[Shotimes] SLO overheating in winter weather: possible culprits? Hey, it's on topic!

[George Fourchy]

On Thu, 5 Feb 2004 09:58:06 -0500, Koper Jim wrote:

>I am considering back flushing the core only (removing both hoses at the
>core and putting garden hose to core outlet to determine flow-through).
>
>Say it is a bad radiator--wouldn't I still be getting heat through the
>vents? I've got a new rad ready to install, but am not convinced that would
>resolve the problem.
>
>There is no evidence of head gasket damage, something the 3.8s are famous
>for. Don't wanna get to that point either!
>
>ANY suggestions or advice? I'd love to resolve it this weekend! Thank in
>advance.

Hi Jim..

The blue Slorider wagon you drove while you were here has had a long history of this
kind of overheating problem.  It's finally fixed (for the first time since it was
two years old..it had some bad hoses then!).  It took a new water pump and new
radiator to do the job this time.  Now it is solid at 195 degrees at all speeds.

During the time it was leaking, it would sometimes show normal on the temp but have
no heat from the heater.  The temp gauge would sometimes fluctuate wildly from cool
to warm and back, over a period of 15 seconds or so.  The cause of this was simply
the fact that it was half empty.  When filling it after replacing a component,
either the thermostat or radiator, or water pump, you must take extra time to insure
all the air is out.  Unlike a SHO, where you can vent the air out a throttle body
hose, you have to wait for the thermostat to open while it is running, then just put
a little coolant in at a time until the bubbles stop coming up the radiator fill.  

What shape was the coolant in that originally came out?  It's almost impossible for
a core to plug up if the coolant is not full of rust or corrosion from years of
neglect.  It can't hurt to run water through it separately, disconnecting both
heater hoses, but I doubt it is plugged.   Don't use too much pressure....it is an
old core, after all.

Once in a great while, the vanes on a waterpump will wear (from what, I don't know)
to the point where it cannot pump at a sufficient rate.  I've heard of that, but
never seen it.  Usually the bearings or seal fail.  The seal failed on my wagon, and
the bearing failed on the Fiesta, with the other parts on both pumps being OK. 
They're funny!  

I think you just don't have it full.  Even if you let it run for 10 or 15 minutes,
it still could have an air bubble in the intake manifold that will move around under
pump pressure, and when that gets to the heater, you lose heat...and when it gets to
the block, it gets hot.  Keep the overflow bottle filled with coolant, and let it
heat up and cool off (normal ranges of temps) a couple of times, checking the bottle
each time.  Just drive it enough to warm it up fully...don't overwork it enough to
overheat it.  As the coolant heats up it expands, going into the bottle, and when it
cools, it takes it back into the system from the bottle.  If there is air in the
system, the coolant won't go into the bottle from the radiator, because the air
compresses more easily than what pressure it takes to push open the radiator cap. 
Over a few days, this should finish filling the system fully with water.  You have
to check the bottle every time you start up, and when you shut down....otherwise if
it is empty coolant won't go in.

George