Stench pipe problems

[efiste2]

In our house we have an internal stench pipe that is boxed in, and last month started to notice a foul smell in the area of the pipe. After a lift of the closest manhole cover we found it to be backed up. so we rodded it thorugh and now it flows freely, and the smell dissapeared. However we can now at times still slightly smell the same smell. but this time all the manholes are clear and running free. Is there a possiblity of the stench pipe being broken or cracked and leaking slightly, perhaps at the bottom where it takes a bend ( under the floor) to run into the manhole, Is there any trick of the trade to test the stench pipe without damaging its boxing in etc ect, Thanks for any advice

 

[mikric]

You could try a "smoke bomb/pellet" used to test chimney flues and readily available from builders merchants, put one in your chamber then put the lid back on then check inside to see if you can see any problems, be mindful of colored ones as I believe they can stain.
Might give an indication of any problems and worth a try I would say.

 

[Alastairreid]

http://www.pavingexpert.com/drain11.html

 

[efiste2]

Thanks for the advice, my pipe is internal so Id have to perhaps lift a floor board to view the pipe where (i presume) it bends 90 degrees to enter into the manhole!!

 

[Hugh Jaleak]

What is the pipework made from? Plastic is unlikely to leak, whereas an iron pipe into a clay drain will probably have a mortar joint at the bottom where the iron enters the clayware. These can crack, older clayware pipes can also leak at the joints and/or crack.

An air test would show a leak but wont help in pinpointing where exactly!