Well I saw them do it. they pressurized it starting from the intake and air was coming out of the upper cover gasket.
But thats what im trying to get at, what other part in the charge system would break and leak air into the crank case then out of the upper timing cover?
When you boost leak test, air takes the following path:
intake piping > turbo > boost piping / intercooler > intake manifold > cylinders
The air then slowly leaks past the pistons into the bottom end of the engine (which is open to the timing area and head). The oil fill cap is opened during a pressure test to prevent air pressure from building up in the crank case/timing area/head. If this isn't done you get air trying to escape from anywhere it can, hence a leak appearing at your upper timing cover.
The same thing happens when your car is running. When your engine is firing, small amounts of gasses blow by the piston rings into the crank case. That's where the PCV (Positive Crankcase Ventilation) system comes into play. It removes that pressure from the crank case so it doesn't cause damage. The reason so many people blow their rear main seal when their PCV goes bad? Pressure builds up in the crank case.
I was informed that this is incorrect, the timing area is directly open to the head on the inside so it does see pressure.
Yes, the timing area is open to the head and the crank case. The only reason for those areas to see pressure is if a boost leak test is performed incorrectly or your PCV system is shot.
It sees pressure in the crankcase, not boost unless the PCV is totally hosed. Did they remove the entire intake pipe from the turbo? If not it’s totally possible they pressurized the crank case thru the back port of the pcv system that is designed to pull in fresh filtered air off boost and all the crankcase vapor when in boost.
Agreed. In OP's case pressure built in the crank case by air leaking past the pistons and potentially air going through the back port of the PCV system (if the shop pressurized the "stage 2" portion of the intake without removing & blocking off the rear PCV connection).
If there is air leaking from your upper timing cover during a boost leak test, the test is being performed incorrectly. Do not continue doing this. You risk causing damage. Pressure in the crank case is bad.
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When I pressure tested my system I disconnected the rear PCV connection and plugged it with a rubber plug. I held the rubber plug in place with a big set of channel locks. Not the most professional but it worked just fine. Note the oil fill cap--it's unscrewed (but sitting in place to prevent any debris from falling in).
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