IR Temp Gun Readings - Defender Source
Defender Source  

Go Back   Defender Source > Defender & Series Technical Discussions > Defender Technical Discussions


Reply
 
Thread Tools
  #1  
Old February 2nd, 2015, 05:24 PM
Ncrover725's Avatar
Ncrover725
Status: Offline
Bobby
1985 110
Member
 
Join Date: Jan 2012
Location: Colorado Spings, CO
Posts: 636
Registry
IR Temp Gun Readings

I was having some issues with my OEM temp gauge and installed a VDO gauge today. I also purchased an IR temp gun to confirm my temp to ensure the gauge was working as it should. On a 300tdi where is the most accuarate place to get a reading and how far off off the location are you holding your gun? Right now I am averaging 10 degrees cooler from the gun reading than what the gauge states (Gauge reading warmer).
__________________
Bobby
1985 110 5 Door
1991 90
1998 D1 (Sold)
1971 109 3 Door (Sold)
Reply With Quote
Sponsored Links
Advertisement
 
  #2  
Old February 2nd, 2015, 05:30 PM
Uncle Douglas's Avatar
Uncle Douglas
Status: Offline
Doug Crowther
A defender in every driveway-motto
D-90 Source Vendor
 
Join Date: Dec 2007
Location: Gods Country- Central Virginia
Posts: 11,835
Registry
Id shoot the casting right next to the sensor for the gauge to know how far off the two are. Then try the water outlet elbow (where the top radiator hose connects). In theory that elbow should be the highest temp of your cooling system.
__________________
Good judgement comes from experience,experience comes from bad judgement.

Dividing Creek Imports
Worldwide Vehicle Shipment and Importation Service
Restoration & Modification work


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

410.693.1391


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote
  #3  
Old February 2nd, 2015, 06:01 PM
sloanfiske's Avatar
sloanfiske
Status: Offline
Anthony Nelson
97 D90 SW
Member
 
Join Date: Mar 2008
Location: New York
Posts: 435
Registry
Same issue I've had. Apparently it's common.

Check the thread VDO temp sensor issue I started a couple months ago.
Reply With Quote
Sponsored Links
Advertisement
 
  #4  
Old February 2nd, 2015, 06:08 PM
javelinadave
Status: Offline
-
-
Member
 
Join Date: Sep 2003
Location: -
Posts: 5,394
Quote:
Originally Posted by sloanfiske View Post
Same issue I've had. Apparently it's common.

Check the thread VDO temp sensor issue I started a couple months ago.
http://www.defendersource.com/forum/...ad.php?t=55393
Reply With Quote
  #5  
Old February 2nd, 2015, 06:25 PM
nathanwind's Avatar
nathanwind
Status: Offline
Jason Lavender
88-90-127-LR3
D-90 Source Vendor
 
Join Date: Jan 2008
Location: Saratoga NY
Posts: 8,741
Registry
Along these lines...what is the temperature "loss" from where the sender threads in internally (i.e. where the sender tip is) and the outside of the casting? Isn't there - in theory - some temperature loss either across the sender (i.e. if you're measuring the outside terminal versus the inside "tip" of the sender), and the same with the casting?

I was wondering about this as well, since I too was thinking mine was running "warm"...but what I would see at the gauge as 190* would be 170* @ sender, 173* @ the stat housing, and 189* @ the elbow. While I was more comfortable with this, I still wasn't convinced that the sender wasn't measuring a more accurate internal temperature, while I was in essence measuring the external temperature.

I also tested the ohms reading of the sender (per VDO specs that they sent me), and that did match up with what the gauge was reading. Which made me think even more that there is a loss of temp across the material(s) from the internal temp to the external temp.
__________________
Jason Lavender
'71 Series IIA
'88 127 #F96 DKN
'94 90 NAS #324
'06 LR3 HSE

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

(10% discount for DSource members, use coupon code "D90")

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote
  #6  
Old February 2nd, 2015, 06:33 PM
javelinadave
Status: Offline
-
-
Member
 
Join Date: Sep 2003
Location: -
Posts: 5,394
Quote:
Originally Posted by nathanwind View Post
Along these lines...what is the temperature "loss" from where the sender threads in internally (i.e. where the sender tip is) and the outside of the casting
If we want to geek out thermodynamically this could turn into an old fashion math orgy but...... once the entire cooling system is up to temp the difference would be negligible between the actual probe and the sensor body.
Reply With Quote
  #7  
Old February 2nd, 2015, 06:35 PM
nathanwind's Avatar
nathanwind
Status: Offline
Jason Lavender
88-90-127-LR3
D-90 Source Vendor
 
