I posted an earlier thread about front driveshaft compatibility between 4.0 and 4.6 D2s as I thought I had a failed U-joint, but now I am not sure so looking for some help in diagnosing it so I am starting a new thread (thanks to everyone who provided advice on the original thread).

Here's the symptom. The vehicle, an '04 HSE with an engine rebuilt with flanged sleeves, exhibits drivetrain clunking, vibration and a combination clicking-whine sound (like a bad belt pulley bearing crossed with tapping lifters) at launch and acceleration up to about 55-60mph, above which speed the sounds and vibration dissipates so long as a constant speed is held. The sounds and associated vibration appear to be emanating from under the front (and not the rear). It started when I was quite a way from home and I nursed it 150-175 miles back to home with these symptoms.

I got under the vehicle once it cooled down and the U-joints seem to be solid (maybe one of the double joint u-joints has just a barely perceptible amount of play in it but I am not sure; I rebuilt both the front and rear driveshafts maybe 40-50K miles ago and have greased them a couple of times since then).

However, there is about 6-12 degrees of rotational "play" in the shaft at both the differential and transfer case ends, or about as much as a 1-to-2 second ticks on a watch face.

And there is a clear leak in the transfer case, though it is at neither at the front or rear output shaft seals, but rather the oil has collected around one of the inspection(?) plates (the larger one) on the side-bottom of the case, which based on replies to my prior thread, seems to point to the transfer case intermediate shaft o-ring. I have not checked the gear lube level, but I am sure it is down, though probably not below the level of the intermediate shaft.

Could it be worse than than the best case of a bad driveshaft u-joint I was hoping for? Could that ever-so-slight amount of play in the double (hookie) joint cause this much vibration and noise ]

(FYI, I have had a u-joint in a manual tranny 2by4 1500 chevy completely lose a cap and all the associated needles bearings and not make this much noise/vibration).

Is that rotational play normal or does it indicate a bigger issue in the axle differential and/or the transfer case? or maybe even in the auto transmission itself

Any advice on how to diagnose would be most appreciated.

 

Lock CDL and pull front shaft and see if that along with topped off fluid in t-case and diffs solves it.

 

Thanks for the test. Sounds like you've been here before.

And stupid question: what exactly does the CDL do? Never mind, did my 4WD 101, now understand what differential locking is.

So you can you drive the D2 with the CDL locked and the front shaft removed without damaging the transfer case?

If it works, what will it tell me? That the transfer case is not the source of the problem? (and that it is the driveshaft, axle or transmission).

I do that at the transfer case, right? I thought I saw a video showing where you lock it using a wrench? Is the procedure for locking the CDL in the RAV? I just watched a video and the narrator said CDL was only available on the 99-01 D2s: is this right, in which case my '04 doesn't have a CDL. Never mind. Read the owner's manual, figured out I can lock the differentials at the High-Low selector.

I am out-of-town tomorrow, will try it Thursday and report back.

And I'll check the gear lube at the axles as well. FYI, over the weekend I had all 4 wheels off to check the brake pads (heard some squealing, maybe it was the start of this issue) and do a rotation and saw no leakage at the ends of the axles.

 

I've been driving with no front prop for a week or so now, and yes, You can do it.
Just waiting for new UJ's for it and a proper tool to change them (fumbled the few first ones with bad/wrong tools as have never done before).

Twice when leaving traffic lights etc, I heard a clunk, also randomly while driving some "chirping" sound like there was birds in the vent (some say "high pitched turkey sound"). Couldn't really reproduce it. I have an audio of it but not avail right now.

This is what the front prop double UJ looked like under the car

I'm still a bit green on these, but I'd say u joints should have no play at all, but it's normal that the props have some play between the diff and transfer case.

 

No damage driving it locked and with front shaft out. I drove from KS to VA in 2wd after I had a front shaft start to go on a cross country trip. If that solves your noise it's the front shaft. To me it's the simplest place to start and with the highest probability of the root cause. U-joints should have zero play but yes I do have some minor play between diff and t-case.

 

Thanks all.

Dervish, that seems like a LOT of play in that U-joint.

whowa004, by "play" in the shaft, do you mean rotational play? And why put it in CDL? (no biggie as I know how to do it now).

I will remove the front driveshaft when I get home tonight, top up the gear lube and see what happens.

 

if you don't lock the CDL and remove the driveshaft then you wouldn't go anywhere. With out locking the t-case then the truck will send all power to the front output as it's the path of least resistance by locking the CDL you force power to be sent to both front and rear outputs equally. The goal of this is still to eliminate the front driveshaft as the issue.

edit: there is no harm in having the front output spin with no driveshaft attached..just to clarify there is zero worry of damage by doing this.

 

whowa004, I got the front driveshaft off, engaged the CDL (after I tried to run it without the CDL engaged -- the front transfer case flange spun like crazy, unfortunately, I hadn't read read your super clear a succinct explanation beforehand as to why the CDL must be engaged when the front driveshaft is removed) and off I went with no clunking or whining. Smooth and quiet.

I also "topped up" the transfer case with somewhere between 1 1/4 to 1 1/2 quarts of 75/90 gear lube. The front and rear differentials needed less than an 1/8 quart each (and probably less than even that). FYI, last time I checked these fluid levels (and changed the lube) was at least 3 years ago and maybe as long as 4-5 years ago.

So what does this test tell me?

Transfer case good? (hopefully that or worst case the front output flange spines are worn, though it seems pretty solid/tight)

Differential good?

Front Driveshaft bad? (the one front U joint and two rear ones seem good and tight and smooth, but that Hooke joint in between the two rear U-joints is "sticky", i.e., it binds and otherwise it doesn't move very smoothly).

 

Front shaft is bad. T-case was definitely a little lower than I'd have liked to hear and could have been some of your issue. Could try lubing shaft and putting it back to confirm you weren't just low on fluid but I'm willing to bet it's time for a new shaft or rebuild the one you have. Diff still spins and would continue to make noise if the issue was there most likely.

 

@whowa004 you called it right.

The hooke joint on "new" driveshaft (from junkyard) moved smoothly compared to the binding on the one I pulled from my D2.

Cleaned it up, greased it (I was sure to push out all the old grease at all 4 of the spindles on all three u-joints, and greased the sliding spine joint as well), installed it, and all is good.

Guess those ball-like joints in the middle of the double/hooke joint can go bad, but surprised it could have had such an impact on the front drivetrain with the scary clunking, whining and chirping.

One lesson is that a visual inspection of just the universals in the hooke joint will not be able to determine whether than inner ball joint is bad: you have to do what you told me to do -- remover the shaft then drive it to eliminate the transfer case as the issue.

I will do a power wash of the transfer case to see if I can identify the leak, but in doing a closer inspection it certainly looks like it must be from the intermediate shaft o-ring as there is no lube above that on the case but a ton below it.

Anyhow case closed.

Thanks everyone for the help.