Help diagnose under car noise
#1
Burning Brakes
Thread Starter
Help diagnose under car noise
I'm getting this noise right when the car starts. I cannot pinpoint the sound with a screwdriver or hose. The best I can say is that it's coming from the bell housing area.
Now before someone says rod knock, when I put the screw driver on the oil pan at any location I don't hear this sounds amplified or feel it. Same goes for the bell housing, exhaust pipes, or torsion tube. I do hear a faint ticking from the waste gate, but I don't think the sound your hearing is coming from that.
As for exhaust leaks, I can't count that out but I simply can't seem to zone in on the sound, even using a hose and checking all around the area.
The only other thing I'm 80% on is that it also doesn't seem rev dependent. I blip the throttle and as the revs fall I hear the sound being constant. I think, it's hard to be for sure with the exhaust sound.
Also every now and then, while it's running, the sound just stops for a minute or two with a light blip of the throttle. But the light blip can bring it back too.
Anybody have any thoughts?
Now before someone says rod knock, when I put the screw driver on the oil pan at any location I don't hear this sounds amplified or feel it. Same goes for the bell housing, exhaust pipes, or torsion tube. I do hear a faint ticking from the waste gate, but I don't think the sound your hearing is coming from that.
As for exhaust leaks, I can't count that out but I simply can't seem to zone in on the sound, even using a hose and checking all around the area.
The only other thing I'm 80% on is that it also doesn't seem rev dependent. I blip the throttle and as the revs fall I hear the sound being constant. I think, it's hard to be for sure with the exhaust sound.
Also every now and then, while it's running, the sound just stops for a minute or two with a light blip of the throttle. But the light blip can bring it back too.
Anybody have any thoughts?
#2
Rennlist Member
The only thing that sounds out of the ordinary is a little bit of clutch rattle. But that is kind of ordinary anyway. Does the noise go away when you push in the clutch?
#3
Burning Brakes
Thread Starter
No it does not. The thing is the sound just goes away every now and then while it's idling, but it also just comes back. But it always happens when the car is started.
#5
Burning Brakes
Thread Starter
I believe your ticking sound are the injectors.
I have injector sounds as well on top the engine. When my loud ticking noise you hear in my video stops, the injector ticking noise is still present.
My noise is much louder below the car than on top.
I have injector sounds as well on top the engine. When my loud ticking noise you hear in my video stops, the injector ticking noise is still present.
My noise is much louder below the car than on top.
#6
Burning Brakes
Thread Starter
I just went out and listened again. It might be engine speed dependent. And I'm pretty a sure it's coming from the flywheel area. Thing is the sound does not change when the clutch is in or out. It's like there's a piece of metal going round the same speed as the flywheel hitting something. But I just don't know what that would be
#7
I hear two distinct sounds.. one faint; one clear & present.
The faint sound mimics the rubbing/whiney sound in Teddy's video..
approx 400Hz.
The clear & present sound mimics exhaust gases ticking out at approx 20 clicks per second.. think German MG42 machine gun speed.
Which sound concerns you?
Cheers
mikey
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#10
Burning Brakes
Thread Starter
I agree that it sounds like an exhaust leak. However I can't seem to pinpoint a specific location. I use a tube to my ear and it just seems like the sound is coming from the bell housing area - up the sides, on the bottom, and front and back. It doesn't seem to be louder than any other specific area in that general location then any other area.
I'm not sure with the easiest way to check for an exhaust leak in this location.
I'm just trying to make sure it's not something more sinister like metal hitting metal.
I'm not sure with the easiest way to check for an exhaust leak in this location.
I'm just trying to make sure it's not something more sinister like metal hitting metal.
#11
While you are under the car listening, have someone briefly cover the tailpipe for a second or two then release. The exhaust noise should be more pronounced and help you pinpoint the leak.
#13
It's what we did sometimes in the Navy to look for possible steam leaks past gland seals.
#14
Burning Brakes
Good point. I guess it might work for a little while on a cold exhaust, but that's it. Is there something he could spray in the intake or add to the fuel to create some extra smoke without hurting anything?
#15
Burning Brakes
Thread Starter
Thanks for all the thoughts on testing for leaks. But I also need to make sure the sound isn't metal hitting on metal. I don't feel a tapping on any other components. I would think if it was something spinning and hitting something else making that sound I would be able to feel it vibrate through the body of a component.
Does that make sense?
I'm also thinking this because I don't smell any exhaust at all while I'm under there.
Does that make sense?
I'm also thinking this because I don't smell any exhaust at all while I'm under there.
Last edited by Last Lemming; 12-16-2013 at 09:01 PM.