engine temps in Southern Cal?

[pgjkc]

Hi Guys,
I bought my y2K 5sp std just before summer, and we've had a scorcher here. One thing I notice is that the engine does run quite hot compared to other discussions I've read.

For example, under normal running, the temp is somewhat >180, and in traffic, the temp gets >225 (>the 2nd-to-last-tick).

One point, if I've been running on the freeway and then get into traffic, the temp goes up, probably because the forced air cooling disappears.

I'm not a particularly aggressive driver, and usually let the temp get to 180 before I take the car much beyond 3k revs. Taking the car to 4-5k revs for gearchanges also drives the temp up - is this normal beyond the obvious?

Anyone have any ideas to share?

thx!

[MNBoxster]

Hi,

First, lacking a very graduated Temp Gauge, the display is somewhat inaccurate. You have hash marks at 180°, 200°, and 250° so you can only estimate the temp if the needle is between these marks.

Second, the temp will swing depending upon speed, load (the types of things you describe in your post).

Start the car, turn the AC ON and get out, walk to the front and get down on each side to be sure you hear both cooling fans operating (they default to ON with the AC on). Turn AC OFF and allow the car to exceed 185° (the threshold for energizing the cooling fans) and get out and listen again. This will eliminate the temperature sensor as a possible culprit.

Check to see that the coolant level is good. That the system is properly bled (there's a Bleeder Valve located under the escutcheon (Black Disc) under the Coolant Cap, Oil Filler Cap and, on your car, Dipstick). Remove the caps and dipstick and carefully pry up the escutcheon. Under it you'll see a Bleeder Valve. Lift the metal ring, replace the caps and dipstick, and start the car and allow it to fully warm., Then rev the engine to say 2500 several times (this will allow any air in the system to bleed off). Close the Valve (careful it will be hot - take necessary precautions), Shut the car down, and after it cools, replace the escutcheon and caps and check the fluid level, top up as necessary.

Now, you may need to clean out each radiator. These accumulate all sorts of debris from leaves, cigarette butts, insects and even birds. As this debris gets sucked between the radiator vanes, it reduces the cooling area of the radiator(s). It's best to raise the wheel on a side, remove the ducting and back-flush the radiator with a Garden Hose to flush the debris out the same direction it went in. If this has never been done on your car, expect to see an almost unbelievable amount of debris expelled. Hope this helps...

Happy Motoring!... Jim'99

[CJ_Boxster]

I live in socal and did clean my radiators already, I usually run anywhere from 90 celcius to 103 on a hot day. I could be needing a radiator flush and maybe need to use more water than antifreeze maybe 20/80.

[MNBoxster]

Originally Posted by CJ_Boxster

I live in socal and did clean my radiators already, I usually run anywhere from 90 celcius to 103 on a hot day. I could be needing a radiator flush and maybe need to use more water than antifreeze maybe 20/80.

Hi,

How can you say that? These are just estimates because the needle will be in-between the hash marks.

The minimum mix you want with your coolant is 50/50. Any lower, and you're reducing the lubricating and anti-corrosive qualities of the mix which will have consequences down the road. Your Boxster isn't any different than anyone else's, if you're running Hot, you need to identify and eliminate the cause, not try to compensate for it. Besides, there's nothing wrong with 103°C, at this temp, and at pressure, the coolant is still a liquid (below boiling point) and providing maximum cooling...

Happy Motoring!... Jim'99

[Brucelee]

Actually, I find an oil temp guage to be much more informative than the coolant temp.

The Covette C5 and 6 has one and it is not a fake out, ie it reads temps by degree and changes pretty quickly.

Using that I have found that the oil temp will usually run about 10 degrees hotter than the coolant, UNLESS you are flogging it. In that case, the oil can get REALLY hot.

If i were tracking my Porsche in the CA heat, I would be running Red Line oil or M1 15W-50, both of which are more shear resistent than the M1 0W-40 oil.

Also, if I were doing a lot of tracking, I would likely get larger oil coolers.

[MNBoxster]

Originally Posted by Brucelee

Actually, I find an oil temp guage to be much more informative than the coolant temp.

The Covette C5 and 6 has one and it is not a fake out, ie it reads temps by degree and changes pretty quickly.

Using that I have found that the oil temp will usually run about 10 degrees hotter than the coolant, UNLESS you are flogging it. In that case, the oil can get REALLY hot.

If i were tracking my Porsche in the CA heat, I would be running Red Line oil or M1 15W-50, both of which are more shear resistent than the M1 0W-40 oil.

Also, if I were doing a lot of tracking, I would likely get larger oil coolers.

