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Discussion Starter · #21 ·
OK, lets back up... my son replied.
1) Last May the clutch pedal went almost to the floor 1 day. ( this was not gradual, it was a sudden thing).
2) We knew it was the line because the slave would not move when the pedal was depressed.
3) We replaced the master, flexible hose, and slave. We then bled by vacuum hand pump because the pedal method would not work.
We had to do this several times before the pedal would get pressure. I assume maybe 5-10 times. There is a topic about this if you look back at this forum in May.

4) My son said maybe 2-3 weeks later in May, the shift stick would almost get caught trying to shift in first. This would happen once a week, then gradually got worse til last month it was daily.
now it is like 25%-50% of the time he needs to shift into first there is resistance.

5) We tried to bleed it by vacuum hand pump last Saturday. He said it seems that doing this made it worse. We pumped again, then it is back to 25-50% of the time it has a problem.
He also said that there was bubbles all the time coming out. I said it might be because the valve was open too much and air was getting into it at the stem end. When I say valve, I am talking abotu the part you turn to stop/start the bleeding process.

SO I guess, this points to the hydraulics again? Maybe this weekend, we can try the pedal method for bleeding and adjust the specs for the pedal and see how it goes?
 

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The 1" of play may be preventing the clutch from completely disengaging, though I would think that at most it would just make the clutch pedal feel a little sloppy. Still, redoing the adjustment is a good plan.

How many miles has it driven since the clutch was replaced?

Does it have any issues shifting into reverse?1
 

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2004 Xterra XE 4WD Auto 3.3L NA V6
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I tend to think along the same lines as @Satito, in that it may not be releasing.

Also, as @Blackberry stated, the synchro on 1st is needed only when downshifting

I would think that if the clutch is not releasing, then the input shaft is spinning and will likely need the synchro to get it to shift smoothly. The only job for a synchro is to match the speed of the input and output shafts with the selected gear. If the input shaft is not spinning, as in the case of the clutch releasing completely, and the output shaft is at a stop, then the synchro has no job to do.
 

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Depending on what clutch was installed it could only last 50k. I do know that my stock lasted for almost 200k, but some aftermarket clutches are made of lesser materials.

Another possibility is that the clutch fork is worn or not seated correctly so it isn't actuating the throwout bearing correctly. Basically it's a matter of addressing things one item at a time starting with the easy and inexpensive/free and working your way up.

1) Hydraulics
2) Clutch fork
3) Drop the transmission and inspect the throwout bearing and clutch components.

On the plus side...
The manual transmission in these vehicles is not very heavy (compared to an automatic) I wrestled mine out and back in by myself. Not saying that it wasn't a pain in the butt, but a couple of ratchet straps slung between the frame rails was handy for holding things more or less in place when I needed a break from lifting it.

Did you check to make sure the transmission fluid was full?
 

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Discussion Starter · #26 ·
Yes the transmission fluid is full. Hydraulic fluid is full... There is nothing noticeable as far as fluid or appearances. No leaks, etc...

I have a few questions.
1) I am old school and am used to thinking in terms of clutch pedal to rods that pushed the clutch fork.
The hydraulics replaced the rods. If so, then that means when the clutch plate wears down, I still have to adjust the clutch rod/pedal? Or is the hydraulics "self adjusting"?
If this is the case, my son and I noticed 2 things.
A) The plastic sleeve on the pin that holds the clutch pedal and the master cylinder rod was missing.
We replaced that by going to Ace Hardware and my son says the pedal feels normal (no looseness).
B) Then we also noticed the threaded rod was at it's max. In other words, we cannot
extend the pedal back towards the driver any more. If there is excessive freeplay, we cannot shorten it up.
We have not had a chance to do the measurements/adjustments. We may try this weekend.

2) I looked at the FSM. If you look at the last line, you see "Clutch does not disengage".
Can this line also be used for "Clutch does not engage"?


And Satito, we are thinking about dropping the transmission, but we want to do the first 2 things you listed, and bleed more, etc... We did look up the price and see a clutch kit at Rockauto is around $150. Not bad. We just don't want to take it down and do that work, unless we are confident it is the clutch or pressure plate, and not something else further inside.

And
 

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Yeah, I hear that. Unfortunately, you won't be able to tell if it's the pressure plate, throwout bearing, or clutch disk until you take the transmission off.



If the clutch disk was replaced, but not the pressure plate then it's possible that the pressure plate has gone. In that event, I would probably still replace the entire kit.

Here's the clutch that I went with.


