[oktaneho]

01 2500 HO w/6-speed 140,000 miles all original driveline


I have the hard to shift 6 speed. Shifts fine when the motor is off but while running and not moving I often can't get it into 1st, 2nd, or reverse. While rolling it sometimes shifts ok and sometimes does not. Reving the motor between shifts helps it slide into gear. I changed the oil this summer and filled it with 6 qts of the appropriate Amsoil. I had the inspection plate off the side of the tranny and cleaned out the shavings off the magnet. There was no change in shifting after the oil change. Removed my floor mat to make sure the pedal was getting full travel.

So correct me if I'm wrong but either the clutch hydros are going bad or some bearing (throw-out?, pilot?) is bad. The clutch fluid reservoir is full and I have never added any fluid. Does that mean the clutch hydros are for sure NOT the problem? Can the hydros go out without losing fluid, or only lose such a small amount that it's not noticeable?

I don't like to just throw parts at things to find out what the problem was. How do you identify which one is the issue? If that bearing is bad does the tranny need to come out?

Thanks in advance,

 

[Junkman]

I would say clutch disk because it is in all gears. Does it engage at a different spot from say 30,000 miles ago? Can you make it slip when it should be fully engaged?

Reving the motor gets the gears at the correct speed similar to what the syncros are supposed to do.

Syncros have only gone out in 1 or 2 gears on the trans I've had.

 

[oktaneho]

Does it engage at a different spot from say 30,000 miles ago? Can you make it slip when it should be fully engaged?

"engage at a different spot" - Meaning does the clutch grab at a different spot in the travel of the pedal than it used to? I would say no, I have not noticed any change there.

It has never slipped on me either.

 

[Junkman]

It is either clutch not disengaging enough or syncros not allowing the next gear.

Is it the same in all gears?

What happens when you are in 2nd and push the clutch all the way in coast for a second then try to shift to 3rd?

My 2-3 shift would grind unless I pushed the clutch, put slight forward pressure on the shifter and blipped the engine. 3-4 was better but still a problem. It was syncros.

HighGear Transmissions in Memphis has NV4500s for a good price if you need one.

 

[SlightlyHazy]

If I ever had an issue getting into 2nd or reverse I put it in 3rd then to the gear I want and always slides right in

 

[dozer12216]

A generally good test of hydraulics is quickly pump pedal 3-4 times and see if shifts better.

 

[Brad92]

When my hydros went out, I could pull up on the clutch pedal with my foot and then shift normally.

 

[bigfish95971]

Sounds hydraulic, not releasing, Dozer's idea sounds good. No noises?

 

[Mopar1973Man]

If hydraulics give up typically you notice either a bleeding clutch that will engage on it own while waiting hold the pedal. Another way I've seen is the pedal will seem to engage way early close to the floor.

A generally good test of hydraulics is quickly pump pedal 3-4 times and see if shifts better.

Dozer right if you pump the pedal rapidly 3-4 time or more and the clutch seems to react better then the hydraulics are typically wore out.

 

[oktaneho]

It is either clutch not disengaging enough or syncros not allowing the next gear.

Is it the same in all gears?

What happens when you are in 2nd and push the clutch all the way in coast for a second then try to shift to 3rd?

My 2-3 shift would grind unless I pushed the clutch, put slight forward pressure on the shifter and blipped the engine. 3-4 was better but still a problem. It was syncros.

HighGear Transmissions in Memphis has NV4500s for a good price if you need one.

While moving, 3rd gear is the hardest to get into typically. Seems to be the same whether I try to shift quickly or wait a while in between gears. If my memory serves me correctly, it drops into 4th and 6th easily and sometimes has a problem with 2nd and 5th. All gears are an issue most of the time when the truck is at a stop. I say most of the time because sometimes it goes right into gear like it should, but that's less than half the time.

It's a 6-spd NV5600 not the 4500.

 

[oktaneho]

A generally good test of hydraulics is quickly pump pedal 3-4 times and see if shifts better.

I've tried that many times. It doesn't make a difference.

 

[oktaneho]

No noises?

Nothing abnormal.

 

[oktaneho]

When my hydros went out, I could pull up on the clutch pedal with my foot and then shift normally.

??

So it shifted normally without the clutch pedal pushed in?

 

[n-mass]

My south bend HD hydraulics just failed on me last weekend, they were just a hair over 2 years old. The truck was hard to shift and eventually would not go into gear without shutting the truck off. I was able to limp it home, luckily I kept my old factory hydraulics, threw them on the truck and it was fine. So much for the HD hydraulics...

 

[rdennisak]

My 2004 (175,000 mi) is doing the exact same thing. i’m wondering is there is a shift linkage that needs adjustment or lubrication. That happened on my 69 El Camino with an M22 4 speed and adjusting the linkage fixed it.

 

[jross036]

Post up in the 3rd gen section, but it’s usually the hydraulics. Buy the whole kit.

 

[CT21Cummins]

You can pull the slave and depress it using a steering whee puller or a 2x4 with a couple holes drilled in it. Then see how much pressure you have on the pedal, if it’s real stiff right away the hydraulics are good. I’m actually buttoning up a DD job on my truck today, it didn’t want to shift good one day then wouldn’t do **** the next. I pulled the clutch out and said how did that ever work, at some time ago it ate a spring out of the center hub, the. Another came out and wasn’t allowing the pressure plate to disengage. If it’s not the hydraulics it could be the throw out bearing or what happened to me.