main cat converter Rattle ?

Horsehammerr · Post by **Horsehammerr** » Sat Apr 18, 2009 5:51 am

I'm hearing a rattle in the area of the trans at idle in park and N. I'm not noticing any malfunction in performance but, it gives a "Whats Up" thought. It stops instantly when put in any gear. The sound reminds me of a muffler when the guts are rotted loose inside, but its for sure right in the tranny area when listening underneath. Any Ideas??

PAFF334 · Post by **PAFF334** » Sat Apr 18, 2009 6:21 am

Heat Shield in the area of the catalitic converter i know that seems to be a big problem with any vehicle.

Post by **HenryJ** » Sat Apr 18, 2009 6:07 pm

Plugged precat.

F9K9 · Post by **F9K9** » Sat Apr 18, 2009 8:08 pm

Did anyone leave or lose one of these?

Horsehammerr · Post by **Horsehammerr** » Sun Apr 19, 2009 1:10 am

Precat chopped

Post by **HenryJ** » Sun Apr 19, 2009 6:42 am

Check the main for the same stuff.

DLP · Post by **DLP** » Sun Apr 19, 2009 7:22 pm

The driveshaft scatter shield on the gas tank rattled on mine when at idle. Had some gravel between the tank and shield.

Horsehammerr · Post by **Horsehammerr** » Wed Apr 29, 2009 4:24 pm

The rattle is for sure in the main cat converter, thanks for the direction Brule. Would it hurt anything to just replace the cat with a piece of clean pipe like I did the precat ? I've gottin used to my SES light being on due to burned out O2 sensors.

Post by **HenryJ** » Wed Apr 29, 2009 4:50 pm

Horsehammerr wrote:Would it hurt anything to just replace the cat with a piece of clean pipe like I did the precat ? I've gottin used to my SES light being on due to burned out O2 sensors.

Obviously you do not have emissions to worry about, since the MIL being on has not been a problem.
Will it cause problems? I really don't think so.

It will be noticeably louder. you will likely experience deceleration popping. This can be solved though.

On a budget? Want to try it? Get a stainless steel muffler pipe band clamp for 2.25"-2.5" exhaust pipe

(NAPA Part: EXH 36148 or Autozone # 65916). Search for "Band Clamp". Price should be $7-$11.

Unbolt the tail pipe from the cat and cut the pipe to the cat a couple inches from it. Remove the cat. Use a bar and hammer to bust up the honey comb and empty out all the chunks. Once cleaned out reinstall using the band clamp to put it back together.
I really don't thin k you will run into operation problems.
I will try it with mine when , or if the time comes.

My '86 S-10 has been running this way for well over a decade. It has no post cat sensor though. I added a Supertrapp to tone it down and get rid of the deceleration popping.

Another option: The cat is a warranty item. You should be able to get a new one installed under warranty if you are under 8 years and 80k miles, or was it 12 years now? Worth checking with your local dealer to see if you are covered.

Horsehammerr · Post by **Horsehammerr** » Thu Apr 30, 2009 3:09 pm

How about 7 years and 129,000 miles ?

Post by **HenryJ** » Thu Apr 30, 2009 3:18 pm

Check with your dealer. Chrysler is covered to 120k miles.
I would like to hear back on what you find out. I think GM is 8-80, but I am not sure.

Horsehammerr · Post by **Horsehammerr** » Fri May 01, 2009 4:30 pm

Supertrapp ??

Post by **HenryJ** » Fri May 01, 2009 4:40 pm

http://www.supertrapp.com/

I added a stainless steel shorty, but disc only would probably work.

As a bonus they are USFS approved spark arrestors. Tuneable and the radial design can actually scavenge exhaust once warmed up.
I run them on the HenryJ too.

