hitmeoff

I have a rattle coming from, I dunno where. I hear the rattle coming from the back, and when I put my hand on the floor board while the rattle happens, I feel it happening in between the back passanger seats, like right in the middle. What is rattling and what can I do about it?

It goes completely away after about a mile or two of driving, and doesnt come back until the car has been off for several (like 8) hours, and then goes back on.

wrencher

iTrader: (2)

Sure the exhaust is not hitting the gas tank heat sheild?

hitmeoff

dunno, to be honest, the headers and exhaust had already been installed on the car when I got it. But thats something I should check out.

But why would the rattle get better as I drive the car? Its the worst when I start up and drive first thing in the morning, but is non-existant 10 minutes into my commute, and only pops up whenever the cars been parked for more than 4-5 hours.

Any more ideas?

natronathon

i dont know much about that, but it could be the rear-end if its coming from the middle of the back. If the fluid is old and or some has leaked out, it may be rattling until it get enough lubrication circulated in the rearend.

Thats just a guess though.

hitmeoff

Thats kinda what I was thinking, something to do with the rear. How can I check the levels of the fluid in the rear and add more if needed?

natronathon

I dont have much experience with rear-end work (you might want to ask one of the more experienced members of this site). i think you just have to empty it and then re-fill it.
How many miles does your car have? How hard has it been driven?

hitmeoff

I got it at 44K...the previous owner had it for 2 years, but only put 2K on the car in that time (hes also the one who put in the headers and exausht, and it was his weekend car, so I guess he drove it hard on the weekends). Its got 46K now.

natronathon

thats not too many miles, for what these cars can handle. It may be a problem with somthin else. If I were you, Id hit the search forum and see what ya can dig up on rear-end maintance

hitmeoff

Well Ive looked at the first 5 pages of threads in the Body&Chassis section of the site. ANd have seen alot of questions about what oil to use and what not...also saw alot of people decribing weird noise problems, but not one talked about HOW TO change the oil, and none of the problems sounded like mine (most were hearing the noises during turns, at high speeds, different gears, etc...not quite like mine).

Imma go on google and see if I can find some maintanence sites or something.

wrencher

iTrader: (2)

Maybe to help diagnois the problem you can describe the noise in more detail;
Does the car need to be moving to make the noise?
Does the noise coincide with vehicle speed or is is a noise with suspension movement?

#41

to add fluid, just jack the rear end up a bit, put it on jack stands. then on the passenger side of the differential youll see a screw looking thing with a square indention in the middle, its for you to use a 3/8 drive ratchet. put the ratchet in there, and loosen it, fluid should not pour out, but you should be able to put a finger in there and feel fluid without having to reach way down into it. if you have to stretch your finger to feel the fluid, then you need to add some. pretty easy to add. and it may take some extra leverage to get that screw outa there... might need to use a piece of pipe or something to help you get some muscle on it.

jimmyblue

iTrader: (11)

I would back it up onto ramps and start wiggling
stuff. I've had exhaust rattles, I've had Panhard
bar rattles (bolts too loose), I still have one I
haven't tracked down (maybe tomorrow). The
exhaust wants to be hung at least a good 3/8" from
anything else so engine torque-over doesn't bring
things into interference.

hitmeoff

Today I noticed the rattle occured while I was at a red light (after the car had been off for about 4 hours). So no, the car need not be moving for the rattle to happen.

Once I get up to speed (40-45+ mph) the rattle is totally gone, its also gone at lower speeds, but when the car has been driven for at least 5-10 mins. I does seems to rattle a bit more when the car is in reverse and backing up, but happens while moving forward too.

Again this is happening in the middle (i can "feel" the rattle when I place my hand on the "floor") of the rear seats.

hitmeoff

Thank #41 and jimmyblue, I might have to go out and buy some stands and go diggin' underneath there.

Hayze

iTrader: (1)

I had the same problem in the same part...

ended up being the exhaust rattling on the car. Just before the part where the exhaust goes up and over the rear axel. Check under your car!!

Heavy Metal

iTrader: (3)

Does your car have Catalytic Converters, there may be a piece loose inside of one of them, usually they will rattle when cold. otherwise check if the exhaust is touching the body

HTH, Aaron

hitmeoff

ok guys, finally jacked up the car today and most of you seem to be right...it DOES seem to be the exauhst. Its th eonly thing underneath there that can physically "hit" the bottom of the car. I grabbed it, rattled it, and manages to somewhat mimick the sound that the car was making before.

So two questions now...

1. how do i fix this (in plain english, im a noob at all this)?
2. If its the exausht, why would it rattle when the car is cold, but not rattle when its been driven for a while?

SouthFL.02.SS

Could be a busted cat, as mentioned earlier.
Does the rattle become pronounced when you rev?
Does it sound like marbles in a can?

Could also be that busted catalytic innards have migrated back to your muffler.
Also, could be your muffler is coming apart inside.

hitmeoff

The rattle doesnt neccessarily become more pronounced when I rev. Seems as if im in neutral and rev, no intense rattling happens (some but not much), when I start to move, as Im shifting I get rattling. BUt I could be driving at high speeds and have NO rattle. I can downshift from 6th to 4th to take off on the freeway, and have no rattle.

It literally sounds as if the exausht is HITTING the bottom of the chassis right underneath the middle of the rear seats. When I wiggled the exausht earlier today it was hittingthe area where I hear and feel the rattles.

I think the exausht is just hitting the chassis as the car shakes and rattles itself while moving. However, I still find it weird that the rattle would stop when the car is warmed up.

SouthFL.02.SS

Sounds like your diagnosis is correct (outside of exhaust banging against underbody).
But, something may be going on internally with your muffler.

I had a busted stock SS muffler (when I had stock exhaust) which would rattle when cold, then quiet down when warm. It was busted either from some guy who backed into me (no external damage notcieable), or by the busted cat that I had which released chunks of catalytic material down the exhaust.

I swapped mufflers and the rattling went away (but also could have been fixed by the placement of the replacement muffler with proper clearance from the underbody).

These things are tricky.