I noticed today that my engine was running at a considerably hotter
temperature than it normally does... I had left it running with my daughter
in it while I was checking the sign on a store to see what their hours
were... When I got back in, the A/C was blowing warm air with seemed
somewhat strange since it had been working a couple of minutes ago... I
looked at the temperature gauge and it was right at the edge of the high red
zone... I remembered someone mentioning in a recent post something about
engine temperature as it relates to the speed you are travelling, so I
decided to try driving it to see if it would cool off any... Once I started
driving it did cool off, so I figured that there must be something wrong
with the fan... I paid close attention to the temperature gauge and it went
back down to normal in a couple of minutes... I completed the errands that I
needed to run and once home, I looked at it a little closer... It turns out
that the electric fan wasn't running... A couple of jiggles of the relay and
it started back up... Apparently some oxidation in the connection... Once
the electric fan was back running, the engine went back down to a normal
temperature fairly quickly... So, I have to assume that the electric fan
controls the air flowing through the radiator... What does the mechanical
fan do?

1995 XJ, 4.0, 109K miles

 

"Jeff Strickland" wrote ...
> You need to check your fan clutch, and the waterpump might have a plastic
> inpeller that wears down after a few years of service.
>
> Either of these will cause you to over heat when standing still, or moving
> slowlly -- as in stop n go traffic on the freeway.

It seemed pretty obvious that it was because the relay wasn't getting good
contact and the electric fan wasn't turning on... Are you saying that even
with the electric fan off and the vehicle not moving, the temperature should
still stay in the normal range? My temperature went right up to the edge of
the red zone... Not enough to cause me to turn the heater on to help remove
heat from the engine, but enough that I watched the gauge a little closer...

 

"Snow" wrote ...
> I was once told by the J**P tech. at the dealer, that the elec. aux fan
> should come on and run if the temperature gets to high (about 110 for my
XJ)
> and should help the mechanical fan to maintain a temperature between 95
and
> 110 (in metric), If the mechanical fan clutch is shot then when your
sitting
> in traffic you only have the elec. aux fan really doing any cooling and
Yes
> you will over heat.

This makes me wonder if I should be concerned whether the mechanical fan
clutch is working acceptably... When I look at it, it seems to be spinning
well enough... Assuming that it is working acceptably and the electric fan
is not, how high will the temperature rise? Is is reasonable to assume that
it will rise to the start of the red zone on a hot summer day?