Skip the auto shop - Our mechanics make house calls

Q: Coolant issue - 2008 Honda Accord

asked by on

Hi, so previously my car overheated and I found out that my reservoir was empty. I filled it up and next day it was empty again so I figured I would just purchase another which I did from auto zone. I switched the reservoirs and then I allowed my car to sit for a few hours.. Then when I came to my car to check.. The new reservoir was empty.. Is there another problem here? I'm really confused

My car has 111091 miles.

A: Hello. When a car is low on coolant, even i...

Hello. When a car is low on coolant, even if you refill both the radiator and the reservoir, air can still be trapped in the system. After you run the car for a while, the trapped air is expelled and then the resulting "vacuum" causes coolant to be drawn from the recovery reservoir back into the radiator.

That might make it appear as if you are loosing coolant or have a reservoir leak, when in fact all that is happening is the system is just normalizing itself. So the reservoir might not have been leaking in the first instance. At this point, if the level of coolant is still falling in the reservoir top off the coolant as this occurs over several days.

At the end of that period, the level in the reservoir should remain steady (you have to judge the level when the car is either hot or cold; the level will vary significantly depending on temperature, so always check cold, first thing in the morning to be able to really accurately judge what is going on with the level in the reservoir).

The point is after a week of "topping off" and/or monitoring the reservoir level, if the level does not stabilize, then you have a leak. Coolant leaks are of two types: external and internal. External leaks are no problem and YourMechanic can identify those via simple pressure testing. Internal leaks through a head gasket are a mini nightmare though. Hopefully, your past overheating experience did not damage the head gasket on the engine, causing an internal coolant leak. If so, the head has to be removed from the engine, checked to make sure neither it nor the block are warped and a new gasket carefully applied in the auto mechanic’s version of "clean room" conditions. If you cannot get the coolant level to stabilize, YourMechanic will find the leak for you and then explain the least costly and most efficient options to get it resolved.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: My radiator seems to forcing coolant into the reservoir.

Hi there: If your engine is not overheating or showing any signs of cooling system problems, then there are two reasons why additional fluid will show up in the overflow reservoir. First, it's possible you might have too much coolant...

Q: What does the Shift Position indicator on the dash mean?

The Shift Position indicator on the dash of your car is pretty self-explanatory. It is just an indication of what gear the transmission is currently in, from park to reverse, drive, first and second. However, you’ll also find that it...

Q: My car is pouring coolant out does a bad water pump pour coolant out

It can, but there are many parts of the cooling system that can do this. If it is the water pump, the coolant or water will be coming from the front of the motor and behind the timing cover. The...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...