Is the truck overheating if you can hear the fan clutch?

[jman11788]

If it’s 84° and above with the A/C on I’ll hear the fan clutch kick in a bit after the truck has been driving for at least 10 minutes after cold start up. I replaced the fan and radiator a year ago with OEM. I can definitely tell I get worse mpgs and have a loss of power. Usually happens in traffic.

I don’t have a scan gauge ATM but I have a temp gun reader and it appears on the radiator the temp gets to around 195-200. But I don’t know how accurate that would be as the coolant could be hotter than the rad? Possibly could have air in the system. Is is normal for us to hear the fan clutch on hot days?

 

[IBallEngineer]

If it’s 84° and above with the A/C on I’ll hear the fan clutch kick in a bit after the truck has been driving for at least 10 minutes after cold start up. I replaced the fan and radiator a year ago with OEM. I can definitely tell I get worse mpgs and have a loss of power. Usually happens in traffic.

I don’t have a scan gauge ATM but I have a temp gun reader and it appears on the radiator the temp gets to around 195-200. But I don’t know how accurate that would be as the coolant could be hotter than the rad? Possibly could have air in the system. Is is normal for us to hear the fan clutch on hot days?

The fan clutch "should" engage when the temp rises, but it is not a true indicator of actual temperature. It is possible it is starting to fail if it is engaging at too low of a temperature. What does your dash gauge say? You can also connect a scan tool and read coolant temp if you have access to one. I believe most auto parts stores can check it for you. Obviously with the A/C on and in traffic the temp is likely to go up, but how much is it going up?

 

[jgue467]

... hear the fan clutch kick Is is normal for us to hear the fan clutch on hot days?

By 'hear' do you mean the roar of the fan like it does upon startup (cold or hot)? this ususally quites down after a block or two of driving.

A while back I sprayed some light lube oil onto the spring in front of the fan clutch, it looked like it had surface rust on it. I think that helped it coil up and back more easily so the roar cuts out earlier. Maybe that will help yours too. Luck. :cowboy:

 

[phattyduck]

The top of the radiator will always be hot - that's where the hot coolant enters. What really matters is the outlet temp at the bottom of the radiator where it is sucked back into the engine.

If the fan clutch is always locked on warm days with AC, you might have something to track down. If you hear it some of the time in traffic (moving slow, pulling away from a light, etc.) that's 100% normal. Once you are up to speed, the fan should generally stay quiet, even with the AC on.

The fan clutch locks up when it 'senses' that the air being pulled through the radiator is too hot. It is not directly based on engine temp.

-Charlie

 

[jman11788]

The top of the radiator will always be hot - that's where the hot coolant enters. What really matters is the outlet temp at the bottom of the radiator where it is sucked back into the engine.

If the fan clutch is always locked on warm days with AC, you might have something to track down. If you hear it some of the time in traffic (moving slow, pulling away from a light, etc.) that's 100% normal. Once you are up to speed, the fan should generally stay quiet, even with the AC on.

The fan clutch locks up when it 'senses' that the air being pulled through the radiator is too hot. It is not directly based on engine temp.

-Charlie

Thanks for the response.

The fan gets quieter around 20 and I can’t hear it at all at highway speeds. Just a little strange though cause I don’t remember hearing it last summer.

 

[mtbtim]

The fan clutch has a temperature sensitive coiled spring. When it gets hot enough, the spring elongates and twists opening up passages in the clutch to let the fluid flow. I can't explain this like a mechanical engineer would be able to but the fluid flowing into another chamber allows the clutch to lock up and then turn one for one with the engine. When the fan isn't locked up, it's spinning slower than the rpms of the engine. If your fan is locked up all the time, it's definitely going to rob you of some power and hurt your mpg. If it's not locking up, you will have overheating issues. The fan clutch can basically fail in both ways, staying locked up all the time and not locking when it should.

Here's a video I did of testing and replacing the fan clutch on my 2000.

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