shamrock

I have done a search but come up with nothing though I can imagine these questions have been asked before...


.. If I have my fan running permanently on high , am I going to end up burning out the fan motor ?
.. Should I not let the oil get to the sort of temperatures that were envisaged during the design of this engine ( ie up at 230F ) , helping to burn off any moisture that has contaminated the oil during colder run cycles ?

Have any of you been running with fan-on-hi for a number of years now?

jimbo3

[QUOTE=shamrock;4985867]
.. If I have my fan running permanently on high , am I going to end up burning out the fan motor ?
QUOTE]

Yes.

ppressle

Yes on the moisture.
Fan is also noisy.

Pete

kdurg

In the summer, I pull the plug behind the passenger side light and let the fan run continuously. I have it connected for the rest of the year. Been doing this for 5 years now and haven't had any problems with the fan motor.

Bull

Why not wire up a simple switch so you can leave it to run automatically on cool, normal days, then switch it to high for hot days and track days? Worked well for me on my 993.

dcdude

Is this a symptom of a burnt-out fan resistor?

shamrock

I'm not sure if you're referring to me , I'm asking this theoretically , my fan seems to be working fine , but I haven't run the car during peak Summer yet (not that the Summer has much of a peak over here!) , so I'm wondering if I should run the fan on High from June to August , and what the implications might be if I do..

TMc993

I have been told by numerous technicians, Porsche and otherwise, that not allowing engine oil to get adequately hot will cause premature wear in any engine.

Today's oils are formulated to maintain their viscosity and lubrication abilites in elevated temperatures and the 993 is designed to function within a set range of operating temperatures referred to by Porsche as "normal."

If you are using the proper oil, are driving primarily on the street, and after warm-up, your engine temperature gauge stays in the normal range, why would you want to screw around with the fan?

I understand that some folks who drive their 993s in heavy traffic during the summer set their fans to run all the time, but I still wonder why...If the fan is operating properly, wouldn't it run when it was needed? Mine does...And it keeps my oil temp in the high normal range, even in temps close to 100 degrees.

On the other hand, if your car is running hot under conditions when it should not, then it seems to me that the thing to do is to determine the cause and correct the problem, not just make the fan run all the time.

Am I missing something?

Terry

Ed Burdell

The ballast resistor tends to fail early and often, so as a short cut, one pulls the plug.

Isn't it true, though, that the oil does not circulate in the cooler until a certain temperature is reached, at which time the low speed fan setting kicks in?

For a car with the plug pulled, the oil still heats up until it reaches the threshold, then hits the cooler, but the fan runs on high speed. This drops the temp down faster than it would, usually below the threshold, at which time it ceases to circulate through the cooler. The oil temp thus oscillates around a lower average temp than it would have, but it's still "warm."

In practice, the oil temp in my unplugged car varies from half way to the first tick to just above the first tick. With highly spirited driving, it tends ever closer to the first tick. Am I accelerating the wear in my engine or keeping things nice and cool? Dunno.

Somewhere in thread long ago, someone explained the main reason for the low speed fan setting was to reduce noise and current draw, which sort of implies that higher speed fan operation is not necessarily detrimental to the engine.

Anyone with a definitive answer?

TMc993

Ed, et al:

Just to clarify, I'm not questioning what others are doing with their cars...This is the only dry sump system I've dealt with and I admit to being more than a little ignorant about the vagaries of this type of system.

I do remember however, once tearing down the 4 cylinder engine of a BMW 2002 I once owned. After we removed the pistons, the guy helping me, a certified BMW technician, told me to run my fingernail up the wall of each cylinder...On the two front cylinders, my nail would catch on a wear ridge at the top of the travel range of the top piston rings. There were no such ridges on the rear cylinders.

The technician said that it was because the front two cylinders ran significantly cooler than the rear two (Closer to the radiator and water pump) and being cooler, wore more rapidly.

That lesson stuck with me, probably beyond it's usefulness.

Regards,
Terry

NP993

Check out this thread: https://rennlist.com/forums/993-forum/393504-questions-on-failed-oil-cooler-fan-switch-install.html#post4809936

From me:

In my semi-informed opinion, this is not all that good for your engine, as it makes it run too cold most of the time, and doesn't let it get hot enough for condensation to be cooked off. Installing a fan switch is VERY EASY and I can't see why anyone wouldn't just do this the correct way. The switch is brilliant, and now I have total control over the oil temps on my car.

shamrock

Thanks Noah , Terry , you've perfectly answered my questions ...
Since logging onto rl , I've been hearing stories of folk running their fans on high , and the same questions kept rattling around in my so-called brain .. It didn't make sense to me to run the fan on constant high , but in any of the associated threads I've read , nobody had a bad thing to say about this practice.
Well you have done now ... sorted thanks.

TargaTango

I think you worry to much. As you note things do not get too hot in your neck of the woods. I on the other hand should worry.

vjd3

I don't think running the fan all the time keeps the engine too cool, it just greatly increases the efficiency of the front oil cooler. The thermostat that controls the oil to the front cooler tends to cycle on and off more frequently as the cooler lowers the oil temperature; the fan is not in play when the thermostat is closed, it's just blowing air.

Porsche's philosophy on the front cooler fan seems to be to use it on high to keep the temperatures from going above 246 degrees rather than to make the front oil cooler more efficient.

As I recall, the thermostat opens at about 194 degrees, allowing the oil to flow to the front cooler (you see it happen when the temp gauge gets just above the first mark, it typically drops down about 2/3rds between the bottom and first mark and then slowly rises.

If the temperature gets to 220 or so, the fan comes on at the low speed. If it continues to rise and hits 246, the fan goes to high speed.

I have seen my own oil temperatures hit 250 (second mark) on hot, humid days, stuck in traffic, and they have not come down below 220 after that even driving on the freeway. Until I pulled the connector and had the fan run all the time; even idling in traffic in 90 degrees the car never went above 210 or so.

I can't imagine a scenario where always keeping the oil temperature between 180 and 210 or so is a bad thing, wear on the fan notwithstanding.

Maybe I'm missing something here.

Leander

I don't understand why we think we know better than Porsche themselves. If it's better for the engine to run on high in regular use (as opposed to track, racing, etc.), don't you think Porsche would have made it that way in the first place?