90 Trooper 2.8L V6-Clutch Problem, Loose Clutch Release Fork

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90 Trooper 2.8L V6-Clutch Problem, Loose Clutch Release Fork

Postby troopdiver » Thu Apr 20, 2017 8:40 pm

1990 ISUZU TROOPER LS 2.8L V6 4WD - MANUAL 5 SPEED TRANSMISSION

Help!

I have recently experienced some shifting issues. The clutch was not going down far enough to accommodate a smooth shift. There were no apparent leaks in the hydraulic clutch system and fluid levels were fine. I suspected the master clutch cylinder and or the clutch slave cylinder. Because of the relatively low cost, I decided to replaced the master clutch cylinder and the clutch slave cylinder, re-bled and everything worked fine for a couple of weeks. I then began to slowly experiencing the same problems all over again and one day I pushed the clutch in and shifted the manual transmission from 1st gear to neutral (shift out of 1st gear was hard) and heard a pop, followed by the clutch pedal immediately going down all of the way to the floor. I thought wow, bad master clutch cylinder or clutch slave cylinder again? I wondered...what could be wrong.

I got under the truck and noticed that the clutch release fork sticking out of the bottom of the transmission on my truck was pressed all of the way in the back position towards the back of the truck and like I said, my pedal was pressed all of the way down on the floor. I immediately thought that the fork should be sprung in the forward position, contacting and compressing the clutch slave cylinder piston into the clutch slave assembly towards the front of the truck, NOT BACK, towards the back of the truck. In my mind, when you press the clutch pedal down, the clutch slave cylinder piston should push out away from the clutch slave cylinder assembly and towards the back of the truck, disengaging the clutch, right?

Also, when I manually pressed in the clutch slave cylinder piston towards the front of the truck into the clutch slave cylinder assembly with my hand, pressure appeared to be restored to the pedal as I was informed by my pedal pumping helper. When I let go of the piston and let the piston extend back out towards the back of the truck, pressure was then lost to the pedal.

I then decided to pull the clutch slave cylinder off and noticed that I could take the end of the clutch release fork in my fingers and effortlessly move it back and forth like it was not connected to anything. I had not noticed this before because the clutch slave cylinder piston was being held in place by the hole in the end of the clutch release fork that is sticking out of the bottom of the transmission.

At this point, I suspect that there is something wrong with the clutch release fork (an attachment point/mount/pivot point/spring or something else and not the closed pressurized hydraulic system because when the piston is in contact with the clutch release fork and fully extended towards the back of the truck there is no travel left. It is maxed out towards the back of the truck. Also, with the clutch release fork positioned towards the back of the truck, the clutch does not appear to be disengaged because the gears cannot be shifted freely.

At this point, I also wonder if replacing the parts/time/effort was totally unnecessary. Please advise, anyone. Thanks!

p.s. Also, If there is indeed an issue with the clutch release fork and not the actual clutch, I am wondering if I can fix/replace clutch release fork and or other springs or such through the square service hole in the bottom of the transmission after removing the rubber boot that surrounds the clutch release fork without disconnecting the drive shaft and UN-bolting and sliding the transmission back away from the engine. Please advise.

Any input would be greatly appreciated, thanks.
Last edited by troopdiver on Mon Jun 19, 2017 7:03 pm, edited 1 time in total.
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Re: Trooper Clutch/Trans Problem - Loose Clutch Release Fork

Postby Ed Mc. » Thu Apr 20, 2017 9:23 pm

The hole isn't very large, but you may be able to see something in there after you pull the rubber boot.

BTW, the clutch fork is on a pivot. So when the plunger on the slave cylinder pushes the fork to the rear, the other end of the fork (attached to the throwout bearing sleeve) pushes throwout bearing forward, into the clutch fingers.

The fork pivot is just a ball; the fork itself has a couple of spring clips. You press the fork over the ball and the spring clips hold it in place. I don't see how the fork could ever come loose if it were installed properly, but if a clip broke, it's possible for the fork to become disengaged from the pivot and ultimately from the throwout bearing sleeve, and cause issues.

If things are working right, you should be able to move the fork front-to-rear and, at the extreme travel rearward, feel it when the T/O bearing hits the clutch cover fingers. Maybe even see that thru the window.

