Apco temp gauge error?
 

Got my infrared gun out and took my truck out again. I ran her 45 mph and the gauge ran up to the red line 190 but not over. I stopped kept engine running and checked with gun. Block was 180 and upper inlet hose where sensor is was 165-170. Also the Motometer was up about an inch well below the marks for average summer temp

Radiator top was 160 bottom 145

So is the gauge off?

I did shut it down and did not take long for gauge to drop to 160 but head temp was lower around 155.

Obviously the engine is not overheating...

Has anyone else have this happen with the APCO gauge?

Thanks much.... THINK SPRING

Re: Apco temp gauge error?
 

That's the main reason not to have a gauge ,..,. wont read right ., the temp probe needs to be in the head completely under water ,..,..,
If an A model runs hot ,.. it will tell you ,.. .,.

,..,?/

Re: Apco temp gauge error?
 

Re: Apco temp gauge error?
 

Barkleydave,
I have the same issue with the APCO gauge in my 28 Roadster. I was concerned the engine was running hot as the needle was 3/4 through the green on flat running then bordering the start of the red zone on climbing a hill. On checking with a digital heat gun I found the temp adjacent the probe was 80 degrees C and less as I went down the radiator. Clearly there was no overheating and the gauge was reading high.
I think a correctly working temperature gauge is a great tool to monitor the engine. I recently did the timing on my 30 TS and accidentally set the timing to far retarded. This showed up on my first drive when I noticed the engine running hotter than normal. A recheck showed my mistake and on correcting it the engine returned to its normal running temps. The TS gauge was purchased a few years ago whereas the Roadsters is more recent.

Cheers,
Gavin

Re: Apco temp gauge error?
 

Also be aware of the sample area of your infrared gun - the sample area is usually BIGGER than the laser dot, and it get's much bigger as you get further away from the surface. The emmissivity of the surafce varies too - If you really want to check test the gauge probe in a fluid like MikeK says, and compare to a calibrated thermometer or similar reliable source.

Re: Apco temp gauge error?
 

Chuck went through 4 (FOUR!) NEW NAPA gauges, to find 1 (ONE!!) that was correct when he boiled them! (Be sure NOT to let them touch the bottom of the pan, when testing. When the water's fiercely BOILING, it should read 212 degrees.) Some mechanical thermometers have a nut on the back & some can be adjusted by turning the stem on the back, a TINY bit. An electric guage that reads too high, can be corrected by adding a 10 Ohm or so, carbon resistor to the sender wire. The color rings on a 10 Ohm one is, BROWN, BLACK, BLACK, & a SILVER or GOLD ring that indicates accuracy range.
Bill W.

Re: Apco temp gauge error?
 

Great to have this input!!! I contacted Snyder's and received a fantastic response!

They also mentioned that a 10 percent error was pretty common with these gauges. They offered to send another gauge for me to try. I am going to take them up on that and test it and compare to the gauge I have installed.

I know the engine is not overheating. I did notice a nut on the back side of the APCO but no mention of its purpose in the instructions? I did not touch it for fear of messing up the gauge.

Again GREAT SERVICE AND SUPPORT FORM SNYDER'S !!!! THEY RESPONDED TO MY E MAIL IN LESS THAN 24 HRS!