94 SL2 Saturn Overheating problems.

Hi guys,

It is summer, and my car is overheating Just the other day I
noticed that fluid was comming out of the cap. I checked it, and it
seems it is broken. I looked into the resevoir and some broken pieces
and a spring are laying in the bottom. Okay so I know that has to be
replaced today.

But I am concerned that it is not the main source of the problem. For
a while now, my saturn has always started to overheat when driving
stop and go or just idling at a red light or drive thru. However when
I drive at highwayspeeds the temp guage will typically be less than a
quater hot. What does that mean? Again when I speed down to stop and
go, the temperature will then begin to rise. Luckily the fan always
engages and brings the temp down to a bout just little over a quater
on the cold side.

Is it the radiator? If so do I have to replace it? is the
thermostate, coolant sensor? or what? How do I diagnose this?

Thanks,
-Manuel

 

Sounds like your fan may not be coming on as it should when the engine
temperature reaches the trip point. The fan draws air through the radiator
to reduce the temperature of the coolant. The fan primarily functions when
idling or at low speeds since the air is pushed through the radiator at
higher driving speeds (highways, etc.)

Fix the radiator cap first. Then make sure the cooling fan comes on like it
should when the engine gets hot. If not, then you can turn on the AC and
this should engage the fan immediately. If the fan comes on from the AC,
but not otherwise, then it is probably a bad coolant temperature sensor
(note that there are two in the early Saturn engines, one that controlled
the gauge and the other the cooling fan). If the fan does not turn on with
the AC, then it could be a defective fan relay or a bad fan motor or the
wiring.

Lastly, if the fan is running, but it still overheats, then you have other
problems, possibly a clogged radiator a bad water pump, or a leaky head
gasket and will need a pressure test of the system.

Good luck.

Bob

 

It sounds like maybe your car is running properly. The temperature has
to go up before the fan will come on. The question is how hot is it
getting before the fan turns on. My fan turns on at 213° which is
normal. The fan turns off at 170°. The radiator cap may be a seperate
issue.

Look here: http://www.current.net/james1549/saturn/eng_temp.html

 

Thanks for the feedback. I have replaced the cap. I got a stant
radiator cap from Kragen and it looks different than the OEM one. But
I think it works fine. No more leaks (yet) but the temp still raises
at idle.

I looked at those pics, I don't know the exact temp, but the guage
needles in your photo positions look very similar to the guage needle
of my car. So is it okay for the temperature to start rising when the
car is in idle? I can literally see the needle moving if I stare at
it. The reason I ask is because other cars I have driven don't seem
to do that. The needle just stays in the middle, or a little bit on
the cooler side. Is this raising temperature when at idle normal for
saturns? BTW yes the fan does kick on when the temp gets too hot,
very similar to the pictures on the weblink.

Just curious, hypothetically speaking, what would happen to the
temperature guage on the Saturn if the thermostate where either stuck
open or closed?
-Manuel

 

If your fan is coming on at 213° or according to the pic, then you
should be ok. Yes the Saturn temperature gauge is different than most
other cars. The reason being that the temperature gauge range is much
less than most - meaning your will see more movement when the
temperature changes. And that is really a good thing. Most other cars
use a gauge with a much wider range causing it hard to see movement
with little temperature change.

It is normal for the temp to rise at idle because no air is flowing
through the radiator until you begin to drive the car, or the electric
fan comes on. I personally would like to see the fan kick on about 201
to 205° but it is controlled by the PCM.

If your thermostat was to stick closed, you would overheat very
quickly and boil the coolant out. If it were stuck open, generally the
engine won't get up to operating temperature. You will notice that
especially in the winter time when you have poor heat temperature in
the cab.

Some say that a stuck 'open' thermostat will cause an engine to
overheat. For over 30 years in my career working on cars, I have yet
to see that.

Good luck, James