Soooo, on Saturday I decided to revisit my "alleged" groaning ABS pump - as per previous thread.....

I have a spare pump, but before taking the plunge and swapping them out, I performed a few more tests - as the ECU diagnostic didn't reveal any faults.

I swapped the relays - but the noise still persisted; I took the Zed out for many test-runs, Julia patiently sat in the back right seat, listening for where the noise may be coming from. We both concluded that it was probably from the pump - I had removed the plastic cover in the boot, just to be sure the groaning noise could be heard to the fullest.

And then, I hit upon another idea - I removed the relays altogether. Naturally the ABS warning light came on, but still the groaning persisted.

I then disconnected all the wires from the pump - thus (in theory) cutting all power to it - yet still the groan could be heard.

What else could it be - can the pump really still make any noise, if fully disconnected? What else, electrical, in the rear off side would groan?

When stationery, there is no such noise. The groaning can only be heard when driving at low-ish speeds; and it all but disappears when I press the brake - which makes me think it is still something in the brake/ABS system. Could it be the ABS ECU itself?

Answers on a postcard, please....

 

Is the ABS light on Richard?

https://www.zdriver.com/forums/300zx-z32-forums-7/abs-warning-light-humming-noise-25577/

Are you sure it's the abs pump! 

Do you have a bose system as my zed has an amp under the plastics just behind the ABS area. 

Just a thought. 

Strange, my cars groaning/grumbling noise normally comes from the front passenger side....usually at a petrol station!

My old black NA used to grumble when accelerating, I think it was the propshaft bearing? It sound like it was coming from the boot of the car

23 hours ago, Gaz 300 said:

Is the ABS light on Richard?

https://www.zdriver.com/forums/300zx-z32-forums-7/abs-warning-light-humming-noise-25577/

Nope - ABS light is off. It only came on whilst the wires to the pump were disconnected - but went out once everything was reconnected and I'd switched the ignition off, then back on.

22 hours ago, JaiKai said:

Are you sure it's the abs pump! 

Do you have a bose system as my zed has an amp under the plastics just behind the ABS area. 

Just a thought. 

I thought it was - but now I'm not sure. I have a UK-spec car and still make use of the OEM amp - which is in exactly the same area as the ABS pump. I haven't ruled that out yet - but only because the groaning goes away when I press the brake 

12 hours ago, TheRealNips said:

Strange, my cars groaning/grumbling noise normally comes from the front passenger side....usually at a petrol station!

My old black NA used to grumble when accelerating, I think it was the propshaft bearing? It sound like it was coming from the boot of the car

In my case, it's not constant - or dependent on speed/acceleration.

Initially all's quiet, the suddenly, there's a gggrrrRRRROOOOAAAANNNnnnn - then it goes, then it returns. When I switch the ignition back on after a drive, there's occasionally a short ggrrRROANnnn from the ABS pump area - with the car stationery - before the engine fires up.

And it's not constant during motion - sometimes no sound at all, for miles and miles, then it starts. And the second I touch the brake, it goes away!!

Hi Richard, I don’t know what your current situation is in regards to health and if you’ve got a local garage open that you’re happy to go to in the current situation, but when my diff was on its way out from my buckled wheels, I had my suspicions it was the diff but we confirmed it by putting the car onto the mechanics lift and driving it in 1st gear. The mechanic had this listening device with a mic and proper headphones, which massively amplified every little noise when he was under the car. This made it super easy to trace the source of the noise - might be worth a try.


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22 hours ago, naz27 said:

Hi Richard, I don’t know what your current situation is in regards to health and if you’ve got a local garage open that you’re happy to go to in the current situation, but when my diff was on its way out from my buckled wheels, I had my suspicions it was the diff but we confirmed it by putting the car onto the mechanics lift and driving it in 1st gear. The mechanic had this listening device with a mic and proper headphones, which massively amplified every little noise when he was under the car. This made it super easy to trace the source of the noise - might be worth a try.


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Cheers Naz - but it's definitely not the diff. It's 100% from inside the car - and definitely an electrical powered component in the boot. The noise often manifests itself briefly when just turning ignition on.

Cheers Naz - but it's definitely not the diff. It's 100% from inside the car - and definitely an electrical powered component in the boot. The noise often manifests itself briefly when just turning ignition on.

Hi Richard, I must have explained that badly. In my instance it was the diff but I was referring to possibly try and get your mechanic to use this diagnostics listening device over the rear right area of the car, whilst the cars on a lift and driving in first gear, as when the noise does crop up, the mechanic will be able to hear it. The benefit is that this device amplifies the noise in so much detail, compared to the vague noise you hear whilst sitting in the car and driving - it’s similar to a doctors stethoscope. It might give you a better steer as to what the issue is.


