Need help with a rattle above oil pan
02-20-2018, 09:50 PM
#1
Need help with a rattle above oil pan
2002 C5 Coupe, Auto, 98k miles
Mostly stock (just has axle back Borla Stinger and air intake).
I've got a rattle I can't find. It happens only after fully warm (30 minute drive) -- and then, it does it at Low RPMS as the RPMs are dropping down off a minor rev. I can make it happen repeatedly by putting it in park or neutral and lightly revving. (it does happen while in gear too).
It's coming from the area i've pointed to in the pictures (NOT my car, again, stock exhaust up there on mine). Above the oil pan, between the oil pan and the exhaust coming down. Its louder on the passenger side, near the middle. Sounds like it's coming from the gap right there.
I've put my mechanics stethoscope on just about everything i could see/reach while under it on ramps. I do NOT hear the rattle through the scope while touching: exhaust pipe, cat, exhaust manifolds, any other exhaust part, oil pan, heads, anything on top of the engine (though the injectors make a little noise, it's definitely not that), any of the heat shields i could see..
Not sure what else to touch/test. I know noises are very hard to diagnose over the internet, but it's worth a shot!
Thanks!
Mostly stock (just has axle back Borla Stinger and air intake).
I've got a rattle I can't find. It happens only after fully warm (30 minute drive) -- and then, it does it at Low RPMS as the RPMs are dropping down off a minor rev. I can make it happen repeatedly by putting it in park or neutral and lightly revving. (it does happen while in gear too).
It's coming from the area i've pointed to in the pictures (NOT my car, again, stock exhaust up there on mine). Above the oil pan, between the oil pan and the exhaust coming down. Its louder on the passenger side, near the middle. Sounds like it's coming from the gap right there.
I've put my mechanics stethoscope on just about everything i could see/reach while under it on ramps. I do NOT hear the rattle through the scope while touching: exhaust pipe, cat, exhaust manifolds, any other exhaust part, oil pan, heads, anything on top of the engine (though the injectors make a little noise, it's definitely not that), any of the heat shields i could see..
Not sure what else to touch/test. I know noises are very hard to diagnose over the internet, but it's worth a shot!
Thanks!
Last edited by ninety6; 02-20-2018 at 09:59 PM.
03-23-2018, 10:54 AM
#5
I got this in to my preferred shop -- and he heard the sound right away. Something in the torque tube bearing area right behind the engine. He agrees is not exhaust or engine sound.. He'll be tearing into it next week, ugh.
bonus (I guess), i'm going to have him replace my worn out shocks and front wheel hub assemblies while it's all apart. so that will save me some effort.
bonus (I guess), i'm going to have him replace my worn out shocks and front wheel hub assemblies while it's all apart. so that will save me some effort.
Last edited by ninety6; 03-23-2018 at 11:02 AM.
04-05-2018, 09:22 PM
#6
Closing this up. Rattle was the flexplate. Seemed to be the thin rear-facing layer moving. It's bolted and riveted on to the main part of the flexplate -- and you can tell (barely) there was some movement of that thinner piece against the rivets. New flexplate is in, and noise is done.
not cheap, but fair pricing. $810 for R&R of the whole rear end and torque tube and flexplate (and put in my provided shocks while it was apart) and alignment. $225 to install my provided front shocks and wheel bearings. $281 for the flexplate itself. All OEM parts.
$2200 down the tubes for this one. Bonus, it rides much better and hopefully good for another 100k (fingers crossed)! (rolled into the shop with exactly 100,000 miles on the odometer).
Tires are next!
not cheap, but fair pricing. $810 for R&R of the whole rear end and torque tube and flexplate (and put in my provided shocks while it was apart) and alignment. $225 to install my provided front shocks and wheel bearings. $281 for the flexplate itself. All OEM parts.
$2200 down the tubes for this one. Bonus, it rides much better and hopefully good for another 100k (fingers crossed)! (rolled into the shop with exactly 100,000 miles on the odometer).
Tires are next!