Clutch going bad? Slave cylinder?

[DemoFly]

My dakota has a hydraulic self-adjusting clutch. And it is almost all the way at the top of the pedal before it engages.

It is pretty much an on-off switch. It doesn't slip like a normal clutch should in first gear from a stop. I have to feather it and let it out very slow.

Synchros aren't working the way that they should. I can shift fine but shifting down into first takes quite awhile before the synchro will engage it. Upshifting into second is also a very slow process. I have to be gentle going into third, and then fourth and fifth are fine. These synchro issues are also intermittent. Some days it will be fine and others they will be a lot more grumpy than usual. Transmission temperature has no effect.

I have some clutch engagement noise, but I do not have input shaft bearing noise. I also have a whine in first and second gear that may or may not be normal.

I plan on having this truck for decades, and the clutch is original with 157k highway miles. I know I will eventually have to replace it but I'd like some reassurance before I put in the labor. It would suck to change out the clutch only for it to be a slave cylinder or transmission issue.

 

[GSCJR]

Sounds like the friction disk is worn out. Just my 2c.

 

[EricJRoy]

The friction disc could be worn: rivets grabbing/gouging the flywheel, or the hub is siezed up on the shaft splines.

Shifting down into 1st from 2nd isnt good in any manual trans. Try a slight tap on the gas with the side of your right foot to match synchros.

Also, I would change the transmission fluid. It may have a heavier than factory fluid, try Red line syn GL-4 fluids like DT4, MTL, or MT90 depending on required oil weight. GL-4 is good for synchro action, GL-5 is bad due to Extreme Pressure additives.

I had an Explorer 5spd that a schmoe put gear oil into instead of Mercon 5 ATF, which ruins the needle bearings in an ATF lubed trans. You can diag this issue by depressing the clutch in neut. w/ engine running. If the noise goes away as the input shaft slows down, then starts again as you reengage clutch, you prob have bad bearings.

 

[KrisZ]

My first thought is clutch hydraulics. It could be the slave cylinder, master cylinder, fluid leak or air in the system.

Start with the simplest task, check for leaks, check the fluid level and move up from there.

 

[The_Jeff]

If you have the HD New Venture gearbox that will sound whiney. Also rear axles tend to go bad and whine on these trucks. I was led to pennzoil synchromesh for the NV3550 in my jeep liberty; this may not be far from your truck's transmission in design. It quieted it down nicely, particularly the neutral spinning bearing noise.

I tend to also agree with the idea that the clutch itself is bad. Try "pumping up" the hydraulics by rapidly pressing the pedal; if it gets better the hydraulics have an issue.

 

[DemoFly]

No fluid leaks and hydraulic fluid is at the proper level.

I just put fresh Pennzoil Synchromesh into the trans about 800 miles ago.

The clutch/transmission makes zero noise in neutral whether the clutch is engaged or disengaged.

On my drive home I will pump up the hydraulics and see if it makes a difference.

 

[AandPDan]

At 160k your clutch is likely about done. If the slave cylinder is leaking down you'd notice it as it would slowly engage without you moving your foot at all. If it had air it would be spongy. How's the fluid level?

When the clutch wears it grabs near the top.

I don't think it is the fluid either but if you do change it it must meet Chrysler MS-9224 specs. Amsoil, Pennzoil, and Royal Purple all make a Synchromesh fluid that meets these specs - be careful when choosing. Of course you can also get the fluid from a Dodge or even a GM dealer.

2000 Dodge Dakota 4.7 5-speed NV3500 4x4.