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VinceDrake · 05-29-2009, 08:32 PM

Hi Kato!

If you can stop the clutch fan with your hand when the radiator is good and toasty, and it doesn't hurt, that clutch is *definatly not working.* With a hot engine, and a hot radiator, engine borderline overheating, you should hear a noise from the clutch, like a jet aircraft taking off, and it should be moving a metric fork-ton of air.

They make very little consideration for noise when designing the rad fans on any vehicle, it just has to move a whole schwack of air.

Usually I keep a couple of Nissan clutch fans in stock, as they are notoriously unreliable. They seem to either not work at all, or engage all the time, making a terrible noise at highway speed.

If a clutch fails to resolve the issue, some super-cheap after market pumps use a *plastic* impeller. Whoever thought of that should be shot. What tends to happen, is the plastic impeller cracks, and then spins on the pulley shaft, so instead of a impeller turning at 3000rpms, you get an impeller turning at maybe 500rpms, or whatever it feels like at that moment. Some of the worst ones will slip when the coolant is hot, making the plastic expand.

Usually the symptoms of cheap, crappy water-pump disease are almost exactly the same like a blown headgasket, but without the white smoke, or cloudy oil.

Nissans of that era, usually used a tin impeller, but if someone at some point in time already changed it, it could have been one of the awful ones.

Hopefully this is of some help...
--Vince

05-29-2009, 08:32 PM	#39
VinceDrake Join Date: Nov 2007 Location: Southern Saskatchewan Posts: 491	Hi Kato! If you can stop the clutch fan with your hand when the radiator is good and toasty, and it doesn't hurt, that clutch is definatly not working. With a hot engine, and a hot radiator, engine borderline overheating, you should hear a noise from the clutch, like a jet aircraft taking off, and it should be moving a metric fork-ton of air. They make very little consideration for noise when designing the rad fans on any vehicle, it just has to move a whole schwack of air. Usually I keep a couple of Nissan clutch fans in stock, as they are notoriously unreliable. They seem to either not work at all, or engage all the time, making a terrible noise at highway speed. If a clutch fails to resolve the issue, some super-cheap after market pumps use a plastic impeller. Whoever thought of that should be shot. What tends to happen, is the plastic impeller cracks, and then spins on the pulley shaft, so instead of a impeller turning at 3000rpms, you get an impeller turning at maybe 500rpms, or whatever it feels like at that moment. Some of the worst ones will slip when the coolant is hot, making the plastic expand. Usually the symptoms of cheap, crappy water-pump disease are almost exactly the same like a blown headgasket, but without the white smoke, or cloudy oil. Nissans of that era, usually used a tin impeller, but if someone at some point in time already changed it, it could have been one of the awful ones. Hopefully this is of some help... --Vince __________________ "Sometimes it is better to say nothing, and let people think you're an idiot, than to open your mouth and prove it."
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