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4 hours ago, naz27 said:

Hi Richard, I must have explained that badly. In my instance it was the diff but I was referring to possibly try and get your mechanic to use this diagnostics listening device over the rear right area of the car, whilst the cars on a lift and driving in first gear, as when the noise does crop up, the mechanic will be able to hear it. The benefit is that this device amplifies the noise in so much detail, compared to the vague noise you hear whilst sitting in the car and driving - it’s similar to a doctors stethoscope. It might give you a better steer as to what the issue is.


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I get you!

My local garage is sadly closed at the moment - failing that, I'll get Julia to drive, whilst I crouch in the boot....

On 05/05/2020 at 20:28, RichardS said:

What else, electrical, in the rear off side would groan?

Is the electric aerial working?

47 minutes ago, RichardS said:

I get you!

My local garage is sadly closed at the moment - failing that, I'll get Julia to drive, whilst I crouch in the boot....

Don't forget to strap yourself in with the targa straps....

Don't forget to strap yourself in with the targa straps....

Hahah - the things we do for our cars [emoji23]


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On ‎08‎/‎05‎/‎2020 at 15:37, AndrewG said:

Is the electric aerial working?

Yup - no issues with it.... Although I did wonder if that was the source of the noise; perhaps I'll disconnect the power, just to be sure!

Good call Andrew; thanks!

Since it is when you are moving, I suppose you have ruled out worn/dry suspension bushes/ suspension strut etc as its next to a turret?

8 hours ago, Dave said:

Since it is when you are moving, I suppose you have ruled out worn/dry suspension bushes/ suspension strut etc as its next to a turret?

Yup - as above, I'm certain it's an electrical component. I also get the sound albeit only for a second, upon turning the ignition back on, just after a drive - so it's not exclusive to being in motion!

It's not always continuous; after about 10 minutes driving, it's like a single, long "grooooooaaaaaaaan" and then nothing. It returns intermittently - but disappears immediately if I touch the brake mid-sound!

Yup - as above, I'm certain it's an electrical component. I also get the sound albeit only for a second, upon turning the ignition back on, just after a drive - so it's not exclusive to being in motion!
It's not always continuous; after about 10 minutes driving, it's like a single, long "grooooooaaaaaaaan" and then nothing. It returns intermittently - but disappears immediately if I touch the brake mid-sound!

The only other thing that springs to mind in the rear end is the fuel pump. Not sure exact location on these cars as I’m still familiarising myself but assume it’s more centrally located or nearside rather than the offside. You mention it’s when restarted, so I guess if the pump is getting temperamental, it might add up. Also I guess it could make sense for the pump to make a noise, when you lift off the accelerator and start braking, fuel load drops, starts groaning due to whatever issue it has. Bit of a random thought I know but it is a bit of a random issue! [emoji2375]


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Maybe it is just the abs block, and the valves within it as pressure leaks past worn o rings. Enough of them floating around if it needs changing. I have a low mileage one if you decide it is that part.

Not changed it myself, but plenty like Jeff who could advise.- I assume change a bleed- bound to be in manual.

2 hours ago, Dave said:

Maybe it is just the abs block, and the valves within it as pressure leaks past worn o rings. Enough of them floating around if it needs changing. I have a low mileage one if you decide it is that part.

Not changed it myself, but plenty like Jeff who could advise.- I assume change a bleed- bound to be in manual.

That's what I thought it was last year - and then I got a replacement one, had it fitted, but still the noise persisted.... Granted, the replacement could be goosed as well but my local mechanic and I thought it unlikely. Thanks for the offer Dave; I do have another  - and swapping them out should not be too difficult.

Assuming you and me are both referring to this part.....

 

17 hours ago, naz27 said:

The only other thing that springs to mind in the rear end is the fuel pump. Not sure exact location on these cars as I’m still familiarising myself but assume it’s more centrally located or nearside rather than the offside. You mention it’s when restarted, so I guess if the pump is getting temperamental, it might add up. Also I guess it could make sense for the pump to make a noise, when you lift off the accelerator and start braking, fuel load drops, starts groaning due to whatever issue it has. Bit of a random thought I know but it is a bit of a random issue!


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Cheers Naz - Craig suggested that during our conversation on Sunday.

I'm not 100% sure which side the furl pump is either - but the noise is definitely on the off-side.