Hi,

Excellent points. Your Oil is actually responsible for carrying away 60% of the heat produced by the engine, while the Coolant removes 35% and Airflow around the motor accounts for the other 5%. And, while the Coolant flows around the engine, it's the Oil which removes the more critical heat from the Journals, Big-Ends, and such where the Coolant does not flow. This surprises most people.

And don't forget the importance the Sparkplugs play in managing heat by carrying heat out of the Combustion Chamber to the Head where it is extracted by both the Coolant and the Oil flowing through it...

Happy Motoring!... Jim'99

[CJ_Boxster]

Interesting, well i can say that cause i wasnt estimating those numbers i gave, I used my AC controls to tell me the coolent temps... So 103 is fine???? weird cause i remember in a previous convos on this forum you were telling me that my car running at 93 celcius was too high. Ill find that convo....Heres the quote from you in the past

"That said, 216°F is a little on the high side (not fatally, but high) for normal conditions. Make sure both your fans are working (turn on AC) and that both radiators are free of debris (a common problem). No two cars are exactly the same, so some variation is normal."

With that said, your beginning to give me one answer and then another in later days.

Originally Posted by MNBoxster

Hi,

How can you say that? These are just estimates because the needle will be in-between the hash marks.

The minimum mix you want with your coolant is 50/50. Any lower, and you're reducing the lubricating and anti-corrosive qualities of the mix which will have consequences down the road. Your Boxster isn't any different than anyone else's, if you're running Hot, you need to identify and eliminate the cause, not try to compensate for it. Besides, there's nothing wrong with 103°C, at this temp, and at pressure, the coolant is still a liquid (below boiling point) and providing maximum cooling...

Happy Motoring!... Jim'99

[CJ_Boxster]

Do the radiator fans in the front of the car turn on when the car reaches a certain temp or do they only turn on when the AC is turned on?

[subgraphic]

My needle stays on the 8 in the 180° mark, no matter how hard I drive...

[CJ_Boxster]

Originally Posted by subgraphic

My needle stays on the 8 in the 180° mark, no matter how hard I drive...

Do you ever hear your radiator fans infront of your car turn on while your AC is off?


I called the Porsche Service and they told me that they are suppose to click on in the 180 range...estimation*** and also if the AC is turned on, They said it im reaching the 190 to 200 range without them turnin on, then he said something is wrong... They also said that the fans have 2 stages... regular and high...I guess they will spin faster if the car continues to get hotter.

[MNBoxster]

Originally Posted by CJ_Boxster

Do the radiator fans in the front of the car turn on when the car reaches a certain temp or do they only turn on when the AC is turned on?

Hi,

The Radiator Cooling Fans have two different speeds and are controlled by the DME. The operation of the Fans, or the selection of the Fan speed, is not temperature dependent alone. The DME uses several other variables to determine the Fans operation.

These include: Ambient Temperature (determined by Intake temperature from the integral Temperature Sensor in the MAF), Driving Speed (from the Wheel Speed Sensors, to judge the airflow through the radiators - another reason why keeping the Radiators clean is important), Engine Speed (to judge the vol./time of the Coolant flow - Coolant Pump flow is rpm dependent), Immobilization time since "Ignition OFF" (to judge heat buildup), AC Refrigerant Pressure (from the AC Pressure Switch, to judge load placed on Engine, affecting Engine Speed, especially at idle).

So, you cannot judge the proper operation of the Fans by the Temperature Gauge alone. In one instance, at one displayed temperature, the Fans may operate, or may operate on either High or Low. In another instance, with the same temperature displayed, the Fans may not operate at all, or may operate at a different speed.

For example, at idle, say at a Stoplight, the Fans may operate on High speed at Coolant Temperature X, while at 65MPH, at that same Coolant Temperature X, the Fans may operate at Low speed, or may not operate at all. There is a Temperature Default in the DME software which will override the other variables given the following conditions:

The Fans will always work on Low speed: When the AC is switched ON, or if the Coolant Temperature exceeds 96.75°C (206.2°F).

The Fans will always work on High speed: If the Coolant Temperature exceeds 102°C (215.6°F), or the AC Pressure Switch is CLOSED (when Refrigerant Pressure exceeds 16 bar or 232 PSI).

The caveat here is that the Fans may indeed work in the Default Mode, but due to a failed or failing Switch or Sensor, may not work optimally under normal driving conditions. This may account for some of the varying operating Coolant Temperatures some owners report having, but there are so many variables involved, that it's impossible to say for sure.

Hope this helps...

Happy Motoring!... Jim'99

[CJ_Boxster]

Originally Posted by MNBoxster

Hi,



The Fans will always work on Low speed: When the AC is switched ON, or if the Coolant Temperature exceeds 96.75°C (206.2°F).



Hope this helps...

