How to check the temp guage's accuracy?

[AaronM]

My car's non-numbered temperature guage gets very close to the red zone if I drive for an hour or so, but my cooling tin is in good shape, my impeller isn't missing any blades, the flaps are operating properly, and I'm running 20W50 Mobil 1. The engine also doesn't stink or lose any power when the oil temp guage is reading that high. Not only that, but if I let the car sit for 5 minutes or so, then when I start the car again, the needle is no longer nudging the red zone, but is roughly in the middle, though it climbs back up close to the red zone with about another 10 minutes of driving.

My theory is that either the guage or the sender has succumbed to old age and is no longer reading at the proper level. I know that it's possible to test the sender on my 924S with a multi-meter, can something similar be done with the 914?

Aaron

[Dave at Pelican Parts]

Not really...

If you want to check it, take it out but leave it hooked up (ground the threads). Dip it in boiling water and see what the gauge says. You'll likely need a camp stove for that.

You can also use one of those infra-red pyrometers to get at least a vague idea of the oil temp. Or you could put a thermocouple sender on the end of the dipstick and shove that all the way down into the sump and measure its output.

--DD

[pbanders]

Recently, many cheap DMM's (digital multimeters) have thermocouple attachments. Do what DD suggests, but insert the thermocouple in the water, too, so that you can get a direct reading. Only at sea level are you going to get 100 C for boiling. I found when I was temperature calibrating the response of the TS2 sensor that I had to do this to get accurate readings using boiling water as a temperature setpoing.

[Barber Dave]

Aaron: I have 4 or 5 oil temp. gauges , 1 is nos. bring your 914 over to my house ,we can hook them up in succession and get a average that way. Dave

[Joe Bob]

A hand held pyrometer is a good thing to have.....I use it on a lot of things. Temps on tires, heads, oil, calibrated my oven, etc....

Personally, RANT MODE ON.....the 914 temp w/o numbers was a piece of crap back when it was installed and is still 30 years later......

It varied in readings from one car to the next, never did squat unless it was pegged.....

IMHO, buy a new VDO guage and sender with numbers, trash the stock one and be satisfied with new equipment. What's 100 bucks when an overheated engine will cost ya much more....

RANT over.....back to your regularly scheduled meltdowns.....