Spin it however you want, but it’s a good thing to know if your fan clutch seizes.
Start up roar
- Thread starter HuyFZJ80
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I see what you did there.......
mudgudgeon
Resident galah
I don't agree. The fan, clutch, pump etc is all designed to work at full load.
Any neglected component is going to lead to failures. None of the above is particularly special, or deficient if maintained adequately.
I disagree. Not 100% of the time…
My whole point for even mentioning a seized fan clutch is to not let it go for very long. That’s all!
Yep Mr t over engineered everything on the 80 but left us with a weak water pump.
so don't let the fan clutch lock up if it does pull over !
so don't let the fan clutch lock up if it does pull over !
mudgudgeon
Resident galah
Might explain a few head gaskets . . .Yep Mr t over engineered everything on the 80 but left us with a weak water pump.
Most typically, when the fan clutch fails, it fails "open" so the fan doesn't lock up. The fan will spin freely and not engage in order to do the actual cooling necessary. So, it is caught because the engine starts to overheat while driving because the fan is not doing its job.
I drove on a "failed" fan clutch for well over two years, but it would only start to heat up on long pull hills at highway speed, or when dragging a trailer.
I have since installed a new blue hub fan clutch that also did little more right out of the box. I then drained the original oil, added back 55 ml of 15K silicone oil, now my fan roars at every startup, and the hottest my engine has seen since is 192°F. If anything it runs on the cold side now, as in the winter, I'm running about 178°F.
Now, if the fan clutch has run so long that the bearing in it wears out, then it can cause a vibration, but so many here are OCD that they never get to that point because the engine is overheating way before that stage.
I currently have over 178K to 229K miles on my current water pump (it MAY have been changed at 145K when the HG was replaced by the PO) and I have done the fan clutch once in that time, and that was about 30K miles ago. Currently at 374K miles.
Ok, I’ve been researching to ease my mind about the results of continued use of a seized fan clutch on our 1FZ engines. In this thread: Early 1FZ Fan Clutch (Black/Blue Hub) - https://forum.ih8mud.com/threads/early-1fz-fan-clutch-black-blue-hub.366322/page-3. Starting on page 3, post# 41, my clutch has seized. Kevin’s post# 44 mentions possible ex$pensive results if not replaced. He doesn’t specify water pump, but I was relying on my 70 yr old memory 
. This an excellent thread to reference or add to your “watched threads” list.
. This an excellent thread to reference or add to your “watched threads” list.
He clearly talks about the fan coming apart which would cause damage to the radiator and fan shroud.Ok, I’ve been researching to ease my mind about the results of continued use of a seized fan clutch on our 1FZ engines. In this thread: Early 1FZ Fan Clutch (Black/Blue Hub) - https://forum.ih8mud.com/threads/early-1fz-fan-clutch-black-blue-hub.366322/page-3. Starting on page 3, post# 41, my clutch has seized. Kevin’s post# 44 mentions possible ex$pensive results if not replaced. He doesn’t specify water pump, but I was relying on my 70 yr old memory
I do agree that if the hub is not disengaging or engaging correctly it should be replaced/fixed
It would also be my opinion that if the hub is designed to lockup that it’s also designed to run like that for extended periods of time.
On any case I think the OP got his answer the truck should roar on startup.
but is it supposed to roar, or ROOOar, or rooooAAAARRRR, or ROOOOOOUUUURRRRR??
Yes.but is it supposed to roar, or ROOOar, or rooooAAAARRRR, or ROOOOOOUUUURRRRR??
mudgudgeon
Resident galah
Ok, I’ve been researching to ease my mind about the results of continued use of a seized fan clutch on our 1FZ engines. In this thread: Early 1FZ Fan Clutch (Black/Blue Hub) - https://forum.ih8mud.com/threads/early-1fz-fan-clutch-black-blue-hub.366322/page-3. Starting on page 3, post# 41, my clutch has seized. Kevin’s post# 44 mentions possible ex$pensive results if not replaced. He doesn’t specify water pump, but I was relying on my 70 yr old memory
I think you're worrying about it too much.
The pulley dtive ratio means the fan spins faster than the crank (assuming the clutch hub fully engages, with minimal slip).
I would trust Toyota has designed it to run fully locked at full engine RPM as a minimum design requirement. And then, they will have designed in a safety factor so it doesn't fly apart 50rpm above redline.
Evidence of this, is the high number of guys who have loaded them with heavier oil so there's even more definite engagement.
Then, there's guys who have installed smaller overdrive pulleys on the water pump to intentionally spin the fan faster..
Simple answer, if you're worried about it, replace your clutch hub and water pump as preventative maintenance at an interval that makes you happy
And to make this thread continue into oblivion one might as well replace the fan at the same time as the fans in these rigs are getting OLD, like most of us
