Another vent pipe leak question

[Jack]

When it rains, I am getting a leak of water at a vent pipe union where 4 pipes meet. Here is a bad drawing. The 'x' represents the union. Where the pvc pipe from the roof meets the 4-way fitting, (just above the X) I am getting a leak. It's not running down the outside of the pipe. The water seems to be coming from within the pipe and leaking out the top joint.

roof || ||

---X--- || || to bathroom

Any idea why this might be happening. The toilets and sink seem to vent ok. Is there anyway to fix this? Thanks for your time. sorry for the bad drawing.

[Jack]

[PipeDown]

There should be a clear path from the roof to the sewer down each of the three branches (not going to the roof). Water should not pool anywhere in the vent. Try running a pipe auger down from the roof opening and see if you can find an obstruction (that far up might be a dead bird or some leaves). Given your descroption the right and left branches are clear and lead to the sink and tailet but the downward branch seems to be clogged. It may vent a drain or it may be a drain for the vents.

If the pipe is ABS, try slopping some ABS cement on the outside to patch the crack. else you will have to cut out the bad union and replace it.