Rattling sound
Thread Starter
Race Director
Joined: Oct 2011
Posts: 16,089
Likes: 819
From: Dallas Texas
2025 C4 of the Year Finalist - Modified
Rattling sound
Here is when the rattling sound occurs.
If you rev it above 3k in P or N.
AC on, usually more frequent when you are idiling in D.
AC off, you don't hear it unless you rev higher than 3k rpm.
93 lt1
If you rev it above 3k in P or N.
AC on, usually more frequent when you are idiling in D.
AC off, you don't hear it unless you rev higher than 3k rpm.
93 lt1
Pro
Joined: Oct 2003
Posts: 506
Likes: 12
From: Savannah GA
If you are sure it not the AC compressor. Next time you have the car up take a hammer handle and tap on the pre cats. Don't 93s still have them?
A brick in the pre cat came loose in my 87. I didn't do anything until it came apart. I almost didn't get it home since it nearly completely clogged up the main cat!
JS
A brick in the pre cat came loose in my 87. I didn't do anything until it came apart. I almost didn't get it home since it nearly completely clogged up the main cat!
JS
Racer
Joined: Apr 2017
Posts: 396
Likes: 58
From: Katy Texas
The cats are my guess as well...went through this on my '89. It started with an occasional rattle, then more, and then sounded like rocks in a coffee can. Mine did completely fail and dump their contents downstream into the main center cat leaving me stranded on a road trip.
Melting Slicks
Joined: May 2014
Posts: 2,894
Likes: 592
From: New Port Richey FL
Rattles are a PITA to chase the above are not wrong in looking at pre-cat's/exhaust, but if you feel the a/c is involved you may want to pop the accessorie drive belt off to rule out front of motor noises.
Last edited by s carter; Aug 24, 2018 at 01:45 PM.
Melting Slicks
Joined: May 2014
Posts: 2,894
Likes: 592
From: New Port Richey FL
You can run an LT-1 for a Limited time without the Belt, the Lt1 has the water pump driven by a connection Directly from motor. So your water pump is still working but your Fans are running on the Battery if they kick on. So for the 2 or so minutes to do your tests your good.
Last edited by s carter; Aug 24, 2018 at 08:39 PM.
