Normal coolant temp?
10-17-2015, 02:03 PM
#1
Drifting
Thread Starter
Normal coolant temp?
So I need some opinions from my esteemed RL colleagues.
I recently replaced both radiator fans and resistors. I've put about 100 miles on the car since. Yesterday I was monitoring the coolant temp via the climate control hack. I was in stop and go (first gear the whole time) traffic for about 30 minutes. The ambient temperature outside was around 85°. The hottest that the car got in that situation was 101°C. I don't believe that the high speed fans ever activated. The low speed fans were on due to the AC running.
What say ye? Abnormal? Normal?
I recently replaced both radiator fans and resistors. I've put about 100 miles on the car since. Yesterday I was monitoring the coolant temp via the climate control hack. I was in stop and go (first gear the whole time) traffic for about 30 minutes. The ambient temperature outside was around 85°. The hottest that the car got in that situation was 101°C. I don't believe that the high speed fans ever activated. The low speed fans were on due to the AC running.
What say ye? Abnormal? Normal?
10-17-2015, 04:12 PM
#4
Drifting
Thread Starter
10-17-2015, 05:03 PM
#5
Drifting
Some may know this but it is worth stating for the noobs:
The temperature gauge is only approximate.
The sensor for it measures coolant flowing INTO the the engine on bank 1.
You really need to know the temperature after it exits bank 2(the hotter bank).
The radiator area accumulate lots of debris that you can't see unless you move the a/c condensers out of the way to clean between .
There is a useful mod on Rennlist for the engine compartment fan(not coolant!)
The best way to test all this imho is up on a rack with Durametric + an I.R. temp gun engine warm and at low/high revs. Log the data and report back.Tedious and time consuming but...
Without accurate data from specific locations and not knowing if fans are working correctly(Durametric) you could chase your tail.
The temperature gauge is only approximate.
The sensor for it measures coolant flowing INTO the the engine on bank 1.
You really need to know the temperature after it exits bank 2(the hotter bank).
The radiator area accumulate lots of debris that you can't see unless you move the a/c condensers out of the way to clean between .
There is a useful mod on Rennlist for the engine compartment fan(not coolant!)
The best way to test all this imho is up on a rack with Durametric + an I.R. temp gun engine warm and at low/high revs. Log the data and report back.Tedious and time consuming but...
Without accurate data from specific locations and not knowing if fans are working correctly(Durametric) you could chase your tail.
10-17-2015, 10:01 PM
#6
Race Director
So I need some opinions from my esteemed RL colleagues.
I recently replaced both radiator fans and resistors. I've put about 100 miles on the car since. Yesterday I was monitoring the coolant temp via the climate control hack. I was in stop and go (first gear the whole time) traffic for about 30 minutes. The ambient temperature outside was around 85°. The hottest that the car got in that situation was 101°C. I don't believe that the high speed fans ever activated. The low speed fans were on due to the AC running.
What say ye? Abnormal? Normal?
I recently replaced both radiator fans and resistors. I've put about 100 miles on the car since. Yesterday I was monitoring the coolant temp via the climate control hack. I was in stop and go (first gear the whole time) traffic for about 30 minutes. The ambient temperature outside was around 85°. The hottest that the car got in that situation was 101°C. I don't believe that the high speed fans ever activated. The low speed fans were on due to the AC running.
What say ye? Abnormal? Normal?
That the fans on low speed kept the engine "cool" in 30 minutes of 1st gear stop/go speaks highly of the car's cooling system.
10-18-2015, 02:34 AM
#7
https://rennlist.com/forums/996-foru...l#post12576096
Trending Topics
10-18-2015, 09:41 AM
#8
IslaTurbine - the high speed turns on at 103 (mine does).
Ahsai - that diagram is great. Also, does the coolant circulate when the car is at idle? I almost wish there was a "flow meter" to indicate such. Placed way up at the radiators (ha).
Ahsai - that diagram is great. Also, does the coolant circulate when the car is at idle? I almost wish there was a "flow meter" to indicate such. Placed way up at the radiators (ha).
10-18-2015, 12:24 PM
#10
Drifting
This is a useful correction to the conventional wisdom by Ahsai.
Obviously there is still something sub-optimal with the circulation/sensing because Jake gives a cryptic comment about using "Epoxy".
