1991Runner

Hello,
Nine years ago I bought a gently used 1991 4Runner that had 49,000 original miles on it. It had been garaged its whole life. It now has just shy of 91,000 miles on it and has been garaged since I bought it as well. I only use it for few weeks each summer for road trips as I have other vehicles that are my daily drivers.

A little vehicle history……. According to Toyota service, all recall services have been performed. The head/head gasket recall resulted in Toyota replacing the entire engine at 30,000 miles. I was told by the previous owner that the clutch had been replaced at about 45,000 miles but I have no way to verify this and it seems odd that a clutch would need replacing at 45k. I have never seen any signs that the tranny has ever been removed. The vehicle was in pristine condition when I bought it and very tight with no rattles, squeaks or other signs of abuse or poor maintenance. After 41k additional miles, the vehicle remains pristine. The vehicle has averaged less than 4200 miles per year and most years sees far less than that.

I can’t recall what year the problem started but about 4-5 years ago I began to have problems with the clutch not disengaging completely. I could usually get it to shift into first by hitting third then first with a little difficulty. I’ve read all about the broken clutch bracket problems and done a thorough inspection of my own but cannot see any issues at all. I searched out images of the cracks others have posted to ensure I was looking in the right area. I’m 99.9% sure that is not the problem.

Here is the really odd, and I believe significant clue. When the problem first began, the clutch worked perfectly until I had been using the clutch frequently for about 20 minutes like you would in a city. If I got directly on a highway where using the clutch was not needed, the problem was delayed until I began using the clutch frequently near my destination. If I parked the vehicle for an hour or so, the problem would cease until I had been using the clutch frequently again. The pattern of malfunction was always the same…..initially fine.…..after 20 minutes or so of use it would begin not disengaging completely……let it rest for an hour, a day, or six months, and the pattern would repeat. Although I think this odd pattern is a clue, I have no idea what it points to.

Beginning about three years ago, the problem became immediate, meaning that I no longer had a period of trouble free operation before the clutch did not disengage completely.

With regards to the failure to disengage, it is not severe. I can start the vehicle in gear with the clutch depressed and there is no lurching. However, the problem is just bad enough that if I do not get the tranny into first before coming to a complete stop, it can be a pain to get it in at all. Sometimes I have to stop the engine, put it in gear then depress the clutch and start then engine. Again, there is no lurching. If it were not for the difficult shifting, I might not even notice how mild the incomplete disengagement really is. On a very level surface, the vehicle will roll forward ever so slightly if I let off the brake but I notice no drop in rpm until I lift the clutch about one inch from the floor.

My first thought all those years ago was that either the master or slave was leaking externally or leaking down internally. Despite not finding any external leaks I replaced the master and bled it properly but the problem remained. I’ve had surgery on my left ankle each of the last two summers so I’m only now getting around to investigating the matter further. Despite not finding any external leaks on the slave I replaced it yesterday and bled the system again but the problem is still there.

Today I decided to adjust the master cylinder push rod just for grins. I turned the push rod out, towards the master cylinder about a turn and a half which translates to about 1.5mm of adjustment in the pedal push rod play. The problem got better! I could shift very easily and smoothly into any gear with the clutch depressed even when shifting to neutral, letting the clutch out and then depressing again and shifting.

I then test drove the vehicle for about forty minutes and it began to exhibit the original symptoms after about 20 minutes of frequent use.

I know that hydraulic clutch systems typically require no adjustment to the mechanical components such as the push rod, pedal height or free play but I cannot think of any other problem that might exist.

The clutch has always felt solid and smooth and does not chatter or make any noises or emit any hot clutch aromas. It has never shown any hint of slipping under heavy power either.

My thought is to adjust the master cylinder push rod a bit more and I’m curious what any of you might think is going on.

One curious thing about the pushrod adjustment is that the rod is very hard to turn. I loosened the lock nut and the nut moves freely with my fingers but the rod threading into the clevis is very tight. If it were meant to be this tight I would expect a spot to grab the rod with a small wrench. I initially tried to use common pliers to turn it but I could not get a tight enough grip. I finally used a small pair of vise grips to turn it.

Thank you for taking the time to read this. I’ve been turning wrenches since I was 10 years old and this problem has me stumped.

j2the-e

You might have an oil soaked clutch disc or a seizing pilot bearing. In either case, tranny needs to come out. If it were me, I would have a new clutch, rear main seal, and trans input seal ready to go. Do it once, do it right, and don't look back.

1991Runner

Thanks for the response. I will say that there is not a single fluid leak on this vehicle. The back of the engine is dry and the top of the bell/tranny is dry so don't suspect an oil soaked disk. An oil soaked disk would exhibit other symptoms and odors in my experience. The pilot bearing is a bigger possibility but that should cause some sort of noise right?