OK, I've got a 1994 civic with the 1.5 litre with 110K miles.

The car was overheating and dumping coolant into the overflow resevoir. The gauge would run really high then I would turn up the heater and then it would return to normal. I ended up changing the thermostat and radiator. The water pump was changed about a year ago. The temp was ok for a couple of weeks then it started to jack up again. I noticed that the radiator wasn't getting hot so then I figure coolant wasn't getting to the rad. I took out the termostat and now it's fine, though, it takes a long time to get to operating temp.

The thermostat works after testing it (and I would like to use one in the car) and coolant is now getting to the radiator. I want to put it back in (and I DID make sure it went in correctly) but I'm think I'll have the same problem.

Anyone else have the same problem? Also, is there a chance that the engine would over-heat because the coolant is running thru the system TOO quickly and not cooling the engine?

Thanks in advance.

 

I did and it was that the thromostat wasn't opening all the way ......and to it was to high a temp .what temp is the one you have?

 

The thermostat is stamped with 170F. Which is pretty low, isn't it? The Haynes manual said 195F so I figured I was OK.

 

That is what mine had and I tried the 195 and that was to much so I did the 180 and all is good now my prob was the 195 didn't open all the way .........might be a head gasket.

 

hmmm... how would the headgasket be the issue? I don't have a leak -- water not getting into engine. I checked that.

 

im not certn it is the gasket its just one of the signs when it blows coolant in the radiator it could be just a bad radiator cap.

does the fan come on?

how did you test the thermostat ?

i know that my car would not shift into 4th when it was cold out with a 170 did that happen to yours? just curious .

and like you say you should run a thermostat it will make the far end of the motor run hotter than the rest ,.. and so i would defiantly run a thermostat

i just had hell with mine and it was just a pain so i will try and help out as much as i can i might not be as smart as some but i can help out due to my experiences.

 

tonyhatchetman! Thanks for responses!

to answer your questions, yes, the fan does come on.

Also, I threw the thermostat in boiling water and watched with a thermometer until it hit 170F and then in opened.

And, it wasn't cold out -- I'm in Oregon and it was probably 60 - 70 during the day.

I keep reading about the situation where an air bubble gets caught around the thermostat when the system is refilled that prevents the therm from working. Maybe I did actually correct one issue by changing the radiator but created another one when I possible did not re-fill the system properly?

Also, aren't most thermostats connected to the upper radiator-hose instead of lower one for the 94 civic? I just thought a little different.

 

You need to bleed the cooling system when refilling. Car must be parked on a level surface or pointing slightly uphill, so the radiator is the highest point. Move the heater control on the dash all the way to hot. Open the bleed bolt on the fitting where the upper radiator hose connects to the engine. Pour in coolant until some comes out the bleed fitting. Close fitting and start engine with the cap off. Top off radiator if necessary and put the cap on.

All Civics, and many other Japanese cars, have the thermostat in the lower hose. Make sure the copper sensor bulb of the thermostat is on the engine side not the radiator side, and the little air hole in the flange (with "jiggler pin") is on top. A 195 degree thermostat is stock, and will work fine as long as the rest of the system is in good condition.

Like the other guy said, a bad cap will cause coolant to migrate from the radiator to the reservoir and not return. This eventually leads to overheating due to lack of coolant in the radiator and engine.

 

How far did the thermostat open?

Try the bleeding of the system and try a new r/cap see what that does.

Let us know

 

thanks for the help!
I put the thermostat back and bled the system while re-filling. Now, it seems be working -- coolant actually getting to the radiator!
thanks again, I really appreciate it.