C5atthebeach

Hi folks,
I am wondering if there is some way of testing the oil and water temp gauges. Mine is a 93 coupe, non ZR-1. They seem to be displaying rather low. Water temp barely goes up, even after several miles. and the oil temp goes up barely. I was thinking they should be halfway or close to it. I have checked levels and they both are what the manual says. Does either or both go through the ECM? I know there is a problem with it and am planning on having it refurbished in the near future.
Thx for listening.
Jim

belairbrian

The gauges do not go through the ECM and they aren't very accurate.

How are the digital values in the speedometer LCD? The LCD is fed from the ECM.

They all get 12v from the same wire so if the volt meter reads good then that is good.

You could change the senders but it may or may not improve the situation.

C5atthebeach

The digital values in the speedometer read:
158 deg for oil temp
166 deg for water temp
14.4 v
All after running the car for a day, on the freeway, and in town.
That seems OK with me. Sounds as though the senders are reading OK, but gauges seem to be off.
Thx

PatternDayTrader

Sounds to me like you better replace the thermostat.
Those temps are to low.

C5atthebeach

Which thermostat would you recommend?
Would replacing the oil temp sending sensor also help?
Thx again.
P.S. this is my 5th corvette, and the hardest to delve into. But then again, it's the newest too...

PatternDayTrader

​​​​​​​I think 195 is stock and that's what I would use. It's cheap and easy to install, and if that ends up not being the problem, you shouldn't be out more then 20 bucks. I would not do anything with the oil temp until I was certain that coolant temp was up where it belongs.

aklim

Hook up a scanner and interrogate the ECM. See what the ECM sees first. That way you can decide where to throw your efforts. If the gauges are bad, get them recalibrated. If the ECM sees the numbers as low, you hit those sensors with an infrared thermometer to see what is going on.

Palanon

aklim's way is most likely going to show pretty quick where the problem is. If you don't have those tools, they're cheap online. Necessary tools for the box. I even use my infrared thermometer to get track temps.

If it's the thermostat, make sure to get one for LT1 Corvette. It's two levels because of the reverse flow cooling. The extra level is for controlling flow to the water pump and radiator. If a standard GM is installed, cooling won't work correctly. Not sure but, maybe it would cause your low temp problem? Not sure. Last week I was going through the FSM and briefly read about the thermostat. Wasn't the problem being chased so I was skimming. Thought the special thermostat was odd. Made sense but never would have thought of it at the parts counter.