'04 Civic Coupe DX leaking.
Thread Starter
Registered!!
Joined: Mar 2015
Posts: 2
Likes: 0
Rep Power: 0 
'04 Civic Coupe DX leaking.
04 Civic Coupe DX with 166k mi., leaking at thermostat housing/upper radiator hose and thermostat housing.
Here is the deal, the car overheated twice about 3 quarters to top but never hit the H. The second time, I noticed the fans weren't coming on even when it was that hot so I figured out the coolant temp switch was faulty by process of elimination. Fuses, relay, and fan motors all good. So replaced that and the thermostat because I was right there and it's never been replaced since we had it. Anyways, it cracked the radiator at the top where it is plastic so I patched that up and it isn't leaking there anymore. But for the life of me cant figure out why it is leaking there. It only seems to leak after car warms up and continues to do so until it is cooled off. After everything, I put new coolant and burped the system. Doesn't overheat anymore and heater stays blowing warm now too! But. That. Leak. It is driving me nuts! Any ideas? Took everything back off and inspected and cant find any cracks or anything....Car runs normally, it has always had a little more vibration to it, but has been that way for a while.
No CEL or codes.
Water Pump?
Head Gasket?
Pressure Buildup?
Troubleshooting help would be great! Thanks in advance!
Here is the deal, the car overheated twice about 3 quarters to top but never hit the H. The second time, I noticed the fans weren't coming on even when it was that hot so I figured out the coolant temp switch was faulty by process of elimination. Fuses, relay, and fan motors all good. So replaced that and the thermostat because I was right there and it's never been replaced since we had it. Anyways, it cracked the radiator at the top where it is plastic so I patched that up and it isn't leaking there anymore. But for the life of me cant figure out why it is leaking there. It only seems to leak after car warms up and continues to do so until it is cooled off. After everything, I put new coolant and burped the system. Doesn't overheat anymore and heater stays blowing warm now too! But. That. Leak. It is driving me nuts! Any ideas? Took everything back off and inspected and cant find any cracks or anything....Car runs normally, it has always had a little more vibration to it, but has been that way for a while.
No CEL or codes.
Water Pump?
Head Gasket?
Pressure Buildup?
Troubleshooting help would be great! Thanks in advance!
Last edited by JWiley Coyote; Mar 18, 2015 at 10:39 AM.
Thread Starter
Registered!!
Joined: Mar 2015
Posts: 2
Likes: 0
Rep Power: 0 Re: '04 Civic Coupe DX leaking.
I used an epoxy from Autozone. Since the crack was/is in the front just to the lower right of the radiator fill neck it is easily visible, so I see no leak there. I figured out it is at the bottom rad hose where it connects to the thermostat housing or the housing itself. Going to pull of the thermostat and check the gasket again.
If you think a good mechanic is expensive, try hiring a bad one
Joined: Dec 2011
Posts: 32,017
Likes: 256
From: Midwest. Aiming about mid-chest
Rep Power: 519 
Re: '04 Civic Coupe DX leaking.
I'd say to clean and dry the suspect areas so the exact location of the leak can be pinpointed easily. Use a pressure tester if necessary.
When you changed the thermostat, did you get a brand new rubber gasket? Did it look exactly like the original, or way different?
Is it correctly oriented?
When you changed the thermostat, did you get a brand new rubber gasket? Did it look exactly like the original, or way different?
Is it correctly oriented?
Thread
Thread Starter
Honda Civic Forum
Replies
Last Post
oneheadlight
Mechanical Problems/Vehicle Issues and Fix-it Forum
3
Apr 29, 2015 11:30 PM
CapYoda
General Automotive Discussion
9
Nov 11, 2001 05:17 PM
