I filled my radiator with water and it is pouring right back out of the rear of engine as fast as i fill. It seems to be near or behind the transmission.


How can I find the source of the leak?

  • Put it on youtube and post a link here.
    – Moab
    Commented May 7, 2016 at 23:00
  • A video of this leak can be found here. youtu.be/27qV-ufMsQc Commented May 8, 2016 at 0:04
  • There is no question in this question, even though there's one question mark. Commented May 8, 2016 at 6:27
  • Very nice video. Sounds like a rainforest.
    – gh0st
    Commented May 8, 2016 at 17:33

1 Answer 1


There are three places I can think the water would be flowing out of from the back area of the engine. The engine in your Yukon should be the GenI Small Block Chevrolet (SBC) engine (I believe they started putting LSx motors in them in 1999). The SBC has water passages through the intake manifold at the front and back of the engine. If one of these passages had an issue with the intake manifold gasket, it would leak off the back of the engine.

enter image description here

The second place to look for is in the side of the block where the freeze plugs are at. If one of these has corroded through, it would be dumping coolant like nobody's business. (The block in the picture doesn't have plugs in it yet, but there'll be some there before it gets used!)

enter image description here

The last place, and most likely is another freeze plug, but at the back of the engine. This would be inside of the bell housing of the transmission. You'd see it coming out the bottom of the torque converter dust cover. (The plug in the center of the picture is there to plug up the hole where the cam goes; no coolant there.)

enter image description here

  • Are there any coolant hoses back there? On my car everyone thought it was a freeze plug but it was just a coolant hose that had sprung a leak. Commented May 8, 2016 at 4:02
  • 1
    @RobertS.Barnes - Not on an SBC there isn't. All of the hoses are up front. The heater hoses run off to new side, but that would be pretty obvious. Besides, the OP stating it runs out as fast as was put in is this type of behavior. I just thought of one other thing, though. A cracked block could do this also, but I think that possibility is pretty remote. Commented May 8, 2016 at 4:07

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