Noise from rear - 986 Forum - The Community for Porsche Boxster & Cayman Owners

DWBOX2000 · 04-25-2019, 06:09 AM

I have a strange noise in the back right when I first start driving. It's like a low tone knocking. I think it goes away when the car warms up. I've had the car to a shop twice to look at and they haven't seen anything ($500 later). Said suspension is fine. It feels fine too. Could there be something up in the engine compartment that might bounce around a bit and snug up as it warms up? AOS, Coolant tank, other?
Suggestions?

I took the center console cubby out yesterday and wrapped in insulation tape and reinstalled. One rattle gone. Funny how things only happen at certain RPM's.

Htci · 04-25-2019, 06:35 AM

If this noise happens at low speeds over small bumps search rear trailing arm noise.

Quote:

Originally Posted by DWBOX2000

I have a strange noise in the back right when I first start driving. It's like a low tone knocking. I think it goes away when the car warms up. I've had the car to a shop twice to look at and they haven't seen anything ($500 later). Said suspension is fine. It feels fine too. Could there be something up in the engine compartment that might bounce around a bit and snug up as it warms up? AOS, Coolant tank, other?
Suggestions?

I took the center console cubby out yesterday and wrapped in insulation tape and reinstalled. One rattle gone. Funny how things only happen at certain RPM's.

DWBOX2000 · 04-25-2019, 07:32 AM

Wouldn't the mechanics have a way to test that? Considering they are Porsche Indies, they should have done that. Well I would hope.

How would I check?

78F350 · 04-25-2019, 07:57 AM

Can you have someone outside the car listen for the noise and you drive by slowly? It may help to locate the source. Maybe record a short video to put on Youtube to share so we can hear it?
The trailing arms make a rattling noise over small bumps.
A burr on the inside edge of a wheel will make a click if it hits the parking brake cable.
The metal guard for the brake rotor will make a scraping sound if it is bent and slightly rubs the rotor.
A worn out mount (engine or transmission) will make a thump with a change of torque.
Wheel bearings groan or whine.
Cats meow.
Cows go Moo.

Paul · 04-25-2019, 10:58 AM

CV Joint maybe?

DWBOX2000 · 04-26-2019, 06:05 AM

Thanks guys. I will memorize the list below.

Now the noise. It's strange because it occurs when the car is cold (first get going in the morning). To make sure I wasn't nuts, when I got home last night I turned around and went my morning route. No noise. Maybe there, just not as prevalent. Now my mechanics are Porsche indies (ex dealership guys, owner was head mechanic). From my two previous visits for the noise, wouldn't they be able to check all the stuff below? They said other than a little wear, nothing wrong with the suspension. 1st time in they tightened and lubed sway bar bushings (i believe). Second time they did something else.

I did notice the heat shield on the right side is not fully attached.

Funny, the plastic tray in the console was vibrating at certain RPMS so I pulled it and wrapped in insulation tap and reinstalled two days ago. Vibration gone, Snug as a bug...
Going into my garage last night (next day) my clutch was suddenly squeaking when engaged. Old cars. Guess I'll be lubing that this weekend.

Anyone have any cheap ideas for sound insulation? Not as a fix to my 1st problem but just to help eliminate some of the regular road sound. I'm getting softer as I get older. Use to tear all the weight out, now I am adding by the day.

NewArt · 04-26-2019, 04:30 PM

Quote:

Originally Posted by 78F350

Cats meow.
Cows go Moo.

But, what does the fox say?!!:dance:

DWBOX2000 · 05-03-2019, 12:09 PM

Noise is definitely when the car is cold. I heard when I left the house this morning and 20 minutes later, very faint if anything. Could it be the coolant tank moving a bit when cold and not when warm?

thefunkygibbon · 05-10-2019, 11:11 AM

i've noticed the same on mine. its def like a knocking sort of rattle (1-3 knocks at any given moment) from the rear when going over bumps. i originally thought it was from the front but its def from the back. I purchased the car yesterday and i noticed it for the first time just after filling the tank with fuel. it was fine in the test drive. I thought it was relating to the fuel tank maybe since it was empty when i test drove it and started when full.
speaking to the garage they say it might be struts, trailing arm or bushes. none are apparently dangerous, but more an annoyance and could get worse over time.