Make: Honda

Model: Civic

Year: 2007 (European version but shares many of the same systems as US version)

Gen: mk8

Fuel: petrol

I've just drained my coolant so now I have air in the system which I need to bleed out.

I've added the fresh coolant via the radiator cap and tried to massage air out of the radiator hoses as much I can before starting the engine.

I don't have one of those special funnels for this job, where the fresh fluid sits in there as you fill via the radiator cap with the engine running. So I've seen youtube videos where people run the engine with coolant filling up out of the radiator cap into this large funnel.

Given that I'm not equipped with one of these, should I:

  • run engine with cap off? Can I cause harm by not being fast enough with adding more coolant once engine drinks some down?
  • run engine with cap resting?
  • run engine with cap on tight, then turn engine off and release air by removing cap once cooled down?
  • Many cars have a cooling system bleed valve. Please include your make, model, and engine version and it might be possible to help you.
    – jwh20
    Aug 17, 2021 at 23:19
  • 1
    Here's the thing, bleeding a system can be different for many different cars. Some systems are self bleeding, meaning, fill it up and away you go. Describe the system we're talking about (ie: what is the year/make/model/engine) and we can help you. IOW: There is no generic answer here. Aug 17, 2021 at 23:19
  • JWH20/Paulster has this exactly right. Until you share make, model and model year nobody here can help you. One generic assist we can provide is the recommendation that you purchase a service manual for your vehicle. Chilton or Haynes have pretty good offerings, and should have solid recommendations on refilling your specific cooling system.
    – zipzit
    Aug 18, 2021 at 2:25
  • Some vehicles needed the front jacking up to change the slope of some pipes otherwise they would never bleed.
    – Solar Mike
    Aug 18, 2021 at 6:14
  • I've edited post: it's Honda Civic mk8 petrol 1.8L
    – jsstuball
    Aug 18, 2021 at 11:22

1 Answer 1


This particular vehicle has no air bleed valve.

You should fill the overflow tank to the midpoint between the LOW and HIGH marks and then drive it for a few miles.

After it cools off it should draw any needed coolant into the system from the tank.

If the tank falls below the LOW mark when cold, add some more to bring it back up to the line.

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