TheRiffleBoy

Hello,
I have a 2003 Honda Civic EX with 195,000 miles that has been overheating ever since I got the car. Before I explain the symptoms caused by the problem, I think that it is worth noting everything that I have done to the car in order to narrow down the cause. So far, I have changed the water pump, the thermostat, the air filter, the radiator cap, the reservoir tank and the fan relay switch. I have also examined the transmission fluid and my oil countless amounts of times, in order to see if any mixing was going on with coolant just in case my head gasket is blown. I have not seen any mixing going on at all or any leaks from the engine, so I came to the conclusion that a blown head gasket isn't the problem (I could possibly be wrong).
Basically, my car only overheats when I idle after a long drive on the freeway. I've had this problem long enough to notice that it is caused by an excessive amount of pressure. When I drive long distances at high RPM (3.5k to 4k RPM), the problem seems to come up significantly faster. I've always stopped to open the hood after the heating comes up, and I notice that coolant is forced through the reservoir tank, causing it to spill out through the top! I've searched this symptom up everywhere and it seems to be caused by many different problems and not just one. When this happens, I also notice that the reservoir tank is full, unless I really push it and keep driving even when it overheats (in which all of the coolant from the reservoir tank is forced out). My guess is that something in the cooling system is causing a back up, resulting in a pressure build up in the reservoir tank... But I'm no car expert so I'd like to get some input from others to get an idea of what's going on and possibly fix it!
Oh also, I'd like to mention that I turn on my heater when my car begins to heat up, which temporarily stops the overheating for about 15-20 miles. Not sure if this will help, but it won't hurt to mention it.
If you have any other questions that might possibly help me narrow this down, then feel free to ask. Thanks!

sdaidoji

iTrader: (1)

https://www.civicforums.com/forums/3...reference.html

Colin42

this, your headgasket is blown

Wankenstein

.

For future reference it's best to test first than guess and replace.:
Thermostat: https://axleaddict.com/auto-repair/H...ostat-is-Stuck
Waterpump: https://axleaddict.com/auto-repair/D...r-Pump-Failure
Fan Relay Switch: http://troubleshootmyvehicle.com/hon...n-relay-test-1
Radiator cap: https://repairpal.com/radiator-cap
Reservoir: Only needs to be replaced if it's leaking. Otherwise, remove and clean the inside of it and the hose that leads from the radiator to reservoir to ensure there isn't blockage.

Coolant mixing with oil is only one of many signs and types of head-gasket breech. Honda engines rarely have that particular sign when their head-gasket fails. The most common sign of Honda engine head-gasket failure is loss of coolant in the radiator with increase or overflow of coolant in the reservoir when checked while engine is cold. Here's a related read: http://www.agcoauto.com/content/news/p2_articleid/200

Does the radiator fan engage during idle?
A Block Test may verify a head-gasket if exhaust gases are entering the coolant. Can rent a block-tester from Autozone or O'Reillys for free. The blue test fluid is around $10. If the blue test fluid turns green or yellow then there is a head-gasket breech and exhaust gases are entering the coolant. If the test fluid remains blue there still could be breech of another type.

Until you get the issue (most likely head-gasket breech as others stated) resolved it's best to drive it with the heater on to avoid potential damage caused by overheating.

Slumpertcivic

Mrs.John Pickle

HEY! I have a 2003 honda civic ex that is doing EXACTLY the same thing! I thought i figured it out and fixed the issue several times! I've had the fan relay and thermostat changed..my reservoir hose that connects right behind the radiator cap came off, so I had to put a durable clamp on to hold it..I've bought a radiator cap, then ordered a honda cap with my VIN. I did, and am doing the exact same! Checking for leaks every where! I've also constantly ran back and smelled my exhaust right when I started it , because a mechanic informed me that after sitting for a day or two you can smell the coolant if there's a leak. I also bought a pressure tester, and hooked it up a few different times while leaving it for over an hour each time, and NEVER lost any..I've also givin up and put k-seal in my system twice (which claims to permanently fix and seal leaks with only one use)..it just ends up blown all over the top of my motor from the reservoir tank. I've also purchased two caps for that as well, and have now been driving it for well over a month without one. Because my car has eventually blown them off. It's like my coolant has no leak anywhere to push out of when it gets hot. Even my radiator cracked. thankfully as soon as I pulled in my drive. I accomplished replacing it myself with no help, or clue how. When I first got the car, it started randomly setting of the code for a #2misfire. So I took it back to the guy, and he put some sea foam in the tank. Said that it was probly old gas, and to put premium gas in it at least every third gas tank a few times. Just last week or so, I had passed a couple of tractor on the highway, so I'm sure that's why my car acted out in half the time. It got hot fast all of a sudden so I pulled over right there. And this is the first time that it didnt start right back up...and it sounded HORRIBLE! I thought it was done for! After maybe 10-15 minutes, I got it to start..but maybe made it a block or two before it died on me. So I sat and wait til I could open it up and get more coolant in it. After all that. It started right up and I headed straight home! But, shorty after, I had to pull over again.. i can only drive it so hard, and long before I can count on it acting a fool. The next time I take it on one of those long drives, I'm gonna pull over for about 10-15 minutes every so often, and see if it ever gets hot.. cause I can drive it around my town ,no problem. But when I was sitting and waiting. terrified that I was stuck, and that my car would never run again..I came across a web page that talk about the fact that a clogged fuel filter can cause your car to overheat. One of the symptoms is not being able to find your coolant leak. It said that clogged fuel filter will cause your gas pump to get hot, and as a precaution it will shut off . And in doing so, will cause your engine to overheat. So I guess when I have the money, that will be my next Mission. Good luck with yours! And if you do get it figured out, PLEASE let me know and I will do the same.

FRSam

This is textbook head gasket failure.

Colin42

Blown head gasket, potentially the block is junk now as well