Hey everyone I would like to get everyone's input on a question I have. I have an Autometer short sweep electric water temp gauge and I can visually watch it move to different temps depending on engine temp. Now, here is my question, why is this? I have a 93 Buick Roadmaster and once it's warmed up, the temp gauge NEVER moves. The same was so for my 93 Honda Civic, 98 Mitsubishi Turbo Eclipse, and my 88 Nissan Hardbody Pickup. Why is it that I can see the temp gauge move in my Camaro? As far as I know, thermostats work the same no matter what type of car it's in and electric fans work the same no matter what type of car it's in. Hell, clutch fans work the same no matter what type of vehicle it's in. In fact, my Nissan Hardbody was a clutch fan and once it warmed up, it never moved. Why is it that my Camaro temp gauge moves all around? Thank you.

Dunno. The short sweep electric gauge in my Camaro does some moving around, too. With a 180 thermostat, mechanical fan, and alluminum rad, she might get to 185 in traffic on a hot day. down to 175 on the highway, and on cold days she never gets over 165 or so.

My truck runs at 210, period, and every day, any every weather.
The vette runs at 195, period, tho before I cleaned the crud out of the radiator I had some major temp gauge movement.

I can't understand it. I know my rad is clean(new). EVERY other car I have ever owned has warmed up and staying rock steady, unless there was a problem(blown head gasket, low coolant, etc.). Like you said, in cold weather it stays on 165 with a 180 thermo, but in warm weather it goes to 200*(electric fan turn on) and then drops to 185*(fan turn off). They should operate the same as any other vehicle.

On a side note, do they make a fan switch for people who run a 195* thermostat? I have the 180 and in order to get my fan to cycle, I have to run the 200 on and 185 off. For the 160 thermostat you would run the 185 on and the 170 off. What do people do for a 195 thermostat? If I used the 200 on and 185 off, my fan would never cycle. Once on always on. Can I go to the parts store and buy a fan switch for a new car that runs on a 195* thermostat? As long as the threads are the same, it should work. I believe the thread size is 3/8NPT.

I believe you may have a defective or weak stat which is opening and partially closing continuously.....I never have that problem however I'm running a mechanical gauge which I believe are more accurate.

Badbird, so you are saying that once you car warms up, the gauge never moves? I have had three different stats, all do the same. Current stat is a Balanced Stewert's stat.

Badbird, so you are saying that once you car warms up, the gauge never moves?


That's correct!:yes:.....Basically "the song remains the same", unless it's really, really hot outside!:yes:

Also, be advised, I'm running a 180 stat.

New cars do that because the manufactureres have HEAVILY damped gauge movement so that the guages barely move once they have reached operating temperature. People panick when they see there temperature going up and down, and they bring their cars down to the dealers for service wasting everyones time. The gauge in my Cadillac STS moves about a 1/2 a needles width from 195 degrees to 225 degrees. Theres even one manufacturer that has a completely fake temperature gauge in their cars that has no relation to the actual temperature of the water. Older cars with gauges and aftermarket guages don't have this dampening and have a tendency to swing around quite a bit.

A discussion came up in the work shop morning tea last week
A custmoers japper car the temp needle moved more and hovered in a slightly diffeerent place...wasnt an issue just a piont of interst
A nice old retired gentleman, long time customer.
He resently had work on radiator, alternator, aircon, thermostat , and a few other bits and pieces...
Darrly, a very cleverand good mechanic, put it down to a combo of load on the battery, alternator, air con on off....
So after morning tea , just to ONCE prove Darrly wrong ...we put the test gear on
But once again it was a wate of time, it just proved Darrly was right on the nail AGAIN!
The voltage to the temp gauge varied slightly as to the load on the battery and alternator.
Darrly also mentioned, thu it was not the case with this car, such a variation is a early indication that an alternator could be going down..but could be months away before it does.

Maybe its the same in your case?

Steps, My alternator is a special built 250amp CS style unit. I know that it's not problem. I have a competition style stereo system in my Camaro and I can play the stereo at VERY VERY high volume, heater on full, wipers going and the volt gauge NEVER moves off 14.6. It's definately not the alternator.

Mark, when you say new cars have closely modulated gauges, the gauge in my Roadmaster is a simple needle that moves back and forth. It's not even closed in like an Autometer gauge. You can see the "GUTS". No liquid or anything. You may be right about that part, but I can't see the factory doing that because what if something was actually wrong and the car caused some kind of major injury to the passengers? They would be in for a MAJOR lawsuit. Here is an example. When my father bought the Roadmaster, he ordered it with the towing package. It also came with a crappy style plastic spoke wheel. Well, he wanted the better wheels. When they changed the wheels, they took them off of another Roadmaster without the towing package and the tire size was different. We noticed this and returned to the dealer who gave us 5 new tires free due to the liability factors. This would be the same with anything in a new car that could cause bodily harm to a consumer.

I really feel like there is something else we are overlooking on this issue.

