This is my car ->(1990 Honda Accord EX Sedan 4 door 5 speed manual)

Ok this is the first time I have ever seen a leak from my car. I bought it in Primo condition & I only use it for errands around town. 2 days ago, I noticed white smoke or steam coming from under the hood I just happened to be near Auto Zone so I pulled in & asked one of the guys to come look as I was looking at the leak as well it was spot after spot into the driveway & a puddle of coolant. So I drove home & let her sit awhile before I checked the radiator & it was bone dry so instead of wasting my anti freeze I filled her up with H2O took a drive came back no leakage.

I Looked again this morning & the radiator is still full.. My question is what just happened to my car & why isn't the water leaking out now? I'm entertaining the idea of taking my car to a shop, because I don't know what to check for & I don't want to get ripped off. what should I do? Thanks folks, I hope you have some answers

  • Did you see exactly WHERE it was leaking from? Radiator, hose, overflow bottle, engine area? When you took if for a drive after refilling it, did the car get up to normal operating temperature? The coolant system can pressurize up to 16psi when the coolant is hot. What were the conditions before noticing the steam? Did it overheat? Were you on the highway, or sitting idling at lights?
    – rpmerf
    Commented Aug 11, 2015 at 17:29

3 Answers 3


Your car overheated and the coolant leaked out of the overflow bottle. It happened a couple of times with my Opel Astra Coupe and my Subaru Forester too. If you're really lucky, nothing major is wrong with your car, but I'd advise a compression test just to be safe. The danger here is that BECAUSE the car overheated and all the coolant was lost, you may have a warped cylinder head that may cause a blown headgasket if it hasn't blown already.


I would go ahead and replace the radiator cap, it's a cheap fix (about $6 at Advance Auto) and is probably the culprit. The cap is also a relief valve that keeps the pressure at a certain level to raise the boiling point, but if it fails the cooling system can lose all that pressure out through the reserve tank.


I had a similar problem & here's what I learned.

The leak is small so it will not come back in one day.

The coolant can get so hot that it may bubble out the overflow bottle. You will hear it & then temp will rise. Especially in stop & go traffic.

Turning the heater on may divert the coolant away from the leak or prevent bubbling out the overflow. Turn the heater on as soon as the temp rise between 1/4 & 1/2.

It takes 15 minutes for the car to warm up, so short distance may not get hot enough to need any anti-freeze which will prevent you from noticing the leak.

Look for white spots left behind from the anti freeze leak. It dries white & does not wash off without using vinegar. Check the seals & hoes. Rubber hoses & seals deteriorate with time.

When temp rises pull over & look for leaks. Overflow bottle & Radiator leak as result of another leak elsewhere. Both are plastic & melt or pop easily due to steam pressure. By that point a large amount of air got into the system or coolant boiled. Air causes coolant to expand which is why if you open it when its hot the coolant will shot out at you.

Bars copper leak stop actually stopped a big leak. I added about 1/4 & ran it for 15 minutes with coolant flowing out the water pump with no effect & then added more coolant & another 1/4 to stop the leak.

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