Temperature Gauge ( educated guesses)
Burning Brakes
Joined: Aug 2018
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Might as well throw this out there since it crossed my mind: Does your car have the cooling flaps, and if so are they opened after it warms up? You can check after your next run to the store or something, if your MY has them that is.
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From: Memphis, TN 1987 S4
Burning Brakes
Joined: Aug 2018
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OK, your replacement fans, are they new Bosch or used? Also... In this thread it was pointed out to check the speed that the fans are running at, not sure how you would do that but does it look and sound like they are running at full speed when the engine is up to temp?
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From: Memphis, TN 1987 S4
OK, your replacement fans, are they new Bosch or used? Also... In this thread it was pointed out to check the speed that the fans are running at, not sure how you would do that but does it look and sound like they are running at full speed when the engine is up to temp?
Burning Brakes
Joined: Aug 2018
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Glad you got that CE panel back in as is, it has an ugly spot but it works perfectly.
Take Care.
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From: Oman
Ash,
For purposes of clarity, I understand the temperature gauge "suddenly" changed characteristic behaviour on your last Memphis trip in that the needle suddenly moved higher and this was different to what you previously saw during your ownership- correct? You subsequently found the problem with the fans. For clarity I work on the premise that the fans are needed for low speed operation and at speeds in excess of around 40 mph or so they play little to no role in the cooling process as the air blast effect takes over
When you measured 200F [94C] with your IR gun- where was the needle sat on the display gauge? If that number is correct it corresponds to 94C leaving the engine and thus the coolant return temperature will be about 88C. The fan control programme responds to the coolant temperature leaving the radiator. At a coolant return temperature of 88C the voltage to the fans should be 10 volts -if you can measure such. If the temperature value you measured is correct I would say that is normal operation on a motor that is running the a/c system during warm summer time operation.
I am somewhat sceptical about believing values read on IR guns unless I know they have been calibration checked. If you boil a pan of water and shoot the temperature what reading do you get [at sea level]?
Assuming you have the correct thermostat [opens at 83C] it will not be fully open until the coolant temperature leaving the engine is about 90C and the fans are not driving at full volts until the temperature leaving the radiator reaches 95C and that corresponds to 101C [214F] leaving the engine. These numbers give some clues as to the correct operating temperature of the engine which appears to be a coolant temperature leaving the engine of about 96C give or take a few degrees.
For purposes of clarity, I understand the temperature gauge "suddenly" changed characteristic behaviour on your last Memphis trip in that the needle suddenly moved higher and this was different to what you previously saw during your ownership- correct? You subsequently found the problem with the fans. For clarity I work on the premise that the fans are needed for low speed operation and at speeds in excess of around 40 mph or so they play little to no role in the cooling process as the air blast effect takes over
When you measured 200F [94C] with your IR gun- where was the needle sat on the display gauge? If that number is correct it corresponds to 94C leaving the engine and thus the coolant return temperature will be about 88C. The fan control programme responds to the coolant temperature leaving the radiator. At a coolant return temperature of 88C the voltage to the fans should be 10 volts -if you can measure such. If the temperature value you measured is correct I would say that is normal operation on a motor that is running the a/c system during warm summer time operation.
I am somewhat sceptical about believing values read on IR guns unless I know they have been calibration checked. If you boil a pan of water and shoot the temperature what reading do you get [at sea level]?
Assuming you have the correct thermostat [opens at 83C] it will not be fully open until the coolant temperature leaving the engine is about 90C and the fans are not driving at full volts until the temperature leaving the radiator reaches 95C and that corresponds to 101C [214F] leaving the engine. These numbers give some clues as to the correct operating temperature of the engine which appears to be a coolant temperature leaving the engine of about 96C give or take a few degrees.
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From: Gone. On the Open Road
*precision* : which hose? There are 4.
And this is why —-^
Exactly. I use a lab-grade contact thermometer.
And this is why —-^
I am somewhat sceptical about believing values read on IR guns unless I know they have been calibration checked. If you boil a pan of water and shoot the temperature what reading do you get [at sea level]?
Exactly. I use a lab-grade contact thermometer.
Burning Brakes
Joined: Aug 2018
Posts: 806
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I’m just throwing things out there, but there has to be something stupidly simple going on here. Some cars I’ve read about here run at the top end of the needle and it seems fine to their owners. My car has new fans and a 25% antifreeze mix and runs at the first white bar with the AC on after 30 minutes of idling in the driveway in 100 degree heat. So whose car is working right? I have no idea because there are so many variables, but I do like that my car stays at the lower end.
I read something from back when you were refilling your coolant that the level rose as the car warmed up and it nearly overflowed so you shut off the car. I wonder if there is a sizable pocket of air in there. Were you able to get the full 4 gallons of antifreeze/water in to the car? If not, that’s a clue. Mine did overflow after my last coolant change, there was a huge quantity of air that was expressed. If you want to try it, and why wouldn’t you as it costs nothing and takes 15-20 minutes, then just remove the reservoir cap and let your car run up to temp in the driveway and observe the coolant in the reservoir.
I read something from back when you were refilling your coolant that the level rose as the car warmed up and it nearly overflowed so you shut off the car. I wonder if there is a sizable pocket of air in there. Were you able to get the full 4 gallons of antifreeze/water in to the car? If not, that’s a clue. Mine did overflow after my last coolant change, there was a huge quantity of air that was expressed. If you want to try it, and why wouldn’t you as it costs nothing and takes 15-20 minutes, then just remove the reservoir cap and let your car run up to temp in the driveway and observe the coolant in the reservoir.
