wen61dan

I have read the previous reply's with great interest as I am having problems. I have a 2005 civic that seems to be loosing coolant and can't find any leaks. The operating temperature is fine, the heat inside is ok . The oil is clean and no variation in level. The thermostat and rap cap have been replaced and still a issue. I have no noticeable smoke from the exhaust and do not smell coolant. Anyone have any ideas what should be checked next?

Metalzone

I'd suggest that you do a pressure test on the radiator to make sure that there are no leaks.

wen61dan

Thanks I will have a pressure test done.

Metalzone

Hey, I'd like to ask…. When you fill up your radiator with coolant and close the cap, does it make its way to the reservoir? IF YES, does it return back to the radiator? IF NO, there is a POSSIBILITY that you may have a crack in the reservoir tank which is preventing pressure buildup and therefore not returning coolant back into the radiator.

A crack in the reservoir will cause air to escape and an overheating problem because all the coolant that is making its way from the radiator sort of gets trapped.

Hopefully your case is as simple as replacing a cap/hose/reservoir tank..

Im posting this stuff from the experience that I had with a cracked/leaking reservoir tank…. it was a tiny leak.. but it caused a huge problem!!

Keep us updated!

wen61dan

I had a pressure test done. No leaks in the system. I wish mine was as simple as a reservoir but I just received the bad news that I have a head gasket gone. Exhaust gases are getting into the system , building pressure up and therefore pushing the coolant out into the overflow bottle. This now explains the rad being continuously down and not recovering from the reservoir bottle. I am hopeful the head is ok . Car is still at the garage and should no more by Thursday.

Metalzone

That sucks bro :/

How sure are you that it is a head gasket?

Same thing happened to me!
I went ahead and replaced the engine because of an overheating/head gasket problem…

After I replaced it, it was still overflowing through the reservoir tank!!!

Turns out I had a bad radiator cap and my reservoir tank had a crack.. Little things like this can cost a lot if left un-repaired.

If you decide to fix the head gasket, make sure that you check for warpage with a precision ruler and make SURE that there is no warpage, if there is… u will need to go to the machine shop to resurface it, otherwise it will be a temporary fix, and it will happen again..

Good luck

2004CIVICLX180K

Sorry to hear about the blown gasket, but I had the same issue and once the head gasket was replaced, I haven't been overheating. Hopefully we'll go another 100K without another major repair!

Will

prodjay10

After a radiator flush, the car ran fine for a month. Then started to over heat again on long trips. Only when slowing to stop.

After checking the fluid levels at a gas station, I realized the radiator was cracked by the fill neck. I could hear the hot air and coolant bubbling out.

Replaced radiator, new coolant, and replaced hoses. It has now been 3 months since an overheat. No more bubbles in coolant, no more reservoir over filling, or coolant smell. Total cost of repair $100. Hoses were fine. Could have used old ones and saved some cash.

My suggestion, if the first thing out of your mechanics mouth when you give him the symptoms is head gasket, run! They should take the time to diagnose especially since that repair is as costly as it is...

190,000 miles and still no exhaust gases coming out of radiator. Car runs great.

prodjay10

Any idea how they diagnosed a bad head gasket? Did they check for exhaust gas in coolant?

I had same issue. Bubbles in coolant and coolant coming out of overflow bottle. I refused to accept it was a head gasket because the block tester came out fine 3 different times. Turns out I had two problems. First was clogged radiator. Mechanic flushed radiator with acid and it worked great for a month. Then second (maybe developed afterward) hairline crack in radiator which I discovered second time it started overheating.

I replaced the radiator, hoses, coolant, and made sure the system was burped. I haven't had an issue for 3 months or 3000+ miles.