Happy Motoring!... Jim'99

THanks, this is the peice of information i was looking for, When i get home Ill let my car idle for awhile until it reaches 96.75 cel and see if they turn on at all. Cause i dont ever recall them turning on at all UNLESS i turn the AC on. Thanks Jim

[MNBoxster]

Originally Posted by CJ_Boxster

THanks, this is the peice of information i was looking for, When i get home Ill let my car idle for awhile until it reaches 96.75 cel and see if they turn on at all. Cause i dont ever recall them turning on at all UNLESS i turn the AC on. Thanks Jim

Hi,

Be sure to read my ammended post, because even though the Fans come ON in the Default Mode, doesn't mean that they are necessarily operating properly outside the Default parameters. The only 2 things which the Default Mode really tells you is that the DME is recognizing the Default parameters, and the Fan Motors work. Hope this helps...

Happy Motoring!... Jim'99

[CJ_Boxster]

Originally Posted by MNBoxster

Hi,

Be sure to read my ammended post, because just because the Fans come ON in the Default Mode, doesn't mean that they are necessarily operating properly outside the Default parameters. The only 2 things which the Default Mode really tells you is that the DME is recognizing the Default parameters, and the Fan Motors work. Hope this helps...

Happy Motoring!... Jim'99

Ok, got it, Im just worried weather not they are turning ON at all when the AC isnt on...cause sometimes i know i get really high temps in slow traffic on hot days but all i hear is the engine fan turn on. but never the radiator fans, I just would like to see if they trigger Low Speed at least when the temps reach over 96-97 celceius at a stand still...

[CJ_Boxster]

Ok Jim,

Heres what i learned...

My radiator fans will not turn on at 96 celcius, They turn on at 103, and stay on until the coolant temp reaches 100. If it matters, the Ambeint outside Temp was at 61 degrees.

Why would the fans turn on so late? i checked them twice, during idle they will turn on only at 103 celcius until temp goes down to 100 celcius. Can the dealer program it to trigger at 96.75?

[MNBoxster]

Originally Posted by CJ_Boxster

Ok Jim,

Heres what i learned...

My radiator fans will not turn on at 96 celcius, They turn on at 103, and stay on until the coolant temp reaches 100. If it matters, the Ambeint outside Temp was at 61 degrees.

Why would the fans turn on so late? i checked them twice, during idle they will turn on only at 103 celcius until temp goes down to 100 celcius. Can the dealer program it to trigger at 96.75?

Hi,

If I had to guess, and this is essentially what I'm doing, I'd say that either your Coolant Temperature Sensor or your Cooling Fan relays are showing their age and not operating at 100%. The Software in the DME didn't suddenly start looking for 103°C instead of 96.75°C. Ambient Temp would have nothing to do with the Default Parameters, though it would with normal operating ones (1 component the DME uses).

We're only talking about 6°C here and that could well be within any innacuracies of the Temp Sender or the Gauge or Climate Display. It's not affecting anything. I doubt the MAPs are affected, nothings going to melt, you're not creating appreciably more emissions or suffering any reduced performance. I think you're just obsessing. But, if it bugs you that much, start by cleaning the radiators, replacing the Fan Relays, and changing the Coolant, and see what effect that has on the readings. Hope this helps...

Happy Motoring!... Jim'99

[David N.]

I actually had a problem with the engine compartment fan not coming on when expected, and indeed it seemed to be a worn out relay, so such things are certainly possible (this was on a 2000S with 48k miles).

But concerning the radiator fans...is there any mode in the AC diag that accurately tells you radiator fan speed? I tried the line item 'fan speed' but hasn't budged from 0 even tho I know the radiator fans are on.

Also, for what it's worth, my car in Los Angeles goes from 90-92 coolant temp at 80mph on the freeway to 100-103 idling in traffic. I need to clean the radiators still, but I'll bet it only buys you a few degrees at the most. Still, I'm getting over the fact that 103 isn't that hot, I probably wouldn't worry -too- much..


One more for Jim, where did you get that 60% engine-cooling-from-oil number? Are you referring to just Boxster engines?


-David
Ocean Blue 2000 S

[CJ_Boxster]

Originally Posted by MNBoxster

Hi,

If I had to guess, and this is essentially what I'm doing, I'd say that either your Coolant Temperature Sensor or your Cooling Fan relays are showing their age and not operating at 100%. The Software in the DME didn't suddenly start looking for 103°C instead of 96.75°C. Ambient Temp would have nothing to do with the Default Parameters, though it would with normal operating ones (1 component the DME uses).

