Do I have a problem?

[JThacker]

Took my 04. 5 6 speed in for the problem I spoke about earlier and they could find nothing wrong, let my try to explain the problem and get some good advice from you all. Mechanic drove the truck and said everything was normal but the truck is doing something now that it never done before, I have 8400 miles on it. On pulling out I use 2nd gear and never need any gas, when I let the clutch out the truck makes a vibration, this also occurs in 1st gear, the problem is worse when decelerating and downshifting as I mentioned earlier if I let the engine bog at all when I press the clutch in I hear the noise and you can hear the body vibrate. Yes, I know I shouldn't bog the motor but the truck never did this before, I have experienced this lotsa times in other vehicles and I know it's normal but this is a change from previous in my truck and it can be very exaggerated at times. If I keep the rpm's up and press the clutch in it does not make the vibration. Does anybody else experience this and what do you think it is? Clutch, maybe but I baby the clutch and the truck is brand new.

 

[rbattelle]

Well, if you're starting out in 2nd gear you're automatically not babying the clutch, in my opinion. And if you bog the motor enough you will damage it, so perhaps you've bogged it down enough that you've damaged the engine. I sincerely hope that's not the case, but it's possible. You're saying that you used to bog the engine and it never vibrated but now when you bog it down it does vibrate. That would seem to indicate you bogged it enough to hurt something, be it the clutch, flywheel, or something much worse (like main or rod bearings).



I think we need a little more information before we can make a more intelligent assessment. I will say this: if I try to start out in 2nd gear without giving it any gas the engine COMPLAINS LOUDLY... always has. As a result, I always start in 1st and I've learned to give it enough fuel to hold RPM steady at about 800. When I first got my truck I started in 2nd, but quickly decided that wasn't what the engine liked.



What's your rear axle ratio? Be sure to fill out your signature so we know what you've got.



-Ryan

 

[JThacker]

Thanks, I filled out my sig. I usually give it fuel when pulling out in 2nd. I am just saying that when I try it with no fuel it vibrates. Jesus, you have scared the s*** out of me, surely I haven't damaged the engine, clutch maybe, does everybody start out in 2nd I thought everyone with these trucks starts in 2nd. Any more info is greatly appreciated, thanks.

 

[whamby]

I have been starting out in 2nd gear for 85000 miles. No problems yet. I have done it loaded and unloaded. Granted it can be difficult depending on the load and it is obviously better to use first when loaded. But starting in first is totally uncalled for in my opinion when unloaded. Of course my clutch or transmission my fall out tomorrow but I doubt it will be from starting out in 2nd. More than like from my heavy foot. :-laf

 

[Gypsyman]

Everyone I know including myself starts out in second. Your not going to hurt the truck one bit. You may be feeling a little clutch chatter or rear axle wrap. Try driving it a little more aggressively. If you've really been babying it you may have never seated the clutch. Bogging the engine will transmit a lot of the low rpm vibration into the vehicle. What kind of noise are you hearing? When bogging the truck with the stock clutch I could hear a lot of transission noise due to the vibration but none with the SBC that I currently run. Sounds pretty normal to me.



Richard

 

[DPelletier]

My guess would be an out-of balance clutch assembly possible due to a bad pilot bearing. If left unchecked the imbalance can cause premature wear and failure of the transmission input shaft bearings. An imbalance can be especially noticable at extremely low RPM's (like when letting the clutch out from a stop in 2nd with no throttle).



Dave

 

[DPelletier]

These things are hard to diagnose second hand, but clutch chatter and spring wrap are relatively normal occurances. Clutch out-of balance vibration isn't and should be rectified. Unfortunately, I don't know which you are experiencing.