Overflow tank and radiator are checked regularly now to make sure levels are good and they are fine.

wen61dan

Head gasket was replaced ,car is working great. No more bubbles in the coolant. The pressure test revealed no leaks anywhere. There was exhaust gases in the coolant. The head was sent to a machine shop and thank goodness it was ok. My Honda is back on the road again and hopefully no major break downs for awhile.

slhodson

So I just purchased a 2004 Honda civic 1.7L vtec. It has roughly 100,000 miles on it. After test driving it and driving it all the way back to my city at 70 - 80mph on the freeway, everything was fine, until 5 miles from my house. Out of no where the heat started rising so I pulled over. It got up pretty high before I got it pulled over. Although I didn't spot leaks, the overflow did boil over. I got it back home by letting it cool and babying it. I figured it was the thermo so I picked one up today and refilled the coolant in the rad. After I filled it I noticed a leak from the back of the block on the drivers side. Could this be a freeze plug? I've check the oil and there's no coolant in it and there's no white smoke coming out of my tailpipe. Any guesses on what I could do to fix this?

Mk0813

I have an 04 civic lx coupe that keeps randomly overheating. When I'm going fast on the highway it's fine but when I'm in stop and go traffic or hit lights, it overheats. But it doesn't do it all of the time. Heat cuts out too when not moving. I've replaced the radiator, thermostat, fan switch, and tested the head gasket with negative results. No one can figure out what's wrong. Maybe a small crack somewhere? My mechanic suggested putting in a new engine. I just want to make sure it's nothing else before I spend all that money.

1991_crxsi

iTrader: (1)

Putting in a new engine? lol nice mechanic... sounds shady and/or incompetent. You definitely need a new mechanic before you need a new engine. I have 4 things to suggest. 1) properly "burp" the system to ensure you have all the air pockets out; 2) replace radiator cap; 3) check to make sure the fan is coming on. Sounds like it could be an air pocket to me; 4) sell me the car for $100 and let me fix it .

Mk0813

Hahah good one. Anyway, car was properly burped, there are no air bubbles coming up.
Radiator cap and radiator itself were replaced. And the fans are coming on.

xW01FxGANGx

To start of I would like to let you guys know that yes I have researched this topic already and found similar threads but didn't find my answer. I am posting because I am truly stumped

Car: 2002 Honda Civic LX
Trim: 4 Door
Transmission: 4 speed automatic
Mileage: About 155k

This is my mom's car and I have been trying to fix this problem for her since its now the cold season. When we bought the car about 1 year ago it was blowing hot air, now it just blows cold air.

If I turn the heater on sometimes it wants to overheat. It has done it twice so far and but it is random when it does it.

If I leave the **** on hot but DONT turn the heater on, very little hot air comes in depending on my speed.

What I have done so far:
- Replace the thermostat
----> When I removed the thermostat housing I noticed it didn't have a thermostat. The previous owner said it used to overheat on him and replacing the O2 sensor fixed it but I guess he also took out the thermostat. He claimed that it had overheated a couple times on him too.

- Flushed the heater core:
----> While flushing it water and air was going through it perfectly so definitely not clogged but I did it anyway.

- Swapped the coolant temp sensor:
----> I put on the one from my 99 civic since they are the same, this didn't make a difference at all, yes the one from the 99 civic is working I know this for sure.

- Checked the heater control valve:
-----> It does open and allow water to pass, I saw it moving with my own eyes.

- Checked for leak from the heater core:
------> there is no leak

-Checked coolant level and bled the coolant too:
-----> It seems fine and I got rid of all the air in the system too

The last possible thing on my mind now is Blown Head Gasket

My mom called me and said that her car was randomly stuttering, like when the engine wants to turn off, when she came to a stop or was coming to a stop. I took the car to autozone to read the CEL codes.

They were as follows:

P1457 - Emission control leak
Cause: Cracked manifold/cat converter

P0302 - Cylinder 2 Misfire
I went to the junkyard to get a ignition coil but the car just stopped stuttering by itself. I still swapped the coil pack either way. Has not done it since.

P0128 Cooling system malfunction
I believe this is what is causing the heater not to work

Today 11/27/2014 I checked her Oil cap. It has water on it. The radiator cap also has oil on it. I am almost 100 percent sure she has a blown head gasket. Unless I got a little oil on the water when I was replacing the thermostat. I used a little PB Blaster just in case the bolts were tight.

Currently there is no white smoke coming from her exhaust.

Is it possible that a blown head gasket could cause the car not to output hot air?

I NEED THIS PROBLEM FIXED ASAP ANY HELP WOULD BE APPRECIATED.

