Rep Power: 0

Hi guys,

I have a 2005 Civic that seems to get air in the cooling system. I can hear it gurgling in the heater core when revving the engine, or when starting from a stop. The car never overheats, the heater itself works fine, I'm not losing any coolant, overflow bottle level rises and falls as it should.

I jacked up the front and bled the air out and replaced the rad cap just in case, but it came back 2 weeks later, after driving for an hour on the highway. I thought it might be the head gasket, so had a leakdown test done. It showed < 10% leakage in each cylinder, no visible air bubbles coming out of the rad neck during the test. The shop also noted that the water pump seals and radiator neck looked dry, although they didn't do a cooling system pressure test.

So, my questions are:

1. Is the head gasket leaking?
2. Should the leakdown test be performed with a cold or warm engine? The shop did it on a cold engine.
3. Where is all of this air coming from? It only seems to come when driving the car for a long time.

Any help would be greatly appreciated, this is driving me nuts. Thanks!

 
Rep Power: 209

im a bit confused, you need to remove the timing cover to look at the water pump which is quite a big job, did they do that?

my money would be on a bad head gasket

 
Rep Power: 0

They looked at the under-side of the timing cover. Apparently the water pump, or at least part of it is visible from there?

It does sound like the head gasket, but the leakdown test showed no leakage. What can I do to be sure?

 
Rep Power: 209

uuummmm.....no

the water pump is fully concealed/covered by the timing belt cover, the only way to see the water pump is to remove the timing cover,

going by your comments i would be very skeptical of this shop/mechanic, they are obviously not being 100% honest with you

 
Rep Power: 518

The weep holes can be seen from there.
Use my methods..

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

 
Rep Power: 0

So I finally got around to using the method you described. I got the shop to apply 200psi shop air directly to each cylinder, with the engine warm. When air was applied to the #2 cylinder, the coolant level in the radiator neck very slowly rose, maybe at about 0.5mm/s.

Although, the #2 cylinder was giving us some trouble finding TDC compression stroke and they ran the engine for a few minutes after doing #1, 3, and 4 before doing #2, and the rad cap was taken off like a minute before applying the air.

Does the very slow rise indicate a head gasket leak, or was that just an artifact of the coolant still expanding from getting hot?

 
Rep Power: 518

Yep.
Easy to tell.....
Remove air pressure from the cylinder. If the coolant level immediately stops moving, you have your answer.
Apply pressure again, you can confirm your answer.

 
Rep Power: 0

That's a trick and infallible way to nail that diagnosis down... sano.