If water is flowing through pipe, no head pressure can build up. Blocking off flow of water will create head pressure in pipe as long as pipe is vertical. A vertical column of water creates head pressure.
Granted that the force was enough to crack the pipe, it would crack in the middle.
If you have any water at all coming into the sump, there will always be a little in the bottom unless it stays dry long enough for it to evaporate. The design of the pump doesn't let it pump the last little bit out. If there is not a check valve in the discharge pipe, what is left it the pipe going out will drain back into the sump. If the discharge pipe is connected to the house drain and there was not a check valve in that pipe, depending on where the kitchen clog is, the sink could drain into the sump.
Head loss will decrease
Nothing as long as the pressure pipe is not used for potable water as you cannot make a direct connection and depending on the GPM flow what size the larger sewer pipe is as 1 GPM (pumping) is considered 1 fixture unit when sizing the drainage system ALSO make sure the pumps system enters at a right angle 45 deg so your not eroding the side of the larger pipe out
To quote someone else, the breather pipe may be blocked. Unclog it and it should work fine.
Its the exaust
Diesel coming out of the tank breather pipe on a 1997 non-turbo diesel van may indicate a few issues. It could be due to overfilling the fuel tank, causing the excess fuel to escape through the breather. Alternatively, a blocked or malfunctioning tank vent can create pressure that forces fuel out. Lastly, a faulty fuel cap or damaged breather hose might also contribute to this problem.
pressure in the sump caused by engine breather pipe being restricted or blocked is one cause for oil coming up through the dipstick hole
Probably a breather pipe for the front differential.
Engine oil coming from breather pipe
A breather is something you put on your gas tank to let the fumes out. It is the hose coming out of your tank.
The engine blow by is exhaust gasses trough out the breather pipe
To remove the breather pipe on a 1999 VW Polo, first ensure the engine is cool and disconnect the battery for safety. Locate the breather pipe, which is typically attached to the valve cover and the intake manifold. Carefully release any clips or clamps holding the pipe in place, and gently pull the pipe off, taking care not to damage any surrounding components. If the pipe is stuck, you may need to wiggle it slightly to loosen it before removal.
in the breather tube/pipe
under the bonnet!
it is just a breather pipe