[OFB Cafe] Engine overheating

[Chris Olson]

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From: "Peter Hollings" <PeterHollings at Comcast.net>
Sent: Wednesday, July 16, 2008 7:08 AM
To: "An Open Discussion Forum on Just About Everything,Especially for 
Techies." <cafe at ofb.biz>
Subject: Re: [OFB Cafe] Engine overheating

> I think the fan clutch is a better explanation. Also, it is cheaper.

It's a better solution, I don't know about explanation.  And viscous fan 
clutches aren't cheap, but by the time you get done fiddling around wiring a 
power supply to a relay, then from the relay to a fan motor, find a spot in 
the intake manifold to screw in a temp sender for it, figure out a way to 
mount an electric fan and shroud on a big cross flow radiator (I assume this 
is Rick's Durango with the 360 in it), you can just put the new clutch in 
and be money ahead.

You can replace the clutch yourself too.  I don't remember if the Mopar 360 
has a bolted hub or threaded, but I think its threaded.  Leave the belt on 
the pulley, and with an air chisel, bite into the front side of the big nut 
on the clutch hub (the hub is LH thread so you have to turn it the opposite 
direction - clockwise - to screw it off the water pump shaft), and squeeze 
the trigger on the air chisel to break it loose.  The 360 in a Durango is a 
tight fit so you have to take the bolts out of the fan shroud and move the 
shroud to get the fan and clutch assy out.  And be careful that you don't 
nip any radiator cores with the fan blade when pulling it out.  Those 
radiator cores are fragile and its pretty easy to put a hole in one if you 
don't watch what you're doing.

After you get it out, unbolt the fan from the old clutch and inspect the 
fan.  If it has any cracked blades, replace it (a busted fan blade @ 5,000 
rpm will blow the shroud right off the radiator and come thru the hood).  To 
tighten the fan hub, assuming you don't have a fan hub wrench, you can grab 
the nut with a big Channel Lock pliers with the movable jaw to the 
counterclockwise side of the nut.  Then hit the handle of the moveable jaw 
with a rubber mallet a couple times to snug it up.  The clutch hub will self 
tighten under normal operation and won't come loose because it takes quite a 
bit of power to run the fan - if you tried to run that fan with a 5 hp 
Briggs and Stratton lawnmower engine you'd only get it to about 2,600 rpm.
--
Chris