Note that the fork would move with very little effort until it hits the clutch fingers, and then it's gonna take hydraulic force to disgengage the clutch.

If the fork moves all the way to the rear and "bottoms out" on the edge of the hole, without ever encountering any resistance from the clutch, then perhaps the clutch itself is broken. Another rare occurrence but stranger things have happened!

If you suspect something is messed-up within the bell housing, a borescope might let you get a better look at things. Maybe check at your local Autozone to see if they rent them.

HTH & let us know what you find.........ed
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Re: Trooper Clutch/Trans Problem - Loose Clutch Release Fork

Postby troopdiver » Thu Apr 20, 2017 11:09 pm

Ed, thank you so much for responding. Especially for the the PIC. Helps to see a picture of what I need to look for.

I'm wondering now if the fulcrum/pivot point has snapped off because there is absolutely no resistance or feel of contact with anything when I move the end of the fork back and forth.

Also, I saw a picture of a fork that had cracked and snapped in half at the fulcrum. I even saw a PIC of a hole worn through the fulcrum cup, hopefully it is just a spring that has come loose.

Well I plan on pulling the rubber boot this weekend some time to see what I can see. I will let you know what I find.

Again, Thank you so much.
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Re: Trooper Clutch/Trans Problem - Loose Clutch Release Fork

Postby troopdiver » Fri May 05, 2017 2:58 pm

Ed
Well, I discovered that the clutch fork was operating correctly. I thought the fork had no travel left, but I was wrong. I was able to grab the clutch with a pair of channel locks and get the clutch for to travel further back which disengaged the clutch. Remember when I said there were no obvious leaks? Well one thing I failed to mention before was that there was a swishing air noise coming from the clutch master cylinder when the clutch pedal was depressed. I though it was an air bubble coming from inside the clutch master cylinder. I was wrong. Because I was unable to get any clutch pedal at all, I decided to start all over and inspected the whole system. I started at the clutch master cylinder and found a rather large crack in the metal line at the base of the flare. Not good. I re-flared the end of the line and continued to search. At this point I was confident that all of the lines leading up to and including the NEW slave were good to go. I put everything back together and attempted to bleed the system. I discovered two leaks in the line, one at the lower end of the rubber hose and one around the compression fittings on the clutch slave cylinder. I tightened the lower rubber hose connection a little bit and it stopped leaking. The leak at the slave got worse. After numerous attempts at replacing the compressing fitting, 4 sets, about $10 dollars worth (Highway Robbery for copper washers, ha!) and bleeding, I decide to take a step back again. I got under the truck from the front and inspected the slave from the front. Lo and behold, I discovered a leak coming from the front of the clutch slave cylinder casting. There was a micro fracture about 1/8" in the slave assembly itself, right where the banjo bolt screws in. The crack was so small, thin and tight that it was almost invisible. The only way I was able to see it was when it was leaking wet with clutch fluid. Anyways, replaced and re-bled and clutch system is still hold strong for now, ha!

Conclusion: What a nightmare this was. Are things never what you think they are not. Was the slave rebuilt in China and not pressure tested, then sold with the crack in it. OR, did I crack it when I installed and tightened down the four sets of compression fittings? Hum, we may never know for sure.

I'm off to AZ State emissions inspection now that I can drive the truck. The second nightmare begins, ha!.

Thanks for all of your help Ed.
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Re: Trooper Clutch/Trans Problem - Loose Clutch Release Fork

Postby Ed Mc. » Fri May 05, 2017 3:24 pm

Glad you got to the root of the problem. At least you didn't have to pull the transmission to fix it!

I sure never had any issues with the clutch cable on my old '86 Trooper 2.3. Sometimes keeping it simple is the way to go.

G'luck with the Smog Nazi's, fortunately I don't have emissions testing in my area............ed
'90 3.4 Troop LS;
'89 Troop RS (Exhaust Valve Challenged), now gone to a Good Home!
Yes, I am a Trooper-Holic!!!
Keep On Troopin' !
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Re: Trooper Clutch/Trans Problem - Loose Clutch Release Fork

Postby troopdiver » Fri May 05, 2017 5:28 pm

Ha!
The thought of converting mine to a cable system crossed my mind several times during the process.
I just might do it if it rears it's ugly head again, if it is possible on my truck.
Thanks again!
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