Hey everyone I would like to get everyone's input on a question I have. I have an Autometer short sweep electric water temp gauge and I can visually watch it move to different temps depending on engine temp. Now, here is my question, why is this? I have a 93 Buick Roadmaster and once it's warmed up, the temp gauge NEVER moves. The same was so for my 93 Honda Civic, 98 Mitsubishi Turbo Eclipse, and my 88 Nissan Hardbody Pickup. Why is it that I can see the temp gauge move in my Camaro? As far as I know, thermostats work the same no matter what type of car it's in and electric fans work the same no matter what type of car it's in. Hell, clutch fans work the same no matter what type of vehicle it's in. In fact, my Nissan Hardbody was a clutch fan and once it warmed up, it never moved. Why is it that my Camaro temp gauge moves all around? Thank you.

All systems have a response time, some are faster than others. Stock systems are well damped because folks get alarmed when the gauges are moving.
If you want to see some changes in system response time, use your oil pressure gauge for an experiment. Start with 10 feet of 1/8" tubing then swap to about 12" of 3/8" tubing as your gauge line. You will definitely be able to see every pulse of the oil pump with the larger line. If you were to instrument the system with some real quick response sensors, you might actually be able to detect that your oil pressure goes to zero more often than you think.

Nova, you are comparring two different types of gauges. Oil is mechanical where the water temp is electric. BadBird says once his warms up, it NEVER moves. How do you explain that? I surely can't. He is using a full sweep mechanical gauge which has a larger temp range shown on the dial so his would show more than even mine would and he said his stays steady. I can't understand it.

Response time isn't based on what kind of gauge you have, it is usually referenced to time to full scale. If your mechanical oil pressure gauge will take ten seconds to respond to a full scale step change and your electric temperature indicator takes the same ten seconds for a full scale step change, they would have the same response time. Mechanical gauges use different means to set the response than electric meters, but the result will be the same.

Guages (both electrical and mechanical) can DEFINITELY be damped to slow needle movement.

Wanna do a test? Disconnect the fuel sender wire in the trunk and watch how long it takes the gas gauge needle to peak, it will be nearly 10 seconds.

Now take the sender wire off that autmeter temp gauge. Ground it to the block, then unground it. The gauge wil go "Flip" "flip" the needle will move full scale almost instantly, MUCH faster than any mechanical gauge can.

Wanna try another? Mechanical temp gauges are VERY slow by nature. Put the bulb from room temp into a pan of boiling water. It will take a good 10 seconds for it to go from 70 to 212 degrees.

Onovakind, I agree with you completely this time!
And I don't even think you are splitting hairs or overly complicvating the discussion for no reason!

Onovakind, I agree with you completely this time!
And I don't even think you are splitting hairs or overly complicvating the discussion for no reason!

You are most definitely in my will.

I was not trying to discount Nova's findings. I was asking for clarification. I am just a little confused on this response time. If a mechanical gauge moves slower than an electric gauge then how can the response times be the same? To me response time is reaction to something else. For example, Dwight Freeney from the Colts has a GREAT ball snap reaction time and our Baltimore Ravens Johnathon Ogden found that out when he couldn't keep Freeney from the QB. The time it takes to change readout from the time the signal changes, to me is response time. If the mechanical gauge does move as soon as the signal changes, then its response time is slower than an electric gauge. My electric temp gauge, apparently responds very quickly to voltage variances, where the mechanical temp gauge must have a slower reaction time if what you are saying is true. Perhaps it's not that fact that the factory gauges are dampened, perhaps they have slower reaction times and they can't keep up with the rapid change in coolant temp signals like an electric gauge can?

Nova, you may be saying the same thing I am, but in a different way. I am not saying you are wrong, but maybe I am just not getting what you are saying, the way you are saying it. Sorry.

I didn't say that your gauges have the same response time. The response time is what it is.
There are many things that contribute to response time and some processes are inherently slower than others. You can change the oil pressure in your engine a lot faster than you can change the temperature. Your choice of temperature sensor will have a definite affect on your response time. If you use a low mass thermocouple in an electric sensor as opposed to the big capillary slug in a mechanical sensor, your thermal time constant is reduced considerably. You can only indicate change as fast as you can read it.

Response time is a "design factor" in any measuring device. For that matter in lots of devices.

It's generally "known" what designs of device tend to be fast or slow. Mechanical pressure gauges are capable of being very fast. Electric gauges can be very fast. Mechanical temp gauges are generally very slow.

But all can be designed with different levels of internal damping to speed them or slow them.

One good example is the temp guage in my 93 vette. This is an electric gauge, with both an analog (needle and scale gauge) and a digital readout (I can display the temp digitally on the driver information LCD display.)

The analog gauge is relatively slow and does not show small changes at all.
The digital readout has a resolution of 1 degree, and shows any change instantly.
Both run off the same sender.

Ok, so mechanical gauges usually react to changes slower than electric gauges? Now I am getting a clearer picture. So by the time the mechanical gauge can register a cooler temp change, the temp has already risen again so the needle hardly moves? Is this right? Where as the electric gauge can react to changes in temp faster therefore showing a larger fluctuation in the needle movement?

You're getting the idea. The rate of change of the needle is based on the time constant of the device and by the amount of change in the process.