djork

Hi. First off, I'm new here and this is my first post. I've been lurking and just signed up because I want to know more about Honda and maintenance.

I have a Honda hybrid and have a two-part question.

1. This morning before I started the car (so with a cold engine) I removed the rad cap and just as I turned it loose some coolant flowed out. The coolant level in the radiator was at the filler neck line. So according to the manual this is normal level. What concerned me was ssome coolant coming out as I turned loose the cap. Is this normal? I thought there should be no pressure in the cooling system when the engine is cold. Is the compression gas? I've not opened the rad cap in almost 4 months, so I doubt it's air.

2. I keep tabs on the coolant level via the reservoir tank. In almost 4 months I see that the level has dropped a tad over 0.25" from the MAX line. All checks are done when engine is cold (usually in the mornings. The level drop is actually really small. For example, you wouldn't notice if you checked every day, but after maybe 2 weeks, you'll see a drop of 1-2mm. In the span of almost 4 months, it's down to 0.25 inch!

I see no visible leaks, oil looks clean, no oil specks or blobs in radiator (when I checked this morning), and the oil cap looks clean with no milky residue under it. The car doesn't overheat and maintains temp. I also don't smell coolant after driving. Where's the coolant going?

Is it normal to see coolant level drop a quarter inch in the reservoir tank? I rarely open the radiator cap, but this morning I did because I wanted to see if the level was low there. Nope, it's right up at the filler neck. I have read that it's normal for cars to lose small amount of coolant over the span of a few months, yet I've also read that it's not normal.

Should I worry?

enemy no1

why are you concerned over a 1/4 inch loss of coolant level over 4 months??? I could understand your concern if it was half gone or something but a 1/4in?

fcm

In a word, no.
Although the coolant system is sealed, the reservoir tank is not, so evaporation will happen out of reservoir tank.94

djork

Thanks for the replies, guys.

This is my first Honda and I must say that I really appreciate the simplicity of their cars. The engine seems pretty straight forward to work on, granted that I have the proper tools and some basic knowledge.

I know that coolant loss (as seen in the reservoir tank) is normal, but I normally hear people say in the span of a year. For example, I've read that someone might see a 1/4" to 1/2" drop in coolant level via the reservoir tank after a year. I was just concerned that my drop was within 4 months

Snooping around under the engine bay, I see that Honda has a lot of water hoses of various diameters criss-crossing here and there. There is a small water hose (approx. 1/2" in dia.) that appears to be missing a hose clamp--the one that looks like a wire looped into a circle with tabs to squeeze. The hose looks to be snugged in the metal tube it connects. But I wonder if the lack of a clamp is allowing coolant vapors to escape over time. The hose is apparently in a location that is hard to reach, grrrr. I don't see any dried residue at the insertion point of the hose though.

fourthgenhatchB17

You're fine. Honda did not forget any hose hose clamps. It is normal for ANY CAR to lose a slight amount of coolant over an oil change interval time period. Again, this is normal!

djork

Speaking of oil change intervals, I forgot to say that within the nearly 4 months of that 1/4" drop in coolant level, about 2000 miles was only put in. Mostly city driving but went on the freeway a few times, but no long trips.

So with the 2k miles and a 1/4 level drop, is that pretty suspicious? Bad?

fourthgenhatchB17

What you may also notice is the level of coolant in the reservoir will vary. Sometimes it will appear low, other times not, even if you do all your checks at the same temperatures. My Civic does this. 1/4" level change is no big deal. Its when that bottle is bone dry (consistently) is when it should prompt someone to worry.

I will repeat and say every car will see a slight loss in coolant over a certain, somewhat extended, period of time. I used to work at mercedes as a tech and with their 10k+ mile/annual oil change intervals, it was not uncommon for the coolant expansion tank to require something like .5 quart of coolant added during the oil chg service. Completely normal, and the exact amount of each car's coolant "loss" was different.

If you're still not convinced, it wont hurt to continue to keep tabs on the level. Note changes in severity. Maybe you'll notice a pattern thats specific to your car..who knows..I sure as heck would not be concerned at this point.