2001 EX, 5 speed, 4 cyl ULEV, 256K,

For quite awhile now I have had not a coolant leak but a coolant osmosis?

Awhile back, I had her in for inspection and the mechanic made a comment that I would need a new radiator as I had a leak.

No "leak" as in coolant puddles on the ground.

You can smell coolant when the car has been run for a period and is hot and parked, i.e. park it in the driveway after driving home from work I can smell the coolant.

If I open the hood, I can still smell it but can't see any leak/wet areas at all.

The only thing I can think of is on the hoses you can see "streaking" of a white residue like possibly from a super pinhole leak or something that literally shoots molecules out. Also, of the two fans behind the radiator, left one (passenger side) looks brand new while the right side one looks almost corroded. Hoses look fine, could probably change them I guess.

I have to add coolant maybe twice a year.

Ideas? I forgot to get pics, will try to get some tomorrow.

 

Try pressure testing the cooling system. Pump it up to 15psi and look for leaks. Auto parts stores loan out pressure testers.

 

Chances are it is the radiator hoses slightly leaking coolant.

 

Ok, the mystery is no more, I've looked before and never saw any leak but after driving it today I had to recharge the A/C system. The radiator cap is leaking.

Stupid question, will a new cap fix the leak? Hopefully. Is there a seal or anything under there? Car is still hot and can't take it off yet.

 

There's 2 places in the radiator neck where the cap seals. A big scratch, gouge, or some kind of defect in the radiator neck will leak even with a new cap.

Look at the cap, there's an outer rubber gasket, way up in the top of the cap, with the largest diameter. That one seals against the top rim of the radiator neck. A leak here will leak out & be visible right there.

Now there's an intermediate-size rubber disk inside the cap. That one seals against a ridge that's recessed into the radiator neck. That one seals the pressure, and a leak will allow coolant to pass over to the reservoir. It won't leak at the cap, but it might overfill the reservoir.

The smallest disk in the cap is a vacuum break. That seal is self-contained in the cap, it doesn't seal against the radiator neck. That one allows the engine to suck coolant back in from the reservoir.

So... will a new cap fix the leak? That depends on EXACTLY where & why it leaks.