I have a 1997 Honda Civic that has been having coolant issues since July of this year. I believe the problem started after a mechanic checked my radiator but didn't screw the cap on properly. The next day I was driving, smelled coolant, and opened the hood to find the radiator cap open hanging off of its threads, with coolant all over the engine, and the coolant overflow compartment empty. I made the mistake of closing up the radiator without adding coolant to it. I did fill up the overflow compartment to the proper line. About 20 minutes after driving it I saw on the temperature gauge that the car was getting hot, so I pulled over, let the car cool down, then filled the radiator up with coolant. After that I had no issues for a couple of weeks.

Then I drove the car cross country, and on the third day of my trip started having issues with overheating after driving for 4-5 hours on the highway. I would see the temp gauge going up, pull over, let the car sit for a half hour, and then fill up the radiator and keep going. After this happened a couple of times over the course of 2 days, I stopped using my A/C, and the car stopped overheating. However, I started checking my coolant levels regularly before driving, and found that, after having driven for a couple of hours, the coolant would fill up the overflow compartment (to the point of overflowing), and I would not be able to see any coolant in the radiator. This was after the car had been sitting overnight.

This was when I finally got the car into a shop, and they told me I needed the head gasket replaced. So I spent $800 to get that done, they said the car was fixed. I drove it around, and after a week or so of running errands around town with it, the same issue was happening. The coolant was overflowing out of the top of the overflow compartment, and emptying out of the radiator without ever refilling there. I took it back to the shop, they replaced a hose and a valve and said it was good to go. I drove the car for an hour and a half that day, and the next morning opened up the hood to find that the coolant was doing exactly the same thing as before.

My mechanic at this point seems hopeless, just tells me its an old car and he's not sure what to do. I needed to visit my aunt the following day, so I took a gamble and drove the car for 3.5 hours to her house. The temp gauge stayed steadily just below the center for the entire trip. But then once I got off the highway it slowly started going up. I made it to her house as it was continuing to rise, but before it reached the top of the gauge. I let the engine cool off overnight, and the next morning checked the coolant levels to find them all normal! Not what I was expecting. The overflow compartment was filled to its "max" line, not above. And when I opened the radiator cap I could see coolant, and wasn't able to see the top of the radiator.

Hopeful that somehow the car had fixed itself, I drove back home. No problems until I got off the highway, but then, as before, the temp gauge slowly started creeping up. I turned the heat on full blast and that quickly lowered the gauge back to normal. At that point I was an hour away from home, so I kept on going, keeping an eye on the gauge. It fluctuated as I was driving ~ it would go up as I accelerated up hills, but then would return to about the halfway point. I made it home without the gauge ever reaching the top.

This morning I checked the coolant levels :: the overflow compartment was at its "max" line, but when I opened the radiator cap I couldn't see any coolant. So now it appears that the coolant is going somewhere else, other than the overflow compartment. I tried turning the car on and looking for any leaks, but wasn't able to see anything. It was parked on grass so I wasn't able to see any coolant puddles.

I have checked the fans and they are working properly. I've been told to put dye in the system to see if that will help show me where the issue is. I'm also thinking about replacing the thermostat to see if that fixes it. And also wondering if the radiator is bad? I don't see any signs that the head gasket is blown: the exhaust is clear, doesn't smell like coolant, and the oil looks normal.

Thank you to those of you that read this long post! Any ideas or advice would be greatly appreciated. I love this little car and want to get it back to running smoothly.

 

You have a blown head gasket still. Possibly they didn’t mill it ,or you cracked the cylinder head overheating the motor.