Infrared Thermometer Gun

richard5933 · June 15, 2017, 03:10:00 PM

We're picking up our bus tomorrow for the journey home. One worry I have is that during our (pretty lengthy) test drive the temp gauge didn't appear to be functioning.

So, in the interim I bought an infrared thermometer gun so that I could do my best to monitor the situation until the gauge is repaired. The drive home is about four hours from Rochester MN to the Milwaukee area. Not a terribly taxing drive, but the weather is in the upper 80s this week and I don't want my first journey to end in failure.

Question for the experts out there...

Where should I be pointing this thing? What measurements am I hoping to find? I know that internal temp as measured by the sending unit(s) might be different than what an external temp would be, so i thought it best to know what I'm looking for.

Also, since I have this handy-dandy temp gun, I'm assuming it can be useful to monitor things like brakes (for drag, etc) tires, and more. Any suggestions on where else to use this little gadget?

Thanks!

luvrbus · June 15, 2017, 03:27:47 PM

Pay close attention to the instructions that came with gun they are not all created equally, if the gun has a fixed emissivity setting different colors will read different temps and watch the spot range your reading will be all over the map if not careful.I don't know what gun you purchased but I hope you bought a good one that adjusts

richard5933 · June 15, 2017, 04:18:03 PM

Quote from: luvrbus on June 15, 2017, 03:27:47 PM
Pay close attention to the instructions that came with gun they are not all created equally, if the gun has a fixed emissivity setting different colors will read different temps and watch the spot range your reading will be all over the map if not careful.I don't know what gun you purchased but I hope you bought a good one that adjusts

The emissivity is adjustable... Came from the factory set at 95 I believe.

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eagle19952 · June 15, 2017, 04:54:39 PM

Quote from: richard5933 on June 15, 2017, 04:18:03 PM
The emissivity is adjustable... Came from the factory set at 95 I believe.

Sent from my SM-G935V using Tapatalk

i would be aiming it at the sending unit....

but... i would at least wire a secondary gage to the sending unit....it might prove that it works and takes two-ten minutes and $10 to install...way cheaper than an engine

why wouldn't u fix it ? you can't aim a temp gun from the drivers seat

Jaymz · June 15, 2017, 04:56:21 PM

In my extremely short experience is a het gun won't do much good. Let's say your water pump is slipping on the shaft at higher RPMs. You may overheat while under a load, but by the time you pull over, walk back and open the door, point the gun, your back to a normal temp. Point is, spend the $35 and get a thermostat and a spool of wire and temp install a gauge. It's what I did and took me 15 min. Toughest part will be to find a 12V source near the gauge
Good luck

PP · June 15, 2017, 04:59:36 PM

Quote from: Jaymz on June 15, 2017, 04:56:21 PM
In my extremely short experience is a het gun won't do much good. Let's say your water pump is slipping on the shaft at higher RPMs. You may overheat while under a load, but by the time you pull over, walk back and open the door, point the gun, your back to a normal temp. Point is, spend the $35 and get a thermostat and a spool of wire and temp install a gauge. It's what I did and took me 15 min. Toughest part will be to find a 12V source near the gauge
Good luck

For the short term this is what I would do too. I use my temp gun for keeping an eye on axle bearing temps mostly. But whatever you decide, have a safe trip and come back to the board and let us know how much fun you had on your maiden voyage.
Will

richard5933 · June 15, 2017, 05:36:55 PM

Okay - this all makes sense. Hopefully the previous owner will be able to show me where the sending unit is so I can string up a temporary gauge. There is a box of manuals, but I have no idea if the proper one is in there for this.

Anyone have a picture of what I'm looking for? It is a 8v71 in a 1964 PD4106 and Allison automatic.

Does the gauge usually run single wire or double? (Assuming that electric gauges will be the common option here)

J_E · June 16, 2017, 05:13:58 AM

Another thing to keep in mind: infrared temp guns look at an area. Something like a 1.5" circle at 12" or what ever the applicable ratio is for that gun (it's printed on the side). The better the gun, the better the ratio to an extent. Take that into consideration when you use it. If the point you are trying to read is near the exhaust and you are a fair distance away, it could skew your numbers.

luvrbus · June 16, 2017, 05:27:51 AM

Quote from: J_E on June 16, 2017, 05:13:58 AM
Another thing to keep in mind: infrared temp guns look at an area. Something like a 1.5" circle at 12" or what ever the applicable ratio is for that gun (it's printed on the side). The better the gun, the better the ratio to an extent. Take that into consideration when you use it. If the point you are trying to read is near the exhaust and you are a fair distance away, it could skew your numbers.

A good IR gun costs you to me the H/F gun is worthless shooting a chrome or shinny spot but for 20 bucks they beat nothing

J_E · June 16, 2017, 02:13:35 PM

I wasn't trying to say that you need an expensive IR gun. I was just trying to give folks a heads-up that there is a little more thought that goes into it beyond point, shoot, read temp. My favorite personal IR "gun" is about the size of a key fob and from back when I ran Nitro RC cars. The only thing is that if you are not practically right up on whatever you are trying to read, you will get some funny numbers.

When my employer is buying the tools, we buy better quality tools. For my personal tools, often as not, I buy the cheapest tool to get the job done correctly. If I use it alot and it fails, then I start looking at the higher quality options.

luvrbus · June 16, 2017, 02:22:05 PM

Quote from: J_E on June 16, 2017, 02:13:35 PM
I wasn't trying to say that you need an expensive IR gun. I was just trying to give folks a heads-up that there is a little more thought that goes into it beyond point, shoot, read temp. My favorite personal IR "gun" is about the size of a key fob and from back when I ran Nitro RC cars. The only thing is that if you are not practically right up on whatever you are trying to read, you will get some funny numbers.

When my employer is buying the tools, we buy better quality tools. For my personal tools, often as not, I buy the cheapest tool to get the job done correctly. If I use it alot and it fails, then I start looking at the higher quality options.

Failures were my problem I spent so much on cheap guns I could have bought a good one to start with and been money ahead

I own a good gun now

DoubleEagle · June 16, 2017, 04:32:26 PM

A good gun would be something like one of the Fluke models that send out two laser dots, and the temperature is read between the dots. The more the gun costs, the higher the accuracy (generally).

richard5933 · June 16, 2017, 05:46:58 PM

The gauges seem to be having some electrical issues, so I didn't try to wire a new temp gauge. That's a project for the shop Monday. PO said he's never had a overheat problem, so I stopped frequently and checked.

Temp external at water pump was about 165-170. Ditto for radiator top and bottom hoses. Won't try another trip un-gauged, but things worked out nicely this time. Now it's on to find the leak in the Perkins generator engine (fuel pump)...

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PP · June 16, 2017, 06:40:41 PM

Glad to hear you didn't have any problems on your trip. I'm a gauge watcher (OCD) so not having a temp gauge working would drive me nuts. The only gauge on my dash that isn't accurate is the fuel gauge, it's always on the half mark. I'll let you decide if that's half full or half empty,

Will