Diagnosis of hot engine temps...normal or not?
07-25-2012, 05:29 PM
#1
Burning Brakes
Thread Starter
Diagnosis of hot engine temps...normal or not?
I'd like to tap into the RL braintrust and see if there is an actual problem with the engine temps or if these are "normal" for a mostly track car and install the secondary oil cooler I'm planning on doing to bring temps down. What I don't want to do is install the secondary oil cooler to mask an actual problem and then complicate diagnoses.
Symptoms:
- Engine temps have been running very hot at track events requiring a couple cool down laps after only 10-15 minutes of running hard.
- I noticed this increase in temps after installing a LWF/RS clutch in April 2011 along with all the typical while your in there stuff (new lifters, plug wires, spark plugs, new dist. belt, typical seals/gaskets, SAI port clean, new SAI check valve, RS heater tube, AWDectomy, etc.). I don't have perfect apples to apples comparisons of running the same tracks before and after but I never had to back off due to temps in the past.
Salient Facts:
- Engine temps seem to act normal during initial startup and thermostat opening.
- Engine temps at normal street use are normal sitting around 8:00 cruising on the highway...might approach 9:00 if sitting in traffic with AC on a hot day.
- Oil cooler fan override switch installed and used for any track use.
- Temps on the track get to above 248 degrees, I'd say they could get in the red if I let them but I have always backed off. Worst I have seen is probably 255 degrees the first time before I knew I was starting to run hot.
- Temps seem to take quite a while to drop compared to before running this hot. This could of course be because they are so hot now and it takes longer to bring them down but the rate of drop is what I've noticed is slow.
- Running Mobile 15w50.
- Oil pressure seems to be running normal.
- 80k miles, no engine rebuild.
- Don't have an accurate gauge on oil consumption due to mostly tracking the car.
- I have talked with a well known shop/engine builder in town and he says these 3.6L engines under race conditions just don't have enough cooling and need the secondary cooler.
- Other 993s that are on the track have not seen temps like mine; however, none of them are pushing the car as hard as I am I don't think (based on significant lap time differences).
My thoughts:
- Could the thermostat not be opening all the way (weak spring) and thus reducing the volume of flow to the cooler?
- Could the lines to the cooler be blocked somehow reducing flow? If so, how would this impact oil pressure?
- Could the oil pump not be operating properly reducing flow to the front cooler? Is the pump gear driven? Are there seals that can wear out?
What do you guys think?
Symptoms:
- Engine temps have been running very hot at track events requiring a couple cool down laps after only 10-15 minutes of running hard.
- I noticed this increase in temps after installing a LWF/RS clutch in April 2011 along with all the typical while your in there stuff (new lifters, plug wires, spark plugs, new dist. belt, typical seals/gaskets, SAI port clean, new SAI check valve, RS heater tube, AWDectomy, etc.). I don't have perfect apples to apples comparisons of running the same tracks before and after but I never had to back off due to temps in the past.
Salient Facts:
- Engine temps seem to act normal during initial startup and thermostat opening.
- Engine temps at normal street use are normal sitting around 8:00 cruising on the highway...might approach 9:00 if sitting in traffic with AC on a hot day.
- Oil cooler fan override switch installed and used for any track use.
- Temps on the track get to above 248 degrees, I'd say they could get in the red if I let them but I have always backed off. Worst I have seen is probably 255 degrees the first time before I knew I was starting to run hot.
- Temps seem to take quite a while to drop compared to before running this hot. This could of course be because they are so hot now and it takes longer to bring them down but the rate of drop is what I've noticed is slow.
- Running Mobile 15w50.
- Oil pressure seems to be running normal.
- 80k miles, no engine rebuild.
- Don't have an accurate gauge on oil consumption due to mostly tracking the car.
- I have talked with a well known shop/engine builder in town and he says these 3.6L engines under race conditions just don't have enough cooling and need the secondary cooler.
- Other 993s that are on the track have not seen temps like mine; however, none of them are pushing the car as hard as I am I don't think (based on significant lap time differences).
My thoughts:
- Could the thermostat not be opening all the way (weak spring) and thus reducing the volume of flow to the cooler?
- Could the lines to the cooler be blocked somehow reducing flow? If so, how would this impact oil pressure?
- Could the oil pump not be operating properly reducing flow to the front cooler? Is the pump gear driven? Are there seals that can wear out?