Horsehammerr · Post by **Horsehammerr** » Sat May 09, 2009 11:03 am

Well I finally got job done like Brule suggested and it worked great. No more rattle

. The increase of exhaust sound is very slight ,but does sound a little less like a toy. I'm not getting any popping when backing off so maybe this one just likes it, I do. Never did check with dealer about replacement under warranty, sorry. I just prefer to do things myself even if it is free. Keeps me aware of what's what on my rig.

raven2510 · Post by **raven2510** » Sat May 09, 2009 3:51 pm

the Chevy/gm warranty is 8 years or 80,000 miles whichever comes first. mine cat went bad at 82,000 two yrs ago and they would not replace it. to say the least i was pissed but i understood

Post by **HenryJ** » Sat May 09, 2009 7:51 pm

Horsehammerr wrote:Well I finally got job done like Brule suggested and it worked great. No more rattle . The increase of exhaust sound is very slight... not getting any popping when backing off ...

Sounds great to me. Keep us apprised of any changes in fuel mileage, drivability, and the MIL codes set, if any.
I would pull the battery cables to store a fresh operations sequence in the PCM. The "free'r breath'n" will need a fresh read for the PCM.

Let us know how it all works out.

P.S. If you wheel hard, you may need to get that cut welded. Eventually the SS clamp may stretch and loosen.

Horsehammerr · Post by **Horsehammerr** » Sun May 10, 2009 2:56 am

Glad you brought up the PCM reset. I guess I knew to do that, just was happy to be out from under and forgot the final detail. It does seem to want to power up faster with less effort on the throttle. Had to watch my speedo on the first run through town !

I am planning a full 3" exhaust from the Y back, with combined "muffler for in town" and "Straight Dump for everywhere else" so I'm not worried about the strap .

Post by **HenryJ** » Sun May 10, 2009 5:44 am

Nice. Sounds like a set-up that I'd like to run someday.
I was envious of the electric dump that one member had. Wasn't it Mark's truck?

It will be interesting to see how this all works out for you. I'll be watching.

Horsehammerr · Post by **Horsehammerr** » Sun May 10, 2009 12:56 pm

That reminds me

, didn't you come up with an electric valve to shut off the coolant flow to your heater? I've got a manual shut-off valve on mine and there are times out here in these hills that defrost is needed in a summer fog. It's a real PITA to have to pull over in the fog to open up the coolant flow.

It would also be nice to know more about that electric exhaust dump

Post by **HenryJ** » Sun May 10, 2009 1:04 pm

Yes. Two buttons on the dash to turn it off and on. One closes the coolant flow, and the other closes the cowl vent air circulation.
Heater control valve and Hot Feet Fix II

Mark's exhaust: New exhaust mod

Horsehammerr · Post by **Horsehammerr** » Fri May 15, 2009 12:33 am

The only change I noticed after gutting the Cat. was a smoother acceleration on cruise. The first tank of gas showed no change in MPG. I just filled my second tank and almost flipped !! A jump from 23 to 24.8

. I'm going to watch close, but I like it a lot.

roadrunner · Post by **roadrunner** » Sat May 16, 2009 5:10 pm

Hey Hammerr! If the gas starts "backing up" in your tank cuz you're getting too high MPG's save it for me. I'm sure I can find a place to dispose of it properly. lol

Horsehammerr · Post by **Horsehammerr** » Sun May 17, 2009 4:18 am

So far the MPG's have stayed close to 24.8

. The thing that really gets my attention is the smooth upthrottle I'm getting in cruise. It doesn't hammer the gas to resume speed like it used to,but seems to speed up a little quicker than before.

Anyway I like it !!

F9K9 · Post by **F9K9** » Sun May 17, 2009 4:56 am

roadrunner wrote:Hey Hammerr! If the gas starts "backing up" in your tank cuz you're getting too high MPG's save it for me. I'm sure I can find a place to dispose of it properly. lol

Reminds me of some friends that kept sneaking gas into a coworkers VW when he wasn't looking.

He kept taking it to the dealer who, soon thought that the guy was crazy.

roadrunner · Post by **roadrunner** » Sun May 17, 2009 11:15 am

Yeah f9k9 I heard a similar story up this way but with a twist. After adding gas for a month his "friends" then started siphoning off the same amount per week as they had previously added. Poor dealer was driven nuts by this guy coming in and griping about what had happened to his superior fuel mileage.