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► 01-05 Civic Cooling System Q&A (overheating, fans inoperable, etc.)

Old 01-25-2011, 11:47 AM
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Default ► 01-05 Civic Cooling System Q&A (overheating, fans inoperable, etc.)

Given the rate at which we receive questions regarding the cooling system and it's related components, It Wasn't Me and I thought it would be best to sort of sum up the more common issues people experience.

Overheating
- Symptoms:
A. (Obvious) Temperature gauge showing an engine temperature that is beyond normal operating temperatures (above the half-way mark on the gauge is not good).
B. Slow acceleration or overall decreased engine performance.
C. Car goes in to "Limp" mode. (Where the car will not rev past 4,000 RPMs)
D. Car exhaust produces white smoke.
E. Coolant system seems to be pressurized, when you open coolant fill cap.
F. You have a Check Engine Light.
G. You experience coolant loss.
H. There is a faint smell that's similar to pancake syrup. (Usually a sign of burning coolant.)
I. The heat works while driving / moving, but blows cold(er) air while the vehicle is not in motion.


Possible Causes:
- Blown head gasket (tell-tale signs: white smoke from the exhaust, milky colored oil, coolant overflowing the reservoir)
- Failing water pump
- Air bubble in coolant system (typically caused by an improper coolant system burp, but can be cause by a blown head gasket)
- Clogged or restricted heater core
- Faulty thermostat
- Faulty radiator fan switch
- Faulty radiator fan
- Faulty radiator cap
- Blown radiator fan fuse, or faulty radiator fan relay.
- Clogged or restricted radiator
- Leaking water hose or passage
- Warped head or block surface, subsequently causing a failed headgasket.





Note: Sometimes the engine will show symptoms of overheating if you're overloading the vehicle. For example, climbing a long, steep hill on a hot day with the A/C on. If that is the case, pull the car over and wait for the temperature gauge to come down to the halfway mark, then continue driving. This is not uncommon during the summertime in the hotter parts of the country.



Poor interior heat
- Symptoms:
A. When the climate control is set to it's hottest setting, you get little to no heat in the interior.
B. The heat works while driving / moving, but blows cold(er) air while the vehicle is not in motion.


Possible Causes:
- Blown head gasket (tell-tale signs: white smoke from the exhaust, milky colored oil, coolant overflowing the reservoir)
- Failing water pump
- Air bubble in coolant system (typically caused by an improper coolant system burp, but can be cause by a blown head gasket)
- Clogged or restricted heater core
- Faulty thermostat
- Leaking water hose or passage
- Inoperable or restricted water valve assembly (what controls the flow of coolant in/out of the heater core)

--Currently under construction. There will be more added as I get time to put in to this thread.--

Last edited by toyomatt84; 02-10-2018 at 06:31 PM. Reason: Couple minor fixes =)
Old 01-25-2011, 01:25 PM
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Default Re: ► 01-05 Civic Cooling System Questions? Ask them here! (overheating, coolant, et

Ah, you already started this.

I added a couple more things.
Old 01-25-2011, 01:29 PM
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Default Re: ► 01-05 Civic Cooling System Questions? Ask them here! (overheating, coolant, et

If I get a chance at home, I'll be throwing more situational stuff (ex. poor interior heat issues).
Old 01-28-2011, 07:05 AM
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Default Re: ► 01-05 Civic Cooling System Questions? Ask them here! (overheating, coolant, et

Added more information to this thread.
Old 06-01-2011, 06:54 PM
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Default Cooling Problem HELP!

To make this short:
I was driving back home from San Francisco and there was mild to moderate traffic near certain exits. I noticed in stop and go traffic my temp needle would slowly rise then eventually go hot. But when I get going the needle slowly drops down back to normal.
When I finally made it home I noticed:
1) Smell of coolant in engine bay
2) Coolant Reservoir is full and it looked like it was leaking from there.
3) Loss of coolant in rad

I have checked my oil and it looks normal. Plugs look normal. I replaced coolant and properly burped the cooling system. I also replaced the thermostat. So far my temp has not when above normal. I have not drove in traffic yet. No CEL. No white smoke. My car has 90,xxx mi. Water pump has been done already along with timing belt.

What could cause the coolant reservoir to be full like that? Could there still be air in the system? I am not sure if its my HG. What could be the prob guys?
Old 06-01-2011, 07:24 PM
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Default Re: Cooling Problem HELP!