Join Date: Jan 2008
Location: Saratoga NY
Posts: 8,741
Registry
Quote:
Originally Posted by javelinadave View Post
If we want to geek out thermodynamically this could turn into an old fashion math orgy but...... once the entire cooling system is up to temp the difference would be negligible between the actual probe and the sensor body.
That is good to know...so looks like I'm up against what seems to be the "norm" of a 20* difference between the IR gun (a nice Fluke) and what the VDO reads. I'll try a fresh dedicated ground wire as recommended and see how that works out.
__________________
Jason Lavender
'71 Series IIA
'88 127 #F96 DKN
'94 90 NAS #324
'06 LR3 HSE

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

(10% discount for DSource members, use coupon code "D90")

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote
  #8  
Old February 2nd, 2015, 06:42 PM
javelinadave
Status: Offline
-
-
Member
 
Join Date: Sep 2003
Location: -
Posts: 5,394
The VDO temp sensor is imbedded in the brass housing so it is actually reading the brass temp and not the actual coolant temp.

Reply With Quote
  #9  
Old February 2nd, 2015, 06:44 PM
DannyboyUpstate's Avatar
DannyboyUpstate
Status: Offline
Danny Harrington
1983 110 3-door
Member
 
Join Date: Oct 2013
Location: Albany, NY!!
Posts: 395
Registry
I use infrared temperature meters at work all the time. You have to be careful sometimes when you shoot something shiny, it will throw off the reading.

Also my VDO gauge was all over the place until I replaced my engine ground. Now the readings are solid as a rock. I don't care if the reading is accurate, I just want to make sure I can see the big changes.
Reply With Quote
  #10  
Old February 2nd, 2015, 06:49 PM
Red90's Avatar
Red90
Status: Online
John B.
1991 Defender 90, 200TDI
Site Team
 
Join Date: Sep 2003
Location: Calgary
Posts: 9,233
Registry
Yah, keep in mind IR readings are not that accurate. They need to be calibrated for each surface.
__________________
Pissing people off on the "net" since 1983.

Land Rover. Turning owners into mechanics since 1948.
Reply With Quote
  #11  
Old February 2nd, 2015, 06:56 PM
Uncle Douglas's Avatar
Uncle Douglas
Status: Offline
Doug Crowther
A defender in every driveway-motto
D-90 Source Vendor
 
Join Date: Dec 2007
Location: Gods Country- Central Virginia
Posts: 11,835
Registry
Quote:
Originally Posted by nathanwind View Post
Along these lines...what is the temperature "loss" from where the sender threads in internally (i.e. where the sender tip is) and the outside of the casting? Isn't there - in theory - some temperature loss either across the sender (i.e. if you're measuring the outside terminal versus the inside "tip" of the sender), and the same with the casting?

I was wondering about this as well, since I too was thinking mine was running "warm"...but what I would see at the gauge as 190* would be 170* @ sender, 173* @ the stat housing, and 189* @ the elbow. While I was more comfortable with this, I still wasn't convinced that the sender wasn't measuring a more accurate internal temperature, while I was in essence measuring the external temperature.

I also tested the ohms reading of the sender (per VDO specs that they sent me), and that did match up with what the gauge was reading. Which made me think even more that there is a loss of temp across the material(s) from the internal temp to the external temp.
One is meant to read the actual coolant temp, the other is the surrounding casting. Obviously, one can quickly change the other is slow to change.
__________________
Good judgement comes from experience,experience comes from bad judgement.

Dividing Creek Imports
Worldwide Vehicle Shipment and Importation Service
Restoration & Modification work


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

410.693.1391


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote
  #12  
Old February 2nd, 2015, 07:05 PM
sonoronos's Avatar
sonoronos
Status: Offline
Ed
None
Member
 
Join Date: May 2010
Location: Arlington, VA
Posts: 5,530
Registry
emissivity of the material being measured makes a big difference
Reply With Quote
  #13  
Old February 2nd, 2015, 07:15 PM
nathanwind's Avatar
nathanwind
Status: Offline
Jason Lavender
88-90-127-LR3
D-90 Source Vendor
 
Join Date: Jan 2008
Location: Saratoga NY
Posts: 8,741
Registry
Quote:
Originally Posted by sonoronos View Post
emissivity of the material being measured makes a big difference
I'm pretty sure this is what I was trying to say. But i said it in English .
__________________
Jason Lavender
'71 Series IIA
'88 127 #F96 DKN
'94 90 NAS #324
'06 LR3 HSE

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

(10% discount for DSource members, use coupon code "D90")

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote
  #14  
Old February 2nd, 2015, 07:17 PM
rover4x4's Avatar
rover4x4
Status: Offline
Phillip
1995 SW #487/500
Member
 
Join Date: Sep 2003
Location: The Old North State
Posts: 7,523
Registry
What you recon it is at the back of the block
__________________
Poor gas mileage gets you to the best places on earth
Reply With Quote
  #15  
Old February 2nd, 2015, 09:43 PM
sloanfiske's Avatar
sloanfiske
Status: Offline
Anthony Nelson
97 D90 SW
Member
 
Join Date: Mar 2008
Location: New York
Posts: 435
Registry
Quote:
Originally Posted by nathanwind View Post
That is good to know...so looks like I'm up against what seems to be the "norm" of a 20* difference between the IR gun (a nice Fluke) and what the VDO reads. I'll try a fresh dedicated ground wire as recommended and see how that works out.
I ran a dedicated ground with no change. Let me know if it works for you and where you planted the ground as I'll try again at some point.