I used all of the parts in the kit. It went in perfectly and I've been very happy with it. It was initially a little grabby, but that's all part of having a new clutch. I did find that the tolerances of the new bronze bushing made it difficult to get the transmission to suck up to the engine. There was a 1/2" gap I couldn't close no matter how much muscle I put behind it. I opted to use a ratchet strap slug behind the transmission and attached to the holes in the crossmember under the engine to gradually pull the two together. It worked perfectly with a minimal amount of effort. NEVER use the bolts on the bell housing to pull the two together. It risks cracking the bell housing.

I did drain the transmission fluid before removal to avoid it slopping out the tail end of the transmission since the drive shaft is removed and it's unsealed back there.
The plus side is that since the stick shift is removed, you can refill the transmission through the shift tower before you put the shifter back in. Just fill until a little fluid dribbles out the usual fill hole on the side of the transmission.

Other parts that I replaced:
-fork retainer spring (probably didn't need to)
-Rear main seal
-Input and output seals on the transmission (pretty sure that was overkill, but sometiems I do things just for the experience)
 

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Well, the results of a clutch not releasing and not engaging are going to be different.
When you push the pedal, you are actually disengaging the clutch so that the transmission input shaft can slow down enough for gears to mesh and shift.
When you let your foot off the clutch, it engages to basically clamp the transmission input shaft to the flywheel so that everything spins at the speed and power of the engine.

I guess it depends on perspective and which end of the system you are looking at. Engaging the pedal, releases the actual clutch components. Releasing the pedal, engages the clutch components. But from the chart, they are talking about the clutch pressure plate and disk end of things. So the chart refers to the clutch components not disengaging when you push the pedal. This appears to be your issue, so the chart is correct for your problem.

Caffeine induced word salad!!!! :ROFLMAO:
 

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Discussion Starter · #30 ·
OK, then what about adjusting the rod/pedal.
Does the hydraulics do that automatically or is the fact that the Master rod is at the outer limits, that might say the clutch plate is thin?
 

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Well, the results of a clutch not releasing and not engaging are going to be different.
When you push the pedal, you are actually disengaging the clutch so that the transmission input shaft can slow down enough for gears to mesh and shift.
When you let your foot off the clutch, it engages to basically clamp the transmission input shaft to the flywheel so that everything spins at the speed and power of the engine.

I guess it depends on perspective and which end of the system you are looking at. Engaging the pedal, releases the actual clutch components. Releasing the pedal, engages the clutch components. But from the chart, they are talking about the clutch pressure plate and disk end of things. So the chart refers to the clutch components not disengaging when you push the pedal. This appears to be your issue, so the chart is correct for your problem.

Caffeine induced word salad!!!! :ROFLMAO:
Bravo....well said! Take em to school.
 

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A hydraulic clutch is self adjusts as the disk wears. The purpose of adjusting the connecting link between the pedal and the master cylinder is to remove play from the pedal and ensure that the master cylinder is getting a full compression and not being compressed when the pedal is released. The goal is to find the sweet spot. Usually that's around 1/4" or slightly less of travel.

If you are losing an inch of travel and say the master cylinder piston only has 4 inches of possible travel, you are losing out on 1/4 of the total actuation of the master cylinder, which means that it is pushing 1/4 less fluid into the lines and pushing the slave 1/4 less. Granted, there are other hydraulic physics involved and it isn't all a straight 1:1 relationship, but this gives the gist. If you aren't getting full compression on the master then you may not have enough pressure to fully disengage the clutch from the flywheel. That could actually result in the issue you are having.

So you may find that adjusting the pedal link actually fixes the issue.
 

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Discussion Starter · #33 ·
OK, thank you for all the inputs and explanations.

My son and I will start at the beginning this Saturday with pedal measurements, then work towards the hydraulics, then decide what next.

Crosses fingers!
 

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My Son has a 2000 Xterra , 255,000 miles

When he comes to a stop light and tries to shift into first, the stickshift will get some resistance as if the syncho is worn.
However, there is a same problem with 2nd gear.

I told him I thought there was 1 synchonizer for each gear and the fact that 1st and 2nd have issues shifting smoothly into gear says it could be something else.

What is it like when the pressure plate is worn out or weak? how does it affect the shifting?
Or maybe the clutch plate is too thin?

any ideas?
The type & brand of gear oil can make a difference in shifting. I have an 1999 Infiniti G20 where my mechanic used a regular 80-90 w gear oil and added a limited slip additive, and I had trouble shifting into 1st & 2 nd gear. I changed to Lucas gear oil, and it shifts with no problems. I used this https://www.amazon.com/Lucas-Synthe...5e-8edeab9e03cc&ref_=pd_gw_ci_mcx_mr_hp_atf_m
 

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Discussion Starter · #36 ·
Satito - to answer your question, we didn't change the fluid. It came back that way after the synchonizers was changed out 2.5 years ago. Nothing was said on the receipt.

