2004 Honda Civic Coolant Leak

Tiny
BUZZADAMS
  • MEMBER
  • 2004 HONDA CIVIC
  • 1.7L
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 185,000 MILES
Since mid-winter, the overflow tank on my 2004 Civic EX (original owner) is full to the top rather than maintaining the 'normal' level. Small amounts of coolant is being pushed out the top of the tank. The coolant level in the radiator drops and must be replenished by adding about a cup every 3-400 miles. The engine has continued to operate at normal temperatures and starts and runs fine. The system maintains some degree of pressure even after sitting over night. Its as if the coolant, rather than the 'air bubble' expands into the tank and air is drawn back into the radiator? I haven't noticed any white smoke (or anything abnormal) in the exhaust. The coolant, oil fill cap, oil dipstick and transmission dipstick all show no contamination or turbulence. Although I doubted it would help, I changed the radiator cap. I would change the thermostat but I doubt it would help. Am I looking at a head gasket leak? Something else? Thanks!
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Sunday, April 27th, 2014 AT 9:31 AM

6 Replies

Tiny
HMAC300
  • EXPERT
Normaly your coolant will go down or there will be bubbles in the tank while running. But don't put any coolant in for about a week and see if it stays where it is. It won't hurt anything, if it goes down then have hte coolant system ppressure checked.
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Sunday, April 27th, 2014 AT 11:18 AM
Tiny
BUZZADAMS
  • MEMBER
Thanks. I will let it go for the week and it will most likely have overflowed the tank a little each day, the tank will be full to the top and the radiator will be low.. Wrapping a rag around the tank neck helps keep it from running down into the fan and getting sprayed all over. I figured a pressure check is the next step but I still don't understand why it doesn't draw the coolant back out of the tank and into the radiator. I will update with any findings.
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Sunday, April 27th, 2014 AT 6:54 PM
Tiny
HMAC300
  • EXPERT
If it doesn't draw it may be a bad radiator cap and or just to little in radiator to do it.
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Monday, April 28th, 2014 AT 6:47 AM
Tiny
BUZZADAMS
  • MEMBER
Well, each day a little coolant was pushed out of the overflow tank top. I put a new rag around the tank top each day. By the end of the week, the tank was still full to the top rather than down at the 'full' line. The radiator, which has a brand new cap, was down about the usual 8-10 oz. I guess I will pull the overflow hose off to make sure it isn't plugged, make sure the bottom of the tank is clean, and then flush the system. I doubt this will fix anything but it can't hurt.
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Friday, May 2nd, 2014 AT 4:40 PM
Tiny
HMAC300
  • EXPERT
It's worth a try also try replacing the cap on radiator it may be bad and not let overflow work like it should
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Saturday, May 3rd, 2014 AT 6:19 AM
Tiny
BUZZADAMS
  • MEMBER
Thanks. I'm still just 'maintaining' it for the week. I hope to have time to drain and clean the system out this weekend. I will report back on any results. Thanks for sharing your thoughts.
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Tuesday, May 6th, 2014 AT 7:41 PM

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