Loud Clunking From The Driveline

[MrFlippers]

Finally getting the 720 back on the road after about 4 years. Reason it was parked was, amongst other things, due to a loud clunking sound at random from the drive train. When I would be in gear and and cruising at normal rpm's something would start banging and clunking like crazy underneath the truck, I would press in the clutch and the noise would go away. It also jumps if I try to give it too much power on takeoff and you can feel/hear a lurch and clunk. My first opinion would be the driveshaft, however I'd like to know if anyone else here has run into a similar issue.

 

On another note, at about 1800-1900 rpm when it's running there's a bit of clattering from the motor, it goes away as the rpms rise. Are the timing chain tensioner's a common issue on the Z24's, wondering if those could be making the noise.

[Toxicrain]

u-joints most likely worn out. you can feel it when the engine isnt in-line (same rpm) with the transmission when going into gears. DO NOT drive it like this as the u joint will pop out and driveshaft will fall.

 

the clattering is most likely timing chain slap

my truck has developed but it isnt crazy loud and its only initally startup at the 1800/2k cold rpm rev like yours.

if your comfortable of messing with the timing should be an easy fix.  

[MrFlippers]

I'll grab some spicer's and put them in at the shop, hopefully that solves that side of the issue and I can start working on the front end. Thanks.

[captain720]

Timing chain replacement is easy. The second time it takes like 8 hours and the first time takes like 20. ;)

 

My u joints are starting to make a small amount of noice too, and yeah timing chain failures are extremely common and catastrophic, I have suffered from 2!

[cruznude]

I just had the same problem and it would clunk as I drove mostly when slowing down and it happened to be the carrier bearing in the drive shaft so I replaced it and no more clunk.

[datzenmike]

If you have a two piece driveshaft it's the rubber surround around the carrier bearing. (not the bearing) They rot away and the drive shaft can flop around. I think the 720 is speciffic to the 720 so another model won't work. Try e-Bay?

[cruznude]

Well, I wasn’t specific enough but that’s what I meant to say. Thanks Mike for clearing that up

[Toxicrain]

 

Yea i drove with clunk for 2 weeks and in the corner you can see the result. Local mechanic was suprised it hadnt fallen out yet