# Louder than normal fan noise



## Anyox (Apr 6, 2005)

Yesterday, while going down the turnpike, my '97 Pathfinder (144k miles) was running normally with normal temperature on the guage, but when we slowed down due to traffic, it sounded like the fan was running much faster than it should have been. It sounds as though the engine is racing (similar to the sound at 3500+ rpm) when only at ~1500 rpm. The noise is most noticible in gears 1-4 and is more subtle/not noticible when in 5th and going highway speeds. There is plenty of coolant in the vehicle, no noticible leaks, the fan looks to be in good shape, no worn belts nor anything obviously wrong when looking under the hood. The racing noise is smooth, but just simply loud....no obvious harmonic to it....just sounds like the car is at a much higher rpm than it actually is. Are there any ideas of what could be causing this very loud noise? Is it safe to drive or will this lead to catastrophic failure of something? 

I'm not sure if this is related, but recently the car will also rev (+400-600 rpm) occassionally when warming up and at idle (800 rpm) without any change in gas. After the car has been running for ~5 min, this goes away. 

Thanks for the help!


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## smj999smj (Jan 1, 2006)

Sounds like you have a bad fan clutch. I would start by replacing this first, and then address the idle surge issue if still present.


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## Anyox (Apr 6, 2005)

Thanks for the quick reply! Is there any way to test if the fan clutch has gone bad, or is what I described a pretty sure symptom that this is the problem?


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## smj999smj (Jan 1, 2006)

Nissan's testing procedure is to remove the clutch fan and "check fan coupling for rough operation, silicon oil leakage or bent bimetal." Your symptoms are consistant with a bad fan clutch in that it sounds like it is not freewheeling, which will cause the loud fan noise.


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## Anyox (Apr 6, 2005)

awesome...thanks for the help. It sounds like this is something that I need to get fixed, but that since I'm away from my tools this weekend on a trip, it can wait until I get home and I'll take care of it this week. Is that reasonable, or should I get this fixed before I drive 7 hours tomorrow? From other websites, it seems that the worst thing will be the noise and lower fuel economy.


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## smj999smj (Jan 1, 2006)

As long as it's not wobbling or shows a lot of play in the fan, you should be fine.
Make sure you loosen the 10mm nuts before you loosen the alternator belt.


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## Anyox (Apr 6, 2005)

replaced now and works like a champ! Thanks for the help.


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