close the nipple
5. raise the pedal and repeat
It took several cycles of this to get all the air out.

A pressure bleeder probably also would have worked, but I don't have one.