# 99 Cummins ... CLUTCH problem



## rebelplow (Jan 30, 2008)

Hey guys, heres my situation. I've a 99, 3500, 24v Cummins, 4wd, ex cab with the 6 speed manual. For about the last 2 or 3 months occasionally when you push in the clutch, it will stay slightly engaged, and creep, even with the clutch in. You can really tell when you are in reverse. Back up, push in the clutch, and you have to hold the brake and shut the engine off to be able to shift gears or to fully disengage the clutch. 2 weeks ago we replaced the clutch slave cylinder, and it was fine for about 3 days. Now it is doing it again. Any ideas what's wrong? Thanks


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## elite1msmith (Sep 10, 2007)

air in the cyclinder? warped fly wheel?


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## rebelplow (Jan 30, 2008)

So after being out of town all week driving the truck I have found out when it happens. 

It doesn't matter if you are in gear or not. Moving or stopped. 

Push in the clutch, and hold it to the floor. In 3 seconds it loses pressure and engages on its own. 

2 examples: 
1. Park truck and shut off the engine leaving it in 1st gear. Push in the clutch, and hold it in. Leave it in gear, and start the engine. After 3 seconds with the clutch all the way to the floor still, the truck will start moving on its own.
2. Park truck and shut off the engine leaving it in 1st gear. Push in the clutch, and hold it in. Put it in neutral, and start the engine. After 3 seconds try to put the truck in gear, and it just grinds as if the clutch wasn't pushed.

Now this happens everytime you drive. Every stop sign, every stop light, parking lot, gear shift. Where could I be losing pressure? And what do you think I should replace?

Thanks


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## elite1msmith (Sep 10, 2007)

well that does sound like your lossing pressure... have you had to add fluid to the cluch cyclider? if yes, then you have a leak. If no, then you might have bad seals in the cyclinder by the petal


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## rebelplow (Jan 30, 2008)

No, I haven't had to add any fluid to the clutch cylinder. Bad seals by the pedal.... I never thought of that. Could that be caused by not taking your foot off the clutch when you drive? When my dad drives this truck, which is 75% of the time, he drives with the clutch pushed in about 5 or 10% because his knee is bad and it hurts to lift it off the floor everytime for a shift, so he leaves it on the pedal.


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## elite1msmith (Sep 10, 2007)

ummm, its a thought , he could have caused premature wear on the seals. if you have not lost any fluid, then you dont have an external leak, i would bet thats the case. when you push on the clutch there is enogh pressure to move the clutch, but a pine whole leak in the seal would cause it to return back to its prevoius state. but thats just my thoughts let me guess, if you pusgg the petal very slowly to floor ,like 3 seconds movment, truck in gear... the clutch has no effect....


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## rebelplow (Jan 30, 2008)

I'm heaing to the shop right now to do a few things. I'll hop in the truck and try that and see if the clutch has any effect.


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## B&B (Nov 4, 2006)

Not an uncommon issue...

If you have no leaks in the system, and you've never needed to add fluid then the clutch master cylinder is leaking internally, bleeding off the developed pressure. Needs replaced.


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## elite1msmith (Sep 10, 2007)

B&B;576203 said:


> Not an uncommon issue...
> 
> If you have no leaks in the system, and you've never needed to add fluid then the clutch master cylinder is leaking internally, bleeding off the developed pressure. Needs replaced.


, like i thought .... B&B due you think they make a rebuild kit?


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## rebelplow (Jan 30, 2008)

Alright, so it sounds like we are coming to a diagnosis. 
-
elite and b&b, so is the cylinder by the pedal with the bad seals the master cylinder?


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## elite1msmith (Sep 10, 2007)

umm, im not great with the EXACT tech , terms... so thats a better one for BB , but yes it works just like a master cyclider for your brakes,.... i can tell you it replaces the same way , and the bench bleed should be similar, it also should be located by the petal. .....its alos NOT called a slave cyclinder, which is the part down by your clutch.... u might be able to just buy a new seal kit or a rebuild kit? but if your not fimilair, be better to buy the entire assembly. 

BB ? a little help


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## B&B (Nov 4, 2006)

elite1msmith;576449 said:


> , like i thought .... B&B due you think they make a rebuild kit?


Yes they do but there not worth the time and effort re-building for what a 100% new one costs.

The correct terminology for it is: "clutch master cylinder". Should be less than $100. It's located on the firewall. Will have a small fluid reservoir remotely mounted above it with a small fluid line connecting the two.

Make sure to do a through bleed procedure after installing the replacement cyl as well as clean the reservoir and lines of old fluid. Insures a good clean clutch feel and proper operation.


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## rebelplow (Jan 30, 2008)

Elite and B&B.... Thanks for all your help diagnosing the problem. Last week we put in a clutch master and it works like new again. 

While we were at it, we put in a new 4" Heart Throb exhaust from the turbo back. It sounds sweet, and has quite a bit more snort now.


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## elite1msmith (Sep 10, 2007)

hey thanks for the update...its always nice when we have answers so if the problem comes up again for another member -


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