Lately my truck has been sounding like a jet engine when I accelerate. It does not happen all of the time, but 80% of the time anyways. It really feels like I lose a lot of power when this happens. I replaced the fan clutch last fall. It (obviously) doesn't do this much when it is cool/cold outside. But my understanding is that it should only do this once in a while (when it is hot) and then disengage. I also understand that it should disengage when the motor gets up to 2000+ RPM. Mine does not.<br><br>I also know that there are standard fan clutches as well as heavy duty and severe duty. Most of the parts stores that I have looked at only carry the heavy duty (which is what I put on). On one of the websites that I found, it indicates that the fan pitch determines the clutch that is needed. If you lay the fan on the ground and measure the height of the blade from the ground, if it is over 2.25" then you need the heavy duty or severe. I have not done this yet. But I am guessing it is over 2.25".<br><br>I have listened to the air conditioning compressor and it doesn't seem to make a difference whether it is running or not in conjunction with this noise.<br><br>I guess my questions are: 1. could it be that I received a faulty fan clutch? 2. Is this normal behavior? 3. should I look elsewhere for this problem?<br><br>I have also pondered converting to an electric fan (if that is possible), but everywhere I have read says that electric fans are not sufficient for four-core radiators. Any input on this?