Jacob Williams

This could be something super simple or maybe its not. I don't know to much about cars but I saw a lot of people on here do. I bought a Honda civic stick shift and now when it sits in neutral the engine starts to get hot. But when I start driving it cools right back down? I don't want to ruin my daily. Someone help me out please

Almighty-Si

Needs a headgasket

xW01FxGANGx

Yeah this appears to be the only thing left before checking for a bad water pump or a clogged radiator

Robert Buehler

Sorry if I am hijacking the thread but I have the same sort of problem and I cannot yet post new threads.

I have a 2004 civic hybrid with 325k miles on it. It runs perfectly.

So far I have never seen any evidence of oil in the coolant or water in the oil and the car is not blowing white smoke.

I have changed the thermostat, the water pump, the belt and the radiator cap.

I have flushed the system by installing two hose "t" fittings into the feed and retune lines to the heater core. The system looked very clean and free of obstructions. I blew air through the core and felt no restrictions.

I ran a clear hose between the two lines to watch for fluid flow and it was flowing.

I have checked the shut off valve and it appears to be open.

I have purged the system or tried to several times and ran it until it appeared to be very hot and still not enough flow through the heater core to generate heat at idle.

Last night it was not flowing coolant sufficiently through the heater core and I gave up for the night.

This morning I topped the radiator off (the overflow tank looks like it has the proper amount of fluid in it) and the heat worked at idle. WHY I do not know.

I ran the car for a bit, stopped for about an hour then checked the radiator and topped it off again. Then no more heat at idle.

Plenty of heat at 55 mph but again no flow through the core or very little at idle.

I cracked open the two caps on the feed and return lines to the core to check for air or flow. At first, I completely removed the cap an no flow pushing out the return. I cracked the feed and got only a little flow but then it began flowing. Both lines have the hose fitting caps so I though bleeding air out would solve the problem.

I am at a loss as to how water can be moving around in the motor without always flowing through the heater core if the lines are open. The car had just been running down the highway at 60mph with the heat working but then at idle the flow through the core drops down to almost nothing.

For some unknown reason there is insufficient flow through the heater core circuit. The core appears to be free of obstructions since it works from time to time or all the time at speed but only sometimes at idle.

I thought for sure the old water pump and belt were causing poor coolant circulation but after replacing them (the pump looked fine but thought maybe the old belt was slipping) still no heat. I put the clear line between the feed and return heater lines and had what looked like good flow and hot coolant. I blew through the core with my mouth and felt no restrictions. I hooked the line back up and idled the car for 30 min. and still no heat. The lines felt like they got warm but probably not warm enough since I had no heat. I checked for flow by opening the caps and it even appeared to have some flow. But no heat. Then this morning it worked. WHY. and now its back to only working at speed.

What is going on. Could it be a small head gasket leak that is keeping the flow restricted at idle?

Robert Buehler

Ok I broke down and ordered a 12 volt coolant circulation pump. It was the
Part #: REPA313514
AUXILIARY WATER PUMP, NEW

from Auto Parts Warehouse

Unfortunately they and other companies could not tell me what the inlet and outlet ports diameter was but I think it will be 3/4". This will likely be to large but that can be dealt with. The connection is a simple (+) and (-) so I think it will work.

My research if that is what you want to call it showed that many vehicle (mostly German) have coolant circulation pumps so this is not a crazy idea.

Actually since my hybrid shuts off when you come to a stop, I think a coolant circulation pump would have been a good idea.

I am still at a loss as to why the system stopped consistently flowing coolant through the heater core. If it is the head gasket it is not significant enough to affect anything else that I can see.

Seth Wood

Hey guys, so I'm getting a little worried, my car keeps over heating. I know I said random in the header, but it's actually not that random. It happens when I leave the car idling.

Say I leave the car on for 15 minutes while I run inside to get something, the temp gauge goes up almost to the red. Today, I was driving circles in the mall parking lot looking for a spot and it was 3/4 up the gauge. The other day I was in the line at a fast food place, same thing, almost completely to red. But as soon as I drove away, or picked up speed, it dropped right back down. It's getting kind of concerning.

The only thing I can think of is that my water pump is going bad, or its because I did the intake resonator delete. Thoughts?

