1999 Blazer rattle/vibration?

The noise is a loud rattle/vibration that comes from the mid to rear of the vehicle. It only happens infrequently under acceleration at slow speeds when the vehicle is fully warmed up. It stops when I let off the gas or give it more gas. Any ideas would be appreciated!

Cat convertor

Could also be the baffles in the muffler. Somewhat common to break loose.

Could also be the baffles in the muffler. Somewhat common to break loose.


That is exactly what it sounds like...I have the same problem with my 99...when I turn a corner and step on the gas it rattles/rumbles and is annoying....been that way for along time...

I tell new passengers it's my supercharger kicking in.... :lol:

But I have had my truck up on jack stands looking from top to bottom for something loose...all checks out, but never thought of the INSIDE the muffler.... :uhoh:

I suspect I will have to change one day as I have 159K on her..still muffles sound so I will just live with it until it rusts through....6 years and going strong....'cept for the stupid rumble....

Keep in mind too that a plugged catalyst can sometimes shift, breaking chunks off of itself and lodging downstream in the muffler, or a pipe bend. Get it looked into ASAP before it becomes a much costlier repair or a hazardous problem. I have seen holes burned through pipes and mufflers caused by a chunk of catalyst broken free and lodging in the pipes somewhere else.

Had it checked out today, however the noise would not show up for the mechanic -just my luck. The catalytic converter was fine, inspected the visibe parts of the drivetrain, test drove it - could find nothing wrong. I did not see the post about the muffler until after I picked the truck - still could be the problem. I'll have that looked at next time.

I would start looking around at heat shields too and make sure that all of your under-body armor and skids plates are snug. 35 foot-pounds should be snug enough for all of your bolts there.

I had a similar problem with a rattle that was driving me nuts...thought sure it wast the cat at first. Had my wife put it in gear & I applied just a little upward pressure on the muffler & it went away.
Next step I suppose is to see if the muffler is just loose, or a heat shield....better than it being the cat, either way!

-Mike

I have a similar problem with my 99 Blazer, it will rumble in idle and you can feel it in the drivers seat and front passengers seat. It has never rumbled when I give it gas or turn at slow speeds. I just get that darn clunking noise when I turn.

I have a similar problem with my 99 Blazer, it will rumble in idle and you can feel it in the drivers seat and front passengers seat. It has never rumbled when I give it gas or turn at slow speeds. I just get that darn clunking noise when I turn.

clunking, please explain.

clunking, please explain.
Bad choice of words, sorry. It's like a pop sound when I turn. Not the washer problem on the hood that you had the fix for.

Bad choice of words, sorry. It's like a pop sound when I turn. Not the washer problem on the hood that you had the fix for.

Ever greased the 10-11 grease fittings in your front end?

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