Hello
I normally can figure stuff out on my own or by reading this forum. The forum is great. Me, I'm an idiot.

In this case I want some help to pragmatically diagnose a shifting problem without throwing parts at this truck.

I have a new to me 1994 4Runner 4 cyl with the manual W56 transmission.
Here's what's going on:

• Start the vehicle- it goes into all gears smoothly and shows all signs of functioning normally.
• Drive for +20 minutes and it becomes difficult to impossible to get it into first gear. Reverse grinds but will go in.
• The +20 minutes thing may be a red herring because sometimes it will go a whole day or days without getting that bad.
• It's an inconsistent problem that I can't correlate with anything.
• Second possible red herring- transmission cross member has seen some trauma prior to purchase. Since the clutch problem is inconsistent I don't think this is the cause. See photo.
• Third possible red herring- there is some contamination on the master cylinder pushrod and clutch bracket. It's not wet oil but it is visible. See photo.
• Dead stop does not help.
• Blipping the throttle does not help.
• Double clutching does not help.
• Turning off the car helps every time. It shifts fine with the car off.
• Some improvement is seen when I go from second to first or reverse to first. This is inconsistent and unreliable.
• Clutch test in driveway- with rig running and e-brake on put the transmission in 4th and let out the clutch. The engine stalls immediately.
• The shift lever and clutch lever feel similar to my functioning '94 Toyota Pickup.

Here's what efforts I've made already:

• Inspected clutch bracket for loss of integrity.
• Replaced clutch hydraulic fluid and bled. The oil looked very bad but now it looks very good.
• Replaced transmission fluid. This also looked very bad.
• Tightened clutch master cylinder freeplay. It didn't help so I reverted the adjustment so there is a little freeplay in the pedal.
• Inspected the transmission mount for loss of integrity.

Please help me with my approach. This is what I plan to do. Seems like a lot of "replace" and not whole lot of "verify" or "test".

1. Verify stroke of shift fork compared to my other functioning truck with W56 transmission. I don't think this is going to be super helpful but if the stroke is way off it cold say something.
2. Replace master and slave cylinder.
3. Replace the shift bushing.
4. Replace pilot bearing. Of course I'd do the clutch and rear main seal while I was at it.

Thanks for you rhelp fellow truckers.

 

You need the clutch freeplay if you dont want to wear out your clutch.

Your problem sound like loosen spring in the clutch housing. When the clutch is wearing out the spring in the clutch disk became loosen and touching flywheel or pressure plate. The feeling is the same as if you dont pushing the clutch and try to shift in gear.

Your master cylinder sound "wet" in the area on the picture. Maybe when the engine bay is hotter your master cylinder begin to leak and work worst ?

At the same time with a new clutch master cylinder you will flush with new oil, maybe your oil is worn out with contamination.

Start with new master cylinder and new oil. If the problem persist you need to verify the clutch.

Come back with the result please.

 

Thanks GFK666.

What's frustrating about this problem is it only effects city driving. I literally just did a Northern Oregon to Southern Oregon road trip with a 100 mile jaunt on I5 followed by +- 100 miles of twisties and gravel roads. When I got back I did another day trip dirt biking. I did not have the problem each trip.

I have bled the master/slave cylinder. It's full of clean oil now. I also verified the stroke when the clutch is working and when it isn't. It's the exact same stroke in MM.
I do not think it's a problem with the master/slave cylinders.

I tried really hard to get a visual on the shift fork. I can not see any signs of cracking on that either. Thanks LC Engineering for the phone call!

I have purchased an Aisin clutch kit, LUK flywheel, OEM rear main seal and shift bushing and cup. My next step is to replace the clutch and transmission crossmember.

 

 

Come back with the result after you change your clutch. 👌