Hopefully Ahsai will eventually complete his very useful coolant circulation diagram.Nobody else has produced anything to this standard .Thank you Ahsai !
https://rennlist.com/forums/996-foru...l#post12576096
Obviously there is still something sub-optimal with the circulation/sensing because Jake gives a cryptic comment about using "Epoxy".
Hopefully Ahsai will eventually complete his very useful coolant circulation diagram.Nobody else has produced anything to this standard .Thank you Ahsai !
https://rennlist.com/forums/996-foru...l#post12576096
10-18-2015, 07:37 PM
#11
When the engine is cold, the coolant only circulates within the engine block to speed up bringing the coolant up to operating temperature. The thermostat is closed so the radiator flow (green) is blocked.
Once the coolant temp approaches the set temp, the thermostat starts to open and let the green radiator flow start, diverting part of the hot flow (on the upper right) after the cylinders/cylinder heads to the radiators. The flow returned from the radiator can now be mixed with the red flow at the thermostat (since the thermostat is open now). The thermostat will sense the temp of the mixed flows and regulate the opening depending on the sensed temperature.
You can see that the coolant sensor is at the return path of the coolant after the cylinders/heads and NOT AFTER the radiators, which returns on the left side to the thermostat.
This is a useful correction to the conventional wisdom by Ahsai.
Obviously there is still something sub-optimal with the circulation/sensing because Jake gives a cryptic comment about using "Epoxy".
Hopefully Ahsai will eventually complete his very useful coolant circulation diagram.Nobody else has produced anything to this standard .Thank you Ahsai !
https://rennlist.com/forums/996-foru...l#post12576096
Obviously there is still something sub-optimal with the circulation/sensing because Jake gives a cryptic comment about using "Epoxy".
Hopefully Ahsai will eventually complete his very useful coolant circulation diagram.Nobody else has produced anything to this standard .Thank you Ahsai !
https://rennlist.com/forums/996-foru...l#post12576096
10-19-2015, 10:49 AM
#12
Burning Brakes
Looking at this excellent diagram work-
Question-
Is the red path (radiator bypass) formed by the black water pipe that runs next to the oil filter ?
Comment-
Once the red water temp gets to the thermostat set point, the thermostat opens and water can now take a parallel path through the two parallel radiators. Just as this first occured, the exit temp from the heads (highest coolant temp in the engine) was = to the 190 deg (for discussion sake) temp of the thermostat. Thermostat reacts, opening main gateway to radiators.
Once the radiator flow is established, the thermostat now senses cooler water than what is exiting from the heads, since this engine exit water temp is reduced with the radiator water exit temp (much cooler and a larger flow mass), so the thermostat is not now setting the flow based just on engine coolant exit temp. It would seem that the effect would be that the water temp exiting the heads could now be higher than before, as the thermostat is reacting to the cooler flow blended with the temp values from head exit ports.
Not wanting to take off on a tangent proposing a solution when there is no problem, but it is temping to think about. If this is the case, then a proper way to control temperature is with another temp sensor(s) that look at head exit temps, takes the worst one, and controls thermostat poppet valve opening % as a direct reaction to coolant exit temps. This would have the added benefit of being programmable to lead the heat buildup based on observed engine cool down rates as a % of opening of the thermostat.
I also would assume that the current design works, since the temp sensor installed in the vehicles today is connected to the red path cylinder head exit temps, which in my car is always around 175 degs, even though the thermostat is supposedly set at a higher temp to open (190F ?), which is itself a bit confusing.
Question-
Is the red path (radiator bypass) formed by the black water pipe that runs next to the oil filter ?
Comment-
Once the red water temp gets to the thermostat set point, the thermostat opens and water can now take a parallel path through the two parallel radiators. Just as this first occured, the exit temp from the heads (highest coolant temp in the engine) was = to the 190 deg (for discussion sake) temp of the thermostat. Thermostat reacts, opening main gateway to radiators.
Once the radiator flow is established, the thermostat now senses cooler water than what is exiting from the heads, since this engine exit water temp is reduced with the radiator water exit temp (much cooler and a larger flow mass), so the thermostat is not now setting the flow based just on engine coolant exit temp. It would seem that the effect would be that the water temp exiting the heads could now be higher than before, as the thermostat is reacting to the cooler flow blended with the temp values from head exit ports.
