View Full Version : What could be making this noise???

08-20-2005, 12:57 AM
OK, in the last week or so my car has started making this weird rattling noise from under the car. It's totally random and intermittent so I haven't been able to pinpoint it just by listening. It seems to only really make the noise while decelerating, although today a couple times I noticed a chattering sound while accelerating. If I drive slowly and open my door, it sounds like its' coming from the middle to rear of the car. Also it will still make the sound if the clutch is released which is making me think it's soemthing with the rearend or driveshaft. Could it be a u-joint going out? (I thought they clunked when they went bad). I have not actually been under the car to look, but being that I can't get it to make the sound with the car sitting at idle it may be hard to track down if it's not obvious...

08-20-2005, 01:17 AM
Check the exhaust system.

08-20-2005, 06:14 PM
Might be the shield on the catylitic convertor

08-20-2005, 09:14 PM
Yeah, I vote for something within the exhaust.

08-21-2005, 12:23 AM
Don't have a cat on this car anymore :)

I'm not so sure if it's the exhaust though...usually something on the exhaust will only make noise at some certain RPM, this sounds more like something is rattling against something else and it will do it at any RPM except not when the car is sitting still.

Guess I'll just have to get up under there and look around.

08-21-2005, 07:23 PM
Well, I got up under the car today and found nothing out of the ordinary. Nothing loose on the exhaust system, nothing hitting the driveshaft. I put the car in neutral and spun the tires a bit to see if I could reproduce the noise like that but it wouldn't do anything. So I'm pretty well stumped...

I hope there isn't something wrong with the diff.

08-23-2005, 12:04 PM
I'll share with you my "there's a funny noise coming from under the vehicle" story. About 4 years ago my wife and I bought a used '99 Explorer as our family vehicle. Hadn't had it long and started hearing funny grinding/metallic noises on and off and didn't think a lot about it. It got more frequent, and I had several people help me try to locate the source; I'd let them out on a backroad and roll slowly past them and see if they could hear it - nothing. Even took it to a local mechanic and made him keep it for 3 days, and he still couldn't find anything. Well, we made one last long trip out of town with our then-2 month old daughter and it came back, only louder and didn't quit. On the way home on this 90-mile trip the steering wheel started jerking out of my hands and I couldn't hold it on the road. I thought one of the front brakes had seized. I pulled over 2 different times and each time I stopped again it would have gotten WAY worse. In looking at it from the outside I could see nothing wrong. Mind you, this is on the shoulder of a very business interstate, it's 95 degrees outside, and we don't dare sit in the car stalled on the shoulder with the idiots whizzing past at whatever speeds, and we have a very small baby. When the state patrol showed up he told me I had to get it off the shoulder and someplace safe, and I told him I could no longer drive it. He told me I had to, and he followed me at all of 10 mph along the shoulder to the next offramp. At 10 mph, the motor was screaming and would barely keep it rolling. When I got it safely away from the road, I got out and looked at it again, and it was almost funny and horrifying at the same time. My 2 front wheels were turned full out in opposite directions, so I had been plowing the front wheels this whole last leg. I don't know how I was moving at all. Blah, blah, blah, next day at the dealership they told me my right front wheel bearing had disintegrated and that the only thing holding my right front wheel on was the brake caliper, and that by all rights that wheel "should have" parted ways with the truck when that happened. That would have been a nightmare at interstate speeds. Talk about an Explorer "rolling over"! Point is, check your wheel bearings! Good luck!


08-29-2005, 01:31 PM
I will go with the guys on the exhaust, my cat had some noises and it was the exhaust :tg:

08-31-2005, 10:39 AM
Well I'm almost positive it's not the exhaust on my car, partly because I can't reproduce the sound at idle and also partly because I checked the exhaust and nothing is loose or against it.

My car makes all kinds of weird noises that I can't figure out so I guess this will just be added to them :rolleyes: The driver's side front squeaks when I go over bumps which I presume is related to the spring on that side being broken. There's also a clunking sound on that side that I can feel through the steering wheel, which I also attribute to the spring. I originally thought it was the bearings or ball joints but I've checked both of those numerous times and they're fine.

This sound is definitely driveline related but I just have no clue what's causing it.

08-31-2005, 07:57 PM
I had a funny noise once that I couldn't pinpoint and it turned out to be my drivers side front shock. It was new but defective. When I took it off the rod would fall in and out of the cylinder as I tipped it. Something like that would make you think the car would drive real bad but I didn't notice a thing, nor did I when I pushed on each corner of the car before I took it off. It sounded like it was coming from under the car not up front and it was basically random.

greg wys
09-04-2005, 08:22 AM
my cougar made a screwy rattle and squeaked anytime the car bobbled on the road. turned out to be the driver side spring isolator in back. there pretty cheap and flimsy from production.

09-06-2005, 09:21 PM
I did notice the other day that my driver's side rear spring isolator was pretty chewed up, I figure both sides are like that. I have a set of polyurethane isolators but I've just been too lazy to install them.

87 3.8 CAT
09-07-2005, 01:57 AM
I have an intermittent rattle under mine as well. Only does it when driving, will not in neutral, but will when I power torque the wheels. I'm just not brave enough (or stupid enough) to stick my head under the car while my wife stands on the gas and brake :grinno:
Seems like it's coming from the center-to-front of the car. I thought precat guards but not the case. I can't find or correct the problem, but am betting it's the same as yours from the description you gave. I'd love to know what you find.


09-08-2005, 08:08 PM
I still haven't found anything. The other day I got all kinds of racket once as I was letting the engine brake itself in 2nd gear. But only once. Nothing conclusive so far.

09-08-2005, 08:09 PM
It seems to only really make the noise while decelerating, although today a couple times I noticed a chattering sound while accelerating. If I drive slowly and open my door, it sounds like its' coming from the middle to rear of the car.

You were probably right on the U-Joints. However, the only time a U-joint will clunk is when they're REALLY bad (as in those little cylindrical bearings have turned into dust bad). Every time I've had a U-joint start to go bad, it would start to make a chattering/squeaking sound that will get progressively faster (not necessarily louder) between each squeak the faster you go. Also you're only likely to hear it while accelerating however it is possible to hear it while decelerating also (especially with a manual trans).

If you can, try jacking up the rear so the tires are off the ground (and do it the right way - use jack stands), put it in drive and begin to accelerate with your foot on the brake (You don't have to mash the brake pedal down - you want it pressed down just enough to apply a sufficient amount of resistance on the U-joints while they're moving - like they would be if you were driving it down the road) And if you hear the noise - there ya go. U-joints are fairly inexpensive. Just make sure you get the greasable kind to avoid this in the future. Also it's good to replace them in pairs (hey as long as the driveshaft is out, why wouldn't you?).

Try that out. :D

09-08-2005, 08:14 PM
I wanted to do that but I've just been afraid of my car falling off the jackstands or something.

If it is the U-joints though, I think I'll wait and just do that in the spring before I start driving the car again.

09-08-2005, 09:25 PM
If it IS the U-joints I'd recomend purchasing a set that has built in grease fittings.....

09-13-2005, 09:59 PM
Well it must be the U-joints...I'm gettin all kinds of drivetrain vibration now. Dammit. I was hoping it'd hold off for another month or so.

How long does it take to replace both u-joints? I've never done it before so I'm kinda unfamiliar with it. I'd like to go ahead and do it, but I really only have one day a week totally free (sundays) and it would suck to end up with my car out of commission and have to miss class monday, though I guess it's not really a huge deal.

Advance has "Brute Force" U-joints with a lifetime warranty, and the greaseable ones have a 1 year warranty :dunno: I'll just get the greasable ones.