Hi All

 

My N/A 300ZX Z32 JDM Manual has developed a strange noise when engine is running, it sounds like its coming from behind the dash but I have had the speedo binnacle and the clocks out and cant seem to pinpoint what it is or where it is coming from, it is difficult to hear in the engine compartment so I am at a loss.

 

I have done a short video of the noise if anyone recognises it could they please let me know, its really annoying but more importantly is it the prelude to a serious problem

 

Any help would be great, it does not appear to affect the performance but having not had the car long I don't know if its present performance is as it should be

 

Just a bit afraid of using it in case it's a serious issue

 

Many Thanks in anticipation

For some reason video ling did not upload

 

https://vimeo.com/269342630

Can't help but that certainly is a strange noise.

sounds quite tinny could it be a loose heat shield somewere

I might need correction on this but there is nothing behind the clocks to the dash that is mechanical?

It sounds stronger on the drivers side, it couldn't be the ABS servo could it?

Also Marc does the sound change with engine revs or applying the brake peddle.

Just a few ideas. Other than that I think it's a look under the car as said heat shield/exhaust ?

Thanks for the replies, It makes no difference if the brake pedal is depressed, when you increase the revs its still just audible to about 2000 Rpm but then the volume of the engine sound makes it very difficult to know if the engine is drowning it out or if it has disappeared, it sort of sounds metallic to me hence the concern, I will get underneath and see if there is anything loose, I know sound travels in very strange ways but it really does sound if its coming from behind the dash

 

Any further thoughts from anyone gratefully received

Is it not gurgling AIV ?

 

 

Is the AIV down in the front wing, back behind the front wheel?

Is the AIV down in the front wing, back behind the front wheel?

 

Yes, sound can be hard to pinpoint, opening the door and listening in the hinge area next to the dashboard will usually show it out.

 

Be aware the valves are opened and closed by vacuum, by disconnecting the vacuum pipes in the engine bay by the brake master cylinder its stops them gurgling, and then just leave them, no needs to remove.

 

Jeff

 

 

https://www.300zx.co.uk/forums/showthread.php?184669-Gargling-noise&p=1917377&viewfull=1#post1917377

Edited May 13, 20187 yr by JeffTT

Hi Jeff

 

Followed your suggestion and your link in your last post and thought I would remove the electrical connection to the AIV solenoid as a first step, you were absolutely spot on, removed that connector and then started the car and no noise, let it warm up as the noise seemed to increase as the temp went up and still no noise, so I think we can safely say that has solved the issue.

 

I am in two minds as to whether to remove the whole AIV system or not, the car desperately requires a new exhaust system as the present one fitted by Nissan in 1990 has been patched in various places over the years to get it through the MOT i'm guessing, being a SWB from the conversations I have had I am unlikely to be able to obtain a used Stainless one although I presume that would be the ideal time to remove all the unnecessary pipework.

 

Anyway many thanks Jeff for the diagnosis a weight off my mind

Having thought more about it, I think it best to totally remove the AIV system so does anyone know if the BM catalyst downpipes Part Numbers BM70331 & BM70332 will fit my 1990 Z32 NA SWB I have asked the manufacturers and they required the Vin Number and when I supplied it they told be It did not have sufficient digits, mine has 9 and they require 11

 

Many thanks everyone

Hi Jeff

 

Followed your suggestion and your link in your last post and thought I would remove the electrical connection to the AIV solenoid as a first step, you were absolutely spot on, removed that connector and then started the car and no noise, let it warm up as the noise seemed to increase as the temp went up and still no noise, so I think we can safely say that has solved the issue.

 

I am in two minds as to whether to remove the whole AIV system or not, the car desperately requires a new exhaust system as the present one fitted by Nissan in 1990 has been patched in various places over the years to get it through the MOT i'm guessing, being a SWB from the conversations I have had I am unlikely to be able to obtain a used Stainless one although I presume that would be the ideal time to remove all the unnecessary pipework.

 

Anyway many thanks Jeff for the diagnosis a weight off my mind

 

Not really any downsides to losing it. You can keep the stock exhaust and just put plugs in it, you shouldn't need to worry about being a swb because iirc the downpipes are exactly the same. It's cat back the zorst differs.