Hello all

I have a 2002 ZR2 blazer w/ about 34,000 miles on it.

Org owner and it has never been customized or messed with or changed from stock and or offroaded.

Now I would imagine this would be almost impossible to help me with much over a post forum like this but I have this clunking type rattle that only happens when I go over rough roads in just the right way (typically straight) that as much as I can tell is in the right rear that for the life of me, I cannot find.

I have crawled under the truck an checked over everything I can play with an nothing looks broken or is loose. I did fine the E brake cable a little dangling around but I secured that and it didn't make a dif.

I have pulled the inside panels off and found nothing and road tested it like that and as there was no real change in the sound, I can tell for sure its outside.

Now again I know its just about impossible to diagnosis like this over a forum but I just thought I would ask if there are any common things with this truck that are known to cause this that are things I should most look for.

Btw, I used to be a prof auto mech many years ago at a dealer and have worked on cars including my 78 Z28 all my life.

So if anyone had any ideas, I would greatly appreciate it this truck is totally sound except for this one thing and I would really like to figure out what this is as its annoying the crap out of me.

Thanks for any help.

 

shock bushings i bet. twist shock top and bottom by hand they stand right out. check sway bar bushings and frame mounts too. beat on the exhaust too w your hand cat may be falling apart and laying in the muffler. let us know what u find im curious lol

 

Do you have a spare carrier on there? Is it loose if you do?

 

aw crap zr2 i never thought of that lol good call! i had to put bushings in one of those once yuck pita!

 

mine does the same. i think its one of the bushings in the back somewhere that needs to be replaced.

 

Hey guys, thanks for all the reply's

With the fact there are a few to make this seem less confusing, I won't quote them but to respond.

I have played with the shocks pretty hard, this was one of my first choices as given the sound, I for sure thought one of those had come loose...or even had broken. But at least by hand, the both seem fine.

I have rattled the exhaust around a lot and will admit that the rear bushing hangers are a little loose but its hard to describe why here, but I really don't think it is them, but I wouldn't rule it out. For sure the Cat is OK and while I perhaps should have described this better, perhaps rattle isn't the best word but the sound is more of a low level type clunking. But definitely not like a clanking type rattle like a loose heat shield or metal inside a Cat thing.

I guess the reason I might call it a rattle still is that when it does happen, its a series of clunks with its sound varying from a hard at first to less as it happens to dissipate from the the impact, and also all depends on the harshness of the thing I hit on the road. Anyway, hard to describe or understand without hearing it I know but my point is, its definitely not like a metal sounding rattle like something loose in the Cat.

The sway bar bushings seem to look OK and seem just as solid as any other parts.

One other thing I should add that along with this low mileage for a 8 year old car, its also been garaged all its life and again, I've been around cars a lot and the one thing that struck even me was how clean and in great shape the underside of this truck is.

In fact if didn't know it myself I would say this truck isn't anymore then three years old.

Anyway, as far as the back tire, yes I do have the spare mounted and while I can't say 100% its not that as I know these things can be deceiving, I have been over it pretty good and nothing on it seems loose, but more so, the sound really sounds like it is coming from something below in the suspension.

Then next thing I plan to do is go through all the bolts of everything with a wrench and see if any of them are loose but I would be pretty shocked if they were but who knows, maybe something with the weight on it even though it feels severely secure, isn't.

Will let you guys know if I find anything.

Thanks for all the suggestions.

 

Well just to give a update, I have gone through everything under the truck I can find, I checked every bolt of the suspension and the body mounts and found nothing loose.

I did find one I was able to get one turn on the Pass side rear sway bar to body bolt, but it was hardly loose, and didn't solve the problem.

I have run large tie wraps that I tightened with a tie wrap tool, over the rear exhaust rubber hangers to temporarily lock them up and road tested and no effect.

I have snugged up and wrapped up the e-cable in every-way I can and gone over every other loose cable and hose under there and nothing.

For the life I me I can't find this thing and about the only thing more annoying then the noise is....the fact I can't find it.

Anyway, with the holidays coming up and the cold weather I guess I will just have to live with it for now.

Thanks guys for all the help though.

 

could be something lose in the compartment where the jack is???

 

That is all in the left rear of the truck though isn't it.

But I haven't checked that though so thanks for the suggestion as I didn't even think of that so I'll have to take a look.

Thanks

 

I had the same problem with mine and it turned out to be the bushings on my spare tire mount even though they they felt tight.