OK... back to square one !!

My son brought the Xterra back and said that everything shifts fine except for 2nd gear.
He said that some time after he drove it home from us working on it about 10 days ago, things changed.

As for 2nd gear, it still has some trouble getting into gear ( the gears are not grinding). It is just that the stickshift has some resistance and have to try a couple of times to push the stick into place.
However, here is the strange thing... When he (NORMALLY IN THE PAST) changes gears anytime ( 2nd, 3rd, 4th) , he doe not need to speed the engine up a little bit when changing gears.
This time, only when he needs to get into 2nd gear, if he revs the engine up say to 1.5 - 2.0K, he can move the stick shift just fine into 2nd gear.
What does this mean?
 

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Hmmmm....
Sounds like he is rev matching to get into 2nd gear. To me that points to either the clutch is slipping/worn or the synchro has an issue. Maybe Blackberry has some insight on this.

Rev matching allows you to shift into gear without using the clutch. Basically you are revving the engine so that it's RPM match the RPM of the spinning transmission and they can slip together.

Normally when I press the clutch, the RPM drop off slightly as I shift into the next gear. I don't generally pay attention as to exactly where the RPM are when I actually shift, but I would guess that it's between 2k and 2.2k. The RPM will then decrease more as the clutch is released. Keep in mind that proper shifting also has your foot lift off the gas when you hit the clutch. If your foot stays on the gas you're gonna have a bad time.
 

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Satito - to answer your question, we didn't change the fluid. It came back that way after the synchonizers was changed out 2.5 years ago. Nothing was said on the receipt.

OK... back to square one !!

My son brought the Xterra back and said that everything shifts fine except for 2nd gear.
He said that some time after he drove it home from us working on it about 10 days ago, things changed.

As for 2nd gear, it still has some trouble getting into gear ( the gears are not grinding). It is just that the stickshift has some resistance and have to try a couple of times to push the stick into place.
However, here is the strange thing... When he (NORMALLY IN THE PAST) changes gears anytime ( 2nd, 3rd, 4th) , he doe not need to speed the engine up a little bit when changing gears.
This time, only when he needs to get into 2nd gear, if he revs the engine up say to 1.5 - 2.0K, he can move the stick shift just fine into 2nd gear.
What does this mean?
This has been a good conversation that has covered very well the basic functions of a manual transmission and clutch, and possible causes of the problems you are experiencing. I have had dozens of autos with manual transmissions and offer the following thoughts that have not been mentioned here—perhaps too basic, but may be worth reviewing.
—make sure nothing is interfering with clutch pedal travel—carpet, floor mat, etc...
—adjust the pedal free play to spec
—when bleeding the clutch hydraulics be sure to keep the pedal depressed until the bleeder valve is retightened
—check carefully the soundness of the transmission and motor mounts

A switch from original, old, dino-gear oil to Redline MT90 improved the smoothness of shifting on my 2003 Xterra, but I was not experiencing the degree of problems you describe.
 

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Satito - to answer your question, we didn't change the fluid. It came back that way after the synchonizers was changed out 2.5 years ago. Nothing was said on the receipt.

OK... back to square one !!

My son brought the Xterra back and said that everything shifts fine except for 2nd gear.
He said that some time after he drove it home from us working on it about 10 days ago, things changed.

As for 2nd gear, it still has some trouble getting into gear ( the gears are not grinding). It is just that the stickshift has some resistance and have to try a couple of times to push the stick into place.
However, here is the strange thing... When he (NORMALLY IN THE PAST) changes gears anytime ( 2nd, 3rd, 4th) , he doe not need to speed the engine up a little bit when changing gears.
This time, only when he needs to get into 2nd gear, if he revs the engine up say to 1.5 - 2.0K, he can move the stick shift just fine into 2nd gear.
What does this mean?
I don't understand why you won't just change the gear oil to a high quality as I suggested. It's easy and cheap, but you seem to want to tear apart your car first.
 

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Discussion Starter · #40 ·
Rick, you may have a point, but why change the oil when the problem changed after bleeding the hydraulics again?
Now the only problem is gear 2. No grinding, just some resistance pushing the stick-shift into 2nd gear.
What is causing this resistance? Why did the resistance go away on gear 1 and "R" after bleeding the hydraulics?

We are thinking about bleeding it again, using the clutch method. Not the vacuum pump.
Also, we looked at the Lucas 75-90 gear oil and it is $19 at the autostore.
 
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