Rep Power: 0

I've read a few threads in here but none seemed to mirror my problem. Sorry if this is a redundant post.
Recently my wife tells me her '05 Civic is not blowing warm air, even after the engine gets to the normal temp range. Several days later, before I had a day off to think about it, I noticed an antifreeze smell after driving it. I raised the hood and found the car had been blowing/boiling antifreeze out of the overflow reservoir. My dad said it acted to him as if the thermostat was bad. I replaced the t-stat and the overheating seemed to stop for the past 3 weeks. Wife said it still seems to be slow warming and sometimes it's still not blowing warm air at all but no overheating since. Fast forward to today when we went for a drive in the mountains. All day of slow, curvy, up hill driving the car again performed fine, although we didn't use the heat since it was warm we had no cooling/overheating problems. After stopping to eat, the sun went down and the night cools off, leading to the need for warmth on the drive home. Coming down in elevation, not climbing and not working the motor hard, again we have no inside heat. The temp gauge is in the normal range, but again it's just blowing cold air. After about 15-20 minutes of driving we notice the vent air finally begins to blow warm but the engine temperature gauge is climbing sky high. Car reads high engine temp for 45-60 seconds and the air from the vents cools back off. Suddenly the gauge drops to normal and the vent air gets warm again. I stop and check, and the car is blowing antifreeze out of the overflow again. The rest of the 45 minute drive home it constantly repeats the same process. With the temp **** being kept all the way to warm setting the HVAC blows warm and the engine temp gauge is normal for several minutes. The engine temp begins to climb and the air from the vents cools back off. It only reads high a few seconds and then the process repeats. No codes or check engine lights are on. Never moved the temp selector **** off warm setting. I was thinking the t-stat is sticking even though it's new. Any ideas or advice would be awesome and very appreciative. I'll try and fix anything but I have no idea how to go about diagnosing this one. Thanks in advance.

 
Rep Power: 204

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

 
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Head gasket.

 
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^^^^^^This. OP this is a very common and well documented issue for this generation of civic. I'll save you some time and tell you there's no need to post any questions or comments about what else it could be. Get the HG changed or change it yourself if you can.

 
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Don't let the head gasket get to bad. My car was over heating a while ago really bad and I couldn't figure out what it was, although had a feeling it was the head gasket. I denied it being the head gasket to the point where my car would barely move when coming to a stop and would blow smoke. Fix the head gasket before it does anymore damage or you'll end up like me car less for a week haha

 
Rep Power: 518

Some things just don't go away no matter how much you ignore it........

Like.....Syphilis.

 
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Since starting this thread I've tried several fixes with no success. I replaced the timing belt since it was due based on mileage. While the guy was in there I had him put on another t-stat in case my replacement was bad. I also swapped the water pump. He did a compression check on it and said the head gasket was good. He bled the air out of the system and said it was good to go. 30 minutes later when I got home it was already running out of the overflow again. I thought he might have just overfilled it, so I drained it down between the hot and cold levels. It ran fine for a few days and overflowed again. I did more research and found the rad cap can malfunction,a so I swapped it out. No luck. Thinking it was air locked I had another mechanic bleed the air again just in case. He had some tool that hooked to an air compressor and actually sucked the air out, sucked the hoses flat, etc and we refilled the radiator. I drove it for 30 minutes and the coolant level didn't change so I thought it was fixed. Over the past week I've been checking it. The level in the overflow seems to creep up after each drive. Yesterday when I parked it I smelled antifreeze again. I pop the hood and sure enough, its overflowing again. The temp gauge is never reading hot and it blows warm air when he heat is turned on. I'm at a loss. Except for the two big hoses and the radiator itself I don't know what els I can change.

 
Rep Power: 209

while he was in there you should have had him replace the head gasket too

dude, you were already more then half way to removing and replacing the head gasket, now it will all have to be ripped apart again,

your head gasket is bad, i know you don't want to admit it, but its the truth.....i dont want to admit that i drink too much either




..

 
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I'm not arguing with you at all. I'm definitely not a mechanic. Can you explain how the head gasket causes this to happen? Any idea why it didn't show bad when he checked it? I don't know what he used, but he told me he had a tool or tester that he put in each spark plug hole to check for loss of pressure? He told me it was fine. He's not a typical shade tree mechanic. He retired after 20-25 years of tech service with Nissan, so he's knowledgeable, esp on foreign cars. We were planning on trading this car next summer when my wife graduates college. The only reason I put on the timing belt was I figured changing the water pump might be the problem and I initially suspected the head gasket, too. I told him while it was apart to change it if needed but he told me it was good. Starting to get frustrated. Been working on this for almost 2 months now, and it looks like I've wasted alot of money and it's still not fixed. Thanks for the help.

 
Rep Power: 209

the combustion pressure/gasses in the cylinder are getting pushed through the leaky head gasket and into the cooling system, basically causing air to enter the cooling system,

this air in the cooling system is then pushing coolant out of the rad and into the overflow bottle, eventually causing the overflow bottle to puke/overflow,

 
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Ok. I'll give my mechanic a call Monday morning.
I forgot to add earlier, but I noticed the level slowly creeps up but never returns back down, even after it cools. The coolant level was between cold and hot last week. It slowly crept up and began over flowing. Now it's sitting only a half inch below the overflow cap and it never recedes after sitting over night.
Again, thanks for the help. Looks like another trip to the mechanic soon.

 
Rep Power: 518

There are at least a dozen different ways a head gasket can fail. This test only checked for one of those ways.

Just because it passes one test does not mean all is well. It just means he didn't do the right test.

He needs to do the test that will prove the problem.



Tell your mech to apply shop air line pressure (150-175 PSI) into each cylinder and watch the coolant level in the neck of the radiator. The coolant level will rise when he gets to the leaker.
(I shouldn't need to explain about HOW to do this, each piston at TDC and valves closed and all that.)




More info: Click this link and read everything in the first post: https://www.civicforums.com/forums/3...reference.html

Feel free to peruse the rest of the thread too.