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Tom Powell
Samba Member
Joined: December 01, 2005
Posts: 4855
Location: Kaneohe
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 Posted: Sat Jun 04, 2016 9:08 pm Post subject: IR gun readings |
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There have been a lot of Vanagon cooling systems questions and posts recently. I have an'87 Vanagon with an OG thermostat, a new temperature sensor which causes higher than OG gauge readings, and the lower temperature fan switch. My radiator fan operates at expected times in bumper to bumper traffic or idling on the driveway for twelve to twenty minutes. Overall I believe that my cooling system operates as expected except for the high gauge readings. I received my Amazon IR gun today and have started collecting some readings from the radiator.
Facing the radiator I will call the upper passenger's corner position 1, upper driver's corner position 2, lower driver's corner position 3, lower passenger's corner position 4.
Here are the readings I got before start:
80.6 79.3 77.7 77.1
After a short drive, the engine not yet up to normal operating temperatures according to the gauge which was still below the LED:
79.3 79.1 77.7 77.0
Twenty minutes of city driving and the gauge a bit higher than normal operating temperature:
87.4 93.5 80.9 88.1
The last set of numbers seem very low. Perhaps my measuring points are not appropriate. I'll be unloading stuff from on top the engine hatch and do some readings at points on the engine in the future. Please make suggestions on where to take engine readings.
Aloha
tp |
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Terry Kay
Banned
Joined: June 22, 2003
Posts: 13331
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| Posted: Sat Jun 04, 2016 9:16 pm Post subject: Re: IR gun readings |
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How old is the radiator?
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T.K. |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50338
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| Posted: Sat Jun 04, 2016 10:18 pm Post subject: Re: IR gun readings |
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| What kind of ambient temperature are you seeing? |
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Tom Powell
Samba Member
Joined: December 01, 2005
Posts: 4855
Location: Kaneohe
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| Posted: Sat Jun 04, 2016 11:50 pm Post subject: Re: IR gun readings |
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| Terry Kay wrote: |
| How old is the radiator? |
As far as I know it is '87 OG with 190 K miles.
| Wildthings wrote: |
| What kind of ambient temperature are you seeing? |
Temperature was reported as 82 at 3:00Pm before I started the engine. Probably a bit cooler in the carport.
Aloha
tp |
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djkeev
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Joined: September 30, 2007
Posts: 32598
Location: Reading Pennsylvania
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Terry Kay
Banned
Joined: June 22, 2003
Posts: 13331
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| Posted: Sun Jun 05, 2016 7:28 am Post subject: Re: IR gun readings |
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Time for a radiator.
The reason the lower portion of the radiator is running cold, is that the lower section of it has collected all of the garbage that flows in any cooling system, and that snot is plugging those lower tubes--
Normal sediment collection area of an old radiator, and it just isn't getting any hot coolant pumped through the horizontal tubes, hence the cooler temps in the lower area.
Get a new radiator in the van, and you'll find the entire face of the radiator will be pretty close to the same operating temps.
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Tom Powell
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Joined: December 01, 2005
Posts: 4855
Location: Kaneohe
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| Posted: Sun Jun 05, 2016 11:51 am Post subject: Re: IR gun readings |
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| djkeev wrote: |
If the fan is working properly and you aren't over heating...... If it ain't broke, don't go fixing it? |
My sentiments exactly, but with the new sensor I'm getting higher than OG gauge readings and occasional LED, but no fan. The fan will come on in bumper to bumper traffic or 12 to 15 minutes of idling in the driveway. It's time to get the new IR gun on the engine.
Aloha
tp |
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Tom Powell
Samba Member
Joined: December 01, 2005
Posts: 4855
Location: Kaneohe
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| Posted: Sun Jun 05, 2016 12:53 pm Post subject: Re: IR gun readings |
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| Terry Kay wrote: |
Time for a radiator.
The reason the lower portion of the radiator is running cold, is that the lower section of it has collected all of the garbage that flows in any cooling system, and that snot is plugging those lower tubes--
Normal sediment collection area of an old radiator, and it just isn't getting any hot coolant pumped through the horizontal tubes, hence the cooler temps in the lower area.
Get a new radiator in the van, and you'll find the entire face of the radiator will be pretty close to the same operating temps. |
The highest reading is on the upper driver's side of the radiator and is less than 12º above ambient temperature. The difference around the radiator readings is less than 13º. These are much lower than I would expect and indicates to me that they are poor readings or a radiator that is cooling the engine well.