Dave

 

[ata]

I think what has happened you have compressed the friction springs in the clutch disk. When you are coming to a stop and pull the engine down below idle with the brakes you are putting a lot of torque load on the disk and when you depress the clutch pedal you unload the clutch disk in a reverse direction from what it was made to do and it chatters and vibrates. So with your driving habits you have messed the clutch disk up. The clutch will last a long time the way it is. Get the service writer to go for a ride with you and show him what it does and if your under 12000 miles they might replace the clutch for you.

 

[rbattelle]

Thanks, I filled out my sig. I usually give it fuel when pulling out in 2nd. I am just saying that when I try it with no fuel it vibrates. Jesus, you have scared the s*** out of me, surely I haven't damaged the engine, clutch maybe, does everybody start out in 2nd I thought everyone with these trucks starts in 2nd. Any more info is greatly appreciated, thanks.

I'm sorry about that, I had hoped I wouldn't scare you. I don't really think you did any serious damage to the engine, I was just pointing out that bogging it (or lugging it) is bad and you don't want to do it very often. I think more than likely your vibration is simply a case of running the engine too slowly. Again, I sincerely apologize for scaring the crap out of you.



I'm surprised to find so many people who start in 2nd gear. As I mentioned, I did that for the first few hundred miles of ownership, then was advised not to do so by a number of 2nd gen owners on this board. With 4. 10 gears it's a different animal, and 2nd gear starts seem more appropriate.



-Ryan

 

[DarkRAM]

starting gear

I used second for the first 1000 or so, but thought that it might be more wear on the clutch, so is the extra gear change more wear than the 2nd gear start? If its negligible, then my left knee won't mind at all

 

[JThacker]

I did some more testing and I found this out. I ran in 3rd gear and held the RPM's at 1200 I then let off the accelerator, clutched it and braked it. The vibration is louder when doing this going down a hill and the steeper the hill the worse the vibration, also the faster you slow down with the brake the worse the vibration. It does the vibration only slightly on level ground and hardly at all when doing this up hill. Does this help any guys?

 

[ata]

Do you feel the brake pedal pulsing when you feel the vibration. It almost sounds like your ABS brake system is not work right or you have warped brake rotors. Instead of a clutch problem. Then next time you are going down hill put the tran's in neutral and let the clutch out and see if you still have vibretion. If so then let off the brakes and see if the vibretion goes away. If it goes away it's the brakes.

 

[JThacker]

Thanks ata, I tried that it's definitely not the brakes I get the vibration without using the brakes, it's always associated with the engine RPM's dropping down to about 600 when I clutch it, the RPM's then jump up to about 900 and it vibrates. I am pretty convinced it's something with the clutch. If I clutch it, put it in neutral and let the clutch out so that the engine has time to slow down before I start hitting the brakes it doesn't vibrate. The vibration is worse when associated with clutching it and braking so that the engine RPM's go from about 1200 before I clutch to 600 and then jump to 900 and it vibrates. What do you think now?

 

[Cattletrkr]

Does it do this only when you let it drop to 600rpm?? You do know that the Cummins 600 stands for 600ftlb of torque, right??? :-laf



When my mom drives dad's '02 5spd, she always does the same thing. Ya know what I tell her??



STOP DOING THAT!!!!



It would appear as though you do have a problem, but I'm starting to think, it's operator related/caused. Not trying to rag on ya, but I've never heard of anybody intentionally doing this repeatedly.



Good luck gettin' 'er done.

 

[rbattelle]

Guys, you have to understand: the ECM minimum idle speed is 650 RPM per the 2003 powertrain diagnostics manual. If you force engine RPM below 650 the ECM believes the engine is no longer running! It probably shuts off fuel to the injectors, then when you release the brakes or clutch and RPM jumps up above 650 again the ECM says "oh! we're running again" and stumbles to restart the fuel flow and get everything back up to normal. Actually, it's a testament to Cummins programming that the engine actually manages to climb back up out of the hole when this happens!



Why run your engine down below the specified idle speed of 750, let alone below 650? I don't let mine get below about 900 before pushing in the clutch. I wholeheartedly agree with Cattletrkr - STOP DOING THAT! Thacker, I'm beginning to think you don't have a problem at all, you're just trying to do things to the engine that were never meant to be done.



