Viscous drive / HD cooling

[diyman]

No, not a big issue.... My fan clutch has just gone south!

It started with a strange click click click coming from the front, at first I thought it could be the
tensioner or A/C compressor but nope. Then I noticed the mechanical fan blades were too slow
and I could ( DON'T do this, it's STUUUUPID, I know.... ) stop them with two fingers...
Engine was fully warmed up, and yes, I know HOW the fan is supposed to work :whip: exp. here.
Luckily electrical fan manages to stabilize temps, but I feel safer with both systems working...

Just ordered two spare ones, only wonder why Chrysler changed the code and cut the price in
half... hope quality is the same :shrug:

So You're warned, if Your rig has HD cooling and climate is warm, viscous fan is another weareable
item.

PS: any clue if I'd better change the WP too?

 

[tjkj2002]

The electric fan is the main cooling fan,the mechanical one is the AUX cooling fan and will only "lock" and pull air at about 230+ degrees.This only applies to the 3.7 KJ and not the CRD's.

 

[diyman]

TJ, 99% (if not 100%) of Jeeps have the HD cooling here....

About the 230 threshold, well, You know the joke about the 'No pets allowed' sign and the cat walking in...
Cats don't know how to read... and our viscous drives probably can't do the math either :happy175:, so they
just kick in...
Also, maybe mine is beginning to work the right way just before...going south, if so, I'm worried because
of the click click click thing.....

I never said electric fan ain't working, but keep in mind that we ALWAYS have A/C on :smokin: and, at least
in my KJ, aux fan has been pushing air at any time since new... ( maintaining constant speed as supposed
to do).
Well, You might be right if You say MY unit was defective from start and it shouldn't have worked that much.
Anyway, no WHOOOOSH except 20/30 seconds after startup (I know it's normal).
I'm also swapping it to avoid possible 'radiator chewing' in case of drive's catastrofic failure...

Also, I've read that common opinion is that if You have an optional fan clutch, You shouldn't remove it and
just rely on E-fan, though it would be perfectly possible as You're correctly stating.

 

[tjkj2002]

Yes the mechanical fan pulls air all the time,unless the temps are high enough it normally never turns faster then 300rpm's,but at 1st start will run at full speed for a little time before the silicone flows better and cuts the rpm's.It's all stated in the FSM that the mechanical fan is just a AUX fan for the trailer tow package to aid in low speed cooling.