What do you guys think?
07-25-2012, 05:38 PM
#2
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Adam, what is your oil pressure under throttle and cruising? The top of the red/orange needle should just slightly touch the bottom black marker at 5 bar. At idle, you should see about 2.5-3.0 bar. Any throttle inputs, it should jump right up to 5 bar.
Thermostat would be easy enough to suspect. On the first morning drive, how long does it take to come up to operating temp?
Have you ever removed the front bumper, and cleaned off your oil cooler fins?
Thermostat would be easy enough to suspect. On the first morning drive, how long does it take to come up to operating temp?
Have you ever removed the front bumper, and cleaned off your oil cooler fins?
07-25-2012, 06:21 PM
#3
Pretty easy to check that oil cooler fins aren't filled up with debris, that cooler gets hot at the temp it's supposed to get hot, and that fan is working. It's SOP to put a second cooler on a 3.6 for track usage -- doubt you're exempt from that.
07-25-2012, 06:35 PM
#4
Burning Brakes
Thread Starter
Adam, what is your oil pressure under throttle and cruising? The top of the red/orange needle should just slightly touch the bottom black marker at 5 bar. At idle, you should see about 2.5-3.0 bar. Any throttle inputs, it should jump right up to 5 bar.
Thermostat would be easy enough to suspect. On the first morning drive, how long does it take to come up to operating temp?
Have you ever removed the front bumper, and cleaned off your oil cooler fins?
Thermostat would be easy enough to suspect. On the first morning drive, how long does it take to come up to operating temp?
Have you ever removed the front bumper, and cleaned off your oil cooler fins?
The oil fins are clean, those were one of the first things I checked. I even installed brake scoops without the brake hose to try and funnel more air to the cooler area.
Fins are clean and thermostat opens at the proper time dropping the temp down to the 8-8:30 mark during warm up. The fan works for sure with the override switch (not sure this does that much while at speed on the track of course). Do you have any data points of getting temps this high on a single cooler car while on the track? One reason I think there might be something going on is that other 993 drivers don't have the temperature issues I do. Thanks for your thoughts!
07-25-2012, 07:07 PM
#7
Burning Brakes
Thread Starter
Yes, this is what everyone says and what I plan on doing (gathering the parts). We can all take this practice as SOP for 993 track cars. What would be useful is if you or other 993 folks who track their cars can share your temperature experiences so I (and the rest of us) have some real world data points to go off of. So, if you tracked your car at all before putting in a secondary oil cooler, what were your experiences with temperature? How did this change when you added the second cooler? Thanks.
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07-25-2012, 07:39 PM
#8
Rennlist Member
My car was street when purchased. I would see temp ranges over 248 (3rd line on the gauge) from track driving. I would simply pull in when it would continue to climb. I then added a second 964 style cooler in the fender. Initial problem solved. I also removed the AC at that time. When I switched to the GT2 front end with the stock motor the temps would 194 or less when moving. I removed the fan at that point. Adding the 3.8 RSR motor I am seeing a bit higher temps now, but still acceptable. I just added the cyl temp sensor on the Motec to now monitor cyl #3. Headers are being coated and some added cooling too.
07-25-2012, 07:44 PM
#9
I have two coolers. My temps were still high, slightly above the 10 o'clock line. This past winter I pulled the engine to do a top end. Cylinder #3 head and barrel fins were packed with bird seed. After cleaning it all out my engine now runs below the 10 0'clock line. I drive pretty hard, rpm's between 5 and 7 thousand.
Pete
Pete
07-25-2012, 07:55 PM
#10
Burning Brakes
Thread Starter
My car was street when purchased. I would see temp ranges over 248 (3rd line on the gauge) from track driving. I would simply pull in when it would continue to climb. I then added a second 964 style cooler in the fender. Initial problem solved. I also removed the AC at that time. When I switched to the GT2 front end with the stock motor the temps would 194 or less when moving. I removed the fan at that point. Adding the 3.8 RSR motor I am seeing a bit higher temps now, but still acceptable. I just added the cyl temp sensor on the Motec to now monitor cyl #3. Headers are being coated and some added cooling too.