Besides the ECM getting very confused, think about the bad things you're doing to the engine way down at 600 RPM. For example, at the normal idle speed of 750 RPM your oil pressure is around 20 psi hot. Down around 600 RPM I'd bet it's less than 10. Not good (oil pressure rises extremely fast with RPM on this engine).



-Ryan

Disclaimer - I'm not being mean spirited here at all, just offering my opinions and trying to help out Thacker...

 

[rbattelle]

By the way, here's the thread where we discussed the appropriate starting gear for the NV5600... take it or leave it.



-Ryan

 

[DMcGalliard]

Maybe not a problem!

Oo. Hi JThacker,

You may be worrying too much, not to make little of your concern though. I have been driving for 55 years and have driven lots of manuals as well as autos. All manual make noises between the flywheel and the final drive. Clutchs, trans, and drive lines rattle, its the nature of the beast. My new 05 six speed rattles some depending on how I engage/disengage the clutch and apply the fuel. Remember not much has changed in how manuals are built and used since the first manual was installed right after dirt was invented.



My advice don't worry so much about it, the manual is tough and if it falls out Dodge will fix it. I had a 41 Chevy that had hole in the side of the trany that I drove for couple months before I could afford to fix it and it did not let me down.



Hope this helps, Dave Mc

 

[ata]

Guys, you have to understand: the ECM minimum idle speed is 650 RPM per the 2003 powertrain diagnostics manual. If you force engine RPM below 650 the ECM believes the engine is no longer running! It probably shuts off fuel to the injectors, then when you release the brakes or clutch and RPM jumps up above 650 again the ECM says "oh! we're running again" and stumbles to restart the fuel flow and get everything back up to normal. Actually, it's a testament to Cummins programming that the engine actually manages to climb back up out of the hole when this happens!



Actually the ECM works the opposite, If the ECM cut the fuel off at 650 thinking the engine is no longer running it would stop when you push the clutch in, not come back to life because there would be no fuel. The ECM actually gives more fuel to keep the engine up to idle speed. That's why Diesel engines are hard to stall.

 

[rbattelle]

Actually the ECM works the opposite, If the ECM cut the fuel off at 650 thinking the engine is no longer running it would stop when you push the clutch in, not come back to life because there would be no fuel. The ECM actually gives more fuel to keep the engine up to idle speed. That's why Diesel engines are hard to stall.

Yeah, you're right. Nevertheless, I'd be willing to bet that if you drop the RPM below 650 the ECM goes into a different fuel schedule for starting rather than running. Just a guess. The manual doesn't really go into detail.



-Ryan

 

[joeyou]

Well, if you're starting out in 2nd gear you're automatically not babying the clutch, in my opinion. And if you bog the motor enough you will damage it, so perhaps you've bogged it down enough that you've damaged the engine. I sincerely hope that's not the case, but it's possible. You're saying that you used to bog the engine and it never vibrated but now when you bog it down it does vibrate. That would seem to indicate you bogged it enough to hurt something, be it the clutch, flywheel, or something much worse (like main or rod bearings).



I think we need a little more information before we can make a more intelligent assessment. I will say this: if I try to start out in 2nd gear without giving it any gas the engine COMPLAINS LOUDLY... always has. As a result, I always start in 1st and I've learned to give it enough fuel to hold RPM steady at about 800. When I first got my truck I started in 2nd, but quickly decided that wasn't what the engine liked.





What's your rear axle ratio? Be sure to fill out your signature so we know what you've got.



-Ryan

OH B. S. --I put 145K on my 2nd generation starting out in 2nd gear every time, unless heavily loaded. Never had any engine or clutch problems. With the high torque on the Cummins, you don't need to "give it gas. " You'll do more damage slipping the clutch doing it that way with a high torque diesel.