Overheating on and off
 

I have an 05 civic that has been maintained. Car has 200,000 miles. Every two or three weeks lately the car will overheat. I had a non Honda radiator put in at about 160,000. Just found out radiator fluid is 100% coolant not the 50/50 blend. Ran for over a year and had no problems. The overflow is filling soon after mechanic puts in fluid. For about 6 months I've noticed about a tsp of rad fluid every once in a while. Many times to mechanic pressure test he said were fine. I finally just changed the rad cap and five days and no sign of drip but may come in a week of two like before. I paid to have thermostat changed but it didn't seem to have the two bolts touched. Mechanic said it was changed. His been trustworthy for over 5yrs. Had main timing belt changed at 115,000 with the water pump done too. The last two occurrences of overheating happened about every three weeks prior to rad cap being changed. Does this Honda absolutely need the 50/50 fluid? Would car drive fine for 3or 4 weeks if it was a major engine problem? Can the overflow tank be full because it's 100% antifreeze and not 50/50 fluid? I believe heater core is ok along with radiator, radiator cap, all hoses seem ok. What would be the least expensive route to take in troubleshooting this?

Kind regards.

Re: Overheating on and off
 

first of all you should be using honda OEM coolant which is blue and premixed....what type are you using?

your overflow bottle keeps filling up because you have a blown head gasket, a very common problem on these cars,

you need to replace the head gasket, and if you have let it get to the point where it overheated you many need your cylinder head replaced also

Re: Overheating on and off
 

Just using a standard 100% antifreeze.
Thank you for your response.

Re: Overheating on and off
 

although you shouldn't be doing that, that is not likely the cause of your problems

Re: Overheating on and off
 

I doubt 100% antifreeze has anything to do with your problem but I would correct it before searching for other problems. Running 100% antifreeze can cause an engine to run hotter since antifreeze does not transfer heat as well as water but at the same time it raises the boiling point even further so it runs warmer but doesn't boil over. I have never heard of running or recommending over 75% antifreeze.

Re: Overheating on and off
 

How would you know? How could you tell?

Re: Overheating on and off
 

Thanks everybody for your feedback thus far. I know this mechanic uses either a 185 or 195 degree thermostat depending on coolant. After replacing the rad cap five days ago temp stayed around 35% on gauge. Overflow reservoir 3/4 inch below the very top of white container. Overheating did not happen but now it seems to have a small leak right by where water pump may be. Can a failing water pump cause the overflow res to fill completely? Or perhaps just to much coolant was used thus putting the remainder in overflow? Bad therm perhaps not opening to let overflow be distributed when needed? Engine has no leaks and no knocking and is super quiet!
🤔🤔🤔🤔
All your suggestions are being taken into strong consideration and are very much appreciated 😊

Re: Overheating on and off
 

The two bolts used to remove to get to therm still had the corrosion on it. And there appeared to be no separation between them.

Re: Overheating on and off
 

Pjb3

Very good point you mentioned "runs warmer but doesn't boil over". Interesting you mentioned that because years ago in the winter when using 50/50 this problem was a little more frequent. Perhaps the ratio allowed the boiling point to be more of a nuisance in the winter? Not sure but you did mention a valid point.
Thank you

Re: Overheating on and off
 

Thank you

Re: Overheating on and off
 

Thank you. I think I'm going to have him check for Co2 in coolant first and check out water pump too. Water pump was changed 95,000 ago. I've read other threads and you've mentioned that which has really helped me narrow things down a lot more.
Thanks again.:)

Re: Overheating on and off
 

The water pump is leaking about 1tbsp each night:(:( so I'm thinking this is the culprit. Had 50/50 coolant put in and therm. With the water pump leak does anybody Have an idea if I have "some" time before it fails?

Thank you

Re: Overheating on and off
 

Water pump leak means it has failed already... They leak when the seal inside is shot.

Re: Overheating on and off
 

[QUOTE=GusBuz;4728891]Water pump leak means it has failed already... They leak when the seal inside is shot.[/QUOTE

Ok. Roughly how long before I should replace the Waterpump/Timing belts with the bad seal? Does the seal leak generally get worse?

Thank you

Re: Overheating on and off
 

a honda OEM water pump (properly installed) should last far longer then what you are stating here, did you have an aftermarket pump put in?

you are almost due to have the timing belt replaced anyway, so throw in another pump while your in there,

Re: Overheating on and off
 

Hey Dude

First of all check for leaks/hoses especially around the TB,thermostat housing, upper or lower radiator tank, heater core and water pomp

Second, make sure your thermostat doesnt has no deposits or salts on it *CLEAN AS HECK*

Im no mechanic by no means ..... if everything was great just get an OEM rad or proper one ^_* cheers