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Discussion Starter · #1 ·
Got a 97TJ 4.0 with 90k on OD. Just wondering how to tell when engine fan clutch needs replacing. The TJ runs great at just below 210 on normal driving, but when pulling a long steep highway uphill, the engine temp jumps up to about 218-220. When road flattens out the temp returns to normal. Thinking the engine fan clutch might be slipping when under a hard pull. Any imput out there? Thanks. :wavey:
 

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Fan clutch doesn't engage at highway speeds. The variation in temp is normal, it heats up on a hard pull, then cools off when it's not working as hard.
 

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The fan clutch doesn't work that way. What you'll usually notice when it's time to replace a fan clutch is engine getting hot, noise and or vibration, or roaring if the fan clutch is locked up.
 

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Usually from what I know fan clutches tend to get locked up/always on over time and the fan gets stuck in always on. If your having heat problems i would think it is something else. Ide consider flushing your radiator fluid and putting fresh fluid in.
 

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Yeah, if the clutch is locked up it sounds like you're in a 747 taking off. If its worn out it sounds like marbles in a tin can. I agree, have the radiator flushed and put in a 195 degree thermostat while you're at it.
 

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Discussion Starter · #8 ·
Fan Clutch

Thanks for all the replys. Will do a flush, and see if that does the trick. Happy New Year to everyone.:)
 

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I'd go with a flush and thermostat change. But whatever you do do not use one of those "fail-safe" types, unless of course you like doing a job twice.
 

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If my fan was engaged at hwy speeds I would have to think that something amiss. It not vehicle speed dependent it's engine speed. Would a clutch engaged at 3500 rpm be normal? The fluid inside moves out in and out of the chambers based on engine revolutions and temp.
 

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If my fan was engaged at hwy speeds I would have to think that something amiss. It not vehicle speed dependent it's engine speed. Would a clutch engaged at 3500 rpm be normal? The fluid inside moves out in and out of the chambers based on engine revolutions and temp.
Can you provide some documentation to support your misconceptions? Show me in writing that the fan clutch disengages at some particular engine rpm.
 

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How does one document common knowledge? Do the words thermo-viscous coupler mean anything to you? The fan clutch allows the fan to spin faster or slower depending on conditions such as engine rpm and temp, depending on how heavy duty they are they spin at a faster rate when engaged.I'm not going to end the year arguing stupid shit so believe what you will.
 

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I had my fan go out on me, no noises, just overheated in traffic in manhattan, turned the heat up until got back home, hot night with no top, heat on, on the Lincoln tunnel, no fun...
 

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Have you played in any mud lately? If so make sure you raditor is not clogged with mud. If you have an AC make sure both sets of coils are mud free. You can kind of see thru them.
 

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When it's time to change out you radiator upgrade to an aluminum. It's much more efficient at dissipating the heat. If you run an electric fan, it won't even turn on unless you have been running the engine hard or sitting at idle for a few. It's that good.

If you plan on doing any water fording go with a flex fan instead. It will handle the water. Just make sure it's metal not plastic like some electric types. The engine will stay much cooler even with a fat daddy winch blocking half the grill.
 
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