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Honda Civic 2000-2005 Problems

chiburbschiburbs Posts: 2
edited May 2010 in Honda
Since fall I have had a progressively worsening coolant leak. The problem is, I and two mechanics cannot find it.

They've replaced the thermostat, the hoses connecting the radiator and the radiator cap. No difference. They've tested the oil for any traces of coolant. No traces. They've let the engine cool for about 5 hours and pressure tested it. Nothing apparent.

The leak loses antifreeze over months but seems to be speeding up. I've noticed the heater stops working a few days before the engine begins to overheat (so I put in coolant). There aren't any puddles under the car.

Leak sealant seems to have helped the problem before, but I am not sure it is now.

The overheating also seems to happen in the pauses after long trips. I took a 70 mile trip today, and then it began overheating when I got off the expressway. I had checked the antifreeze levels before I left but haven't checked after because it is too dark.

There was something new today. I also smelled a bit of a chemical smell towards the end of the trip but not during it. Of course, I also went through an industrial area.

There is also no apparent wet spot inside the car and on the floor under the dash, where a leaking heater core would create that mess.

Any suggestions?


  • cz_75cz_75 Posts: 7
    The radiator is a three-piece assembly with plastic top and bottom tanks held on by crimped metal tabs. It is likely starting to separate because of vibration and fatigue. Look around for a one-piece radiator with a good warranty and see about replacing it.
  • kb25kb25 Posts: 1
    I have an 03 Civic Ex.. I bought the car during winter, loved it... As it start warming up outside it started overheating.. No sign of a leak anywhere, just a faint smell of burning antifreeze.. Started adding antifreeze here and there, checked oil, watched for white smoke out of the tail pipe...

    Also replaced the thermostat, got the hoses checked, changed cap, nothing worked.. A buddy looked it up on some software he has for cars and it had like 7 hits for a cracked head gasket.. Then about a month later my radiator blew as I was pulling into my driveway.. Ordered a new one, just got it put in. I still don't know if it fixed the problem because when i started it after getting the radiator put in, my instrument cluster went out... No luck.. But I will let you know after I figure out the instrument cluster...
  • Kirstie_HKirstie_H Posts: 11,042
    Questions are more likely to be answered in general discussions rather than when they're in a discussion dedicated to a single question, so I changed this discussion title for ongoing use.


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  • 2005 Civic - Overheated in June when I stopped after a 2 hour trip. Took car in and couldn't find anything. Replaced Radiator cap, checked hoses and thermostat but everything OK. Last week noticed the heat would not come on right away and then faded in and out. Took it back in and they have now found a "Leaky" Head Gasket. Said the gasket is not cracked but could crack if car continues to overheat. Haven't had another over heating since 1st incident. I'm hesitant to fix the gasket until I can find out what caused the overheating. My mechanic is telling me that the overheating probably caused the leak in the gasket. Does that sound right to any of you. Your problem sounds similar. Not sure what to do!
  • I'm having the same problem with my 2002 Civic. It's leaking coolant but my mechanic can't find the leak. Did you ever find the leak?
  • mrposeymrposey Posts: 1
    Sorry to bother you. I was wondering if you ever located that leak. I have a 2003 honda civic and I and 2 other mechanics cannot locate the leak. I can get about 120 miles out of it till it overheats/runs out of coolant. I changed the radiator cap because the reservoir was filling up and I changed the thermostat just because.
  • chiburbschiburbs Posts: 2
    someone sent me this, which turned out to be right:
    The radiator is a three-piece assembly with plastic top and bottom tanks held on by crimped metal tabs. It is likely starting to separate because of vibration and fatigue. Look around for a one-piece radiator with a good warranty and see about replacing it.
  • Yes this car have a head gaskets problem like the subarus. I just bought one and it over heated on a long trip. I had to do a head gasket repair and sent to cut the head. so, that's the main problem on it. So good luck and keep and eye on does head gaskets.
  • davemartinwooddavemartinwood Posts: 1
    edited December 2011
    I have a 2003 Civic EX at 175k miles. I had a slowly progressing over-heating problem also. I replaced a sometimes failing A/C radiator fan, after replacing the thermostat and both old upper and lower hoses. Eventually, I replaced the radiator and the overflow bottle trying to find out where all my coolant/water was going. I would consistently lose a quart of water to work (45mi.) and again on the way back. Even when watching it in overheating mode, :sick: there were no obvious leaks. I eventually am doing a head-gasket replacement. I have it apart now and the gasket and head look pretty good for 175k. I was disappointed when I didn't find the obvious gasket burn through I had expected. But, it seems that this engine (D17-A2) lasts forever until an eventual mystery coolant leak occurs. It also seems that most folks find a head gasket replacement fixes the problem. I plan to increase the head-bolt torque to 55-60 lbs/in., as some do, when I put it all back together this weekend. I'll update with the results. Keep motoring.
  • @ DaveMartinWood:

    My 2002 Civic EX with 175k miles is behaving the same as yours. I've only replaced the thermostat & added coolant. Worked great for one week, then it was overheating during a 30 mile drive. Towed car to trusted mechanic & he couldn't find any problems. He added coolant from loss due to overheat. Burped the system in 65degree shop for 40 minutes. Civic worked just fine for one week. Then during a 50 mile drive....overheating again. PLEASE let me know if you figure out this problem.

