Noise from exhaust

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Jim
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Noise from exhaust

Post by Jim »

The other issue I have had recently is a noise that I can only describe as a bong when the engine is idling and a tinny, rattling noise when the car is rev'd between approx. 2000 and 3000 revs. You can hear the bonging noise when you are away from the car quite clearly and is most prominent when you are under the car near the exhaust at the front.

Does anyone know what this could be?
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Re: Noise from exhaust

Post by Mc Tool »

I had a bong in my car too , the police are real good at finding them 😁.
I bought a ford escort that had a rattle from the exhaust ....turned out to be half a valve seat.
I guess the thing to do would be to make sure all the fasteners are tight and that the exhaust is not touching anywhere. Pushing something like a bit of wood against the exhaust ( as a dampener ) at various spots can help to locate the noise.
I have a car that the exhaust buzzes and rattles as it heats up but thats small stones in the heat shield , there could be a stone sitting on/in a bracket somewhere. Does the noise change as the car warms up ? Can you simulate it by tapping on the exhaust while car is not running ? And are you sure its the exhaust .....dont get tunnel vision coz it might not be the exhaust ........they are the usual culpret but you never know 😊
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Re: Noise from exhaust

Post by Jim »

Thanks for your reply Mc Tool. I've had another listen and a feel whilst its running and it seems to becoming from the starter motor. Would make sense as I have had trouble with the starter motor recently where the car will make a conking noise but not start when turning the key. Should the starter motor be going though whilst the engine is running?
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Re: Noise from exhaust

Post by Jim »

Took the starter motor off this morning and cleaned all the connectors. Didn't dismantle the starter motor but the teeth appeared ok. Refitted and the car fired up pretty quick but the rattling noise is still there. The bong noise has gone though. Almost sounds like something small rattling and ticking about in the bell housing.
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Re: Noise from exhaust

Post by STEVEW »

Hi Jim,
You wrote,
Almost sounds like something small rattling and ticking about in the bell housing.
Many years ago, I had a similar problem with a Ford F 250 (1970s vintage), which was caused by the clutch friction plate.
The " steel fingers" connecting the centre torsion spring holder to the friction discs had broken causing a rattling sound and in this case, no drive!
It's possible yours have started break.

You also wrote,
I have had trouble with the starter motor recently where the car will make a conking noise but not start when turning the key. Should the starter motor be going though whilst the engine is running?
This could also be the cause of your noise.
The starter "dog" should be free enough to spin into the starter ring when you turn the key and also be free enough to return to its "parked position" when the engine is running. Over time they can attract gunge and goo which makes them sticky. In your case the rattling could be caused by the starter teeth tapping the starter ring whilst the engine is running.

As removing the starter is obviously easier than removing the gearbox that's where I would start.
All the best.
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Re: Noise from exhaust

Post by Jasonmarie »

I wonder if the exhaust gasket is sealed ?
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Re: Noise from exhaust

Post by D366Y »

I've had a similar problem in the past and it was as Hamish has suggested - the exhaust was hitting something on the underside of the car, and exactly like he has suggested, if you pry the exhaust away at various points with a piece of wood I found where it was touching and moved it.

However, quite an odd thing to just start doing on it's own - Mine was just after I'd installed a new exhaust

The starter issues sound more like the culprit to me - have you tried the trusted method of twatting it with a hammer repeatedly until the car starts? my starter started doing exactly as you described a few years ago, twatted it repeatedly and the issue mysteriously vanished and has yet to rear it's head again!

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Re: Noise from exhaust

Post by Major_Tom »

Haydn Gnarlerboy on here (a few people will remember him) had an issue similar to what you describe here and it turned out to be exhaust baffles resonating in the silencers. That sounded like a hollow, metallic rattling at certain engine speeds.

Blowing exhaust gaskets sound more like flapping, popping, bursts of sound, progressively more loud and severe at higher revs.

No idea what the bonging could be though. Can you record it?
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Re: Noise from exhaust

Post by Andrew 2.8i »

D366Y wrote: Fri Jun 03, 2022 9:30 pm Mine was just after I'd installed a new exhaust
I can confirm that your exhaust makes a lot of noise ! :D :D :D

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Re: Noise from exhaust

Post by Jim »

Thanks for the reply guys.

Had my MOT and the technician listened to it whilst it was in the air and it is definitely coming from the bellhousing. He pressed the clutch and it disappeared so he reckons it's the clutch release potentially not coming away enough when released so it's tapping on the clutch.

I listened to the noise whilst pressing the clutch while driving after the MOT but could still hear it so not 100% sure now. Will try adjusting the clutch to see if that makes a difference.
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Re: Noise from exhaust

Post by Mr B »

Jim wrote: Sat Jun 04, 2022 7:42 pm Thanks for the reply guys.

Had my MOT and the technician listened to it whilst it was in the air and it is definitely coming from the bellhousing. He pressed the clutch and it disappeared so he reckons it's the clutch release potentially not coming away enough when released so it's tapping on the clutch.

I listened to the noise whilst pressing the clutch while driving after the MOT but could still hear it so not 100% sure now. Will try adjusting the clutch to see if that makes a difference.
Could also be the clutch fork arm rattling around a bit, often found this to happen when the clutch cable has too much slack in it, do all the gears select easy and smooth?

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Re: Noise from exhaust

Post by D366Y »

Andrew 2.8i wrote: Sat Jun 04, 2022 6:44 am
D366Y wrote: Fri Jun 03, 2022 9:30 pm Mine was just after I'd installed a new exhaust
I can confirm that your exhaust makes a lot of noise ! :D :D :D

Andrew.
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