I've gotten used to the 10* or so difference now. I know it's not overheating for sure.
Reply With Quote
  #16  
Old February 2nd, 2015, 09:48 PM
nathanwind's Avatar
nathanwind
Status: Offline
Jason Lavender
88-90-127-LR3
D-90 Source Vendor
 
Join Date: Jan 2008
Location: Saratoga NY
Posts: 8,741
Registry
Quote:
Originally Posted by sloanfiske View Post
I ran a dedicated ground with no change. Let me know if it works for you and where you planted the ground as I'll try again at some point.

I've gotten used to the 10* or so difference now. I know it's not overheating for sure.
Will do. My main concern is the voice in the back of my head that keeps telling me the gauge is right, and the IR reading could be off or there is a loss of temp across the material from inside to outside.

The one definitive tell would be to tap a mechanical gauge in the system to get a real true internal reading.
__________________
Jason Lavender
'71 Series IIA
'88 127 #F96 DKN
'94 90 NAS #324
'06 LR3 HSE

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

(10% discount for DSource members, use coupon code "D90")

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote
  #17  
Old February 2nd, 2015, 10:04 PM
javelinadave
Status: Offline
-
-
Member
 
Join Date: Sep 2003
Location: -
Posts: 5,394
Quote:
Originally Posted by nathanwind View Post
Will do. My main concern is the voice in the back of my head that keeps telling me the gauge is right, and the IR reading could be off or there is a loss of temp across the material from inside to outside.

The one definitive tell would be to tap a mechanical gauge in the system to get a real true internal reading.
It's a motor, not a nuclear reactor. 10 degrees isn't going to hurt anything since you know which way hotter or colder it reads. It's also a hell of a lot more accurate that the original gauge.
Reply With Quote
  #18  
Old February 2nd, 2015, 10:04 PM
sloanfiske's Avatar
sloanfiske
Status: Offline
Anthony Nelson
97 D90 SW
Member
 
Join Date: Mar 2008
Location: New York
Posts: 435
Registry
Quote:
Originally Posted by nathanwind View Post
Will do. My main concern is the voice in the back of my head that keeps telling me the gauge is right, and the IR reading could be off or there is a loss of temp across the material from inside to outside. The one definitive tell would be to tap a mechanical gauge in the system to get a real true internal reading.
I've got a 97 NAS V8, so I'm able to hook up the obd2 scanner to get the engine temp reading. It's always about 10 degrees cooler than what's on the gauge.

It's a bit of "horseshoes and hand grenades" right now.
Reply With Quote
  #19  
Old February 2nd, 2015, 10:05 PM
Viton's Avatar
Viton
Status: Offline
Deaf Ember
Smart 4x4
Member
 
Join Date: Jan 2009
Location: La
Posts: 1,231
On your IR gun, does it indicate the accuracy range ? Many are +/-5F.
Mine is +/- 2F.
Reply With Quote
  #20  
Old February 3rd, 2015, 09:24 AM
sonoronos's Avatar
sonoronos
Status: Offline
Ed
None
Member
 
Join Date: May 2010
Location: Arlington, VA
Posts: 5,530
Registry
yeah, basically it has nothing to do with thermodynamics. different materials have different surface emissivities. the temp gun has no idea what you are pointing at, so it assumes some calibrated emissivity. this is why temp measurements differ.
Reply With Quote
Reply

Lower Navigation
Go Back   Defender Source > Defender & Series Technical Discussions > Defender Technical Discussions

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
False Gauge Readings Shearpin Defender Technical Discussions 1 August 18th, 2008 11:17 PM
Gun nut test Rod Hayward Misc. Chit-Chat 9 January 12th, 2008 11:20 PM
Unusual oil pressure readings. bomilcar Defender Technical Discussions 3 October 30th, 2007 05:53 PM
OEM Land Rover Gun Box RFA Wanted 4 February 20th, 2005 09:14 PM
rivnut gun mattdh Defender Technical Discussions 6 March 30th, 2004 06:46 PM


All times are GMT -5. The time now is 02:17 PM.


Copyright