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3rd Gen. Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission Ect...NO ADVERTISING

Thread: 4x4 knocking Reply to Thread
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  Topic Review (Newest First)
12-08-2019 02:50 PM
KATOOM If you have the ability to jack the truck up off the ground and running in gear stable on jack stands then you should have a better chance to isolate the problem using a mechanics stethoscope...or a long wooden dowel with a semi pointed tip.

You hold the other end of the dowel in your fist and hold it to your ear, then touch the pointed end to a running surface. The noise transmits through the dowel and into your hand. Easy way to find noises...
12-08-2019 12:54 PM
deer hunter PLEASE HELP!! I too am having this same issue. 2004.5 2500 4x4 Cummins. Knocking sound "ONLY" when in 4 high under light load not under acceleration at speeds between 40-55. Front drive shaft has been rebuilt with all new u-joints include the double joint and noise remains. Truck was driven by me while tech road shotgun and used remote listening devices to try and hear but unsuccessful. Sounds like its under the driver's seat. We thought t-case so Tech put truck on alignment rack and raised by the axles and used a stethoscope and informed me that he believes the sound to be in the front end not the t-case. Has your truck been repaired yet and what was the problem?
02-09-2019 07:48 PM
Matt Blank i just went through this problem with my 06. after misdiagnosing it as a transfer case problem and replacing it, i found out that the front driveshaft was bad. they use this thing called a double cardon joint. its basically 2 ujoints and a strange ball joint between them.if that is the problem its about 80 dollars worth of parts to fix it. or if its as bad as mine, its best to just buy the whole driveshaft, between 350 and 500 bucks.
01-21-2019 07:12 AM
rghavana As far as OP , If you read original post "after shifting into 4x4" noise starts, could still be front axle issue, load applied to weak component ie u joint, but should check t-case , for clutch gear or mode hub, mainshaft and/or shifter fork issue, since noise only occurs when 4 wheel drive is engaged.
01-20-2019 09:02 PM
Digit09 Lets address the OP for a change, don't give a hoot what ya'll want to call an engaged and disengaged transfer case. You're not being helpful at all.

Couple of questions:
1) Does the knock only happen in 4wd mode?
a) If so, will the knock happen in forward and reverse?

2) If the knock is not present in 2WD mode then inspect all the rotating joints, if you can giggle your front driveshaft the front slip joint will probably need greased.

3) If the knock is there in 2WD mode also, you'll need to inspect your flexplate. Flexplate knocks get louder with throttle input and quiet down under deceleration conditions. If they break in the right manner, and do not shatter into pieces, (I have pictures if you want to see) the huge washer will/may keep them from coming apart under mild driving conditions. Hopefully this is NOT your issue.
01-20-2019 09:00 PM
BRBurns
Quote:
Originally Posted by KATOOM View Post
That is how ALL 4wd systems work...
Re-read what I said previously about the differences in full-time vs part-time systems.
Not quite all. I have a 2005 Yukon and it is full time 4 wheel drive. Options are 4high, 4low and nuteral. It eats tires, but is a beast in snow......there are others like that too. And Iím sure there are sensors that affect how much the transfer case is engaged, but itís full time.
01-20-2019 08:50 PM
KATOOM
Quote:
Originally Posted by bigfish95971 View Post
Full time 4x4 has no 2wd mode, always has power to front axle.
Actually thats not accurate. And frustratingly wherever you look for such information, you'll get multiple different answers. Thus the confusion so many people have.
Full time 4wd can be used in either 2wd or 4wd. AWD is when all four tires are constantly getting power.
01-20-2019 08:25 PM
bigfish95971 No Katoom that is not full time 4x4 it is a full time live front axle. Full time 4x4 is when the Transfer/case is always engaged in 4x4, either lock or AWD and/or a center differential in the TC. Full time 4x4 has no 2wd mode, always has power to front axle.
Front axle u-joints are always moving unless there is free hubs. Same for drive line if no CAD or hubs. Bad U-joints on either, or Cardin joint, may not make noticeable noise or vibration until TC engaged and under load, either accelerating or decelerating.
01-20-2019 08:03 PM
KATOOM All transfer cases are part-time unless they have an integrated differential or viscous coupler which allows them to be used as an AWD system. The entire 4wd system is either part time or full time based on the engagement of the front driveline. If the front driveshaft spins along with the front axle then its considered a full time system which has the disengagement at the transfer case. Thats what the 3rd gen trucks have. The ONLY disengagement is in the transfer case.

Yet if the transfer case has a differential or viscous coupler then it can be called either an AWD or full time transfer case. The trouble is the industry confuses people by forgetting the distinguishing differences between a part time and full time transfer case and simply labels their entire 4wd as they market it.

Example being, Jeeps Quadratrac 4wd which used a Borg Warner 1339 with an internal center differential. The Quadratrac could be used in both two wheel drive or full four wheel drive at all times because of the center differential.

Another example, Dodge called the part-time 4wd NP241 transfer case "shift on the fly." But then they also called the NP241 with full-time 4wd as shift on the fly too. Trouble is if you install a full time 241 in a CAD axle truck then you'll find it wont shift into 4wd "on the fly" because the part time 241 has a syncro ring to spool up the front driveshaft for engagement while moving, whereas the full time 241 does not. Why?...because the full time 241 does not need the syncro ring as the front driveshaft is always spinning at road speed therefore you can literally engage 4wd at any traveling speed.

I will admit that its overly confusing...but since Dodge has utilized the CAD in two different generation 4wd systems this is what we get.
01-20-2019 07:11 PM
rghavana No, your confusing everyone,

The NV271 transfer case is a part-time transfer
case
with a low-range gear system. It provides three
operating ranges plus a NEUTRAL position. The low
range position provides a gear reduction ratio of
2.72:1 for increased low speed torque capability

The NV273 is an electronically controlled part-time
transfer case
with a low range gear reduction system.
The NV273 has three operating ranges plus a NEUTRAL
position. The low range system provides a gear
reduction ratio for increased low speed torque capability.
01-20-2019 06:45 PM
KATOOM
Quote:
Originally Posted by rghavana View Post
You can word it however you want.
Truck is 2wd drive until you activate transfer case, then truck is in 4wd.
Not sure what you're point is...but I'm wording it correctly and accurately so that others reading the forum understand what the difference is and how it works.

You strangely want to argue for whatever weird reason. Maybe you're thinking that "full-time" 4wd is the same as "all wheel drive". Its not...
01-20-2019 06:39 PM
rghavana You can word it however you want.
Truck is 2wd drive until you activate transfer case, then truck is in 4wd.
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