Horrible clanking mountain coasting(sound clip)

[Rendoll911]

First time poster! Great forum, already helped me fix a bunch of issues I've had with this 03 ext, 170k.
The problem: When coasting down steep grades in the Colorado Rockies the engine RPMs drop ~1500 and starts producing a really bad sound. I'll try to describe it: like change rattling around in a coffee can, a skateboard with bad bearings, gusting wind with a window cracked. Sound bit here: https://drive.google.com/open?id=1X__HMNZIHJ85YcWCak9MI7uQw6Ruzgn9

The noise stops immediately when any throttle is applied and the engine kind of thunks back into gear and everything sounds normal until the next downhill coast. I tried switching to neutral when this sound was occurring but it didn't have any effect, seemed like the truck was already in neutral. Tried switching to "auto" 4x4 and a horrible winding grinding sound started until slowing to a complete stop.

Known issues with the truck:
1. The 4hi and 4lo don't work. 4auto works. All the lights on the switch work 95% of the time, occasionally it will blink and nothing will light up. This is remedied by going into neutral and clicking from auto to 2hi/ 2hi to auto.

2.Fan clutch intermittently not working. Had a code for high fan speed a few times but usually turns off by itself.

Thanks for any inputs reading such a lengthy post. This car is my source of income (uber driver), so I really appreciate any help.

 

[mrrsm]

One of our Legendary Members... "The Roadie" might have answered a whole gamut of questions about the 4WD Issues here:

http://forums.trailvoy.com/archive/index.php/t-81813.html

 

[Rendoll911]

Thanks for the link. I have indeed read through that entire thread as well as many others. Couldn't find anything that explains the coasting issue. Though I did use the diagnosis diagram to troubleshoot the 4wd issues. Do you think they are related?

 

[christo829]

You might be fighting multiple issues. Have you checked the front differential fluid and the transfer case fluid? You might have a bad U joint, dry bearings or worn CV joint that stops making noise when torque is applied, but starts rattling when freewheeling.

Do you have a "service 4wd" light? The lack of 4hi or 4lo might be the encoder not locking in place. Do you hear the encoder motor attempting to cycle when you flip the switch to 4hi? When you say A4WD is working, are you referring to the switch light, or have you actually had the A4WD activate while driving?

The grinding might be occurring due to the splined disconnect being dried out or damaged, or really any part of the front drivetrain if there's insufficient lubricant.

Good Luck!

Chris

 

[Mooseman]

I'm also thinking a U joint.

 

[Rendoll911]

No service light. Lights on 4wd function normally for the most part. Sometimes I need to go into N to get a solid light on 2hi or auto. Auto 4wd engages when slipping, but 4hi/ol don't. I hear the encoder when cycling the switch.

Haven't inspected fluids yet. How to I inspect the ujoint?

 

[mrrsm]

This video is just suggestive of the appearance and procedures on a GM Truck...and even though this VOP is performing the actual R&R of the U-Joint... it will give you a good idea of where and what to look over down there. Please take note of the Rust present and the possible factor of Winter Road Salt acting so successfully as an Electrolyte to ruin anything made of Bare and Unprotected Ferrous Metal Hardware. U-Joints in vehicles are damned near as complicated in their component articulation and design as The Human Shoulder, Arm and Clavicle Suspension.

If the in-dwelling Needle bearings inside of the U-Joint Cups- even on Non-Serviceable U-Joints- go Bone Dry for the lack of Grease... they will eventually Rust...and grind themselves down into a Fine Brown Powder. I have seen drive shafts fall out of vehicles at highway speeds and do some incredible damage when they dig into the roadway and try to stop the forward motion of a vehicle like a Knight getting knocked off of his Destriere Battle Horse at Full Tilt in a Joust!

