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Premium Member
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Discussion Starter #1
Morning all,

Yesterday i noticed that my car was blowing cold air even when the engine temp gauge was up to normal running temp.Eventually it went warm.

This morning i was taking the mrs to work, the dash said outside temp was 6d, sounds right. Normally the car is warm by the time i drop her off, but still cold this morning.

So i drive home, still cold, so i whack it to "hi" and it was still cold when i got home.

Any idea what is happening?
 

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Premium Member
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406 Posts
Discussion Starter #3
My engine temp dial goes up as its always had, to just below half way.

This morning i had my engine running to scrape the car, by the time i got in it was blowing luke warm. When i started to drive it went to blowing cold again, and continued to blow cold all the way way there :(

Anyone able to help me? last thing i want is my heating to balls up now the weather is freezing :(

  • My outside dash temp seems to be reading fine
  • My engine temp dial seems to be working fine
  • It can blow warm then stay cold for rest of journey
  • After 20-30mins of driving it can start to get warm again
 

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Premium Member
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406 Posts
Discussion Starter #4
Also noticed this morning that when it starts to blow cold, the engine temp rises very high, see pic.

Then it drops to normal and the temp goes warm again.



What can this be lads??
 

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Ex-Pat Geordie!
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2,241 Posts
Thermostat. Happened to me in a different car and had to partially block the front grill with card for a couple of days till I got it sorted.
 

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Premium Member
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Discussion Starter #7
Thanks for the this guys,

Guess ill change the thermostat then, is there a guide? Can't seem to see one on the wiki.
 

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Premium Member
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that is a tell tale sign the head gasket might have gone

classic symptoms are while the engine is idle water is allowed to flow but as soon as you start to drive or accelerate water stops flowing round because of exhaust gasses leaking into the coolant ( because of a leaking head gasket ) pressurising the water system enough to stop the water circulating. the rising temp gauge combined with the cold air gives it away for me

the gasket leak will be between a cylinder and a water way rather than being between a cylinder and oil way which is easier to detect because of the oil and water mixing ( known as mayo ) but when the leak is between the cylinder and the exhaust one of the first signs is the heater blowing cold air and the temp rising when driven but gets warm again when idle and the temp settles back down

or i might be completely wrong and it could be an open thermostat but open thermostats tend to just blow warmish air when the engine is up to temp and the temp gauge tends not to go higher than normal
 

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Discussion Starter #9
That's not good news,

I'm going to check coolant levels now.

I take it a new head gasket it going to cripple me??
 

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more torque than the mrs
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6,714 Posts
that is a tell tale sign the head gasket might have gone

classic symptoms are while the engine is idle water is allowed to flow but as soon as you start to drive or accelerate water stops flowing round because of exhaust gasses leaking into the coolant ( because of a leaking head gasket ) pressurising the water system enough to stop the water circulating. the rising temp gauge combined with the cold air gives it away for me

the gasket leak will be between a cylinder and a water way rather than being between a cylinder and oil way which is easier to detect because of the oil and water mixing ( known as mayo ) but when the leak is between the cylinder and the exhaust one of the first signs is the heater blowing cold air and the temp rising when driven but gets warm again when idle and the temp settles back down

or i might be completely wrong and it could be an open thermostat but open thermostats tend to just blow warmish air when the engine is up to temp and the temp gauge tends not to go higher than normal
could be right but i have never known one go on the 8th gen..
 

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Premium Member
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1,212 Posts
could be right but i have never known one go on the 8th gen..
iv'e not either and it would be very unusual if it has gone but the symptoms described sounds exactly like i had a good few years ago although it was a pug engine and not a honda

i can't think of anything else that would cause the same
a thermostat stuck open wouldn't really cause the engine to overheat

have you ( the OP ) checked to see if the oil is not contaminated with water ?
i would expect to see a small amount of mayo in the oil filler cap if you only do short journeys but the dipstick should be clean oil

you can also check to see if water is flowing through the expansion tank as it should
 

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Premium Member
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406 Posts
Discussion Starter #12
Hi guys,

Just drove home from work and car was behaving but them bam heaters went cold and temp gauge went sky high. I had the temp on 'hi' and it was cold AIT with engine temp gauge nearly hitting Max.

Luckily I was turning into my street so turned the engine off a few seconds after.

I've took the rad cap off and can see fluid in there at the top ish.

Checked oil and that's between min and Max, not opened filler cap yet.

I can't believe the head gasket has gone the car sounds and drives sweet and I never 'rag' it.
 

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That sounds like my problem. Today I just got my car back after it has got a new condenser, it had a hole. I took the car for a test ride. It cools fine again, but the temp gauge was rising rapidly to the red line. I could get it to normal again when i set the temp to hi. I also recognized, that the air blowing in the cabine, was not so hot as normal. The next 15 min. the temp gauge was going up and down, but after that it got stable again, and I couldn't provoke a high gauge temp again. I will test drive it again tomorrow. Some years ago, I had a almost similar problem, two new sensors in the engine bay fixed that problem.
 

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Premium Member
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406 Posts
Discussion Starter #14
Any idea what coolant I buy and do I just pour it in the expansion tank that's a pita to get to?

Need to rule out low coolant before I do anything else.

Also just read about the block cracking issue arghhh! Won't sleep tonight now .
 

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Premium Member
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1,643 Posts
Put the coolant in the rad. My other car an astra has a fooled thermostat and it takes forever for the heating to start coming through. Cheap fix if it's just that althought never know a temp gauge to go crazy like that
 

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Premium Member
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Discussion Starter #16
Are you sure i top up from the rad as that is pretty full but can't see anything in the expansion tank.

Never known you fill from the rad before.
 

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Premium Member
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The last time I had this problem on a car 89civic the water pump was worn / not turning=water sits idle and the air was being sucked into the system
 

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Premium Member
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you fill it at the expansion tank just don't fill it to the top there should be 2 lines on the tank min and max just fill it to the middle of the marks ( about half way ) and keep a check on the level
 

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Premium Member
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406 Posts
Discussion Starter #19
where can I pick up some coolant asap, Honda all weather type 2 according to handbook. can't see any on halfords or euro car parts
 

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more torque than the mrs
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6,714 Posts
i would take it to a garage mate let them do a complete coolant change approx £30 especially if you don't know what coolant is in there, do you know what coolant is in there is it honda's coolant? honda advises not to mix coolants as there is a chance your car will overheat, thinking about it your symptoms sound similar to someone doing this very thing..also wonder if there is an airlock..
 
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