Car: 94 Honda Civic EX
Engine code: D16Z6
Problem: The temperature gauge stays normal for the first 5 minutes of driving. After 5 minutes the temperature gauge jumps from normal(close to half way mark) to close to red. It isn't a smooth, slow transfer but a quick jump back and forth depending on how fast the car is going, if you are holding the gas pedal down, etc.

Any ideas on what is the problem and how to fix it?

 

Does the needle move below mid-range at highway speeds??? Your symptoms do resemble a bad thermostat...

 

also resembles low coolant

 

any compression mods?

try changin the thermostat... they do that man.
if your engine is making more heat you may need
to drill a hole in the thermostat so the coolant flow
isnt restricted.

 

true.. but a low coolant level would cause the idle to become erratic before the temp guage gets all whacky.. of course this would depend if the car was OBD I,II ..

 

OBD-I and there are no compression changes, all I have is intake and exhaust.

 

Sticking thermostat

Get a new one.

 

have you tried bleeding your coolant?

 

Just to be on the safe side... hehehe

Pull the rad cap off while it's cold, then let it warm up. Start watching for bubbles in the coolant, while the thermostat opens. Keep watching the coolant, until the cooling fan(s) have kicked on a few or more times. Also, watch the flow of coolant in the rad...

 

A quick jumping of the gauge would lead me to believe the thermosensor is going bad. A stuck thermostat or air in the cooling system would result in a slower movement on the gauge. The thermosensor in most cases is on the back side of the block, near the oil filter. If you want to be sure you've got the right one, turn the ignition on when the engine is warm. Unplug the sensor. If the gauge goes to zero, you've found the right sensor.

 

I think that it may be a power issue or a loose connection.
I say this because I have a battery voltage gauge in my car and it seems to jump everytime the temp gauge jumps. I have also seen my speedometer jump to 60mph when I was at a dead stop yesterday.

I had a situation just today when trying to start my car, the car would not start but the battery was not dead and the radio came on. I left the key in the ignition at the third turn, ordinarilly my fuel pump would begin to pump and you would hear it, but it didn't happen this time. I popped the hood and checked out the wires around my starter and everything seemed connected well. I nudged some wires and then heard my fuel pump. I tried to start the car and it started up fine this time.
I think i have loose connection in that area.

 

also, check your positive lead on the battery. you are having similar symptoms to what i had. as soon as i replaced the terminal with a better fitting one, everything was cool.

ryan