my wastegate was not working properly, all the boost was escaping.
I opened it and saw that the screws inside are loose.



the wastegate is out of the car with its dump tube.
the diaphragm & springs are perfect.

when I pour some water into the dump tube (or vice versa), there's still some water coming out of the other way. (the flange is fit)

is this normal ?

 

Nope. Contact TiAL about this. Hell, they may already be watching.

 

I am still scratching my head why you would be pouring water anywhere...

Those screws come with blue loctite from the factory. If it was taken apart, it may not have been set back to the factory torque either. These screws practically strip when coming out if the loctite isn't heated before removal. If you must, use some very high temp RTV around the bevel before installation.

I have never seen screws back out on TiAL products personally, but if this was used, it is hard to say who was playing around before you.

 

Good point. As I've never seen this on new units either. I've never purchased a used unit but this is a distinct possibility.

 

I got this unit second hand so everything can happen of course.

I installed the wastegate today and things seem fine, however, there's still a little bit of exhaust gas is escaping from the dump tube.

What can be the reasons ?

it feels like the piston is not pressing with enough power to close the gaps of the manifold v-band connection.

or even if it presses enough, can there be a problem on the surfaces of the firering or wastegate piston ?

 

It is too hard to say. You should have taken more pictures. You are also talking about two different problems. Are you sure the fire ring was installed? If there is enough pressure that you have to put down the "cap" to the wastegate, then it has enough pressure to seal the valve. Was the valve face burned on the edges at all? How about the fire ring?

The band on the wastegate either fits tight, doesn't fit, or is extremely loose. At this point this thing sounds like a basket case of operator error.

 

actually everything looked fine. the fire ring is in its place, the springs and diaphragm are perfect, and all the screws and nuts are locktited perfectly.

between the piston and the fire ring, there's a leak.