Not wanting to take off on a tangent proposing a solution when there is no problem, but it is temping to think about. If this is the case, then a proper way to control temperature is with another temp sensor(s) that look at head exit temps, takes the worst one, and controls thermostat poppet valve opening % as a direct reaction to coolant exit temps. This would have the added benefit of being programmable to lead the heat buildup based on observed engine cool down rates as a % of opening of the thermostat.
I also would assume that the current design works, since the temp sensor installed in the vehicles today is connected to the red path cylinder head exit temps, which in my car is always around 175 degs, even though the thermostat is supposedly set at a higher temp to open (190F ?), which is itself a bit confusing.
10-19-2015, 10:56 AM
#13
Three Wheelin'
From reading hartech that makes sense. Just a Monday AM armchair guess, and my personal opinion, but it seems that the oil starts to break down when the engine isn't up to temp and the happy pedal is to the floor.
They also talked about some design changes, although personally I think it's due to the engines not being up to temp and/or not being driven enough after coming up to temp (or driven hard enough) that causes a lot of our issues.
10-19-2015, 01:23 PM
#14
The black water pipe (like 3/4" in diameter) that runs next to the oil filter is for the heater core if memory serves.
Comment-
Once the red water temp gets to the thermostat set point, the thermostat opens and water can now take a parallel path through the two parallel radiators. Just as this first occured, the exit temp from the heads (highest coolant temp in the engine) was = to the 190 deg (for discussion sake) temp of the thermostat. Thermostat reacts, opening main gateway to radiators.
Once the radiator flow is established, the thermostat now senses cooler water than what is exiting from the heads, since this engine exit water temp is reduced with the radiator water exit temp (much cooler and a larger flow mass), so the thermostat is not now setting the flow based just on engine coolant exit temp.
It would seem that the effect would be that the water temp exiting the heads could now be higher than before, as the thermostat is reacting to the cooler flow blended with the temp values from head exit ports.
Once the red water temp gets to the thermostat set point, the thermostat opens and water can now take a parallel path through the two parallel radiators. Just as this first occured, the exit temp from the heads (highest coolant temp in the engine) was = to the 190 deg (for discussion sake) temp of the thermostat. Thermostat reacts, opening main gateway to radiators.
Once the radiator flow is established, the thermostat now senses cooler water than what is exiting from the heads, since this engine exit water temp is reduced with the radiator water exit temp (much cooler and a larger flow mass), so the thermostat is not now setting the flow based just on engine coolant exit temp.
It would seem that the effect would be that the water temp exiting the heads could now be higher than before, as the thermostat is reacting to the cooler flow blended with the temp values from head exit ports.
Not wanting to take off on a tangent proposing a solution when there is no problem, but it is temping to think about. If this is the case, then a proper way to control temperature is with another temp sensor(s) that look at head exit temps, takes the worst one, and controls thermostat poppet valve opening % as a direct reaction to coolant exit temps.
I think the coolant sensor itself though is already at the right spot for controlling the fuel/air mixture as it reads the coolant temp right after it exits the heads/cylinders.
This would have the added benefit of being programmable to lead the heat buildup based on observed engine cool down rates as a % of opening of the thermostat. I also would assume that the current design works, since the temp sensor installed in the vehicles today is connected to the red path cylinder head exit temps, which in my car is always around 175 degs, even though the thermostat is supposedly set at a higher temp to open (190F ?), which is itself a bit confusing.
10-19-2015, 01:26 PM
#15
From reading hartech that makes sense. Just a Monday AM armchair guess, and my personal opinion, but it seems that the oil starts to break down when the engine isn't up to temp and the happy pedal is to the floor.
They also talked about some design changes, although personally I think it's due to the engines not being up to temp and/or not being driven enough after coming up to temp (or driven hard enough) that causes a lot of our issues.
They also talked about some design changes, although personally I think it's due to the engines not being up to temp and/or not being driven enough after coming up to temp (or driven hard enough) that causes a lot of our issues.
Also, if after I stop the car I hear the radiator fans running, I'll let them finished before turning the engine off. The worst temp build up is right after the engine is stopped so I try to avoid stopping the engine when it's too hot.