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Discussion Starter #1
Hi Everyone, I have a cooling system issue that I am trying to better understand. have a 2004 Accord 4 cylinder. I am experiencing issues with various temperatures coming through my vents. For instance, I have it set on full hot and then warm or cool air will come through. It is inconsistent over a 25 mile trip. Issus I currently have..leaking but not sure from where, Radiator is not sucking back fluid from the overflow when the radiator is low. The temperature gauage is where is should be, no overheating. Do you think the issue is related to a faulty thermostat or that air is getting in to the system? I understand a low fluid condition can cause the heater to not blow hot but I have been making sure that the radiator is full. The temperatures in my area are currently between 25 and 40 degrees F. Thanks for the help.
 

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Try switching the hot/cold switch back & forth a couple times, pausing in between, maybe a stuck blend door. Could be a thermostat, be careful with bumping any of the connector plugs as the wires become brittle with age & can break @ the connector, they are no longer available new for the 7th. gen 2.4. Your heater core could be plugged up but sounds like you may have a blown head gasket, do both your fans come on ? How many miles on car, how long have you owned it ?
 

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Discussion Starter #3
Thanks for the input. I'm original owner. 126,000 miles. I don't believe it is the heat control knob acting up.

I haven't seen either of the fans come on. Perhaps because it is cold here.

The fluid leaking doesn't appear to be the radiator because the pool of liquid is further back more in the area of the oil pan. I couldn't feel wetness at the thermostat. It's hard to see if the water pump is leaking.

Would a pressure test identify the issue?
 

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Take a look at the heater control valve, they have been known to leak. It is mounted on the firewall, in line on the heater hose. The leak generally occurs in the center of the valve. The water pump has a weep hole below the center shaft, that is where you will see coolant leaking.

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I recently had no heat and heater control valve was the culprit. The lever was rusty and was moving freely without opening/closing the valve.
 

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I have had intermittent heating issues in my 2007 4 cylinder. I fixed it recently. It is critical that the radiator is completely full, if it is not, then often / frequently the heater will not work, especially at idle. HCV was not my issue, even though I did replace it (it was in great shape). So, make sure your coolant in the radiator is fully topped off by adding directly to the radiator. If you have a leak - as you note - then for sure you will need to address that first.
 

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Discussion Starter #7
I had a coolant pressure test done. Unfortunately it turned up a crack near the top of the block. I can see it, it's hard to get at behind the exhaust manifold. They did fill the system completely before I drove off. I thought it would blow warm with an absolutely full radiator but it wasn't. The leak must be pulling in air. Do you think repair shops would weld on the block? I forgot to ask the shop tonight.

BTW, I did check the hcv prior and it is ok.

I have owned this car a long time..sad to think it's probably over.
 

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Are you sure it is not a bad head gasket??

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Discussion Starter #9
I stated that wrong. The crack is on the front behind the intake, not exhaust. I could see where where the coolant is coming out of the block.
 

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In general, unless it was a bad casting, the block would not crack unless it there was no antifreeze (just water) and temperatures went below freezing. Also, I think there is a threaded plug on that side of the engine to drain the coolant. If you could take a picture that would be great. Failure of a head gasket is much higher possiblity, especially if the antifreeze has never been changed.

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I looked and the only thing on the intake sideof the engine is the knock sensor. The coolant drain plugs are on the front and back of the engine. There is also one on the exhaust side of the engine. The intake completely covers the block, not sure how you can see that side of the engine clearly.

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Discussion Starter #12
517149


Attached is a picture. It's hard to tell how far down the crack extends because the block casting curves downward. It is in a tough to reach spot. I am not sure how difficult it would be to pull the intake off to get closer to it. That said even without the intake it looks like there are a few other things right in the vicinity that would make it hard to apply a repair.
 

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I do not think that is the block, there is a large casting that the water pump mounts on called the water passage. That is part number 19410-RAA-A00.


There is a lot going on in that area as far as coolant is concerned, the water pump, thermostat housing, hoses. I think you have to tear it down and see where the leak is coming from. I do not think it is the block. Number 12 is the part I am talking about.




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Discussion Starter #14
Thanks for the input. I am calling it the block since that is what the repair shop said and also what it looks like to me. You are right, further teardown would help. I just don't want to do it myself in the cold and I am not sure if the next shop I take it to will say the same thing.
 

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I looked at a bare block and the picture you have the arrow is pointing to the block. If you are sure the leak is coming from there and not coming from around that point.


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