If you wind up having to do this work yourself... Add a Magic Marker to the Tool Kit you bring and mark everything in their relationships to one another ...BEFORE performing the U-Joint R&R so your Drive-Line remains in Balance when the New One is installed. You have two options for the tools needed to do this job:

(1) The Maddox Ball Joint Tool Kit for $90.00 from HF for pressing out the Old U-Joint Cups and installing the New Ones: :

https://www.harborfreight.com/ball-joint-service-kit-for-2wd-and-4wd-vehicles-63258.html#reviews

(2) The inexpensive One Ton Arbor Press that HF selling for $60.00 to press out the Old U-Joint Cups and allow you to install the New Ones:

https://www.harborfreight.com/catalogsearch/result/index/?dir=asc&order=EAScore,f,EAFeatured+Weight,f,Sale+Rank,f&q=arbor+press

Get some Red-Line High Pressure Grease to ADD to the light coating the New U-Joints came shipped with as they will NEED this extra protection under your vehicle. Before you slip the center four point axis piece into the cups... run your Pinkie Finger inside first to make certain that none of the Needle Roller Bearings have come loose and fallen or become mis-aligned. NOTHING is more disconcerting when doing this job than having just one of those little needle bearings fall down inside the bottom of the cup and block the insert of the 4 Point Posts into the cups... and then have to press the whole damned thing apart again just to remedy the problem after realizing that you cannot press the cups below the Spring Clip Grooves! Remember to run a length of Tape around the two remaining Cups so they do not fall off B4 the Drive Shaft is seated into the neck if the Rear Differential and literally... Strapped Down.

The cups on the Driveshaft are press-fit in both sides and held in place with Safety Spring Clips and therefore...they must be pressed in so the top of the cups is just a very little bit below the Locking Grooves where those Spring clips slip in and lock them in place. So be careful not to press either of the cups in too far on either side. When you are done... the U-Joint center should be able to articulate with just a little bit of tension... but if you cannot move it around... you will have to adjust the depth on both cups to accommodate this slight movement... but still...with NO END PLAY when you are finished.

This one shows the Needle Bearing Damage more distinctly and an Alternative Method and Tool Kit to perform the Dual Cup R&R:

 

[Rendoll911]

Thanks so much for the input! I'm getting under the car tonight to inspect the u-joint and fluids after I replace the fan clutch. I'll report back soon.

 

[Rendoll911]

The ujoint looks decent. Wasn't any play when torquing the drive shaft. The front differential and transfer case oil are full. Diff oil seems new. Case oil is pretty dark blue. I lifted the passenger side wheel in 4hi and the wheel spun freely. The front prop shaft spun.

 

[NJTB]

I didn't see it mentioned in the videos, but when changing universal joints mark the yolk and the driveshaft so they go together in the same orientation. Sometimes it will cause a vibration.

 

[Rendoll911]

Update on the situation. Definitely not the ujoint. The transmission is slipping into neutral on downhill coasts, seemingly only on longer drives. Last night it was slipping into neutral on coasts then clunking into gear when throttle was applied. I put the car in park and the car started rolling like it was in neutral still then it wouldn't go back on gear, just grinding. The only way I could get it into gear was to switch to 4auto with a loud grinding clunk. New engine code. P0105

 

[Mooseman]

Quite possible the transfer case is stuck in between modes. Try removing the encoder motor. This should allow the transfer case to move on its own to 2hi. Or try turning the shaft by hand to different positions. Another thing to try is while having the encoder motor unbolted but still connected, change modes and see if it moves like it should.

That code is completely unrelated and should be in a separate thread.

 

[Rendoll911]

I disconnected the encoder motor and watched the motor as I switched through different 4wd modes. The motor seemed to be turning properly. Once I put it in 4lo i wasn't able to turn back into 2hi as the motor wasn't spinning anymore and the service 4wd light illuminated. At this point I tried to turn the spindle on the TC by hand but it wouldn't move even in neutral. I had to unbolt the torx screws on the motor and spin it by hand to reconnect the motor. After reinstalling and disconnecting the battery for a while the 4wd seems to be functioning properly. Guess I'll just wait to see if it malfunctions again.

 

[Mooseman]

You haven't mentioned the fluids yet. If it's very low or black, the TC could be borked. Fluid is normally blue.

 

[Rendoll911]

The front differential and transfer case oil are full. Diff oil seems new. Case oil is pretty dark blue.

 

[Mooseman]

OK. As you said, monitor and see if it returns.

 

[Rendoll911]

Just wanted to update this thread. Shortly after my last post 4wd stopped working again, so I'm still trying to figure this one out. My next step will be grabbing a switch and encoded motor off a junker.