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What's this hideous noise?


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Hey guys i'm new to the forums and also a new s30 owner. I'm 19 and this is really the first car I've ever owned. I own a 1975 280z with a recently rebuilt/newly built engine, but my question today is WHAT IN GODS NAME IS THIS NOISE?!?! Below is a link to a video I took of the car with this horrendous sound. I also noticed I could feel what ever was making the noise on the gear lever.

 

 

https://www.youtube.com/watch?v=5OH0hKrfz6I

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Sounds like your flex-plate is broken or torque converter is bad.

Thanks for your input, I plan on talking to Clark Crawford at Z Car's by Clark Crawford in northern Nashville on monday to see what he has to say about it too. How much does a new torque converter or flew plate usually run?

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torque converter and flex plate is on an auto car, manual has the flywheel and clutch. Get close to the car and pinpoint where the noise is from then, could be related to flywheel and clutch, could be your engine getting ready to throw a rod. Regardless you shouldn't drive it, at first I woulda guessed torque converter but you said it was manual.

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I'll take a stab at it. On one of my 240Zs an exhaust header came loose and blew out the header gasket on one cylinder. It made a mechanical sound very similar to this.

Edited by Miles
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torque converter and flex plate is on an auto car, manual has the flywheel and clutch. Get close to the car and pinpoint where the noise is from then, could be related to flywheel and clutch, could be your engine getting ready to throw a rod. Regardless you shouldn't drive it, at first I woulda guessed torque converter but you said it was manual.

 

It sounds like its coming from the front of the car. 

I'll take a stab at it. On one of my 240Zs an exhaust header came loose and blew out the header gasket on one cylinder. It made a mechanical sound very similar to this.

Crap, is that an easy fix?

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Make a 1 to 2 minute video of the engine compartment with the engine running:  one view from the driver's side of the engine and one from the passenger's side of the engine.  Have someone raise and lower the engine speed a few times in each view. Same for a front view.

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Well we figured out what causing that horrendous noise, the crank pulley came completely undone. The only thing that was holding it in place were the belts.  :shock: But on another note, I've noticed after the car has been running for a good while (driven around for an hour or two) it starts making this noise as well. Could it be that the engine isn't getting enough airflow? 

 

https://www.youtube.com/watch?v=kVSRaXH5pHE

Edited by aquosman99
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That second video sounds like a bad misfire.  Check the ignition components (plugs/wires/cap).  I would also check the temperature switch.  The early 280s ran a dual-pickup coil in the distributor (one for when the engine is cold and one for when it warms up). When the engine gets warm enough to trip the temperature switch, it trips a relay that changes the ignition timing in the distributor.  If this is not working properly, then it could be using the "cold start" timing which will cause the engine to run rich and misfire at low rpms.

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Sounds kind of like a cracked exhaust pipe/header gasket like miles said for the second video, although if it only occurs after an hour or two that kind of makes me wonder. 

 

Noise is really hard to find. You kind of have to give us a bit more input, especially when you are capturing the noise on a phone with a tiny microphone. 

 

Little inputs like, louder at certain road speed, at certain revs, location front or back, will help us out a bit. 

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Sounds kind of like a cracked exhaust pipe/header gasket like miles said for the second video, although if it only occurs after an hour or two that kind of makes me wonder. 

 

Noise is really hard to find. You kind of have to give us a bit more input, especially when you are capturing the noise on a phone with a tiny microphone. 

 

Little inputs like, louder at certain road speed, at certain revs, location front or back, will help us out a bit. 

I think its a misfire like Pillar said. But it only happens at low rpm after running for an hour then starting up again. An example would be say I went to Downtown Nashville and stopped to get gas after driving around for an hour with mixed road speeds and rpms, turned the car off, get gas, turn it back on and what happens in the second video starts up again. But once I get going again (bringing it from 950-5500) it goes away...

 

But some info on the car exhaust wise: I had a custom built magnaflow exhaust built for it by a local shop. All the exhaust piping is stainless.

Edited by aquosman99
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Doesn't really matter what exhaust you have if the header gasket is blown, but sounds unlikely.

 

This sounds more like it being a vapor issue. Next time it happens, try cooling the fuel rail by fanning it or applying a cold cloth (I hesitate to say water as the injector plugs are right there and the exhaust runs right under it) and see if that helps. They have a little fuel rail cooler that they sold on 280zx cars that may help the issue.

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