lt1c4

Hi Guys,

I'm new to this forum and also a new civic owner. I've done a search for what I need help on, but couldn't find what I was looking for so...

The other day, I got off the highway after about 40 miles of driving at ~70mph. Pulled into a store and left the car running. Came back in and found the car's temp gauge at redline. Ran the heater and it cooled down right away. I don't know if the fan came on or not. I checked the fuses which were fine. Coolant overflowed from the overflow tank a bit, but the level seemed ok.

Later that day, I took it for a spin and then let it run in Park and observed the fan coming on after a while. Upper and lower radiator hoses were both hot so I believe the thermostat was opening. I'm thinking either the temp switch on the thermostat housing is on it's way out, the fan relay may have been sticking or even the thermostat may have stuck closed temporarily. Any ideas on what could have caused the overheating?

Also, how does the cooling system in the civic work? flow into the engine from the lower hose, out to the radiator to the upper? how does the heater core play into this to cooldown the coolant if maybe the thermo was sticking? just trying to learn about my new/used car. TIA.

lt1c4

ttt

JaeOne3345

firt check the radiator for any obvius signs of leaks, check coolant hose as well. make sure your fans are working properly. if these produce no results, then check the thermostat, it may have went bad and is stuck closed. if thats not the case. i probaby have a blown headgasket. pull the head off and see..u might be lucky and not need to resurface it but most of the time u gotta make the surface flat again because it may warp due to extreme heat.

BreakStuff

also make sure you have nothing blocking the "elements" of the radiator...seems strange the car would run at highway speeds and still stay on the hot side.. (the car didnt overheat in the parking lot unless you were in the store for over 20 minutes)...

I don't think your cooling fan kicked in when they should have for the fact you stated the car cooled down normally when the heater was turned on..

a stuck t-stat, fan relay,fan motor,thermal switch would also cause this, but you already answered this yourself..

This diagnosis will take a bit more of research because of the amount of variables in your situation.. try to duplicate the situation and make sure the fans come on.. tell us where the temp guage is when driving at highway speeds, and also when the car is parked( get the car up to normal operating temp first).. also, is the a/c being used and is the condensor fan kicking on as well...

Take notice of the temperature of the heat coming from the HVAC system.. if you are overheating due to a bad headgasket, then it will be due to a considerable amount of air in your cooling system.. the air coming from the vents would be EXTREMLY hot.. too hot to keep your fingers in front of the vents for a short period of time.. your coolant overflow resovoir would actually be boiling over, more steam than coolant.. good luck and keep us informed.. you may also want to direct this to the "tech" forum were the "problem solvers" hang out..


[Modified by BreakStuff, 11:20 PM 5/16/2002]

lt1c4

cruising at highway speeds the temp gauge is below midline, on the cooler side. A/C was not running when I went into the store (about 5 minutes).

i checked the hoses and radiator for leaks - looks ok.

i tried to duplicate the scenario today and noticed the temp gauge go up a bit (halfway between midline and redline). it stayed there for a bit then cooled down on its own. (i think i heard the fan kick on.)

how likely is it for the thermostat to get stuck closed once in a while? or do they just fail closed & don't open again?

thanks for the help.

dwnthehatch

iTrader: (1)

Just replace your thermostat. Its only $15. Replace the radiator cap also while you are at it. If the cap isn't holding the proper pressure your car will overheat.

RepPenInLine4

check the water pump... if it only over heats when it is parked the fan prolly doesnt werk... thats what happened to my car...try putting on a new radiator car... that makes a diffrence too

elmerfudd

I had a similar problem that the mechanics could not diagnose. Ended up blowing the head gasket a couple of months down the line. You will see bubbles in your radiator if you have a head gasket problem. Laters,
Elmer

samdawgsol

do a coolant change anyway. Run it with a radiator cleaner to get rid of hard water deposits. Then when you fill it, use distilled water instead of faucet water, it wont leave mineral deposits like tap water does.

that might help. Plus dont use A/C ever on highway it gets hot real fast, but cools down quickly once you turn it off.