Overheating Diagnosis Help
 

Hello guys, I have a 2005 Civic LX (Manual) | 240k+ miles (bought it in 2012 and I have never changed the radiator and don't know if it ever has been by previous owner.)

Currently, I'm thinking about replacing my radiator because of a coolant leak. I diagnosed it myself and have come to the conclusion that it is my radiator; however, your input would be greatly appreciated...I'll post my train of thought below and let me know what you think. (My Mechanical/Diagnosis ability is limited so I hope this post helps)

Tests/Visual Inspections
- Pressure tested rad cap (it passed)
- Pressure tested radiator itself (losing pressure)
- Noticed leaking under front bumper about 2 weeks ago. Reservoir stays full but having to top up the radiator with coolant.
- Noticed coolant accumulating along the top seams of the radiator where the plastic/metal meet (the top corners of the radiator has coolant collection also).

Ruling out Waterpump/ Heater Core/ Thermostat / Head Gasket
- Waterpump: I keep having to put a quart of coolant each day(I drive around 50 miles a day) Since the coolant is being pumped throughout the car and doing its job, can I safely rule out water pump as the issue?
- Heater Core: Heater works fine when the coolant level is full; not as good when coolant is low. I have noticed no leak around the heater core or any puddles accumulating inside of the car.
- Thermostat: No leak around thermostat and temp gauge seems to be working appropriately.
- Head Gasket: No "milky" oil in dipstick and no white smoke out of the exhaust.

Can you guys confirm with the information I've given that it is most likely the radiator leaking and not something else?

Radiator-related questions
Q1. Does a new radiator come with a rad cap?
Q2: Should I go ahead and change upper/lower hose & clamps while i'm at it? It doesn't seem to be the cause of leak but wasn't sure of the life of it.

Re: Overheating Diagnosis Help
 

Is coolant overfilling the reservoir and leaving the radiator low? If the reservoir was overflowing you would see coolant under the front bumper. If this is the case it is most likely a bad head gasket. Here's a thread with more info.

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

Re: Overheating Diagnosis Help
 

Defiantly don’t replace the radiator until you do more observations on the system. Sure sounds like you have a blown head gasket and a bad radiator too.

Putting a new radiator in, only to have super heated coolant steam ruin the neck is more typical than you would think.

Re: Overheating Diagnosis Help
 

Yes, my reservoir is overfilling! I will check out this thread when I get home from work and investigate more. Thank you.

Re: Overheating Diagnosis Help
 

I think I understand what you mean. Thanks for the tip before I ruin a perfectly good radiator.

Re: Overheating Diagnosis Help
 

In that thread there are two ways to test the head gasket, I would recommend cheap method 2 that Ezone came up with. There is a video of the test procedure as well.