Donn144

As I have stated before; I have my newest Z for 2 years and never asked questions about it because I was on Z31.com for nearly 10 years and right about 2 years ago, the site went down. SO, to repeat; it's great to be here!

Since I bought the Z even when I test drove it, I knew the engine sounded too high pitched. Almost as if the fan belt it tuned at a higher pitch. I guess I can make a video and post it on youtube and link it here so you can hear.

I know it is higher than it should be , because I drove my 88 for 16 years and have a good ear for sounds etc. Although the engine is not revving or under load, it SOUNDS like it is. I have had it tuned up and no body at the shop said anything.

Please keep in mind, I only have 40 K on the engine..it is very fresh!

Any in initial ideas?

zxguy1986

Couple of possibilities come to mind. Can you let us hear what you are hearing?

Donn144

I made a video today..but my darn phone ..well it won't play.
I try again..and post the link. Thx

The sound I am almost sure is not the engine. When I rev the car I can hear the engine by itself roar..the sound is sort of "on top or behind" of the engine sound. It is only because we know the sound of the car that we can detect something slightly off. Others do not.

Donn144

MIC00002.mp3I do not think it is evident from this recording right underneath the hood. The recorder did not pick up the subtle sound..or maybe I am so used to it, and you can hear something. It is right at the end when the engine starts falling from its peak that you hear the "whine". Only a Z guy can hear it.

rogerz

might help to know what z you talking about. 31, 32 or 350,370. turbo or n/a. 5 spd or slush box

Donn144

Z31 1987 na 40k Stick

Donn144

I made another recording today. The digital recorders do not pick up this frequency too well. The sound is best heard right when the engine is letting up. A higher pitched whineMIC00007.mp3

Donn144

ZX Guy 1986..What are your ideas?

Gerbil

AFAIK, all z31 turbos have an electric cooling fan located between the radiator and a/c condenser (located in front of the radiator), I think the noise may be from that fan cutting on(that's what it sounds like to me).

If that isn't the problem, then i'm not sure. Any change in idle would show up on the tach.

zxguy1986

Donn144, did you figure it out yet? A person standing in front with the hood up and leaning in should be able to point to the source, no?

Donn144

I'll test it tomorrow..weather is just getting to the point of being tolerable

Donn144

OK, I lifted the hood and accelerated the engine manually. I am convinced the sound is coming from the fan at the front of the engine. Almost as if the fan itself is of a differing size to create the different frequency. It does not necessarily sound like a tight belt.
It is definitely connected with the fan..again, it is a smooth sound a slightly higher pitched subtle whine.

zxguy1986

Well, it 'sounds' like you are zeroing in on it. Wonder if your fan blades are out of alignment. Also whether your fan bearings are shot or damaged. You might just replace all the belts up there to see what happens with the sound - plus that's good maintenance anyway. Noisy water pump is another possibility - or a timing belt tensioner. Lotsa guys skip replacing tensioners when doing the timing belt. When replacing your belts, you can check all that or replace it all just to be safe.

Donn144

I am sure it is simpler rather than complex. It is all very smooth sounding.
Fan blades out of alignment..never heard that before..but it is a sound frequency thing.

Do you mean the fan is somehow warped?

zxguy1986

I am noting that your weird sound is keyed to your RPMs. The fan blades can warp or chip or crack, being plastic. I remember a timing belt change where we found pieces missing from the blades - the shroud had slipped down because it wasn't reinstalled right and it whacked chunks out of the blades and the blades whacked it back. Replaced both with recycled parts.

Sounds to me like the issue is in that region for you. Lots of stuff to whine and whistle up there. Why not switch out your timing belt while you are digging. That will expose just about everything to inspection and give you a whole set of new belts correctly tensioned .

LA KINGS

if you listened to the recording you would have been able to answer that on your own. also, this might sound crazy but we are currently in the Z31 section of the forum so maybe he is like asking a question about a Z31!?

Dont think about it too hard man it might blow your mind.



Couldnt really hear your issue tho in the recording. probably something youd have to catch in person. my deaf uncle heard your fan clutch tho thats for sure. lol