litterbox

Hey,

Well it snowed in nova for the first time last night. I went to start my car this morning, it was slow, but it started. After warming up I noticed that the engine temp gauge would fluctuate from where the needle normally sits (a little under halfway up) to a little higher than halfway. It would then fall down to it's normal temp. Why is this happening? The engine wasn't overheating or anything but sometimes the temp needle would rise pretty high for a couple of seconds then fall back down.

Last weekend I had swapped out heater core and fan blower and replaced those hoses. There aren't any leaks or anything, but when I was replacing the hoses some of the coolant spilt. I didn't get a chance to fill it up last night. I do not have a full tank of coolant in the car right now, but there's plenty. Could this cause the problem?

I don't think it's the thermostat. It's been fine since I've had the car (may 04). Would the thermostat just go bad all of a sudden or does it take some time for it to slowly go bad?

Any thoughts?

Thanks,

George

flood

Sounds like you introduced some air bubbles into your coolant system. This is very very bad. If the air bubble gets trapped in your head, the head won't have coolant. Could cause a blown head gasket eventually. It was the main contributor to my old Daily Drivers engine failure.

When the bubble hits yoru temp sensor it will cause the sensor to read cold, then when coolant passes by it again you get the jump in temperature.

Completely flush/fill the cooling system ASAP.

litterbox

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by flood &raquo;</TD></TR><TR><TD CLASS="quote">Sounds like you introduced some air bubbles into your coolant system. This is very very bad. If the air bubble gets trapped in your head, the head won't have coolant. Could cause a blown head gasket eventually. It was the main contributor to my old Daily Drivers engine failure.
When the bubble hits yoru temp sensor it will cause the sensor to read cold, then when coolant passes by it again you get the jump in temperature.
Completely flush/fill the cooling system ASAP.</TD></TR></TABLE>
Will do.

driveslow

back from the dead thread,

This sounds like the issue I am having but is it necessary to completly flush, I just swapped out rads. Couldnt I just bleed system via bleed bolt?

honda.lioness

The correct response is indeed just to bleed the air from the system using the procedure in the owner's manual or a decent manual like the one specific to your Civic free online at autozone.com. It goes beyond just filling until coolant and no bubbles flow out the bleed bolt. After the latter step, the car must be run (cabin heater setting on high) with the rad cap off or barely tightened (so no pressure builds) until the rad fan comes on twice. In cold temperatures, this may take 50 minutes or more. Even when the ambient temperature is 95 degrees F, from cold startup the Civic will take around 20 minutes to warm up so that the rad fan comes on twice.