1998 Civic DX auto with 186,294 miles on it

I've noticed over the past year or so that my coolant level drops often. When the car is cold (been sitting over night for example) the coolant is at or slightly below the minimum line on the tank. Once the car has been running for a while, the coolant is about an inch or so below the maximum line.

Is this normal? I've see the oil that comes out of the engine during oil changes and it looks nice and clean with no milky residue. I see there is some residue where the tube that comes from the top of the radiator into the engine on the engine end of the tube. Could that be leaking (I haven't had time to really look at it)?

I recently stuck some cardboard underneath my car at night. There was this one spot (I took this picture when I got home so it had soaked in and spread a bit). Doesn't look like coolant to me. The left side of the cardboard is at the front of the engine to give you something to go off of for the location of the leak.

 

Any smell? Do you have to refill the coolant system ever?

Are you talking about the coolant reservoir level going up and down, or did you remove the cap (ONLY WHEN THE ENGINE IS COLD) and see a different level?

 

I'm talking about the overflow tank. When the car is cold, where should the level in the overflow tank be? Min line, halfway between min and max or at the max line? My mechanic checked it over and said he didn't see it leaking anywhere. No smell and the temp gauge never goes above where it has been for the past five years.

 

Normal.

That is the purpose of the overflow bottle since things expand when they get hot.

 

But even once the car has been driven, the overflow tank is still empty.

 

In your first post, you said that the coolant level in the overflow tank was an inch below the max line after running for awhile. Now you say it's empty after running for awhile. Which is it?

Your overflow tank should be at max when engine is hot, at min when it is cold.

What does that drop on the cardboard smell like? What does it feel like? It looks like oil, but hard to say. It's def not water, or it would dry and not leave any residue behind.

Also, if the left of that cardboard was at the front of the engine, I'd say that drop is about right under where your tranny and engine meet.

 

The reservoir should never be empty. Fill it to the minimum line when cold. It's still not clear what you're saying. If it goes lower and lower after several trips, it is leaking out somewhere.

While the engine is cold, take the radiator cap off and check that the radiator is full to the top. Add coolant there if necessary.