motc7777

I think I know that this likely is a bad t-stat, but just mentioning it here to see what you all think.

With engine cold, needle is at zero. Then after about 5 minutes, it goes all the way up past 100 just a bit, and stays there. Never goes any higher. BTW, I have run into this issue in the past, and yes, so far, my gas mileage is being affected.

t-stat, or something else you think?

2001 chevy silverado

changing your thermostat is easy but throwing parts is the wrong thing to do. a mechanic should always diagnose and exclude what does work, then bench test the unknowns and operate purely on fact.

however: you can't do that with a chinese "all in 1 instrument cluster" (which, btw, in the 1980's consumers protested againt). also you can't "see if the thermostat is working".

you can check hose pressures and temperatures but the thermostat goes into the engine (no hose to check). but you CAN check your indoor heater temperature after the car warms up. the engine cooling cuircuit design is the "older/better kind" it is simple. (in newer jap cars 5-tier cooling circuits are impossible to diagnose without serious time/work)

but jumping from 0 to hero tells me you may have a guage problem. 96-200x chevy guages are known to "stick" or go wild under certain conditions. you should never be at 0 after you start. you should be on ambient outdoor temperature (about 80-100 degrees?). there are articles to find on guage sticking issues and how they sometimes can be fixed without replacement on 96-299x chevy.

Do you have heat after 10 minutes of running? Do you have any other symptoms? Does your wax pellet fan (if your fan is not electric or on belt) never run or always run? Do you have bad gas mileage or some other symptom other than the guage reading?

motc7777

I found them, and those videos. Enlightening. However, my gauge isn't instantly going to 100. I'll explain more below.

I am having bad gas mileage.

• I started with my scan tool looking at live data. Temp started out on the tool at ambient temp right at start, and the temp gauge on the cluster matched it.
• As the engine warmed, I saw the temp increase. On the cluster it increased with the same pace showing on the tool.
• Finally, sitting at idle, was reading 182-185 F.
• I took it on a test drive, watching the scan tool and the gauge. It increased to 192-199 while out driving, and it's hotter than hell outside right now, with temps near 100 F. I had the AC running as well on full blast.
• It never got into the 200 range. I've tried looking online for the temp ranges, and from what I found, it says that with AC running I should be right on the 210 mark I believe. Is that right
• In fact, I gunned it hard after running for 20 minutes prior to driving it, and got it up to 85mph and the temp dropped to 192 on the scan tool. The gauge looked like it was keeping up with what I saw on my scan tool.

I don't think I have a sticking gauge, so t-stat issue it would seem?
​​​​​​​

motc7777

I was partially right and wrong about my issue.

1. I did have a t-stat problem. I went with this because, as I stated before, never hitting the 200F range at all, and gas mileage is crappy. Old t-stat literally was plastic, except for the spring. When I replaced it, scan tool showing temp around 203, but the gauge, while marginally better than before, still not reading right.

2. Was the temperature sensor for the cluster. Got one from Rock Auto, and replaced it tonight. Idled up for around 15 minutes and gauge is reading right near dead center.

Thanks for the guidance everyone. Gas Mileage is still crappy. I don't think the distributor cap and rotor, along with plug wires have been changed. Plugs have been awhile I'm sure. It just rolled 240K miles on the odometer this past weekend.

2001 chevy silverado

So you feel it's sitting in hot water or 100 deg weather and reads 0 right?

2001 era Chevy guages can "get stuck"

Leave it alone for a while it might come back by itself.

If it doesn't come back: take of the lower dash, pop the upper dash. Bump the needle genly to get it moving.

Do NOT open the speedo proper, it's anti-tamper and will quit working if you do, and you don't need to do that.

motc7777

I don't know if you saw on my previous reply, but the issue is resolved. It was a two part problem.

T-stat was starting to go bad for sure, and the temp sensor on the side of the engine block was bad. When I replaced the temp sensor, it's been reading correct now. When I start cold it's at 0, and then rises to ambient temp, then after running awhile gets up to operating temperature.

I've also verified with live data from my scan tool. Appreciate the follow up!