: Noisy engine



SCSTS
09-19-05, 03:29 AM
Hey, my '99 sts was doing great until a couple days ago I started hearing a rattling sound kinda like when it's low on oil but it sounds maybe a little deeper maybe even under the car. Any ideas?

Ranger
09-19-05, 12:24 PM
Does it make this noise only on cold start up or all the time?

SCSTS
09-22-05, 02:30 AM
All the time. I had some guy tell me it was the catalytic converter.

If that's true I'm not worried but if it's the engine I think I have a real problem.

danbuc
09-22-05, 03:12 AM
It's more likely the heat sheild on the Catalytic converter housing. If it comes loose, it can make a loud rattling sound as it bangs against the outer casing of the Catalytic converter. When the car is cold, get under there with a small rubber mallet. Tap on the heat shield to see if it moves at all. If it looks like it's bouncing around a little under there, that could very well be you problem. I would check that before you do anything drastic.

edit: Also if it is the cat heat shield, the noise will be coming from around the middle of the car, and not the front.

mcowden
09-22-05, 03:37 AM
All the time. I had some guy tell me it was the catalytic converter.

If that's true I'm not worried but if it's the engine I think I have a real problem.

It's possible the catalytic converter is shattered internally. Have you seen any Service Engine Soon lights and/or codes indicating low catalyst performance? If the cat is broken inside, it will rattle and it can become very loud. It could also just be the heat shield that has come loose as danbuc suggested. If it's a metallic-sounding rattle, I'd bet on the heat shield. If it's more clunky-sounding, it's probably the guts of the converter. Take a look at that shield if you can. Listen closely underneath the car on one side. You may be able to pinpoint more easily from there. One way or another, let us know what you hear or see.

SCSTS
09-22-05, 06:40 PM
Thanks !

I wil check it out.

lry99eldo
09-22-05, 08:06 PM
Oh yeah, Always look to the catcon. Now that we've experienced these things for what, 20 years now, they seem to cause all sorts of noises and symptoms that seem to be something else. They are not made out of Hastoloy or Inconel that would handle the heat cycles, they're simple coated steel construction for the most part. So when they decide to let go they'll have you thinkin the sky is falling. If it is the catcon, have it replaced soon because if it's still functional and the heat sheild is gone you run the risk of fire when you least expect it. They are really not that expensive to replace anymore either.
lry99eldo

eldorado1
09-22-05, 08:45 PM
You can say that again... ebay has them for $50.