    I would appreciate an email direct:
  • Kirstie_HKirstie_H Posts: 11,042
    We would actually appreciate if it were posted in the Forums, rather than privately, so that any other members having the same problem could benefit.


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  • I've done everything that everyone else has done here from thermostat to head gasket and the car is still loosing coolant. The mechanic thought it was the water pump. This is water pump number two. Use the copper stuff which worked for awhile. The care has 200,000 miles on it. This has been going on for awhile.

    If the car goes above 60, that is where there is most fluid loss. There is NO dripping at this point or coming through the radiator cap. There is no white smoke. There is no water in the oil. There is no water in the cylinders. The car drives smoothly as it did when I bought it. At this point, I'd just like to know what it is.

    Any ideas appreciated.
  • Did anyone ever get a answer to this? I have the same problem but im losing oil after doing the haed gasket the mech did the head twice and it still has the same problem and its getting worse.... Anybody .lol

  • gcastro239gcastro239 Posts: 2

    Had the same problem with my 03 civic ex. The mechanic found that a plug that connects to the air box area was loose and plugged back in. He said this would happen because it was loose and said something like the thermostat would not be able to work properly by not being able to read what the sensor is telling it to do. I'm not a mechanic so my explanation isn't great. Try some the plugs that are around the air filter system. That should take care of the problem. Good luck.

  • gcastro239gcastro239 Posts: 2

    My explanation was for the problem with the heat initially coming out warm from the vent but then coming out cold afterwards while the thermostat is reading a normal temp and no leaks.

  • My 2003 has 260378 miles on it and I started having the same probem. I have changed the water pump, themostat, hoses, radiator and the radiator being the last it went a week before overheating again. I find it hard to believe the mechanics can't find what's wrong. I drive 35 miles one way to work and I have to add fluid in the morning before I leave and in the evening before going home and can't find no leaks and the oil is clean.

  • I, too, have a 2003 Civic that is losing coolant and overheating. Rose has 149,000 miles. Oil is clean, doesn't bubble when the radiator cap is off, replaced the thermostat, replaced the sensor that tells the fan when to kick on and cool the engine. Had the routine water pump and timing belt replaced last summer. I'm putting coolant almost every single day and I'm getting to the point where I am nervous to drive my car. :( The Honda mechanic said 2003s are known for this. So where isn't there a recall if so many of us are having the same problem?
  • Why isn't Honda offering this to the 2003-2005 models who are experiencing the same thing??? :(
  • ajandaajanda Posts: 1
    2002 Acura EL 1.7. I'm having the same issues. Wondering if anyone has found the key, there must be a solution right?!!!

    Thermostat changed twice, hoses done, cap replaced, fans tested, rad replaced, a gas test done resulting in engine being changed. Just when I fianlly thought we solved the problem. Overheating again with rad fluid spilling everywhere. Getting rather discouraged. I have always been a Honda fan. I'm beginning to change my mind about that. Any suggestions are welcome. 
  • My girlfriend has an '03 Civic that started overheating out of the blue. She first experienced the heater blowing cold air thing, and luckily she knew to shut the engine down as soon as she noticed it starting to overheat. Turned out to be something very simple. The little hose connecting the radiator to the coolant overflow tank had come off. This meant when the engine heated up coolant was coming out where that hose was supposed to have been connected, but when the engine cooled back down again it couldn't suck the coolant back into the radiator. She never saw evidence of a leak, presumably because it was mostly happening as she was going down the road and evaporating quickly. As a result she lost coolant slowly until it was so low as to cause overheating.

    I reconnected the hose and put a zip tie on it to make sure it doesn't come off again, then bled the cooling system. It's very important to bleed the cooling system on this car as it does not like air in the system at all. Some cars have bleeder valves at the top of the engine somewhere but I don't think this car does. So to bleed it, do this:

    1. Wait for the engine to cool down completely
    2. If that little overflow hose is disconnected, connect it back up again
    3. Remove the radiator cap
    4. Top off the radiator with coolant. Leave the radiator cap off
    5. Start the engine and turn the heater on full
    6. Monitor the coolant level as the engine runs. As bubbles escape and the level of coolant drops, keep topping it off. It might take 15 minutes or so before all the air escapes from the system and the coolant level stays at the top.
    7. Put the radiator cap back on and check the overflow reservoir for proper level.

    That fixed my girlfriend's problem.

    One more thing to check if the above is not your issue - there is a molded coolant line running from the top left side of the engine around the back to the air intake area. There's two of those molded lines in the intake area. They can develop pinhole leaks. To check them you'll have to remove the battery, the air intake resonator box and the air filter housing. Search Youtube for videos showing how to do this.
  • i am having problems with my 2005 Civic.The cooling system will start to have an odor then the thermostat will register hot, then cold. It would take a long time for the car to warm up and the air would run cool. When I looked under the hood, some of the coolant spilled on to the fan from the coolant reservoir. The radiator and the reservoir had coolant. The manic could not find out what the problem is but bleed the line and it worked for a while. Now, it is doing the same thing. These are the most recent problems. Last year, I had the Thermostat changed and the water cooler twice. It stops for a while then starts back up. What can I do? What I tell the mechanics to do?
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