Need temp gauge help!

My temp gauge quit working in the '69. I've replaced the gauge and sender, still nothing. I briefly grounded out the wire and the gauge went up to the top, so it's seems be be OK. Any other ideas? I can't figure this out.

Thanks,
Matt

It seems like it might move just a little bit off the bottom, but not much. I made sure the engine got good and hot. The gauge is new from Corvette Central and the sender is from lectrical limited.

If you grounded the wire that goes to the gauge and it went up, the problem is at the sender.
Either you have a new bad sender,...OR the sender is not grounded. It may not be making contact to the engine. Did you use teflon tape? That can insulate the electrical contact. Use RTV or even better, nothing. It is a pipe thread and will seal without anything in most cases.

Thanks Ken! It seems to be working now, but it only goes up to about 130 degrees, what is normal operating temp? This seems a little cool.

Matt

My guess is you still have a poor ground at the sensor, 130 is too cool.

But before I make that leap of faith, the gauge may be correct. Was the engine running long enough? Perhaps a bad thermostat not allowing it to warm up? Use another temp measurement of some type to make a compairson. Then go from there.

I had the engine running for 45 minutes. I felt the top hose to make sure the thermostat opened. I loosesed up the temp sender and retightened it a couple times to try to make a better ground, same result every time! This is getting frustrating, I wonder if I got a bad sender? The old sender and gauge did the same thing though, weird.

Matt

If you can hold on to the top hose, the engine is not warmed up, even if it feels hot. A fully warmed engine will burn you in a very short time. Get a thermometer to measure the actual temp. You can use a meat thermometer in the coolant with the radiator cap off. Just don't take it off hot. Cool the engine, remove the cap, then warm it up. You should not have good flow until you get close to the rating of the thermostat.

and make sure all the air is bled out...

drill three 1/8" holes in a new thermostat and let the car idle for 20 minutes with the radiator cap off...

air in the system can do some weird stuff..

I had a similar problem with my '69 too. After tring an expensive (about $12.00) replacement temp sender from one of the major Corvette parts suppliers, I followed some advice and bought a Wells TU-5 temp sender for about $4.00 at a local parts store. I strapped a simple AC thermometer (the kind you see all the refrigertion techs carrying in their shirt pockets to the radiator hose right at the thermostat housing with a couple of stainless steel hose clamps (it ain't a laser thermometer!) but it read close enough to the guage to convince me that the Wells TU-5 works.

I've also read quite a bit about putting a resistor into the wire lead from the temp sender, but someone sent me a long article about why this was not a good thing to do. It might have ben Chuck Gongloff. I'll see if I kept the email from him and if so I'll send it to you.

Good luck,
Jim

I bought a cheap temp sender from a parts store to try for comparison, same thing. I took a meat thermometer and took off the radiator cap. I got the engine up to 175 (on the meat thermometer), the gauge still read 150. I spoke with someone at Corvette Clocks, they said they work on more temp gauges than all the other gauges combined. They suggested that I send in the gauge and they will calibrate it, anyone had this done?
Thanks,
Matt