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I have a 2005 4 door LX Honda Civic that I am in need of some diagnosis help. There are a couple of separate issues that I am looking at. I am not sure if both issues are related but hopefully, someone can assist.

The first issue is that the car is losing coolant from the radiator and the overflow reservoir. The coolant is not dripping down to the ground. I just did a coolant flush last week and the level in the radiator has already gone down some. I did a pressure test and the radiator and the presssue went down to zero after about an hour. I know that there could be a lot of issues that it might be, i.e. heater core, and hopefully not the head gasket. Any other thoughts or ideas that it might be would be helpful...

Secondly, I noticed that there is some oil residue on the bottom of the valve cover and I have found some oil on the 4th spark plug. Assuming that the this might is probably meaning that the valve cover gasket probably needs to be replaced?

I know that it is hard to diagnosis issues without seeing the car but if there are questions that you need to ask me to help narrow down the issues, please let me know. Thank you.

 
Rep Power: 517

Head gasket? Radiator? Cap?
Most head gasket problems will push liquid out of the radiator and into the reservoir, which overflows while driving and either leaves very little evidence, or it soaks the battery tray and fan shroud

Start here, first post has the info https://www.civicforums.com/forums/3...reference.html


If oil is getting into the plug tubes, good chance the lip of the ring seal got caught over the top of the tube instead of sliding down the side of it. Or it just needs a valve cover gasket set.....which would be part of the head gasket job your engine might need.

 
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what makes me wonder about the radiator is the fact that it doesn't hold pressure?? I have not tackled a head gasket job but isn't this somewhat of a "major' job? I know that a valve cover gasket is not bad....

I took to a shop to have a "professional" look it over. No sweat on the valve cover gasket. The same garage replaced the timing belt so the valve cover gasket would be under warranty if it does need to be replaced.

As far as the coolant, it was suggested, "replacing the thermostat, flushing the system and squeezing the hoses to get rid of the air pockets.

I just flushed the system last week and got rid of the air pockets. If I go back and replace the thermostat, in your opinion, is it necessary to to re-flush the system? I understand it is necessary to burp the air but re-flush?

 
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I was able to hook a scan machine up to the car to test the car and test the coolant temperature and the thermometer. It was registering within specifications with the thermometer open. So this makes me think that the thermometer is working ok.

I am going to blow out the heater core and see if that could possibly be the problem just due to the fact that I am not sure what else to try.

Any other suggestions of things to try?

 
Rep Power: 517

You mean thermostat.



Coolant level in the radiator going low can cause air pockets in the heater system.....that causes very poor heater output. If that's the case, heater output returns to normal when the system is refilled and burped of trapped air, and lasts until the system gets low or more air is trapped again.

The heater system has a cable operated valve that shuts off liquid flow through the heater core too, make sure that valve is wide open.



Done head gasket checks yet?

 
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You mentioned the cable, where is this located and how do I check to make sure that valve is open?

What kind of checks do I do to check the head gasket?

 
Rep Power: 517

Follow the heater hoses between the engine and the firewall. The water valve is there. Find its cable.

Key ON
Run heater temp control to full cold, then check valve position.
Run heater temp control to full hot, then check valve position.
Lever on valve should have moved about 90*


But does the lever movement on top of the valve actually open and close the passage inside? More work may be needed to figure that out.

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

 
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Thanks, I will attempt to give the cable check tomorrow and I'll let you know.

 
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I checked the coil and all was good. I went ahead and blew the heater coil out just to check that. I put a new thermostat just in case. I noticed that there is some moisture coming out of the exhaust pipe--that I can see when I put my hand up to the pipe(normal?)

What I am seeing is, I fill the radiator up to the neck of the opening with coolant. I burp the system as filling while running the car. I operate the car as normal throughout the day. I check the coolant cold the next morning and the coolant in the radiator has dropped once again(see pic). I can't see how far down into the radiator the coolant level has fallen.

I fill and burp the radiator once again. It takes about 16oz of coolant to once again to reach the neck of the radiator.

