wierd cooling system problems 2003 civic
 

I have a 2003 honda civic... its a beater..

Great MPG and has run like a champ until tonight.

I went for a food run and it started to overheat.. so I dashed home before the gage went into the red.

I turned on the heater to full hot just to help a bit but the air came out cold... Now Im thinking.. did I run out of fluid?! The drive was short. maybe 5 min but the temp was fluctuating up and down, trending into the red.

When I got home the coolant was topped off and the oil was fine. Any ideas what to check next? besides the fridge for more beer?

thanks

Its the headgasket isnt it..!? oil isnt milky.. no oil in the coolant..

could it still be?!

Maybe the first ugly signs of a head gasket letting go. Just starting to let combustion gasses into the coolant, but not sucking coolant into the cylinders yet.
I use a block tester, but I think any shop with an emissions machine can test for co in the coolant . You may be able to smell it as well. I have never seen a water pump impeller break on a Honda. May want to check/ replace your thermostat as well.

Bad water pump?

Broken radiator, can't guarantee it, but it is what was wrong with my integra with the same symptoms. Plastic and aluminum, cracks where they are bonded together.

Easy fix, $400 for the radiator, upper and lower hoses about, buy a Honda one. Took me about an hour by myself.

If there is no loss of coolant only four things could possibly be. 1) Cooling fan(s) inop 2) t-stat stuck closed or partial closed - it does happen 3) Head gasket leaking cylinder pressure into the cooling system upsetting the balance 4) Waterpump impellar failed - although I have never seen this on this car -

My guess. Part clogged radiator. Could be head gasket... its not a 3.2 ford so I doubt it.

could not replicate the next few drives out....

makes me think the t-stat is sticking....

Had several Accords and they go through radiators every 7-10 years... found one on the internet for a good price and was back going in a couple of days for a reasonable price.

With the engine warm gently grab the upper radiator hose and rev the motor. You should feel coolant circulating indicating a functioning water pump. If not, water pump or t-stat.

Why would you guys diagnose a plugged radiator? All of the sudden it just "plugged" one day and pegged the temp gauge? And usually when they crack they leak coolant... C'mon...

I also vote for stuck thermostat since you aren't getting hot air from the heater. Cheap thing to try first.

Had an '85 Civic several years ago. Could idle it all day and it would run cool. Get on the interstate and do a long run and it would overheat. # of different mechanics could not figure it out, did all sort of stuff to it, even jive-rigging the cooling fan to run continously.
A little guy at a radiator shop that I just happened to run across in a hot dog joint over heard me telling a "knowledgeable" person about my problem. He immediately told me that I had a clogged radiator despite seeing and feeling coolant moving through it. Those things have very few flues for the coolant to circulate and if a couple get clogged it'll run hot.
Obviously the people who worked on the car were less than swift.
Maybe not your situation, but I'm just sayin'.

Had the same problem on two Civics. Clogged radiator.

The radiator on these cars is laughably small and prone to this sort of thing.

Mine cracked on the top, lost very little coolant, of course I stopped when I saw my temp gauge acting funny.

My '93 Accord had similar issues. The car would overheat going up hills in the warmer months. I never noticed the issue in the cooler months. The car had aluminum cooling fins, and they were corroded. I changed the radiator, and went to an "upgraded" one that had all copper construction.

Seen it on a couple cars I've owned (Nissan/Honda)...bad thermostat on the fan.

It was the radiator cap. It was letting coolant into the expansion tank but not back into the radiator..

It was the first part I threw at it!

damn it. i was going to say radiator cap!! it is ALWAYS the first thing i do if a car overheats. cheap enough..