That's what thermostats do.  Up and down how much from where to where?
what's the outside temps been?   when the temp goes up does the fan get load
like a roar,
and then go away when the temp drops?
Also make sure coolant isn't low.

course if she is the original fan clutch, and you got 60k or better the fan
clutch is due for change..

Whitelightning

Greetings,

Is this a new set of symptoms for this truck or just the first time you've
driven the truck?  There is a possibility that depending on the
circumstances this could be perfectly normal behavior.  However, you also
could have low coolant level/air in the system - fill your overflow
container, bleed your cooling system and replace your radiator cap (easy and
cheap).

Cheers - Jonathan

Your water level may be too low.
This can cause that effect because the temperature sensor sees air part of
the time.

old john

Hello, Robin!
You wrote  on Fri, 24 Feb 2006 03:37:42 GMT:

RS> Help, I have a 95 Chevy 3/4 ton small block 350. The engine temp goes
RS> up and down while I'm driving. It acts like the thermostat is opening
RS> and closing, I have never seen one do this. I think the fan clutch is
RS> ok. Any idea's??

RS> Thanks for any input, Robin

With best regards, ajeeperman@comcast.net.  E-mail: ajeeperman@comcast.net