Rep Power: 209

no signs of a coolant leak anywhere on the engine or floor/ground,

replaced water pump and thermostat about 16 months ago with OEM, about 15,000 miles put on them,

coolant level was stable till about 3 months ago,

coolant is basically disappearing at a slow rate, i always check when the engine is cold right in the morning, rad is always full,

but overflow bottle slowly goes down at the rate of maybe 1/2 inch per month, car is driven everyday a good amount,

i guess that isnt a big loss, but it shouldn't be losing any at all,

i guess this isnt really a question, more of a venting, no signs of coolant in the oil at all,

i am suspecting the water pump and a leak behind the timing cover, which i cant believe because its practically brand new,

my original water pump lasted 150,000 miles, and was still good, i just replaced it cause i was doing my timing belt, i will be pissed if this one is gone so soon,

 
Rep Power: 243

That sucks!

My rad was leaking only when the car was running. The part where the metal fins meet the plastic ends was leaking. I only noticed because I was loosing heat when the car was idling, due to the low coolant level. Once I added more the leak became more apparent.

 
Rep Power: 518

A LOT of Hondas do seem to use coolant slowly, even when fairly new. Could be evaporation though.

I have to top off coolant reservoirs quite often during routine oil changes.
If they never used any coolant at all, I would never need to top off the reservoirs.

That doesn't sound like much.

Look around for blue/green crusty seepage evidence anywhere there is rubber first. Top hose at the head is a common place to seep.

I see them with seepage evidence around the water pump (rubber gasket) from time to time, along with crusty buildup on the aluminum (block) where the WP gasket has to seal. If the aluminum isn't completely clean and smooth where the rubber gasket has to seal, that can promote continued seepage.

 
Rep Power: 518

Hey, speaking of radiators......

I took pics of this one that I thought looked really bad. Turns out I was right, it lasted ONE MORE DAY! (Next afternoon, they called and said to order the radiator, it blew up.)

This was on a 96 Odyssey that a kid drives, his father was a customer of mine back in my Mazda days.

I figured a pic is worth many words......





Those are stress lines in the nylon tank. The blowout happened in front of the top hose, below the level of the foam pad. (It had not blown out yet here, the dampness was from trying to clean it for a better pic.)

 
Rep Power: 243

Damn! Those are some serious stress lines. Is that from normal wear and tear?

 
Rep Power: 518

Yes.
Thermal cycling eventually weakens the nylon.
There was no obvious indication that it has ever been overheated.

It was just weird that I was able to catch one right on like the very last day of its life (AND take a pic of it) and called it right on the work order, "Hey, uh, I know you only came in for an oil change, but you need one of these right away! This looks really bad!"

 
Rep Power: 243

That's because you has skillz!

 
Rep Power: 518

Even though I get paid barely enough to keep ONE eye open.....

 
Rep Power: 209

this makes me feel better, but its strange that this car has never lost or consumed coolant in the past, i have had it since new,

this just started about 2-3 months ago, and i have not done any work on the car in over a year other than routine maintenence like oil changes etc, but nothing that involves the cooling system

 
Rep Power: 366

LOL!
proof on hands!

 
Rep Power: 0

Do a block test to check for emissions in the coolant system. It may the beginning of a head gasket failure. I JUST completed a head gasket change and it started with unexplained disappearing coolant.

By the way, ezone, do you have any advice on this. As I said, I just finished the head gasket job (the first time I've ever been this deep into an engine of any sort), I cranked it up today and it started fine and purred untill I got it out on the road. After a couple of miles, it started idling up and down from 1,000 to 2,000 rpms while the clutch is depressed. If you could point to a post that would help address this, that would be great. Thanks.

 
Rep Power: 518

Uhhhh.....Stuck IAC or a vacuum leak, most likely?

Something is causing the idle to be too high while the throttle is closed, that's an air leak somewhere.

Cork up the IAC passage with your fingers in the throttle body, if the idle drops to nothing then the IAC is likely stuck open. Tap on it.
If idle speed is still high, then it's a vacuum leak.

'Sall I got.

 
Rep Power: 0

Thanks, I'll give it a shot.

 
Rep Power: 209

thanks,

since i posted this i have taken about 4 long distance trips (about 300 miles round trip each time) in the car and the coolant level has been stable throughout all of these trips, i have not needed to add a drop....so im basically back to scratching my head on this one,

 
Rep Power: 0

I'm still thinking it could be that gasket. I bought my wife's car from a buddy of mine. He told me that the coolant disappearing was intermittent at first. But it became more of an issue over time. I would still say do the block test, just to be safe. These things, I have learned, are known for head gasket issues.

 
Rep Power: 0

and, ezone, I needed to do the idle learn procedure. I did it today and the wifey's car is road ready again.

 
Rep Power: 518

Humm. All that I've encountered with needing idle learn have had low RPM idle issues. Thanks for the info.