Metallic rattle at 1300 & 2800 rpm and sizzling

[Guest ReyXLP]

I have a strange sound that I can best describe as sounding like a metallic rattle that is coming from under the car. It seems to consistently happen around 1300 and 2800 rpm, in any gear or neutral. The sound is also harsher on decelleration than acceleration.

 

It's a '97 SE with around 93k on the clock.

 

Also, I am hearing a sizzling sound after I park and turn off the car, coming from the front underside. I don't recall this before, and it sounds like something is leaking onto something hot, but I don't see any oil on the floor, just some water when I'm using the A/C.

 

Any advice or suggesitons would be greatly appreciated.

 

Thanks very much!

[k9sar]

The rattle is probably a loose heat shield. There have been other threads here with similar issues.

 

As for the sizzle.... pop the hood and get in there to look. It may be a small coolant leak spitting from a hose onto something hot. There probably isn't enough to puddle but it should be easy to find. If you can't isolate where the sound is coming from (here I go again ) Get yourself a 3 foot piece of tubing (about 1/4 I.D.) and shove one end in your ear. Use the other to probe around and it will work like one of those expensive automotive stethescopes.

[vengeful]

The sizzling could be the condensation from the A/C dripping onto your exhaust. Mine does it. Try running without A/C for a couple days and see if it still does it.

[Guest ReyXLP]

K9 -

 

Thanks for the speedy reply.

 

Actually, I had the heat shields removed about three moths ago because they were coming loose.

 

Could this noise be related to the way the shields were removed? (I.E. Improper procedure, etc.)

 

Are their other issues that might be the source, especially at those specific rpm?

 

Meanwhile, I will get looking for that leak -- thanks!

[deej]

What's the octane of the gas you are using?

[Guest ReyXLP]

K9sar & Vengeful:

 

Thanks a lot -- yes, it is the a/c leaking on the exhaust. Took me a while to find it, but flashlight made all the difference.

 

Deej:

 

I used 87 for the first 8x,xxx miles, and recently switched to 91/93 the last 10,000 or so. Curious to see if performance would improve. Can't say I've really noticed much of a difference. Could this be causing the metallic rattle at 1300/2800 rpm?

 

Thanks.

[vengeful]

A blown catalytic converter could cause a pretty bad rattle from under the truck. My former roommates Hardbody rattles like a can of screws, and it's cuz his cat is blown out. Maybe using 91/93 blew out your cat....

[Mark]

I CAN SAY WITH 95% CERTAINTY WHAT YOUR RATTLE IS.

 

I had the same sound at the same RPMS you're talking about with my '96 and for months I looked everywhere. I stripped the heat-shields (good riddance anyway) and that wasn't it. The mechanic told me he couldn't hear it.

Another mechanic told me it was the honeycombe inside the cats, breaking loose from age.

The exhaust guy said 'no' it wasn't.

He said it was something else.

The auto engineer said it was in the tranny. :confused:

The transmission guy said it was the cats!!!

 

Finally I saw ANOTHER exhaust guy and he discovered that one of my cats was touching the cross-member under the chassis and vibrating against it BUT only at certain RPMs because of the way the motor torque-twists on it's mounts (normal) at those specific RPMs.

He heated up the exhaust-pipe a couple of inches in front and behind the cat, stuck a pry-bar in there and jimmy'd it upward about an inch.

The problem that had been plauging me, buggin the $h1t out of me for months and really causing me worries about what may happen to my credit card was solved for $30. :bow:

 

I hope that this is the same for you. Let me know.

[Mark]

Was I right?

Or do I owe you an apology?

[jjeffri]

My 96 pathy makes a rattling noise at a couple of key RPM's, I think at about idle and 2500. I found a bracket, right beneath the front passenger door, in the exhaust line that was broken. I had a buddy rev the engine until the rattle and then I pressed around the exhaust with my shoe until the vibrations were dampened, I then noticed the cracked bracket. I haven't replaced it yet, but it is not a serious issue, just an annoyance.

[dkpath96]

Mark:

 

How loud was your rattle? Did it get faster and higher with higher RPM?

 

The reason I ask is that I now am hearing another rattle, fainter and getting

more consistent in the cold weather, that sounds again like paper in a fan, but

much fainter than the heat shield noise I had before.

And this time it only can be heard when I accelerate.

Did anyone mention header or manifold issues in your quest to fix your noise?

thanks!

[deej]

I'll ask again only cuz I had been having the "paper in the fan" noise.

 

What octane gas are you using? When I use less than 89 octane gasoline, the noise is there, when I use 89 octane or higher the noise is gone....try it for a tank, I think your RPM noise will be gone.

