2nd Gen Non-Engine/Transmission 4WD clicking?

[Tinman]

For several months now, my front axle makes a clicking sound when 4wd is engaged. It was intermittent, but now it's every time 4x4 is engaged. At first putting it in reverse and backing up a few fee would solve it. I am getting power to at least one front wheel. I thought it was the CAD vacuum actuator so I replaced that but no change. I was about to order and new collar and fork but got to searching old post and it seems that if the CAD is working if either wheel gets power. So before I spend a but of money (that fork is about $300) I figured I better get some more info. The 4x4 light does work so I assume the CAD engagement shaft is moving enough to engage the collar. It sounds like gears not engaging, that's why I went after the CAD in the first place. I live in the mountains and until recently, we living in a neighbor that had about a 20% graveled grade to get out. I would use 4x4 everyday, so I won't be surprised if something was worn, but what?

 

[fest3er]

Axle u-joints. If you see rust dust around the cap seals, you know they're past worn out.

 

[Tinman]

I guess that could be, but the U-joints, wheel bearings, and ball joints all replaced about 30K miles ago . They are the greasable u joints and I keep them topped off. I'd be disappointed if that were it.

 

[BDaugherty]

Check the cv on the front driveshaft. A worn out ball and socket will cause a sound similar to what you described. Also double check you axle joints. Lastly you need to know for sure its the front axle making noise. Sound really travels and it could be the chain in the tcase making noise. Also dont forget the ujoints in the front driveshaft.

 

[DonFitzwater]

I just replaced the fork and collar in my shops 3500 and it was less than 100 dollars for both parts. The front end was making more of a popping noise. It turned out to be the inner, passenger side axle shaft was worn and causing the sliding collar to pop off and on the shaft under load.

 

[NGuzik]

Axle u-joints. If you see rust dust around the cap seals, you know they're past worn out.

U-joints would click all the time if they were bad not just in 4x4.. I would check for a vacuum leak, even the 4x4 light is triggered with vacuum..

 

[JR]

Might be time to pull the fill plug and check for any metallics in the oil. Maybe pull the actuator and look for any worn components. If this is a symptom that only exists in 4 whl drive you can eliminate the front u joints. May have to unbolt the front driveshaft to axle flange and flex the universal and cardone joint to check for any wear.

 

[mwilson]

I would give the axle u-joints another look even though they are not that old.

My '97 would click at the left front wheel ONLY when in 4WD and while there was strain on it, turning made it worse. Tore it apart, sure enough the LH u-joint was junk.

The '06 started in doing the same thing pulling the trailer out of a somewhat soft campsite this summer while in 4WD. I'm sure that the LH u-joint is on it's way out.

If the collar on the actuator is slipping off it is a more violent bang, at least it was when mine when bad.

Mike.

 

[Tinman]

I can see it being a u-joint so I'll give that a fresh look next time is on the lift. The drive shaft and/or transfer case could certainly be it. It's really never been serviced (except fluid changes) and , as I mentioned, it has been used a lot. I replaced the vacuum actuator and there was NO metal inside that housing. The inner shaft splints had just a tad of wear at the tips so I took a dremel and smoothed them slightly. None of that made any difference. I also replace the diff fluid at the same time (had a slow leak) and no metal in there. Is it possible for the CAD to not engage and still have the driver front wheel get power. I know the driver wheel gets power when it is "clicking". I think since the front wheel is engaged, the CAD has to be working or only the inner shaft would be spinning with and open diff. - correct? If that is the case, then if has to be transfer case, drive shaft or u-joints.

 

[mwilson]

I can see it being a u-joint so I'll give that a fresh look next time is on the lift. The drive shaft and/or transfer case could certainly be it. It's really never been serviced (except fluid changes) and , as I mentioned, it has been used a lot. I replaced the vacuum actuator and there was NO metal inside that housing. The inner shaft splints had just a tad of wear at the tips so I took a dremel and smoothed them slightly. None of that made any difference. I also replace the diff fluid at the same time (had a slow leak) and no metal in there. Is it possible for the CAD to not engage and still have the driver front wheel get power. I know the driver wheel gets power when it is "clicking". I think since the front wheel is engaged, the CAD has to be working or only the inner shaft would be spinning with and open diff. - correct? If that is the case, then if has to be transfer case, drive shaft or u-joints.

The CAD / inner axle shaft failure that I experienced worked like this..

No load in 4WD it would stay engaged and 4WD light remained on. Apply power, it would bang and the light would go out. Let off, it would grab again and the light would come back on.

If your 4WD light remains on while in 4WD under strain the CAD is holding.

Mike.

 

[Tinman]

Thought about this old thread the other day while doing some routine maintenance. The final diagnosis was lack of grease - or at least I think so. I ended up greasing the crap out of all the zerks - front u joints, ball joints etc. The issue seems to have resolved. I don't use 4wd near as much as I used to, but the few times I've used it lately (with all the bad weather) there is no noise. I think is was a u-joint and I probably just forgot the lube it as one my maintenance intervals. I proves the point that if is a serviceable fitting, SERVICE IT. That's why sealed bears are so popular today - no maintenance.

 

[KATOOM]

Its probably the Double Cardan joint on the front driveshaft. They make noise when the joints wear and the ball and springs get loose. If it is it then just have a shop repair it as it can be a pain to repair and you certainly dont want to mess things up with it. Also, always use non-greaseable u-joints because not only are they stronger than greaseable but they have three solid seals designed to keep out all water and debris whereas the greaseable ones have one weak seal designed to allow old grease to escape as you're pumping in new grease. Problem is that the one weak seal also lets in water and debris.

 

[Tinman]

Humm... Haven't thought about the non-greaseable vs. greaseable u joints. You make a good point. I just don't like the idea of disposable bearings. Manually greasing them makes more sense to me but I guess there are disadvantages. Either way its seems to have stopped. If it returns, I'll look at the drive shaft. I did the whole front end at once and at 170K the stock front u-joints where still in great shape.