tcarp104

I have a '91 Pathfinder, 5 spd, & recently while going through the first 3 gears the engine sounds like a vaccum cleaner (kinda making a reving/ whooshing sound) once I get to 4th gear it's no longer noticable. It also feels like I don't have full power in those gears. Does anyone have any idea what might be causing this?

 

Animal

Though it shouldn't cause a noticable power loss, the noise could just be the fan. It has a thermal clutch that will disengage once it begins to cool (as happens at higher speeds).

X-Traction

This is definitely the fan clutch. I suspect yours is going bad. When ours went bad, it would make that anguished WHOOOOoooooing noise whenever I shifted, and the engine was noiser than usual all the time, and the mileage dropped off because the engine was being cooled more than it should have been.

The fan clutch is the finned aluminum housing at the center of the plastic fan. I couldn't find any way to get it open to see what was wrong with it. Since it has no electrical connection, I suspect it is engaged by the temperature of the metal spring you can see at one end of the shaft.

I got a used one from a wrecker and changed it myself. Saved a huge amount of money and the replacement has worked fine for about 2 years now. Even better if you can find one with the plastic blades busted, because your blades will be fine and it's easy to change the plastic part.

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'91 Pathfinder SE 5spd (now sold)
'06 Suzuki Grand Vitara JLX-L

Animal

Yep, that's how it works. The "metal spring" is actually a bi-metalic coil. As the heat is transfered to it through the water pump (and I suppose some from the radiator as well) it begins to unwind (or does it wind?). This rotates the shaft attached in the center which engages a clutch inside the aluminum housing.
There are no user servicable parts inside, so when it is bad, replace it.

You could replace it with an electric fan, which would come in handy if you ever do a body lift.

tcarp104

Thanks, what am I looking at to have it replaced ($). What am I risking by continued driving.

 

Animal

New clutch runs $100+. If the clutch is locked (always engaged) the side effects are noise, reduced mileage and maybe noticeable performance loss.

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Life is too short to take it too seriously

tcarp104

I'm semi- mechanically inclined, it sounds like something I should be able to do. Is there anything I should look out for while doing this.

Animal

The radiator. It will remove several layers of skin.

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Life is too short to take it too seriously