[Mark]

Mark:

 

How loud was your rattle? Did it get faster and higher with higher RPM?

 

The reason I ask is that I now am hearing another rattle, fainter and getting

more consistent in the cold weather, that sounds again like paper in a fan, but

much fainter than the heat shield noise I had before.

And this time it only can be heard when I accelerate.

Did anyone mention header or manifold issues in your quest to fix your noise?

thanks!

I drive an R50. We got no manifold stud problems with R50s.

 

With my prob, it was only at certain RPMs 'cuz it was only when I was accellerating a certain amount. Here's why:

 

Y'know how the engine rocks slightly on it's mounts, toward the LHS when you apply the go-pedal? Well this torque-induced rock was bringing my LH Cat into contact with my crossmember. Hence the rattle. It was only at certain RPMs 'cuz when I wasn't accellerating hard enough, the cat wouldn't touch the crossmember and when I was accellerating hard, the cat was hard-up against the crossmember, not just vibrating against it. :o

 

It's also worth trying a higher-octane gasoline and of course broken brackets, loose heat-shields etc are definitely worth checking out, also. -bounce-

 

If all these things fail you, just try looking at your system and imagining what could touch what with some torque applied to the system. Worked for me.

 

Good luck,

[dkpath96]

I was just re-reading my old posts, and just wanted to correct myself - the noise I

have is more like a ticking (paper in a slow fan??) noise, not a rattle or buzz.

 

Well, yesterday I drove around for 200+ miles and heard the ticking all day.

It is originating from the engine area, passenger side. It was pretty loud.

 

Today it was barely audible, even with a cold or warm engine.

 

I've discussed this in another post but this one seems more active. When I

popped the hood to listen for the noise, I couldn't hear it, but I did notice a

rapid puffing noise (like a hole in the exaust) coming from the passenger side

exhaust manifold. It of course increases in rate and pitch with higher RPM.

 

This leads me to believe it's the manifold stud issue. But this week I will try

a higher octane gas just out of curiosity.

 

That puffing noise isn't normal, is it...?

[IndianRider]

My 96 pathy makes a rattling noise at a couple of key RPM's, I think at about idle and 2500. I found a bracket, right beneath the front passenger door, in the exhaust line that was broken. I had a buddy rev the engine until the rattle and then I pressed around the exhaust with my shoe until the vibrations were dampened, I then noticed the cracked bracket. I haven't replaced it yet, but it is not a serious issue, just an annoyance.

i have the same EXACT problem .. after about a year of the annoying rattle, i got rid of the bracket that holds both the exhaust pipes to the underbody ..

 

i need to come up with a cheap home made bracket to tie up both the exhaust pipes from shaking excessively .. maybe one of those aftermarket exhuast clamps with some heavy duty exhaust repair tape might solve the problem ..

[88pathoffroad]

Tried a bungie cord? No wait, coat hanger! Yeah!

[RedPath88]

^^^^

 

Head to the parts store and buy an exhaust hanger or strap. Clamp it to the pipe and secure the other end to the body.. Cost only a few bucks and you'll be done with it.

 

PartsAmerica.com - Tail Pipe Hangers

 

[IndianRider]

redpath88

 

thanks for the tip .. thats what i had in mind .. should get the job done ..

[RedPath88]

No problem

[zonianbrat]

I CAN SAY WITH 95% CERTAINTY WHAT YOUR RATTLE IS.

 

I had the same sound at the same RPMS you're talking about with my '96 and for months I looked everywhere. I stripped the heat-shields (good riddance anyway) and that wasn't it. The mechanic told me he couldn't hear it.

Another mechanic told me it was the honeycombe inside the cats, breaking loose from age.

The exhaust guy said 'no' it wasn't.

He said it was something else.

The auto engineer said it was in the tranny. :confused:

The transmission guy said it was the cats!!!

 

Finally I saw ANOTHER exhaust guy and he discovered that one of my cats was touching the cross-member under the chassis and vibrating against it BUT only at certain RPMs because of the way the motor torque-twists on it's mounts (normal) at those specific RPMs.

He heated up the exhaust-pipe a couple of inches in front and behind the cat, stuck a pry-bar in there and jimmy'd it upward about an inch.

The problem that had been plauging me, buggin the $h1t out of me for months and really causing me worries about what may happen to my credit card was solved for $30. :bow:

 

I hope that this is the same for you. Let me know.

Did you notice any extra heat from removing your heat shields. MIne rattle at certain rpm's and I kinda want to just hack them off but want to know all of the adverse affects of doing this.