Thinking its a CV or prop shaft CV, but dont know

[jamesb1516]

Hoping this is common enough for someone to be able to give me some first hand knowledge. My 2008 Alpha has been making a rotating knocking noise. At first, I assumed it was from the crossmember bushing, so I replaced it with the Scorpworks piece. Noise is still there though, and it seems to have gotten more noticeable. Before it was intermittent but now its mostly always there when letting off the throttle or coasting steadily at lower speeds. I read a post on another forum that said if the crossmember bushing is blown out for too long, you'd develop a clunk when shifting from park to drive which meant that the prop shaft cv was bad. The transmission clunk is gone and the other noise is worse now. Dunno if its a cv axle or a bad prop shaft, but visually everything looks good. No ripped boots or anything. Any ideas guys?

 

[skippy]

a cv would make a clicking sound could be the prop shaft uni joint?

 

[4speedfunk]

Noise on "deceleration" or "coast" usually means its related to the driveline. More specifically...the input side of the driveline. That includes the front prop-shaft and front differential. Considering the slow and steady worsening of the noise, a pinion bearing and/or ring & pinion is the first thing to come to mind.

However, human nature tends to make us always suspect the worse. So for this reason I would check the front prop-shaft first. Check the CV joint on the aft end of it, and look for grease flung all over the the t-case near the front flange. That's a tell-tale sign the CV is dry and that could be the source of the noise. YES, I'm talking about the driveshaft...NOT THE HALF-SHAFTS at the axle. There seems to be some confusion every time this is mentioned, but the H3 does have a CV joint on the rear end of the front prop shaft...and it is prone to failure. Its really hard to see but get a flashlight an look for grease on the bottom of the tunnel.

If that all looks good, then check out the front diff. Grab the input yoke and see if there is any play in it...2 degrees of lash is normal but, "shake" or excessive looseness is not. Also look for leaking oil at the pinion seal. If something looks amiss...then pop the front diff cover, and take a closer look. Check out the wear pattern on the teeth...it should look nice and even. If you see chunks, shavings, or a metallic beard stuck to the magnet...then you should apply for a HELOC and get ready to spend some dough. Also, the transfer case can do some crazy stuff, (including strange sounds)...check the fluid color....Red is good. Black is old. Metallic is bad. You didn't mention your mileage but, the H3 is a very noisy vehicle above 50K. Let us know what you find out...hoping for the best.

 

[jamesb1516]

I had time to slide under and take a look at everything last night. The boot on the prop shaft looks totally fine and when I put the truck in neutral with the parking brake on I didn't get much play or movement. I did notice that the driver side cv axle has some grease on the boot, so maybe the clunk Im hearing is that? Its going to really annoy me if I open the diff and see that the ring and pinion need to be replaced along with the cv axle. I was pushing on the cvs and it seems like theres some looseness in them? If I push straight up on them they both move a bit and the passenger side was a good bit looser at the inner joint. On the plus side, its got 92k miles so its probably due for new diff fluid anyway.

 

[EPAlpha]

Having the exact same issue with my 08 H3 Alpha as well. I've got 68k miles on it. Seems to have started about a month ago. I notice the knocking noise more so when pressing on the gas from a complete stop while on an incline. The knocking increases in frequency until I get up to about 15-20 mph, then goes away. I replaced both half shafts and the front prop shaft this past Feb. Really sweating that its something more severe...about to buy the Scorpworks crossmember with hopes that that will fix it. Doesn't sound like it will :/

Gonna have my mechanic at work take a look at it tomorrow and see if he can shed any light on the situation. I'll share his prof opinion if/when I get it.

Good luck to us both!

 

[Tdavis]

My 2008 Alpha was making the same noise and everything seemed tight and clean underneath. Once I jacked up the front end with the tires off of the ground there was noticeable play in the high speed CV shaft on the front driveline. Rubber boot seemed fine. Bought a replacement and noise went away. Quick fix, 8 bolts and a retaining clip. didn't even have to take the OEM UCP off. Good luck

 

[jamesb1516]

No bueno. I took it to a driveline shop and they confirmed that it probably needs a new cv. They also put a stethoscope up to the front diff and say the sounds coming from there. There was some fluid dripping out of the fill spout so I think they might've put some fluid in. Since then, the check 4wd light hasn't come on anymore. Apparently its going to cost 900-1200 to rebuild the axle? I thought most places did front and rear gears for about that so im not totally sold on it yet. I had the girlfriend drive by me a few times to see if we could duplicate the sound and the only thing I could hear was the high pitched whine. No clunk or knock.

 

[jamesb1516]

Tdavis, Do you mean the prop shaft?

 

[alrock]

JamesB, fill spout on the diff? :huh:There's a breather hole, which should have a breather hose attached, a fill plug and a drain plug. If you have gear oil coming out of the breather tube then you likely have an overfilled diff.

To which CV are you referring? Propshaft or drive axle? I'm unclear on what you're getting rebuilt - you've sorta referenced the front differential (the "pumpkin" in the middle between the wheels that houses the gears), the front propshaft (goes from the transfer case to the front differential and has a CV joint where it joins the transfer case) and either the right or left drive axle (which go from the front differential to the front wheels and contains a CV joint in the middle)

 

[jamesb1516]

What I meant was....
The driver side cv drive axle needs changing but the shop is saying that the noise is coming from the front differential and they'd rebuild it for $900-1200. The only noise I could hear from outside of the truck was the gear whine from the differential.
I don't really want to pay that much and it doesnt seem to be a major problem so im thinking about driving it like it is and then changing the drive axle as soon as I can.

 

[jamesb1516]

And I think its the fill hole on the top part of the diff.

 

[alrock]

I drove around for months with broken pieces flopping around in my front diff, but it's not something I'd recommend. You should at least drain the diff and poke around with your finger, or better yet, remove the cover and visually inspect for any obvious damage. There could be other issues but if all of the gears are intact, with no pitting, broken teeth, etc. you may be fine for regular use.

The "fill hole" is the plug in the diff cover and nothing should be coming out of there. I hope that's where you added gear oil, if you did ever add some. There's no other fill hole on the diff.

This is the rear diff cover and you can see the fill plug halfway up the cover on the right, behind the spider armor. The front is similar except it is a hex head, maybe 13mm or 15mm.

 

[jamesb1516]

Cool diff armor. Ok, so it was the fill plug that had fluid running out of it. not a lot. just a little streak. Maybe they opened it to listen for noises whiel it was running. I sort of doubt they would've topped off the fluid since I didn't pay for the inspection. In any case, my plan is to go ahead and drain the diff and pull the diff cover to inspect everything. Its due for a fluid refresh anyway.

 

[Tdavis]

Sorry, yes the front driveline/prop shaft..... Transfer case high speed CV.