Rattle around 1500 rpm - Any ideas what it is?

**nyarsulik** · 04-28-2009, 11:19 AM

Sorry if there is another post about this somewhere, I couldn't find anything through the search.

I am getting a consistent "rattle" right around 1500 rpm from within the engine compartment. This is a different noise then typical knock and ping, fairly high pitch. The car seems to run great, and the noise doesn't seem to do anything more than annoy the c*** out of me. Most of my 10 mile trek to work is 45mph, which just so happens to be just at the lower rpm limit of where this noise starts.

I am unable to get the noise to happen while in neutral, only while in gear, and it happens through all of the gears. (I have an automatic though)

The only thing I can think of that I have altered lately was replacing the tensioner belt pulley, and adding the SLP large air box cover. Unfortunately, I can't remember if I was getting the noise prior to the pulley replacement.

Any ideas on what it might be? Thanks!

**noxside** · 04-28-2009, 08:32 PM

For me I always got a noise in that range from the exhaust heat shield rattling . Took it out after header install and never heard the noise again.

**TOMASINO** · 04-28-2009, 10:18 PM

Originally Posted by nyarsulik

Sorry if there is another post about this somewhere, I couldn't find anything through the search.

I am getting a consistent "rattle" right around 1500 rpm from within the engine compartment. This is a different noise then typical knock and ping, fairly high pitch. The car seems to run great, and the noise doesn't seem to do anything more than annoy the c*** out of me. Most of my 10 mile trek to work is 45mph, which just so happens to be just at the lower rpm limit of where this noise starts.

I am unable to get the noise to happen while in neutral, only while in gear, and it happens through all of the gears. (I have an automatic though)

The only thing I can think of that I have altered lately was replacing the tensioner belt pulley, and adding the SLP large air box cover. Unfortunately, I can't remember if I was getting the noise prior to the pulley replacement.

Any ideas on what it might be? Thanks!

sounds like a timing chain or water pump try to locate the noise with an stetoscope sorry if i didnt spell that rite, or with a screwdriver put it in ur ear and u can hear rite away if is a pulley proly just the heat shield from the catalic converter...

**nyarsulik** · 04-29-2009, 05:47 AM

Thanks guys. I guess the problem is that I can't get it to make the sound unless I am in gear, driving.

) The one time I had someone around to try and listen while I brought the rpm into that range it wouldn't rattle.

I will check those heat shields and see if they are loose or too close to something else for some reason.

Thanks!

**TA98** · 04-29-2009, 05:54 AM

It could be a ruined catalytic converter. Ive seen nurmous cars come in with the complaint of a rattle and the cat is broken into pieces

**nyarsulik** · 04-29-2009, 06:12 AM

hmmm... Would it still only do that within a certain RPM range? Just out of curiosity, what is the typical cost to have that replaced?

**Fearls1** · 04-29-2009, 06:18 AM

Originally Posted by T/A98

It could be a ruined catalytic converter. Ive seen nurmous cars come in with the complaint of a rattle and the cat is broken into pieces

Yep... Catalytic Converter is notorious for going bad.
http://videos.streetfire.net/video/W...t-to_78424.htm

**nyarsulik** · 04-29-2009, 06:51 AM

Wow, that is exactly it. Thanks for pointing me to the video! Now to see what I have to do about getting it fixed...

There was a note about an exhaust flange being the problem, is that a possibility? Or since it really is limited to 1500 rpm does the converter sound more like the issue?

Thanks!

**nyarsulik** · 04-29-2009, 07:07 AM

*** Had this answered - I guess these are required in KS, and it would also cause my check engine light to constantly be on, so I guess that wouldn't be a good idea ***

Is it legal to run without cats, replacing those with just straight pipe? Are there any performance gains or losses, or is it simply an emmissions issue?

**Fearls1** · 04-29-2009, 07:38 AM

In Oklahoma, we don't have inspections. So, I can get away with no cats so far. Without cats, you will need to either have rear O2 simulators or have them "tuned" out. There is a deffinitely a sound difference. Also, I noticed a small performance increase. Good luck, new cats range in the 200-400 dollar range.

**nyarsulik** · 04-29-2009, 08:50 AM

Does anyone have suggestions on which cat(s) to purchase as replacements? I am honestly not sure if mine is a single or dual cat setup.

It is the stock system, with a single muffler and dual outs.

**JoshieDoom** · 04-30-2009, 04:19 AM

You have two converters. One for each side.

Might want to check the head shields above the cats/near the brake lines.

Mine does it

my cats are hollowed. BUTT.. if you dont have inspections you can get the SES light turned off and get longtubes or an off road y pipe and have a ton more power in the end.

Do you have a visual inspection, a sniffer inspection or a OBDII computer inspection?

**nyarsulik** · 04-30-2009, 06:13 AM

No sort of inspection yet, just the confirmation by watching that video earlier in this thread.

KS doesn't give a mandatory emissions test, but I will probably replace them anyway if I need to. I found some inexpensive hi-flow ones that should work fine.

That would be nice if it was just a heat shield.

I guess the vibration right at that RPM range just sets it off perhaps?

**JoshieDoom** · 04-30-2009, 06:15 AM

Originally Posted by nyarsulik

No sort of inspection yet, just the confirmation by watching that video earlier in this thread.

KS doesn't give a mandatory emissions test, but I will probably replace them anyway if I need to. I found some inexpensive hi-flow ones that should work fine.

That would be nice if it was just a heat shield.

I guess the vibration right at that RPM range just sets it off perhaps?

yup.. it changed with my cutout.. its right about 900 rpm with it in gear.. it gets this nasty VRRRRRRRRRR sound like a metal plate on a washing machine lol..

**nyarsulik** · 04-30-2009, 06:22 AM

Yeah, it is definitely a very annoying sound. It really makes my car sound like poop, like its about to fall apart.

Is the heat shield something that can be bent or moved out of the way a little to help keep it from vibrating?

**JoshieDoom** · 04-30-2009, 06:26 AM

Originally Posted by nyarsulik

Yeah, it is definitely a very annoying sound. It really makes my car sound like poop, like its about to fall apart.

Is the heat shield something that can be bent or moved out of the way a little to help keep it from vibrating?

yep. You could take header wrap and shove behind it or wrap it around the exhaust if it is touching..

**TOMASINO** · 04-30-2009, 09:04 PM

Originally Posted by Fearls1

Yep... Catalytic Converter is notorious for going bad.
http://videos.streetfire.net/video/W...t-to_78424.htm

nice what kinda exhaust do u have on???

**Spikito** · 05-01-2009, 12:03 AM

welcome to owning an f-body???

but seriously, check your metal lines, I had this problem in my trunk, it was a brake line rubbing the fender where it came out of the booster, down by the power steering pump

but my first thought on yours is that it could be the tensioner or idler pulley

**Fearls1** · 05-01-2009, 06:22 AM

Thanks, it came with the car, I think it's a FM. Don't go and get one tho.... I had to repair a crack in the muffler last month. Check out some of my other vids on streetfire.

**Spikito** · 05-01-2009, 11:32 AM

My car does the same thing. But check this out, only if i drive to school on a certain road, and only if its raining. yeah, figure that shit out. But mine does it a idle. We've determined that mine is a messed up baffle that gets out of whack due to like the top half of the muffler being hot, and the rain keeping the bottom half cold.