earossi

I ran my car through an autocross school this last weekend. Though the car's engine ran fine during the entire day, I had my first ever experience with the engine running really hot after making a run and then sitting with the car idling.

Ambient temps were cool....about 60-65 degrees. Engine temp on my car never gets above the 7 o'clock position on the temp gauge......even when it sits and idles for 10 minutes. But, this day things were different. I saw temp readings go to about the 10 o'clock position just short of entering the red area of the gauge. So, I am not sure what was happening.

I would sit in line for about 10 minutes, engine idling, waiting for my turn to make a run on the course. When my turn came up, I would make a run which puts a full load on the engine at high revs. But, the runs would only last about 1 to 2 minutes, max. Then back into line for a 10 minute wait.

AFter about the third run, I noticed the temp begin to creep up. I finally got to where I would shut the engine off and then restart it to move up in line.

Immediately following my run, temps would be close to normal, but would then begin to creep up again.

This last week, since the car is my daily driver, I've noticed that temps are back to normal, never rising above the 7 o'clock position during my usual drive to work.

I have noticed that the electric fan on the engine will cycle on and off quickly.....staying on for only about 20 seconds.

Any ideas on what my issue could be and what to do about it?

Dr. No

There's a thermostat that activates a secondary oil cooling fan when the engine temperature gets above a certain level. Sounds like you need a new one. I had a similar thing happen to me at an autocross.

mcipseric

if the thermostat is bad, the fan will run on high the entire time. i do not think that is your issue. the issue is that the fan's high speed does not kick on until the engine gets hotter that most of us are comfortable with.
A lot of us have installed an oil fan by-pass switch which will help you in this exact situation.
http://p-car.com/diy/fanswitch/

Have fun!

AOW162435

I would think that the oil cooler fan resistor is bad and needs replacing. Very, very common. It's located within the dark confines of the right front fender.


Andreas

Dr. No

If that's the case, it may be the switch that is supposed to kick the fan into high. The temporary fix was to unplug a module located behind my headlight. My mechanic replaced the part and the car is fine.

Dr. No

I think we have a winner.

IXLR8

7 o'clock? Thats at the double lines at the bottom of the scale.

My normal operating temperature is at the first line at the 8:30 position. Most are.

earossi

Alex,

I could be a little off on the clock face description of where my oil temp usually stabilizes. I'm not in the car, but I think that the needle usually hovers around the lower mark which I thought was at the 7 o'clock position. The next line up on my 98 993 is at the 9 o'clock position and then there is one at the 10 o'clock position just at the lower end of the "red zone" area of the gauge.

earossi

I'll admit that I am a "newbie" to the 993, so help me with my confusion. Are there not TWO oil coolers for the engine? The first is mounted on the engine and its operation is controlled by a mechanical thermostat, right? Then the second cooler is the one that is referred to as an "auxilliary" cooler which is mounted in the cavity behind the passenger side front bumper, right? I'm not sure what controlls flow of oil to the aux cooler, but there is a thermal switch located at the cooler that monitors oil temp coming to the aux and then triggers a fan mounted on the aux cooler when temps get too high, right? From the responses to my first posting on this topic, it sounds as though the aux fan can be operated at two speeds, controlled by switching a resister into or out of the circuit to the fan, right? The choice of low or high speed fan circuit is controlled by the relay mentioned by some of you, is that right? Or is it controlled by the ECU mentioned in your replies?

If that is the case, I assume that the ECU gets its input from the thermo switch?

I'm just trying to get all the pieces organized in my mind so that I can attack the checkout of components in a logical way.

Thanks again for all you input and patience.

e9stibi

I get to "9:15" during track events in the heat of Texas. This is hot ...

vjd3

Pull the connector in the headlight bucket and see how it goes (fan will run on high constantly but there is no harm in doing that).

My experience is even in cool ambient temperatures, once the oil temps get hot (9 o'clock), whether from hard driving or just idling stuck in traffic, they tend to stay high, even if you can cool it a little bit driving, it tends to rise again.

Running with the fan on high they won't get hot at all, although you will notice it cycling from slightly above that first thin line and dropping below it (this is due to the oil cooler thermostat opening and closing).

Less heat is good, so I run mine most of the year that way ... big difference.

earossi

If I understand what you say, I sould pull the headlight out and there will be a connector plug behind the light, right? Unplugging this light will result in the aux cooler fan running 100% of the time? What other functions does that plug control? Thanks for the info.

vjd3

You will see the top of the oil cooler when you remove the light; the connector has a metal tab you will depress then you can remove it. It only controls the cooler fan ...

Quadcammer

If your oil temperature hovers around the lower mark even after driving for a while, you have some other issues or your gauge is wrong.

Stealth 993

For an Auto-X it's normal to see higher temps. You flog the car & low speeds, then sit, repeat. There is not airflow over the engine, or cooler. All the hot air stays around the engine bay. Your rear tires also get really hot, & cause understeer. I see it here with all the 993's, but usually it's around the 9 position.

What you can do, is after a run, let it sit for 30 sec, then shut it off, then turn the key to the 1 position, this will turn on the engine bay fan, & blow the hot air under the car. It will help cool the car down.

When I'm done running, I take the car out on the streets & do a little cool down drive about 1/2mi @ 30mph very light throttle. The car cools off fast, then I park it.