Another New Toy- Temp Reader

[spartonboat1]

I have a GM car with the some say "dreaded" orange anti-freeze. I agree- stuff can cause all sorts of problems (ate my water pump) and there are class action law suits around on this.

On to the toy---I was concerned that my engine might be overheating, plus my heater throws limited heat (another symptom of the orange coolant).

So I found a very nice instant temperature reader from my friends at Sears for $45...less that the $100 I expected. It is marketed as a reader for electricians to read panel temperatures. Has a laser marker to indicate the area you are trying to read...very nice. Has a broad temp range from below zero up to 700 deg. F.

I thought it worked great (engine temps appear ok, but heater hose output is cool...no flow I guess). Was very easy to use...point, press button, get instant temp.

Now I next plan to get some readings from the Hatt. The left engine always reads cooler than the right at all speeds.

Toys on a limited budget...

[mikep996]

Toys are great! IR temp readers are very useful BUT, like many "advanced" tools - like digital optical tachometers, etc., you can make yourself crazy for no reason.

Two engines will seldom exhibit the same temperatures at the spot at which you aim the probe. Thermostats themselves will vary + - 10 degrees from their "Specs." So two different engines could, in theory differ by 20 degrees with two brand new thermostats just because of the normal variation in the thermostats.

The distance from the IR probe to the surface will also cause the reading to vary somewhat. Also, engine castings/cooling passages vary from casting to casting - also causing a different surface reading from engine to engine.

My point is not that this isnt a good tool - it is. But you can go nuts for no reason, trying to ensure everything matches when it may be impossible to do so.

Optical tachs have the same issue - trying to match RPM between engines to a level that may not be possible, isn't necessary, and is not visible on the engine tachs at all.

These tools are wonderful and very conveniant - just don't make yourself a basket case!

[farauscher]

Be careful with them. They are very dependent on the surface material and treatment, the factor is emissivity. For example, black anodized aluminum has an emissivity of .82, whereas clear anodized aluminum is .76. The infrared pyrometers all make an assumption for an average emissivity value.

So, what they give you is a repeatable temperature estimate for a certain material and coating. Check one manifold, then check the another manifold. If they're similarly painted, it should be a good comparison and they should run at similar temps. But, if you take the same pair and paint one differently, you'll see a temperature change.

Now don't get me wrong. I think they're great tools. You just have to understand their limitations so that you can use them effectively.

[wshelton]

I've got one of these neat gagets and have used it alot to check engine temps etc. I have a question about this "emissivity" isuue regarding like materials. I would be interested in knowing if the reading I took at the exhaust outlet outside the boat of my power plant would be an accurate reading? I have shot the water coming out of the exhaust at about 2 feet away and got a reading of approximatley 113 degress with the ambient water temp in the 80's. Would this reading be accurate and is this about what this water temperature should be. I have always thought this generator never put out enough raw water assuming everything was working properly. (good impeller, no hose restrictions etc.). FYI, Onan 7.5 diesel..

[farauscher]

But, I recommend that you take a large styromfoam cup (its a good insulator) and fill it with the exhaust water. Then, throw in a good baking thermometer and measure the temperature. Now you know the difference between your pyrometer and the "true" temperature for your exhaust water.

With this information, you can start to regularly check and record the exhaust water temp. If you start to see a bad trend, you know something is getting worse. Of course, this assumes that it is properly working now.

Fred