Hello I am new here and is need of some serious help. I am mechanically inclined, but I am no master mechanic. I have a 2003 Honda Civic Hybrid with 132k miles. I started experiencing issues this winter with the heater blowing cold air then once in a while it would overheat. I would add fluids and it would seem to resolve the issue. As the weather warmed up, I had the chance to look at the car. I noticed that the coolant is always low in the radiator but once the car gets warm it pushes out antifreeze.

Whenever the car overheats it pushes fluids out of the reservoir tank and all over the car. This results in a low coolant level, so is that why it is overheating or is that a result of a head gasket ?

I changed the thermostat along with coolant flushes and heater core flush. The oil was recently changed and has no signs of antifreeze in it or vice versa. I also checked the spark plugs and other then some rust on a few of them they look ok. I enclosed photos of the spark plugs.


Since I took out the spark plugs and wiped them off and replaced them My car has been having issues. It refuses to start until I step on the gas pedal and then I got a p0301 code for a misfire but I also got a code for the other three cylinders could this be a result of me over-tightening or under-tightening the spark plugs?


  • 1
    Welcome to the site. How did you wipe off the spark plugs? Did you reconnect the wires in the exact same place? Is there smoke from the tailpipe when running?
    – CharlieRB
    May 24, 2017 at 18:57
  • Also, after having done the flushes and changing the t-stat, are you still getting overheat issues? Or is it just misfires at this point. If it was running fine before and now you're getting misfires then the ignition sequence could definitely be wrong as CharlieRB is suggesting... May 24, 2017 at 19:43
  • thanks for the response... unfortunately I am still having issues with overheating after replacing the thermostat and the rad cap. One thing I am not sure of is how accurate the parts were. I ended up going to autozone and they gave me a failsafe theremostate and rad cap. I have been researching and came across information about how non oem parts could not work propertly and when dealing with hondas oem is the way to go, so I am not sure if I should replace both with oem or look towards a blown head gasket
    – sayian
    May 27, 2017 at 2:04

1 Answer 1


It sounds like you have 2 separate issues:


Engines overheating and "pushing fluid out" is a telltale sign of the cooling system not holding pressure. Inspect your cooling hoses for cracks, but most likely, your radiator cap isn't sealing properly. It's either not seated properly and just worn out. You can conduct a pressure test.


Since this happened just after you cleaned the spark plugs, it could be linked to that repair.

  • Make sure you didn't change the gap of the spark plugs. Get a gapping tool and check.
  • Spark plugs only need to be "hand tight." I use a socket extension without a ratchet in order to prevent me from overtightening them.
  • Each spark plug needs to be connected to it's specific spark plug cable. If you mix them up, you will mess-up the firing order.
  • Inspect your spark plug cables for wear, test them electrically for resistance, if any are suspicious, just replace them.
  • Spark plugs need a little more than hand tight. Should be about a 1/4 turn if it has a crush washer. There's more than likely a torque spec for ones without. Either way you're right, though, they don't require a lot of torque for it to be solid. May 25, 2017 at 1:23

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