1. Home
  2. Mazda Miata
  3. Odd rattling?

Odd rattling?

Hey guys, I have a problem with my beloved 92 Miata. There is a very annoying rattling that has been increasing in intensity over the past couple hundred miles. It started it's life as only occuring at 3k RPM give or take a 100. Now, it has progressed to virtually anywhere lower than 4K, it is most pronounced when the tach reads closest to 3k and when the engine is dropping revs. It does this in or out of gear. I recently installed aftermarket headers, but I re-torqued all of the bolts and everything is super tight, The down tube does not perfectly mate with the cat however, and so there may be some exhaust gasses rattling the gasket there. I've also read about catalyctic converters burning up and causing similar side effects. Anyone know of a way to check the catalyctic converter, or possibly something not related to the exhaust system that I should check? Also a better way to mate the new headers with the old cat? Any pulley wobble is minimal enough to disregard. This is a fairly new engine, maybe

35k miles on it in a 197k car! I'm a college student and rarely get a chance to play mechanic with my car so I'm looking for a second opinion.
Reply to
Bryan
Loading thread data ...

Could be the cat, especially if it's the original. Test - smack it, literally. If the core has broken up, it will create quite the rattle when it's whacked by hand (cold, obviously). However, another possibility is that the mis-match between the header and converter could be torquing the entire exhaust to the side, causing your muffler to vibrate against the frame where the rear "teeth" attach. Is your muffler still centered in the cutout or has it moved to the port side? If you need a cat, try J.C. Whitney with a direct fit for $99.00. If it has moved the exhaust system, try grinding a small amount of material off the frame and then apply either touch up paint or clear nail polish to the bare metal. Heat shields can also cause noise but it is a different "pitch" then the cat, more metallic and less dull (hard to explain).

Tom

92 Red Bryan wrote:
Reply to
Tom Howlin

smack it,

rattle

converter could

muffler to

your

port side?

$99.00. If it

material

nail polish

a

(hard to

Or it could be something as simple as a loose heat shield. Remove heat shield, no more noise.

Iva & Belle.) '90B Classic Red.) #3 winkin' Miata

Reply to
Iva

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.