I have two coolers. My temps were still high, slightly above the 10 o'clock line. This past winter I pulled the engine to do a top end. Cylinder #3 head and barrel fins were packed with bird seed. After cleaning it all out my engine now runs below the 10 0'clock line. I drive pretty hard, rpm's between 5 and 7 thousand.
Pete
Pete
07-25-2012, 08:17 PM
#11
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Don´t know it this is of any help to you. But for what its worth. My 993 turbo has a secondary oilcooler that someone of the previous owners installed. I do track the car from time to time. On hot summer days and longer stints the temperature will rise to the 9 o´clock mark. If I keep pushing the car it will rise even further and stay there. But usually I do cool down laps at that point. There are no point of pushing the car to far. The brakes needs to cool down as well at that point. Let´s not forget that we are driving streetcars on the track. With that said I want to clarify what kind of tracks we are talking about. When driving the car on the Nürburgring as an example the engine does not get as hot as on regular tracks, nor does the tires. There are long straights thats helps cool down the car between corners unlike a regular track.
When driving the car on the street in constant speed the temperature will stay below 8 o´clock all day long. To go up to maybe 8 when driving slow or standing still at a stop sign a while. Only on very hot days will the temperature go up to 9 o´clock mark. Usually after a very long drive with a lot of stop and go traffic in the end. But there it stays even in "stau" (traffic jams that is in English) on the german Autobahn after doing between 160- 200 km/h for hours.
When driving the car on the street in constant speed the temperature will stay below 8 o´clock all day long. To go up to maybe 8 when driving slow or standing still at a stop sign a while. Only on very hot days will the temperature go up to 9 o´clock mark. Usually after a very long drive with a lot of stop and go traffic in the end. But there it stays even in "stau" (traffic jams that is in English) on the german Autobahn after doing between 160- 200 km/h for hours.
07-25-2012, 08:43 PM
#12
I put in some track days without a second oil cooler, temps were as yours, in the 250 to 260 area and heading into the red.
with the second cooler in front of the ac, during july and august on a hot day I'll still get to 9 o'clock and turn the fan on.
while expensive(I bought the gt cooler from carnewal) installation is easy and my ac works fine.
with the second cooler in front of the ac, during july and august on a hot day I'll still get to 9 o'clock and turn the fan on.
while expensive(I bought the gt cooler from carnewal) installation is easy and my ac works fine.
07-25-2012, 08:52 PM
#13
Rennlist Member
1. What track, what's the ambient, what lap times?
2. You've got plenty of confirmation (including me, now) indicating any above-pony-trot-speed track use will overwhelm the single cooler.
3. Does someone have real data on using the fan at speed on track? We messed around with this in the '80s with both the factory 3.2L cars with fans, and adding aftermarket units to both factory and aftermarket coolers, both in the stock position and in nose spoilers (RS/RSR style). The fan, even in the off position, was a hinderance and actually increased oil temperatures. I note Bob above mentioned removing his at some point as he modified his car. Never did an analysis on the 964/993 setup, as we just started throwing second coolers on the early 964s as soon as we saw the problem in the early '90s.
2. You've got plenty of confirmation (including me, now) indicating any above-pony-trot-speed track use will overwhelm the single cooler.
3. Does someone have real data on using the fan at speed on track? We messed around with this in the '80s with both the factory 3.2L cars with fans, and adding aftermarket units to both factory and aftermarket coolers, both in the stock position and in nose spoilers (RS/RSR style). The fan, even in the off position, was a hinderance and actually increased oil temperatures. I note Bob above mentioned removing his at some point as he modified his car. Never did an analysis on the 964/993 setup, as we just started throwing second coolers on the early 964s as soon as we saw the problem in the early '90s.
07-25-2012, 09:09 PM
#14
Burning Brakes
Thread Starter
Don´t know it this is of any help to you. But for what its worth. My 993 turbo has a secondary oilcooler that someone of the previous owners installed. I do track the car from time to time. On hot summer days and longer stints the temperature will rise to the 9 o´clock mark. If I keep pushing the car it will rise even further and stay there. But usually I do cool down laps at that point. There are no point of pushing the car to far. The brakes needs to cool down as well at that point. Let´s not forget that we are driving streetcars on the track. With that said I want to clarify what kind of tracks we are talking about. When driving the car on the Nürburgring as an example the engine does not get as hot as on regular tracks, nor does the tires. There are long straights thats helps cool down the car between corners unlike a regular track.
