Whooshing Noise When Revving?

[meestapeta]

Hi, I have a '78 280Z with the stock L28 engine. The only modification to it is a K&N filter and large diameter intake tube. Anyway, my problem is, a while ago I started hearing a whooshing noise when I revved the car. It doesn't matter if it is in gear or not, and it gets louder the more revs I give it. It comes from the front of the car, near the fan. I have read that the water pumps on Zs can be weak, and everything else seemed to be in order up there, so I tried replacing that, along with the fan belt for good measure. I put it all together and drove it today and went a few miles running fine, but then the noise came back. The car runs at temp with fine oil pressure, and power doesn't seem to be affected. But the noise can't be good. Does anyone know how I can fix it?

[Brett240]

you said your car has a k & n filter and a large diameter intake. with this kind of setup on acceleration you will be able to hear the intake roar or whoosh as it sucks. are you sure its not this?

[Royce]

How about putting the old intake back on and seeing if it goes away?

Could it be the cooling fan!? If you have a stock fan and the fan clutch is stuck then the fan will be engaged all the time and will make noise as you rev higher. It should really only be fully engaged at idle when the engine is passing normal operating temperature. Testing it is somewhat of an art form but if it is really hard to turn by hand when the engine is off it may be a problem. Try turning it before you start the car in the morning than again later after driving around. Usually, they stop engaging all together but if left they can eventually lock up.

Maybe someone added a Turbo when you were at work? One can dream can't he!

[meestapeta]

I know it's not the K&N, I've had that on for about 6 months, and it did change the engine noise, but this new noise is louder and different from that. I did read about fan clutch problems, as far as I know my fan runs all of the time, hot or cold, high or low revs, as long as the engine is on.

Ok I just checked the fan and it is difficult to turn with the car off, but it does move. Also, while the fan was removed to replace the water pump I messed with it and it seemed to loosen up a little, because I know it was turning freely when I first reassembled the car. Perhaps driving it seized it back up and that's why the noise came back after a few miles. How do you test the fan clutch?

[Brett240]

spin it as hard as you can and it should go around about 180 degrees.

[meestapeta]

Spinning the fan right now will either cause the belt to slip in one direction or turn over the crankshaft and cause the car to move in the other direction. The fan will not rotate at all relative to the water pump housing.

How is the fan clutch supposed to work? Because right now if I rev it to 3000-4000 the fan starts to blow really hard.

PS: I like your 240 setup, Brett. That must be a really fun car.

[Royce]

Unless someone has changed to a direct fan(no fan clutch), your fan clutch is seized! You should not be able to turn over the motor by the fan with a clutch type fan! There are instructions on www.zhome.com for fixing it, however, I wouldn't be surprised if you find it too far gone and need to replace. They are very pricey from Nissan, $100+, but I have seen them for a fraction of that at local autoparts stores.

Hope it helps!

[Brett240]

meestapeta,

you should be able to get a whole fan real cheap from a wrecker. just spin it and check it. and yeah the cars a blast to drive:classic:

nothing quite puts a smile on my face like it!

[Brett240]

oy yeah the fan should start slipping not long after idle speed i think it should go no more than a constant 2000rpm.

i got sick of even that noise and bought a 12 inch thermo fan, they come with wiring instructions and are relativly easy to hook up. you will have almost no fan noise and as a bonus pickup a few HP's.

[JEFF]

Brett240 - is your avistar the Z that you will be selling when you go over seas?

It's really a nice looking car - I'm intrested!

- Jeff

[Brett240]

yeah thats my z, though i was unaware i was going overseas do you want to fill me in?

[Mike]

Originally posted by meestapeta

Anyway, my problem is, a while ago I started hearing a whooshing noise when I revved the car. It doesn't matter if it is in gear or not, and it gets louder the more revs I give it.

Did you check your whoosh-inhibitor? It might need to be replaced.