Help with diagnosing noise issue

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kentonius
Posts: 4
Joined: Wed Sep 07, 2022 5:20 pm
Location: UK

Help with diagnosing noise issue

Post by kentonius »

Hi
I have a Euro 1989 635csi
It's a higher miler - 185k
After a recent long run at speed (2 hours+ at high motorway speeds, for the first time in a while I think), I now have a loud groaning noise from the car when setting off or travelling at low speed. It sounds like it's from the front of the car and there is a very faint vibration through the wheel. The noise only appears once the car has been driven for some time at speed. It's is not there when driven when cold or driven only short distances at low speeds so whatever is causing it seems to be related to the car getting to full operational temperature . It seems to be vehicle speed related rather than engine speed related and it disappears completely above 20mph. Setting off, if I trail-brake while accelerating the noise disappears. The noise is there regardless of steering input.

I've check the ps pump belt tension ,checked and changed the ps pump fluid and filter - power steering and brake function seem fine. I've cleaned and checked the brake pads and calipers front and rear as I thought they might be dragging. Was wondering about wheel bearings and if the long run at speed had killed them (they are the originals as far as I can tell on the front) but the noise sounds more like a groan than the rumbling I'd expect from a wheel bearing and it disappears at higher speeds.
Other thoughts from reading posts on here were prop shaft issues?
Any ideas please on what I should look at next?

Thanks
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86_6series
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Re: Help with diagnosing noise issue

Post by 86_6series »

Sounds like front bearings to me.
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plip1953
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Re: Help with diagnosing noise issue

Post by plip1953 »

Interesting that you don't get the noise if trail braking. My initial thought was wheel bearing too and wonder if some brake application gives a form of support to the bearing?

After a decent run, have you felt the centres of the wheels to see if one is hotter than the other? And with each wheel in the air, is there any top to bottom play?
Phil
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kentonius
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Joined: Wed Sep 07, 2022 5:20 pm
Location: UK

Re: Help with diagnosing noise issue

Post by kentonius »

Thanks for the replies
Checked this out and no play in bearings or heat difference
Bought a wifi microphone (basic clip on youtuber collar mic -only £18, plug and play on an android phone and worked really well) and dotted it around the car engine bay and suspension, and the the noise is from the brake disc so I think it is dragging after high speed runs.
Which looking at other threads would suggest either a seizing calliper or a sticking master cylinder.
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RossDinan6
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Re: Help with diagnosing noise issue

Post by RossDinan6 »

Deteriorating rubber line and corrosion on the slides can also hang a caliper. Sounds like a set of stands and a thorough inspection is in your near future.
Ross
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plip1953
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Joined: Mon Aug 13, 2018 4:15 pm
Location: Leeds

Re: Help with diagnosing noise issue

Post by plip1953 »

kentonius wrote: Wed Mar 01, 2023 8:43 am Thanks for the replies
Checked this out and no play in bearings or heat difference
Bought a wifi microphone (basic clip on youtuber collar mic -only £18, plug and play on an android phone and worked really well) and dotted it around the car engine bay and suspension, and the the noise is from the brake disc so I think it is dragging after high speed runs.
Which looking at other threads would suggest either a seizing calliper or a sticking master cylinder.
If its any kind of seizing that would lead to extra heat being generated in the affected disc/caliper area.
Phil
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