Originally Posted by TailZ
To make this short:
I was driving back home from San Francisco and there was mild to moderate traffic near certain exits. I noticed in stop and go traffic my temp needle would slowly rise then eventually go hot. But when I get going the needle slowly drops down back to normal.
When I finally made it home I noticed:
1) Smell of coolant in engine bay
2) Coolant Reservoir is full and it looked like it was leaking from there.
3) Loss of coolant in rad

I have checked my oil and it looks normal. Plugs look normal. I replaced coolant and properly burped the cooling system. I also replaced the thermostat. So far my temp has not when above normal. I have not drove in traffic yet. No CEL. No white smoke. My car has 90,xxx mi. Water pump has been done already along with timing belt.

What could cause the coolant reservoir to be full like that? Could there still be air in the system? I am not sure if its my HG. What could be the prob guys?
Based on your symptoms, I'd say that you're probably looking at a blown headgasket.
Old 06-02-2011, 07:37 AM
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Default Re: ► 01-05 Civic Cooling System Questions? Ask them here! (overheating, coolant, et

Recently I bought a 2002 Civic DX and now I'm having overheating issues along with the great smell of burning coolant.

It was so bad once that I actually had smoke/steam coming from the engine bay.

I assume this is due to a failing head gasket. Is this correct?

Is there any easy ways to test to see if the head gasket is bad?
Old 06-02-2011, 07:46 AM
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Default Re: ► 01-05 Civic Cooling System Questions? Ask them here! (overheating, coolant, et

Test the coolant for discoloration and you can get the coolant tested to see if its being burnt.
Old 06-02-2011, 08:16 AM
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Default Re: ► 01-05 Civic Cooling System Questions? Ask them here! (overheating, coolant, et

Ok great, Thanks! Does anyone know how theses engines are after the head gasket is replaced? Will I have more issues down the road or are they ok?
Old 06-02-2011, 11:58 AM
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Default Re: ► 01-05 Civic Cooling System Questions? Ask them here! (overheating, coolant, et

Originally Posted by cskinner89
Recently I bought a 2002 Civic DX and now I'm having overheating issues along with the great smell of burning coolant.

It was so bad once that I actually had smoke/steam coming from the engine bay.

I assume this is due to a failing head gasket. Is this correct?

Is there any easy ways to test to see if the head gasket is bad?

Any white "smoke" coming out of the exhaust?

Does the coolant reservoir overflow? (it's the white plastic jug next to the battery)

If not, where is it leaking from?

Does the radiator fan work?

Any symptoms with the heater in the car intermittently blowing lukewarm or cool air instead of warm/hot?

There are a number of things that it could be besides just the head gasket. Have the coolant tested for exhaust gases in it. (combustion leak test) You can buy the kit at a local auto parts store, online, or just have a shop do it.
Old 06-02-2011, 12:00 PM
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Default Re: ► 01-05 Civic Cooling System Questions? Ask them here! (overheating, coolant, et

Originally Posted by cskinner89
Ok great, Thanks! Does anyone know how theses engines are after the head gasket is replaced? Will I have more issues down the road or are they ok?
If the work is done properly, faulty components are replaced with new ones, the system is thoroughly flushed, and nothing is warped or cracked, it should last for some time.

However, nothing is fail-proof, so you never know when the next gremlin will pop up.
Old 06-02-2011, 03:07 PM
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Default Re: Cooling Problem HELP!

Originally Posted by toyomatt84
Based on your symptoms, I'd say that you're probably looking at a blown headgasket.
Damn that sucks!
I'm going to have a shop look at it.
I just can't believe how early it went. My old 3rd gen prelude has never had this problem even with 180,000mi+. Oh well..
Old 06-03-2011, 06:54 AM
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Default Re: ► 01-05 Civic Cooling System Questions? Ask them here! (overheating, coolant, et

I just picked up my 03 and noticed that the radiator didn't have coolant all the way to the top, so i topped it off.
After driving it, that coolant went into the overflow and well, overflowed. The temp gauge still shows it as being normal and i just had the tb/wp service done and the fluids were topped off.

The oil is still clean.
Old 06-03-2011, 12:31 PM
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Default Re: Cooling Problem HELP!

