Blazer Rumble?

97 blazer LS with 148k miles.

i've heard a rumbling, scratching, and rough noise coming from underneath the body during revving and low RPM acceleration. i slid under today and had it revved up and it sounds like its coming from the catalac converter. had a new exhaust put in a few months ago, but not a new Cat. how probable is it, that this is the point my noise is coming from. and if so, how much are they to replace? labor probably wouldnt be too bad, i just hope i dont get hit for $200 bucks to fix a rough noise.

also, would they harm my vehicle to run on this for a while, or does it need replacing soon?

thanks for all the help fellas... ryan

The cat can rattle if the honeycomb inside breaks. If the pieces rattle around and turn sideways, it can cause excessive backpressure and lack of power. May want to check a muffler shop like Midas for a quote.

97 blazer LS with 148k miles.

i've heard a rumbling, scratching, and rough noise coming from underneath the body during revving and low RPM acceleration. i slid under today and had it revved up and it sounds like its coming from the catalac converter. had a new exhaust put in a few months ago, but not a new Cat. how probable is it, that this is the point my noise is coming from. and if so, how much are they to replace? labor probably wouldnt be too bad, i just hope i dont get hit for $200 bucks to fix a rough noise.

also, would they harm my vehicle to run on this for a while, or does it need replacing soon?

thanks for all the help fellas... ryan

Replace it NOW.

You could blow your engine and ruin your exhaust if you don't.

Hmm... BlazerLT .. you seem to know what your talking about from everything ive read.. but, when driving home tonight, i didnt hear the noise at all. driving, idling, revving, nothing there was no noise. but like tomorrow it may be there and later that day gone. still get the whole Cat replaced asap? or is just that thing inside that ricksza said?

thanks again

Hmm... BlazerLT .. you seem to know what your talking about from everything ive read.. but, when driving home tonight, i didnt hear the noise at all. driving, idling, revving, nothing there was no noise. but like tomorrow it may be there and later that day gone. still get the whole Cat replaced asap? or is just that thing inside that ricksza said?

thanks again

Get it replaced. If it breaks apart and plugs the exhaust, you could overheat the engine and cause some exhaust valve damage.

Don't put it off, get it done.

definitely get a new one. my brother ran his 96 mustang with a clogged cat. he was going to the shop(20 mins away) all the sudden the car bogged out and stalled. popped the hood to find the exhaust manifold bright red from heat coming back into the engine. caused some good damage to be done.

Not to disagree with you guys, your a hell of alot more knowledgeable than I am, but check if the heat shield is loose on the cat. That can cause a monster amount of noise, as I found from experience. I emptied my cat with a hammer and a piece of rebar just to find out it was the heat shield. The truck sounded cool though. :2cents:

97 blazer LS with 148k miles.

i've heard a rumbling, scratching, and rough noise coming from underneath the body during revving and low RPM acceleration. i slid under today and had it revved up and it sounds like its coming from the catalac converter. had a new exhaust put in a few months ago, but not a new Cat. how probable is it, that this is the point my noise is coming from. and if so, how much are they to replace? labor probably wouldnt be too bad, i just hope i dont get hit for $200 bucks to fix a rough noise.

also, would they harm my vehicle to run on this for a while, or does it need replacing soon?

thanks for all the help fellas... ryan

Your probably looking at close to 200$. Are you experiencing any lack of power? Had that problem with mine. It was making noises under there, slowly lost more and more power til it would barely run anymore. I eliminated my catylic converter due to a hunch and problem solved. No more gremlin sounds and I got all my power back! Your best bet, however, is to replace the converter. Especially if you live in a state where it will need to undergo smog test just to get it registered. It will NOT pass without a catylic converter.

I haven't been experiencing any noticeable lack of power... yet. and it was weird because last night coming home the noise wasnt there at all. but then again, when i fire it up in a few minutes im sure it will be. i live in michigan, but im not to sure about that smog test law though. i'm going to get the new cat put on later today probably. thanks again

Get the magnaflow highflow cat or the catco off of ebay if you want it cheap.

I haven't been experiencing any noticeable lack of power... yet. and it was weird because last night coming home the noise wasnt there at all. but then again, when i fire it up in a few minutes im sure it will be. i live in michigan, but im not to sure about that smog test law though. i'm going to get the new cat put on later today probably. thanks again


Hahaha, you can do whatever you want in Michigan... I know a ton of people that have cut their cats out... but it's still illegal LOL.

it turns out it is just the heat shield. so this means i can ride on it for a while before replacing. nothing seems to be wrong with the cat.. which is a relief, saves me some money. besides, those things should about last the lifetime of a blazer right?

it turns out it is just the heat shield. so this means i can ride on it for a while before replacing. nothing seems to be wrong with the cat.. which is a relief, saves me some money. besides, those things should about last the lifetime of a blazer right?

When the engine and truck is completely cold, get under the truck and smack the cat squarely with the palm of your and and listen for a rattle or for loose bits moving around inside.

And no, they don't always last the whole lifetime of a vehicle.

When the engine and truck is completely cold, get under the truck and smack the cat squarely with the palm of your and and listen for a rattle or for loose bits moving around inside.

And no, they don't always last the whole lifetime of a vehicle.

and if i hear loose bits then something is broken inside and i need a new cat?

and if i hear loose bits then something is broken inside and i need a new cat?

Definitely.

Definitely.

fuck, im confused. ive driven 'er a handful of times now since i heard the noise and it is no longer there. i crawled under there last night and slapped it flush with my palm and i didnt hear any rattling. maybe the tailpipe just became disconnected with the bracket and then adjusted itself? i dont know, im still gona listen for it again.. thanks for the advice guys.