i have a 1990 4runner 4 wheel drive..



So the other day i was out and all the sudden my clutch dropped to floor.. anyone have any ideas on why?

Does your clutch still work? I would start by assuming you have a leak somewhere in your clutch or your clutch mc took a dump.

no as soon as you push it it just drops to the floor

Try bleeding it to see what kind of pressure you have. Might be a bad master or slave cyl. how is your fluid level?

I had the exact same problem with my '95. Mine was caused by little specs of crud in the master cylinder reservoir that broke loose and clogged the outlet, so no fluid could pass into the line. I had the reservoir cleaned out, and new fluid put in, and it fixed it for a time, but the problem came back twice. I finally just swapped out the master cylinder--problem solved. I guess there was some foreign material still in after the cleanings, so with the brand new one, it took care of it for good. Make sure you bleed ALL the old fluid out, watching the color as it comes out of the bleeder, until it is nice and clear.

its probably the original clutch and needs to be replaced

That may be true, but if the clutch was wearing out then it would be gradual and not all of a sudden.

My money is on a leak or a bad mc.

Yeap me too, the clog idea isn't bad either, I had that problem on my 3rd gen brakes

Aah! Such a timely post, because i just started working on my clutch hydraulics, too!
Agree with SV_Dude.
Completely dropping to the floor, suggests total loss of compression due to gross leak (not seeping), OR piston in clutch master cylinder not pumping anymore.

Leak is easy to inspect.
Just follow the system from the push rod (attached to clutch pedal)
Push Rod End of Clutch Master Cylinder | Flickr - Photo Sharing!

... To the Master Cylinder

Clutch Master Cylinder & reservoir | Flickr - Photo Sharing!
Make sure your clutch reservoir is full and you have the right & good fluid in there- Old fluid loses hydraulic properties and could clog system.

... follow the lines to the Clutch Release Cylinder (seen here from underneath the truck and passenger side of the transmission box on a First Gen U.S.A. model)
Clutch Release From Passenger (U.S.) Side | Flickr - Photo Sharing!

If master cylinder is bad:
It is not compressing the fluid anymore (akin to a French coffee press) because gasket around piston is worn out, or inner surface of cylinder is damaged/gouged. MC can be taken apart, inspected and lithium Soap Base Glycol Grease applied to gasket (Per Chilton's manual). If cylinder surface is damaged, MC needs to be replaced. The beauty of earlier, simpler 4Runners is that parts are inexpensive.

If spongy (but not losing fluid):
Air in lines - needs bleeding.
Bad fluid (had lost hydraulic properties)- needs replacing
MC starting to go bad going bad - inspect, service or replace.

Sorry, It may be unethical to post scans of cylinder breakdown from manual.

Regards from a new guy in the community,
RAD

false.

It's good that you can prove me wrong with a well defined explanation.

Maybe if the throw out bearing went south then I can see it being all of a sudden. But the pressure plate is nothing more than a spring. The spring will lose tension gradually. If the clutch disc went out then it would not really create the "dead pedal" that the OP is describing.

In a forum where people are here to learn and investigate their problems, it is good to try to explain yourself. Don't just state "false" with out any reasoning behind it. It makes you look ignorant!

there are a ton of possibility's... pressure plate could have **** the bed. installation failures. linkage. lack of maintenance. driver abuse. normal failure. i was just ****ing with you

Since the idea of clutch failure is being put out there, I'll just clarify that with mine (a simple clogged master cylinder), the clutch was clearly still engaged with the pedal on the floor--everything inside the bellhousing was still working. There were no leaks, no clutch disc/press. plate problems, just a tiny spec of foreign material in the fluid--when it plugged the outlet, the pedal just went to the floor and stayed there. So one question to ask, YotaGuy, is does your truck keep trying to move with the pedal on the floor, and then die when you stop it? If so, your clutch hardware is probably fine. Master cylinders aren't very expensive, and they're a piece of cake to change--then you just need a friend to help bleed the system.

We post here mainly to help guys out with their rigs. At least make some sense and explain yourself when you suggest that one particular component could be bad. I am not the god of all things mechanical. But I do try to think things through and explain my train of thought.

Since you're bringing up a clutch assembly whether it be the clutch disc, pressure plate, clutch fork, throw out bearing, expand on this please. Give us a scenario where a failure of any one of these items could make a sudden loss of feel to the clutch pedal where the pedal goes all the way to the floor. I suppose if the throw out bearing went bad and the clutch fork isn't moving far enough to apply pressure to the pressure plate then this could be the issue. Maybe the clutch fork snapped in half could be causing this too, but this is very unlikely. Even the throw out bearing would usually give some sort of notice that is is going to kick the bucket.

Heck of a first post, welcome! The Factory Service Manual is available as a free PDF in the stickies up top, don't worry about posting pics!