Originally Posted by TailZ
To make this short:
I was driving back home from San Francisco and there was mild to moderate traffic near certain exits. I noticed in stop and go traffic my temp needle would slowly rise then eventually go hot. But when I get going the needle slowly drops down back to normal.
When I finally made it home I noticed:
1) Smell of coolant in engine bay
2) Coolant Reservoir is full and it looked like it was leaking from there.
3) Loss of coolant in rad

I have checked my oil and it looks normal. Plugs look normal. I replaced coolant and properly burped the cooling system. I also replaced the thermostat. So far my temp has not when above normal. I have not drove in traffic yet. No CEL. No white smoke. My car has 90,xxx mi. Water pump has been done already along with timing belt.

What could cause the coolant reservoir to be full like that? Could there still be air in the system? I am not sure if its my HG. What could be the prob guys?
It's no longer overheating or otherwise getting hot?

Have you changed the radiator cap?

Does the radiator fan work?

Start simple. Worry about the head gasket if all else fails.
Old 06-03-2011, 12:35 PM
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Default Re: ► 01-05 Civic Cooling System Questions? Ask them here! (overheating, coolant, et

Originally Posted by dallison
I just picked up my 03 and noticed that the radiator didn't have coolant all the way to the top, so i topped it off.
After driving it, that coolant went into the overflow and well, overflowed. The temp gauge still shows it as being normal and i just had the tb/wp service done and the fluids were topped off.

The oil is still clean.

As noted in my last post..

Have you changed the radiator cap? What about the thermostat? Is the radiator fan coming on? Did you thoroughly bleed the system for trapped air?

The coolant only needs to be to the bottom of the fill neck on the radiator, it doesn't need to be to the very tip-top brim of it. The reservoir, when the engine is cold, should have coolant in it between the two lines. Too much coolant could cause it to overflow. You'll notice that when you turn your car off and pop the hood, that the level of coolant in the reservoir is higher than it is when the engine is cold.
Old 06-03-2011, 04:14 PM
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Default Re: Cooling Problem HELP!

Originally Posted by It Wasn't Me
It's no longer overheating or otherwise getting hot?

Have you changed the radiator cap?

Does the radiator fan work?

Start simple. Worry about the head gasket if all else fails.

I just came back from a shop and they told me to replace the radiator cap and drain my coolant reservoir.
Radiator fan works.
My car doesn't overheat in the city. I have yet to take it back in stop and go traffic.
How can I drain the coolant reservoir? Do I just unbolt it off the car and drain or is there a hose/plug that I can access to drain.
Old 06-05-2011, 08:33 PM
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Default Re: Cooling Problem HELP!

Originally Posted by TailZ
How can I drain the coolant reservoir? Do I just unbolt it off the car and drain or is there a hose/plug that I can access to drain.
I don't think the reservoir has a drain plug. You'll probably need to remove it to drain it, or else use some clear vinyl tubing (or a hose) and suck it out.
Old 06-05-2011, 08:51 PM
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Default Re: Cooling Problem HELP!

Originally Posted by It Wasn't Me
I don't think the reservoir has a drain plug. You'll probably need to remove it to drain it, or else use some clear vinyl tubing (or a hose) and suck it out.
That is correct. The stock overflow reservoir does not have a drain port. Only the filling port that is connected to the radiator.
Old 06-06-2011, 02:53 PM
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Default Re: Cooling Problem HELP!

Originally Posted by It Wasn't Me
I don't think the reservoir has a drain plug. You'll probably need to remove it to drain it, or else use some clear vinyl tubing (or a hose) and suck it out.
Originally Posted by toyomatt84
That is correct. The stock overflow reservoir does not have a drain port. Only the filling port that is connected to the radiator.
Okay I bought a siphon pump thing yesterday. Drained my coolant reservoir and replaced my radiator cap. So far so good. I do not have any overheating problems at this moment. *knocks on wood* Also my reservoir is not overflowing anymore after a drive.
Old 06-07-2011, 02:31 AM
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Default Re: ► 01-05 Civic Cooling System Questions? Ask them here! (overheating, coolant, et

That's encouraging . How long did you have to run it to get rid of all the air bubbles? Also what is the proper fill procedure ? I think I've been overfilling the system because first I fill the radiator , then bring the reservoir up to the top line (full) .Guess I should check the manual to see what the capacity is .
Old 06-07-2011, 08:59 PM
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Default Fans not working properly. Need to test.. Help