We're only talking about 6°C here and that could well be within any innacuracies of the Temp Sender or the Gauge or Climate Display. It's not affecting anything. I doubt the MAPs are affected, nothings going to melt, you're not creating appreciably more emissions or suffering any reduced performance. I think you're just obsessing. But, if it bugs you that much, start by cleaning the radiators, replacing the Fan Relays, and changing the Coolant, and see what effect that has on the readings. Hope this helps...

Happy Motoring!... Jim'99

Thanks Jim, Ill probably first replace the relays,... are those the thin tube looking thing with a wire coming out of it directly below the fans?

[MNBoxster]

Originally Posted by David N.

I actually had a problem with the engine compartment fan not coming on when expected, and indeed it seemed to be a worn out relay, so such things are certainly possible (this was on a 2000S with 48k miles).

But concerning the radiator fans...is there any mode in the AC diag that accurately tells you radiator fan speed? I tried the line item 'fan speed' but hasn't budged from 0 even tho I know the radiator fans are on.

Also, for what it's worth, my car in Los Angeles goes from 90-92 coolant temp at 80mph on the freeway to 100-103 idling in traffic. I need to clean the radiators still, but I'll bet it only buys you a few degrees at the most. Still, I'm getting over the fact that 103 isn't that hot, I probably wouldn't worry -too- much..


One more for Jim, where did you get that 60% engine-cooling-from-oil number? Are you referring to just Boxster engines?


-David
Ocean Blue 2000 S

Hi,

No, I am not referring to Boxster engines, that's the Rule-of-Thumb for any auto engine. The fact that the Boxster has an Oil Cooler (which most cars do not), this figure may favor the Oil even more. That it is a mid-engine and thus not able to take as much advantage of direct air cooling as a front-engine car does, it may cancel out the Oil cooler to some degree. But, don't forget, you want to manage the heat, not eliminate it. Too cool is also not good because the engine cannot operate as efficiently. You want to live in a narrow band of say 100°C-117°C for maximum efficiency.

Think about it, aside from the heat from the combustion chamber, most of the heat occurs at the Crank and Big Ends. There are no water jackets here, which only leaves the Oil to carry off the heat.

One more consideration, there is a distinct difference between the temperature of the Coolant and the temperature of the engine. To put it another way, who cares if the Coolant is 1,000 degrees so long as it's carrying the heat away from the engine?

Also, remember that most of the combustion heat is carried away from the Combustion Chamber by the Spark Plugs. Look at a Spark Plug. Why is it designed like a Giant Heatsink? Because it carries most of the Combustion heat away and transfers it to the Head where the Coolant picks up this heat and releases it to Atmoshere.

103°C isn't really that hot in a system pressurized to 13PSI. At 13 PSI, water doesn't turn to steam until approx. 128°C (262.4° F) and this is really the key. If the Coolant were to boil, the water galleries in the Head, and the Water Jackets in the Block would not have liquid Coolant to carry away the heat - Very BAD. Also, the Coolant Pump naturally produces bubbles (gas), but the system pressure reduces the formation of these bubbles as well.

So far as cleaning the radiators, I think you are waaaay pesimistic about it's effects. The Heat transfer can incease (or conversely decrease) by as much as 40%, or as much as 10-15° depending upon how restricted they are. It is definitely worth it to insure that the Radiators are operating optimally...

Happy Motoring!... Jim'99

[MNBoxster]

Originally Posted by CJ_Boxster

Thanks Jim, Ill probably first replace the relays,... are those the thin tube looking thing with a wire coming out of it directly below the fans?

Hi,

No, those are the Ballast Resistors, which come to think of it may actually be the problem. They are PN# 996.616.101.00 - $25 (Sunset). These Ballast Resistors control the Fan Speed by varying the amount of current to the Fans. You can test them by connecting a test lead from an Ohm meter (or Multimeter with Ohm function - always a digital). It doesn't matter which lead goes where. But, you should see some resistance, most likely in the 0.75Ω-1.50Ω Range.
What you do not want to see is an 'Open Value' or Infinity (sometimes the display will show - ∞) If you see this, the Resistor is bad.

You also have 4 relays. 1 for each Fan and Fan Speed. They are located in the Relay Block which lives above and behind the left side Footwell Panel above the Fuse Box. The 4 relays are in the 2nd to bottom row and are the 4 immediately in-line of the right side. Their numbers are (in R-L reverse order):

• #22 - Right Engine Cooling Fan, High Speed
  
  #21 - Left Engine Cooling Fan, High Speed
  
  #20 - Right Engine Cooling Fan, Low Speed
  
  #19 - Left Engine Cooling Fan, Low Speed

These are the same part, so you can interchange them to see if they make a difference between the Fans. The PN# for these Relays is: 141.951.253.B - $10 (Sunset). Hope this helps...

Happy Motoring!... Jim'99