Also, my heater only works when i have it recirculating the air, sometimes it will work when I'm pulling from the outside, but that's iffy. And when I go around corners quickly, the heat goes away then comes back.

Civiccity03

Is your fan turning on? Is the coolant level low when you remove the radiator cap?

Will Gabriel

here is the problem. my civic wont crank out any heat, and started overheating once in awhile but then heat would come back and it would be fine. on and off issue. replaced the thermostat, seemed to do the trick. heat was back, super warm and super fast to heat up. now randomly it has been taking longer and longer to heat up, if at all and is cranking out cold air. it was so cold before work one night like almost below zero, so i drove it in lower gears through town so my RPMs were a bit higher than normal like 3.5 - 4 - 4.5 and the heat started to come out, not just freezing air. i thought maybe i had a clog in my lines and my heater core wasnt getting fluid. so i thought if i pushed her a little it would warm up the car and it worked. but i mean i wasnt super sure because it was like a freezing snow stormy kind of night. so it steadily takes forever to warm up the heat and i have to drive it like a race car to get the heat to blow warm. now its doing this thing where its cold again even when the engine is up to temp(like the thermostat issue) but wont kick out heat and will start to overheat. so i get to the gas station, fill up and get back on the road after my engine temp has dropped, and slowly i start to get heat coming through the vents and the engine temp stays where its supposed to be. once i got on the highway it maintained normal engine temp and good heat. not amazing heat like after i changed the therm(its been slowly declining in warmth and warm up time since then) but hot. so when i get to my exit, start slowing down, by the time i reach the bottom of the exit at the light, the heat has turned cold as **** air and the engine temp starts going back up. then i get moving again and slowly it starts to warm up and the engine temp goes back to normal. then when i get to another light it does it again. also when i changed the term about 2 months ago i realized how dirty and old the current fluid was from the old lady i bought it from, she must've not changed or flushed it for awhile. so i was assuming it cant be the thermostat again, maybe it can? could it be the water-pump is going bad? could it be a blockage to the heater-core preventing heat? and the overheating is just like when i had to change the thermostat? but now at every red light i lose all hot air, it blows cold and starts to overheat til i get moving decently and then it balances out. so yeah my question is just like is it the water pump? heater core blockage? thermostat? im afraid to take it to a garage without having an idea of what im looking at and if possible i would like to do the work myself instead of blindly paying for it. any and all help greatly appreciated! thanks!

Former User

Post a picture showing the color of the coolant. Any oil in the coolant?

Check the coolant level in BOTH the radiator and reservoir. Top off if needed, and then bleed the cooling system.

sduncan

mobalized,
I have had the same problem, and the dealer cannot fix it!! I took it to them 11 times, and Honda has a ticket on it. I haven't heard from them for about 4 - 6 months now.

I have a 2004 Honda Civic EX.

My car has had 4 thermostats now.

While the heater fan is on high, and the heater temp is set on high, the temp gauge stays on cold when it's idling, then moves up when I give it gas. Then drops after warming up if I let off the gas for a few minutes. I even tested it during the summer, and it does the same thing.

I also tried leaving the fan off when I started it in the morning. The temp gauge went up, but when I turned the heat on and the fan on high, the air was cold and didn't get warm until I started moving and gave it gas.

I have had the following done...
Heater core and hoses flushed (this fixed it for about 8 months)
After about 8 months, it started doing it again, and they "burped" it. That worked for a few days.
Next, they put on a new thermostat.
Burped it again.
Installed the upper hose.
Next, they installed a head gasket and said the head was not warped (it has never overheated). When they installed the new head gasket, they installed a water pump, and because it had about 160,000 miles, they replaced the timing belt.
They've "burped" it numerous times.
I even took it to a local auto heating/cooling expert, and he put in a higher temp thermostat. That at least helps to thaw the frost on the windshield when I start it in the morning. However, the real problem is not fixed!!

If anyone knows how it fix it, please let me know!!

The auto heating/cooling expert said it may be that the muffler may be going bad with the baffles bent and/or deteriorating. Has anyone else had that happen? I really don't want to put a lot more money into it. I'm just very near getting rid of the car, but I don't want to pass on that problem to someone else who probably won't have the money to fix it.

Thanks!!