2004 Honda Civic Ex Coupe 1.7L Engine

Ok, so my car has been over heating. I already changed the thermostat. I've noticed my fans don't come on at all or come on really really late. I've been trying to get them to turn on several times and I've only gotten them to turn once, when I let the car on for 40 mins and it was overheating. I've turned the car on with with the A/C on blast and they don't come on. Even if the car is already really hot.
Some guys told me that if I disconnected the cable from the fan switch the fans should stay on when I turn on the car. I did that and they fans don't come on. I was also told it would be a relay. I guess thats like a fuse things that send the signal.
How do I check my switch and my relay to determine which one it is?? And why don't my fans come on when they should?
Thanks
Old 06-07-2011, 10:54 PM
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Default Re: Fans not working properly. Need to test.. Help

Originally Posted by vgarcia25
2004 Honda Civic Ex Coupe 1.7L Engine

Ok, so my car has been over heating. I already changed the thermostat. I've noticed my fans don't come on at all or come on really really late. I've been trying to get them to turn on several times and I've only gotten them to turn once, when I let the car on for 40 mins and it was overheating. I've turned the car on with with the A/C on blast and they don't come on. Even if the car is already really hot.
Some guys told me that if I disconnected the cable from the fan switch the fans should stay on when I turn on the car. I did that and they fans don't come on. I was also told it would be a relay. I guess thats like a fuse things that send the signal.
How do I check my switch and my relay to determine which one it is?? And why don't my fans come on when they should?
Thanks
Try some of the DIY's from the FAQ's..
Testing the Radiator Fan Switch: Link
Radiator Fan & Fan Switch Circuit Troubleshooting: Link


You should also buy a manual. http://www.helminc.com/helm/product2...C01&itemtype=N
Old 06-07-2011, 11:00 PM
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Default Re: ► 01-05 Civic Cooling System Questions? Ask them here! (overheating, coolant, et

Originally Posted by rmdevo
That's encouraging . How long did you have to run it to get rid of all the air bubbles? Also what is the proper fill procedure ? I think I've been overfilling the system because first I fill the radiator , then bring the reservoir up to the top line (full) .Guess I should check the manual to see what the capacity is .
I recommend buying one of these. http://www.tooltopia.com/search.aspx...Lisle+LIS24610

Keep it about half-full of coolant while you burp the system. If you don't have one, or don't want to buy one, just do the following.

Loosen the radiator cap, or remove it completely.
Turn HVAC temperature dial to full-hot, then start the car and let it run until the radiator fan comes on at least twice.
Turn the car off (isn't a must) and check the coolant level, adding more if/when necessary.
Reinstall the radiator cap and call it a day.
(Some says it's a good idea to park on a slight incline so that the front of the car is a little higher than the rear, but I've never had to do that.)


You guys really need to start utilizing the Search feature. Overheating and burping the cooling system has been covered numerous times.
Old 06-08-2011, 05:47 AM
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Default Re: ► 01-05 Civic Cooling System Questions? Ask them here! (overheating, coolant, et

Originally Posted by It Wasn't Me
As noted in my last post..

Have you changed the radiator cap? What about the thermostat? Is the radiator fan coming on? Did you thoroughly bleed the system for trapped air?

The coolant only needs to be to the bottom of the fill neck on the radiator, it doesn't need to be to the very tip-top brim of it. The reservoir, when the engine is cold, should have coolant in it between the two lines. Too much coolant could cause it to overflow. You'll notice that when you turn your car off and pop the hood, that the level of coolant in the reservoir is higher than it is when the engine is cold.
No on the cap or thermostat. The fan is coming on also.

The coolant level is to where you state and there was overflow from the reserviour.
This car is taking some getting used compared to some of the other cars i have had.

Temp gauge is normal and everything seems to be operating normally.

No white smoke and only oil is in the crankcase.
Old 06-12-2011, 04:24 PM
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Default Re: ► 01-05 Civic Cooling System Questions? Ask them here! (overheating, coolant, et

I may replace the cap and thermostat. The engine temp creeps up now that i notice. I think that the dealer may have rushed the t/b-w/p install since they started at the end of the day.

Engine oil is clean and no other leaks besides the coolant coming out of the overflow.

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