I read a lot of bad reviews online about the Hayden HD, and I think that I had a newer one on my CRD when I bought it, and it about melted my engine down because it failed. But, I'm now not certain that it was the hayden HD :/ Anyhow, a lot of reviews talked about them being bad out of the box, although I haven't heard that on lost. Then again, most people would never know the difference because a failed one pulls enough air at idle to keep them cool in city traffic... I overheated mine 4x4ing up a long steep grade in the hot desert. That's when I said to heck with the mechanical fan on these. Maybe I'm wrong, but beware, I have seen the hub bearing on the mechanical fail at 160k, and it takes out the expensive radiator, lower radiator hose, and may slash the hood, or worse. Check that bearing. Didn't someone successfully find the bearing and swap it
, because that whole assembly is really expensive.
I pulled a long grade at 90 degrees F yesterday with the FFD, and my homemade shroud that covers the entire radiator, plus the HDS thermostat while towing 3,000 lbs, and the temp gauge didn't budge. 49 mph with TC locked and about 1900 rpms. I am impressed with the greater coolant flow
I do think there is a lot more room for error with the E-fan though, as I've had two failures to work already (a shredded serpentine belt from my experiments knocked a wire off the control, and a blown fuse which was also my fault, but the mech fan is more fool proof)
Maybe I'll throw the mech fan back on for a side by side comparison some time. My e-fan kicks in sooner for what that's worth. I have it set to where I can't see the gauge move and it's on, took a lot of fooling around with the setting, and then I got lucky.
-Maybe the superior shroud makes it actually pull as much or more air THROUGH the radiator EDIT: (versus the mech fan). Who knows?