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I have a 1997 2-door base model chevy blazer with the 4.3L and 4-wheel drive. For about a year and a half I have been getting a loud clunk/popping noise hen going over a bump on the road. The noise I have narrowed down to be coming from under the middle of the truck. I am thinking it has something to do with the torsion bars and where they intersect with the cross member. Does anyone out there have any experience with these trucks? what do I need to possible replace to get rid of this noise? I was thinking the outer two links with rubber bushings that mount the torsion bar support post to the frame could be bad but, I am not very knowledgeable with this setup. Thanks for reading.
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It’s hard for me to remember…but I think that’s a rear stabilizer bar link. I do remember when I worked on the Blazers, there were many complaints about your issue and a customer (after we couldn’t fix their truck after many come-backs) found a hood hinge hitting a bolt under the windshield cowl. I do remember everybody thought the noise was coming from the rear of the vehicle. I think GM put that find in a service bulletin. I’m retired now and don’t have access to any factory info…sorry I can’t help for that service bulletin.
Let me know what your fix is.
Thanks JTF!! With it being a 97 and a PA truck the bushings all looks dry rotted and cracked so it can be like chasing your tail. Advance Auto has the torsion bar mounts in stock and with a TRT30 promo code for in-store pickup I can get both for $52 plus tax. The rear sway bar links look rough too. I could replace them first then go for a drive. They are a lot easier to do verses the torsion bar mounts.
Do you know, do I still need to compress the key with a puller before attempting to loosen then height level adjustment screw if broth front wheels are off the ground? Thanks!
Blazerguy1983 wrote:
Do you know, do I still need to compress the key with a puller before attempting to loosen then height level adjustment screw if broth front wheels are off the ground? Thanks!Yes and be careful
This is the best I can do at this time to explain the procedure.
So I was successful at replacing the Torsion bar mounts. The popping is still there but not as dominate as before. I notice it when on a bouncy road or riding over bumps. I also get it if i turn the wheel all the way and pull over hump (when the suspension is being maxed). All sounds like under the middle. I also notice when I had the torsion bar keys unloaded the keys had a lot of play up and down, side to side. When you move them by hand up and down I hear the same type of sound I get when I am driving it over bumps. Is it possible the inside of key is worn or the end of the torsion bar hex is worn causing this excessive play and noise? I made a youtube video talking about it that you can refer to and see what I have done. Thanks!
Don’t forget to also check the exhaust and it’s mounts as well. More info on finding noises here.
http://www.ericthecarguy.com/faq/diagnosing-noises-in-your-car
Good luck and keep us posted.
Blazerguy1983 stated;
I also notice when I had the torsion bar keys unloaded the keys had a lot of play up and down, side to side. When you move them by hand up and down I hear the same type of sound I get when I am driving it over bumps. Is it possible the inside of key is worn or the end of the torsion bar hex is worn causing this excessive play and noise?
I remember they were loose, but not real loose like you’re saying. I also remember GM had some sort of heavy tar grease on the torsion bar to key interference.
Those rear links need replacing. You ought to be thankful and I’m glad you didn’t get hurt….
Yeah, The way I compressed them was pretty stupid! I am always preaching to others about safety and here I go and do something really dangerous.
On a side note, the noise is still there after replacing the torsion bar cross member support bushing links that you can see in the above video. It really occurs when it rains and I’m driving. Every little bump sounds like I’m loosing something under the truck. I’m thinking too a lot of that tar like grease has fallen out of them. Would you have any suggestions of what kinda and where to get some replacement keys. Ones that aren’t too pricey and ones that will help even if there is wear on the end of the torsion bar hex it’s self? Should I replace new tar-like grease on the new ones I install? I can’t find a cheap unloader tool. The cheapest I can find is well over $100 and non of the local auto parts stock one or rent one out. Thanks again. I am 100% sure my noise is in the key area. I also get the clunk if the tuck shifts the the side when the other side goes over like a hump.
Are you sure the noise is due to the missing grease you mention? No other loose parts that you can find? As in the noise article I posted for you, look for areas that have orange dust around them. That usually indicates a loose part.
Sorry for not getting back quicker.
I’ve be doing some checking on the interference tolerance between the torsion bar and the key. It should fit tight. In fact GM states the fit should be like a socket on a nut. The grease is put on the key /torsion bar to keep moisture ect. out to prevent rust.
I really can’t tell you where to get the new keys. I guess check some on-line places, but make sure you get quality and the keys are tight on the torsion bars.
Also do what Eric said about looking at areas with orange dust around them.
I wish I could help you more.
Thank you JTF and everyone else that has replied. I am still new to the torsion bar setup and learning a lot. I am still getting the noise even after backing the inside of the keys with grease. I have check everything underneath and cannot determine the exact place the noise is coming from other than near the center to rear section. I know my leaf spring bushing are dry rotted and used the squeak when it would get cold and rain. I sprayed them with silicone spray and they don’t squeak anymore. I wonder it that could be another possibility of the noise source. I finally got a rainy day to record the noise on camera. In person the clunking is a lot worse than what the camera picked up. It only makes the noise when it rains. Thanks again everyone, I know I am starting to beat a dead horse and probably driving you guys nuts hear but I guess I am determined to fix this noise! haha. Please watch my YouTube Video below…
Look for areas where there is orange dust around a component. That would indicate a loose part and might be the source of the noise. Otherwise, a chassis ear might be the next step. More info here.
http://www.ericthecarguy.com/faq/diagnosing-noises-in-your-car
Good Morning EricTheCarGuy club! I wanted to update everyone on my findings. I think I have finally diagnosed my knocking/clunking noise when it rains on the 97 Blazer. I don’t know why I didn’t think of this before, but I got an old spray bottle and filled with cold water. Then I climbed under and sprayed one thing at a time and would go for a drive. Finally I was able to duplicate the noise after spraying the upper and lower bushings on the rear leaf spring shackles. I am unsure if it is the bushing that is in the rear of the leaf spring or the one inside the frame where the shackles mounts on the top. I replaced the shackles about two years ago because the where rotted. I found a great deal on a Dorman kit but, I noted the mounting bolts hardware where not as thick as the original and there was some play where the bolts slit through the inner bushing sleeves. I wonder if this movement is causing the clunking? The bushing inside the frame that the top of the shackle mounts to was replaced when I did the the shackles but, not the ones in the actual leaf spring. Does anyone have an easy way to replace the busing on the leaf spring that isn’t going to cost me $500 for a tool or torching the old one out. It’s amazing to see how much a noise can travel and come from an entire different area than it may sound. I also made this cool video when I was attempting to diagnose my issue.
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