enter image description hereI need to now where it's coming from and how to fix it. My Mercury Sable 99 is loosing about 1/2 gallon every time I drive it It started two week ago then I was only dumping 1/4 of antifreeze in it and out of the blue it stopped for 5 days but started back up 12/4/16 it seem to be leaking from the back of the engine left side tonight on my way home I have lost all heat checked oil its still the color of oil

  • Could you tell us the year of the car and when this started happening? Especially of there is any work or other changes that might be related. Also, are you seeing any signs of the leak? Puddles under the car or white steam clouds from the exhaust. Do you smell a sweet smell around the car (most antifreeze has a sweet smell)?
    – dlu
    Dec 6, 2016 at 4:09
  • When I left this morning I poured another 1/2 gallon in and drove to work when I got there the car was smoking and yes there was a sweet smell
    – Trish D
    Dec 6, 2016 at 4:23

2 Answers 2


Many times in older cars when a leak develops it's because of a pinhole sized rupture in one of the coolant hoses. When the car is cold you won't be able to see the leek because it will only show up once the system is hot and the coolant is under pressure. So what you should do is refill the coolant then let the car idle with hood open it until it is hot and you'll probably be able to see where the leak is coming from that point. You might also need to rev the engine for a little while until sufficient pressure builds up for the leek to show. Then it is just a matter of picking up a replacement hose and replacing it.

It might look something like this:

enter image description here

Regardless of where the leek is coming from, many times you won't be able to see it until the cooling system is hot and under pressure.

  • I just down load a picture of where about I think it is coming from there are no hoses that run in the area of where it is leaking I have checked all hoses
    – Trish D
    Dec 6, 2016 at 4:46
  • @TrishD Regardless of exactly where the leak is coming from, you may not be able to see it until the engine is hot and the cooling system is under pressure. I just added a picture of a small pinhole style leak. This was from my car last year. The leak didn't show up until after a drive, because enough coolant had already leaked out that there wasn't sufficient pressure for further leaking. You really need to top off the coolant, then idle the car till it's hot. Then if the leek still hasn't shown up, start revving the engine to build pressure and you probably be able to see where it is. Dec 6, 2016 at 4:59
  • An alternative here is to borrow a coolant pressure tester. You connect a hand pump to the radiator or coolant bottle, pressure it to 13 psi then look for leaks. I believe this tool is in the Autozone free tool loaner program. You do this with engine off, so its quite safe to check every hose in the system. You can do this test hot engine or cold.
    – zipzit
    Dec 6, 2016 at 5:28
  • @TrishD Any luck finding the leak? Dec 8, 2016 at 9:54

If it's not near a hose and it seems to be coming from the engine it could be a corroded core (sometime called freeze plugs) plug, The round thing pressed into the engine block in your pic is a core plug, There is coolant behind that so if it's corroded it could leak. There will be several of them around the engine and in the cylinder heads

They are easy enough to press in but can be hard to get the old one out if it's in an inaccessible spot. I usually knock a hole in it with a punch or large screwdriver and prise it out

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