The radiator was replaced by the PO 08/27/2011 at 185k miles. Present mileage is 191k. From the age/mileage of the radiator and the low temperatures I'll ASSuME the radiator is in good condition.
Aloha
tp |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50338
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| Posted: Sun Jun 05, 2016 1:35 pm Post subject: Re: IR gun readings |
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| If the engine isn't producing much heat then by the time the coolant makes its return pass through the radiator it may not be be that high above ambient. A good way to test, would be to let the engine idle until the fan had kicked on a few times and then time how long the intervals are when it is not running. Lets say the fan is typically off for 3 minutes, then let the fan turn off for 2 1/2 minutes before beginning to take your IR readings. The radiator should now be nice and warm and the readings should be consistent across the front. |
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Ahwahnee
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Joined: June 05, 2010
Posts: 9800
Location: Mt Lemmon, AZ
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| Posted: Sun Jun 05, 2016 5:17 pm Post subject: Re: IR gun readings |
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| Tom Powell wrote: |
| ...It's time to get the new IR gun on the engine... |
Yes. Point it as close as you can to where the gauge sender mounts. If a high reading gauge is what worries you, that is the measurement to start with.
If an engine has a possibly reflective surface where I want to measure, I spray paint a circle of flat black there to get more accurate emissivity. |
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jmranger
Samba Member
Joined: January 14, 2010
Posts: 701
Location: Quebec
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| Posted: Sun Jun 05, 2016 7:19 pm Post subject: Re: IR gun readings |
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IR guns are far from a magic bullet.
First, despite the laser pointer, they measure the temperature of an area, not a point. Wikipedia explains it better than I can:
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| The distance-to-spot ratio (D:S) is the ratio of the distance to the measurement surface and the diameter of the temperature measurement area. For instance if the D:S ratio is 12:1, the diameter of the measurement area is one-twelfth of the distance to the object. |
Second, as Ahwahnee said, the IR gun expects a surface of a specific emissivity. If the surface is different, the measurement will be incorrect. It's also explained in the link above.
So it's a valuable tool, but its limitations are bigger than they appear. |
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Tom Powell
Samba Member
Joined: December 01, 2005
Posts: 4855
Location: Kaneohe
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| Posted: Sun Jun 05, 2016 10:53 pm Post subject: Re: IR gun readings |
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More IR readings:
Ambient temperature 83º
After a half hour drive at speeds between 35 and 45 mph i pulled into the parking lot at Makapuu and idled around twice looking for a parking spot. After parking I left the engine idling while I shot temperatures.
water pump 192º and rising slowly
TS2 154
thermostat top 168.6
thermostat bottom 199.4
temperature sensor 202.1
upper radiator passenger's side 96.4 and decreasing
upper radiator driver's side 100.9
lower radiator driver's side 91.2
lower radiator passenger's side 92.3
While taking the engine readings the radiator fan came on. It went off while I was taking the radiator readings. The gauge was at the high "normal operating temperature" indication that the replacement sender causes. I did not see whether or not the LED came on. It was not on when I started the readings and it was not on when I finished. It is possible that it came on during the readings, but i will ASSuME that it did not.
The limitations of the IR gun are noted and during the time I shot a temperature and recorded it and moved to the next shot some of the temperatures might have changed. That is, the temperatures above are not all at one moment in time.
Bottom line:
Cooling system operates well.
I dislike the high gauge readings with the replacement sensor.
Aloha
tp |
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Ahwahnee
Samba Member
Joined: June 05, 2010
Posts: 9800
Location: Mt Lemmon, AZ
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| Posted: Mon Jun 06, 2016 7:23 am Post subject: Re: IR gun readings |
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| Tom Powell wrote: |
Bottom line:
Cooling system operates well.
I dislike the high gauge readings with the replacement sensor. |
If you are sure of that, then maybe this is for you:
http://www.gowesty.com/product-details.php?id=23433
You can do the same thing for about a buck by trial and error with a package of resistors. A pack of 33 ohm resistors should give you a good assortment that can be paired or put in series to get a suitable 'adjustment'.
A new sensor can change the reading due to variability in the units themselves and also if they get a better or poorer ground path upon installation. |
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