Is this normal? Should the coolant level be stable in the radiator after it has been filled and the car been running? I just find it confusing that the coolant level would drop on a daily basis.

Is this a worry about nothing thing or are there other things to check??? Thanks!

 
Rep Power: 118

If you only had to add 16 more oz of coolant once and the next day it was still full then your prolly good.

If your repeating this every morning then your not good.

Not enough info to say wether it’s leaking rad, hose, heater core, water pump, block or head gasket.

 
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I am not seeing any coolant leaking on the ground or anywhere in the engine. The hose shows no residue(i.e. radiator, hoses, water pump).

Any suggestions on other things to look at/try??

Thanks for the input.

 
Rep Power: 209

Agree.

OP: Keep monitoring radiator and reservoir coolant levels each day for a weak or so. If you notice gain or overflow in reservoir and loss in radiator..then possible head gasket issue.

Have you tried pressure testing the coolant system?

 
Rep Power: 517

I didn't see mention of what you are doing with the reservoir?
Radiator needs to be completely full, reservoir needs to be filled to the max line which will be roughly halfway full.

If all is working as intended, the radiator will stay completely full at all times and the liquid level will rise and fall in the reservoir as the engine heats up and cools down.

 
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Will do. I have done a pressure test and it is not holding pressure.

 
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I did check the reservoir a couple of days ago(have not been looking at it daily as I have done with the radiator). I had the coolant level in it set to halfway in between the min and max lines(I thought that was what the owners manual said to do(?))

The reservoir is SO hard to see the coolant level lines Hints there?

 
Rep Power: 517

That means it's leaking? Where's the leak?

You need to. It's an important part of the complete system.
Use a Sharpie marker over the lines so you can see them better?

I use a Strong flashlight to see liquid level thru the plastic.

 
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I'll these items out and get back with you. Thanks for the input.

 
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You'll have to figure that out yourself. None of us can see/hear/taste/smell it.

Hell it could be missing a gasket on the tester adapter for all I know.

 
Rep Power: 209

If OP used a rental pressure tester from parts store it's very likey the universal attachement is leaking due to improper fitment.

 
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I have previously added coolant uv dye detector and could see leak.

 
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Sorry, in my previous post, I meant to say that I added coolant UV dye and COULD NOT see a leak.

 
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A follow-up to my previous posts:

I checked for leaks.....I had been adding coolant to the radiator daily for the last couple of days(I couldn't see any in the neck of the radiator). The overflow reservoir coolant level was set between the mid and max lines-per the owners manual).

Upon checking under the hood yesterday, coolant had sprayed out in the areas of the lower radiator hose-overflow tank. I checked again the radiator level and it was once again not visible in the neck of the radiator but now the overflow reservoir was almost completely full. I took the coolant out of the overflow and filled up the radiator.

I am assuming the that sprayed coolant was from the overflow tank and not the radiator.

Maybe I am not understanding how the radiator/overflow tank works but doesn't the overflow tank fill the radiator as it gets low? Why would the overflow tank be filled to the top when I had the level set correctly previously? I'm sure it has to do with me filling the radiator daily for the last couple of days??

Please help me understand......Thanks!

 
Rep Power: 221

so coolant is getting pushed out of the overflow?

blown headgasket

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

 
Rep Power: 209

Here's a good read: https://www.quora.com/How-does-a-rad...flow-tank-work

If there's no obvious external leaks (drips, slits in hose, etc..) causing coolant spray/drops on the engine and radiator then try replacing the radiator cap first. Do a block-test on it or better yet a leak-down test on it..refer to links in my signature.

 
Rep Power: 517

Head gasket.
(Assuming the radiator, cap, and overflow hoses are in good condition and seal well.)


This only works when the system is in good condition and the radiator can stay completely full.

The head gasket breach pressurizes the radiator with combustion gases (non-liquid), which DISPLACES liquid out of the radiator into the reservoir.
The radiator is now low on liquid. Maybe a pint or a quart or so.
While the engine cools, the cooling system cannot 'suck' the displaced liquid out of the reservoir because of the large 'air' pocket in the radiator and engine.