'04 Civic Temp. gauge not working

[MARTIE]

Hi. I am having some trouble with my 2004 Civic.
We just replaced the radiator, and now the temp gauge shows super hot after driving 2/10 of a mile.
When I stop at a red light, it drops back into the normal range.

This morning it continued to fluctuate between overheating and normal while traveling down the highway at a constant speed.

No steam came out of the front when I shut the car off.

What is going on? This car has been a heap of trouble since I purchased it last year.

 

[XpL0d3r]

to ClubCivic!

Did you bleed the coolant system after replacing the radiator? Make sure to get all of the air out of there.

 

[MARTIE]

to ClubCivic!

Did you bleed the coolant system after replacing the radiator? Make sure to get all of the air out of there.

Yes. It's been two weeks since the new radiator. I have been having to top off nearly daily since it started acting up this week. Each time it takes about 1/2 cup of fluid.
Is it possible to have a leak or loose tubing to the radiator? But then it seems like it would steam if there is not enough fluid.

 

[XpL0d3r]

It's possible. I've lost an entire thing of coolant before due to a ripped hose, and saw no steam whatsoever. Inspect the bay for ripped hoses. Though, you'd see coolant splatter probably all over the bay or at least underneath the hoses if this were the case.

Are you seeing any smoke from your exhaust? Check for coolant in your oil, which would point towards a head gasket leak. You can further test this by removing the radiator cap (make sure the engine isn't hot!) then letting the engine run to normal temp. If you see coolant bubbling up or splashing out, your head gasket's bad.

 

[MARTIE]

I have not looked at the exhaust, but did slip a new piece of cardboard under the car (radiator) last night to see if there were drips of anything.
I will check to see if the coolant bubbles out.
Thanks for your thoughts...

 

[HeX]

Did you properly flush the engine block as well? If not then that would explain the seeming loss of coolant as its actually mixing with old coolant and evenly filling out the rest of the system you neglected to flush. Make sure to install a new thermostat as well. Thats typical to do when changing a radiator to be on the safe side.

Please confirm you did you 50/50 coolant mix as well. If you didnt and its mostly water then its evaporating.

Definitely check the oil a well for coolant leakage as @Xplod3r suggested, by looking in through the oil cap on the valve cover. Usually you'd check the coolant for signs of oil but since you changed at least most of the coolant then it may not yet be obvious enough, if the head gasket is in fact the culprit. I lean towards me previous suggestions though.

 

[MARTIE]

Well, we bled everything out again...put new fluid in. I did notice you save a bit of cash by purchasing the full strength and diluting it. I thought that was a little nuts. LOL.

Anyway, changed out the thermostat as well. It has been working great, no weird fluctuations, runs right where it should be.

Thanks for your suggestions. I'm glad it was an easy, inexpensive fix.

 

[HeX]

Thats great. Sometimes all it takes is a little extra attention to detail.