When driving the car on the street in constant speed the temperature will stay below 8 o´clock all day long. To go up to maybe 8 when driving slow or standing still at a stop sign a while. Only on very hot days will the temperature go up to 9 o´clock mark. Usually after a very long drive with a lot of stop and go traffic in the end. But there it stays even in "stau" (traffic jams that is in English) on the german Autobahn after doing between 160- 200 km/h for hours.
When driving the car on the street in constant speed the temperature will stay below 8 o´clock all day long. To go up to maybe 8 when driving slow or standing still at a stop sign a while. Only on very hot days will the temperature go up to 9 o´clock mark. Usually after a very long drive with a lot of stop and go traffic in the end. But there it stays even in "stau" (traffic jams that is in English) on the german Autobahn after doing between 160- 200 km/h for hours.
I put in some track days without a second oil cooler, temps were as yours, in the 250 to 260 area and heading into the red.
with the second cooler in front of the ac, during july and august on a hot day I'll still get to 9 o'clock and turn the fan on.
while expensive(I bought the gt cooler from carnewal) installation is easy and my ac works fine.
with the second cooler in front of the ac, during july and august on a hot day I'll still get to 9 o'clock and turn the fan on.
while expensive(I bought the gt cooler from carnewal) installation is easy and my ac works fine.
1. What track, what's the ambient, what lap times?
2. You've got plenty of confirmation (including me, now) indicating any above-pony-trot-speed track use will overwhelm the single cooler.
3. Does someone have real data on using the fan at speed on track? We messed around with this in the '80s with both the factory 3.2L cars with fans, and adding aftermarket units to both factory and aftermarket coolers, both in the stock position and in nose spoilers (RS/RSR style). The fan, even in the off position, was a hinderance and actually increased oil temperatures. I note Bob above mentioned removing his at some point as he modified his car. Never did an analysis on the 964/993 setup, as we just started throwing second coolers on the early 964s as soon as we saw the problem in the early '90s.
2. You've got plenty of confirmation (including me, now) indicating any above-pony-trot-speed track use will overwhelm the single cooler.
3. Does someone have real data on using the fan at speed on track? We messed around with this in the '80s with both the factory 3.2L cars with fans, and adding aftermarket units to both factory and aftermarket coolers, both in the stock position and in nose spoilers (RS/RSR style). The fan, even in the off position, was a hinderance and actually increased oil temperatures. I note Bob above mentioned removing his at some point as he modified his car. Never did an analysis on the 964/993 setup, as we just started throwing second coolers on the early 964s as soon as we saw the problem in the early '90s.
1. Tracks have been SoCal tracks like Chuckwalla (hotest ambient of them all...95 degrees maybe and car ran very hot), Pomona (smaller track but still got high temps...ambient of I'd say 85), Fontana infield (temp around 80 and car was not as hot), big and little Willow (had to back off even at big willow with its two straights). As far as lap times and how hard I'm pushing the car I think it's safe to say I'm no world class driver but no slouch either. I'm one of the chief driving instructors for our PCA region and get around at a decent clip.
2. I'm seeing that now, this is all very helpful!
3. Sorry, can't help here but interesting thought on removing the fan.
07-25-2012, 09:22 PM
#15
Rennlist Member
Haven't driven The Chuck, but I did get a presentation by the Construction Manager a couple of weeks before it opened. That place has to be brutal--either it's hot, or windy. Right? Never done Pomona. What I can tell you is that anything above 80F at Willow caused me to run into-and-past the danger zone with the '92 C4. The one car that was NOT going to be a track car, so I didn't put a second cooler on it. So I used it everywhere for three years, along with the '73 S...... Anyway, I was ~1:35-6 with that car. Once I got into the first RSA racer, and had the two coolers, even 100F+ there was no problem down in the 1:30 range. (I've never been that fast at Willow.) And no problems at Buttonwillow, either. I think one time there we had a 115F day.
So back to the question at hand. I've not ventured South since I got the yellow car, but even on a 100F day at Thunderhill, no problems with the 3.8. And a 2:00 lap there on the full track is sub 1:30 at Willow.
So back to the question at hand. I've not ventured South since I got the yellow car, but even on a 100F day at Thunderhill, no problems with the 3.8. And a 2:00 lap there on the full track is sub 1:30 at Willow.