Burning Brakes
Joined: Jan 2019
Posts: 770
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From: Dallas
x2 on the IR gun.
My experience is that they are not necessary accurate for measuring internal temperatures.
You will get different readings based upon the color or texture of the surface you are shooting (eg, a black hose, or a silver bridge) or angle.
Try a contact thermometer if you have one. That is likely what came with your fan kit as well to regulate its operation.
-Jason
My experience is that they are not necessary accurate for measuring internal temperatures.
You will get different readings based upon the color or texture of the surface you are shooting (eg, a black hose, or a silver bridge) or angle.
Try a contact thermometer if you have one. That is likely what came with your fan kit as well to regulate its operation.
-Jason
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From: Memphis, TN 1987 S4
Ash,
For purposes of clarity, I understand the temperature gauge "suddenly" changed characteristic behaviour on your last Memphis trip in that the needle suddenly moved higher and this was different to what you previously saw during your ownership- correct? You subsequently found the problem with the fans. For clarity I work on the premise that the fans are needed for low speed operation and at speeds in excess of around 40 mph or so they play little to no role in the cooling process as the air blast effect takes over
When you measured 200F [94C] with your IR gun- where was the needle sat on the display gauge? If that number is correct it corresponds to 94C leaving the engine and thus the coolant return temperature will be about 88C. The fan control programme responds to the coolant temperature leaving the radiator. At a coolant return temperature of 88C the voltage to the fans should be 10 volts -if you can measure such. If the temperature value you measured is correct I would say that is normal operation on a motor that is running the a/c system during warm summer time operation.
I am somewhat sceptical about believing values read on IR guns unless I know they have been calibration checked. If you boil a pan of water and shoot the temperature what reading do you get [at sea level]?
Assuming you have the correct thermostat [opens at 83C] it will not be fully open until the coolant temperature leaving the engine is about 90C and the fans are not driving at full volts until the temperature leaving the radiator reaches 95C and that corresponds to 101C [214F] leaving the engine. These numbers give some clues as to the correct operating temperature of the engine which appears to be a coolant temperature leaving the engine of about 96C give or take a few degrees.
For purposes of clarity, I understand the temperature gauge "suddenly" changed characteristic behaviour on your last Memphis trip in that the needle suddenly moved higher and this was different to what you previously saw during your ownership- correct? You subsequently found the problem with the fans. For clarity I work on the premise that the fans are needed for low speed operation and at speeds in excess of around 40 mph or so they play little to no role in the cooling process as the air blast effect takes over
When you measured 200F [94C] with your IR gun- where was the needle sat on the display gauge? If that number is correct it corresponds to 94C leaving the engine and thus the coolant return temperature will be about 88C. The fan control programme responds to the coolant temperature leaving the radiator. At a coolant return temperature of 88C the voltage to the fans should be 10 volts -if you can measure such. If the temperature value you measured is correct I would say that is normal operation on a motor that is running the a/c system during warm summer time operation.
I am somewhat sceptical about believing values read on IR guns unless I know they have been calibration checked. If you boil a pan of water and shoot the temperature what reading do you get [at sea level]?
Assuming you have the correct thermostat [opens at 83C] it will not be fully open until the coolant temperature leaving the engine is about 90C and the fans are not driving at full volts until the temperature leaving the radiator reaches 95C and that corresponds to 101C [214F] leaving the engine. These numbers give some clues as to the correct operating temperature of the engine which appears to be a coolant temperature leaving the engine of about 96C give or take a few degrees.
Hey guys, sorry for the unclear posts. Several months ago I drove to Mphs. 925 miles one way. Car did fine on the trip there. On the way back, it rained the entire way, 12 hrs. Car ran fine with AC on until I got about 30 minutes from home where I ran into stop and go traffic. Needle began to rise to the last hash mark and then into the red. I pulled over and allowed it to cool and added water I had brought along for the trip. Got back in traffic with less stop and go and got home no problem. Checking car out about a week later noticed the fans were not coming on with AC on. Fans were toast. Very hard to turn by hand. Checked fuses and fan fuses were blown and the fuse from pic above had melted. Changed fuses and ordered new fans from Roger. Installed them and began driving the car again.
its at this point I noticed the needle resting farther right than previously. It hasn’t run hot but it rest just left (2 or so needle widths) of last mark and while in stop and go traffic it has made it to the last mark. This is with the AC on.
BREAK, BREAK
So this morning I remembered that I only added water when it overheated. I didn’t “burp” it. I ran the car without the cap for about 20 min and squeezed the upper radiator hose a couple of times (with heater on high). Went for a 40 min drive with AC on. The needle now rest closer to where it did prior to overheating.
Using the IR gun, the temp exiting the center vent is 52 degrees Fahrenheit at highway speeds and didn’t deviate to much when driving the side streets. The temp outside is only about 80 so not to hot yet. I want to see what it does in 95-100 degree heat.
Can an unburped radiator cause the AC not to cool properly? This is the coldest it’s ever felt.
Burning Brakes
Joined: Aug 2018
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You had air in your coolant system is what you are saying, right?
People go to extreme lengths (nose up, nose down, etc...) during coolant changes just to get the last bubbles out, yea it’s not a good thing.
People go to extreme lengths (nose up, nose down, etc...) during coolant changes just to get the last bubbles out, yea it’s not a good thing.
Thread Starter
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From: Memphis, TN 1987 S4
Yes. It may have had air in the system. I’m waiting on it to heat up outside and see if it holds true.