My Accord overheated tonight. Water flowing out best i can tell from under the overflow bottle. Pretty good leak. There is a steel line right under the bottle that looks like it has a compression fitting. A stream of H2O is coming from this area but i can not tell from where. I do not think there is anything up there besides the radiator core. It is not coming from the upper main hose or the plastic radiator core cap.

Any guidance on what this line is? I have replaced the radiator in the past so i am not worried about that i just do not recall this fitting being involved. May just be the core gone bad and this is where it is flowing. Going to tear into it tomorrow but would not mind some guidance.

Thx.

 

Do you think that line is the power-steering fluid? There's a cooler out front of the radiator that looks like just a big hairpin bend of plain tubing.

Then there's a couple of ATF hoses from the tranny to the bottom of the radiator. They would leak ATF, not water.

So I really don't think that line is leaking water. There's no compression fittings on any of the cooling system.

 

leak under the overflow bottle was a red haring. Back pressure was getting into the bottle and overflowing it but at night i did not notice. No leaks were found anywhere. Still need help.

Was running straight water in the cooling system. (I know....) Thermostat was corroded so I replaced it. Radiator cap had hard seals so I replaced that. Drained water and replaced it with 50/50. Water drained was not very clean. (brown)

Water pump was replaced last spring with timing belt. IAC and other valves up by the throttle body with water passages were cleaned out about 6 months ago. Radiator is about 3 years old.

Can go about 2 blocks and it overheats. Hot water is flowing back into the overflow bottle. No leaks anywhere that I can see. Prior to the pats changed today if I had the radiator cap off it would surge water out of the radiator when the engine was on after it has overheated.

When i turn the motor off after test driving it and overheating it the passenger side fan comes on. The drivers side does not. While the fan is on i can pull the fan fuse or the fan relay and the fan goes off. The drivers side fan never comes on. If i jumper the green fan connector at the thermostat both fans come on.

What would you look at next?

Thanks

 

Does the coolant look milky, like when oil enters the coolant?

 

No, coolent and oil look fine.

Ran some more test. Ran car again to overheat it. Neither fan comes on even though the temp gauge is pegged. As soon as i shut off the engine the passenger fan comes on. Drivers side never comes on.

Heater is on full blast and no hot air is coming out. I also re-bled the system to make sure all the air is out. I had the radiator cap off for that and it overflowed out the radiator.

The upper radiator hose is HOT. The lower is cool. Seams like this is a T-stat symptom but i just replaced that. Going to pull it again and test it in hot water as well as verify the direction.

Looking at the radiator, i may be mistaken on replacing it. May have been my old accord as this on is Denso and i would have used an aftermarket one. So likely an old radiator. Maybe clogged? How would you test that?

Still searching.

 

Take a look at the cooling fins on the rad outside near bottom if they are gooey and missing in spots the rad needs to replace.

 

Not real gooey. Some oil down there.

Some more testing. Pulled the T-stat again. It was in correctly. Tested it and it opens at about 200 degrees. Verified that the little vent on the t-stat was facing up. All is good there. Ran again and re-blead the system. Still overheating. Still no hot air on the heater. Still upper tube is HOT and lower tube cold.

Pulled the fan connector at the thermal switch in front of the engine. Passenger fan goes off. Again pulled both fuse and relay in engine compartment fuse box and passenger fan goes off. Drivers fan never comes on. If i short the switch at the t-stat both fans come in.

Could the back thermal switch be bad? Would that cause the overheat? Why does the lower hose not get warm?

Thanks for the help.

 

More testing.

Both fans come on when the AC is turned on.

According to DesertHonda, if the top hose is hot and the bottom cold then it is a t-stat issue. What else could i check up there? (See link, post #20)

https://www.hondaaccordforum.com/for...heating&page=2

Thanks

 

Is that thermostat one from a honda dealership? Most techs suggest using a honda brand, because it opens up at the proper temperature.

Your description sounds like the thermostat is not opening at all. Even though you verified it opens by testing it.

For diagnostic purposes, drain the coolant, remove the thermostat, refill the coolant. Run the system without the thermostat in there. See if the lower hose gets hot.

If it does, then the thermostat is the problem. If the problem isn't solved, then either the radiator is plugged up, or the water pump isn't pushing water through the system.

 

Aftermarket T-stat.

Pupped the t-stat and put it back together without. Top hose HOT, bottom hose a liitle warmer but nowhere near the top hose. I also do not really see flow in the radiator when the cap is off.

So, seams like i have a plug. Since the H2O pump is less then a year old seams like the radiator is what i should target. Anything else i can do to verify that? (H2O pump was genuine Honda part)

Thanks