boost leak? aargh!!

[DeanS15]

i've got a bit of a pain in the arse to share, basically im looking for suggestions as to whats wrong with my car.

i had it set up and remapped to 1.2bar on the t28bb and have the supporting mods to go with it, and for a couple of months it pulled like a train, but then developed a squeal at high boost and now wont make more than 1bar flat out. i was all set to get all the turbo gaskets replaced as i suspected the leak to be coming from there (the squeal is accompanied by a ticking noise from the turbo area that sounds like pulses of air squeezing out somewhere and ive been over all the pipework on the system - seems fine), but when i took the heatshields off there are no telltale signs that there has been any exhaust gas escaping anywhere and the manifold isnt cracked at all. im pretty baffled on this one, all the exhaust gaskets are fairly new bar the turbo to manifold and manifold to head gasket, and when driving at anything other than 1bar the turbo spools fine and the car drives fine, its just down on power due to whats happening.

any help or suggestions on this is really appreciated as taking it up to jez is a long trip for me and if its something i could get sorted here before resorting to that it would save me a 300 odd mile round trip. thanks in advance guys.

 

[Matt_S]

Turbo to manifold is probably the first to go thro wear, the turbo to dump pipe normally goes thro the nuts and bolts coming loose.
When the car is cold, hold the viscous fan still and get someone to start it up. WIth your right hand, feel around the manifold and turbo area and see if you can feel or hear the exh gasses escaping. THats the easiest way. Can you see soot anywhere on the heat shields undersides?

 

[DeanS15]

none whatsoever on the side of the block or under the heat shield, the nuts and bolts that hold the dump pipe on are all tight too with a genuine nissan gasket......fitted only a couple of k ago.......

 

[WATDA]

Mine did the same thing but only when i was running higher boost. Was the turbo to manifold gasket. Nuts worked there way lose. Couldnt tell until i took the whole manifold/turbo off the car

 

[Auss15]

Are you able to get a smoke down test over your way. I had one done to find were my boost leak was, very effective and quick

 

[als_jordan]

@DeanS15 : I've got exactly the same problem but mine has not started to affect boost yet still managing 1.2bar...
Checked all the pipes and can find nothing...
Jez has replaced my turbo gaskets all round and my 'squeak' is still there... I am thinking the next step is to RR the car to find it, (it only does it under load which is a right pain in the ****)
Als

 

[Matt_S]

als, yours could well be your turbo on its way out :wack: or you have a boost leak and cant find it :wack:. YOu can pressure test the system with not a lot of work.

 

[als_jordan]

Please dont say that..... (I doubt it, it only happened after i changed the engine mounts, i reckon somethings come loose, or has got a pin sized hole in it.....

How do you do the pressure test? is there a procedure somewhere? Also the smoke test sounds like an idea, is that available here in the UK (I assume that is a visual version of a pressure test?)

Als

als, yours could well be your turbo on its way out :wack: or you have a boost leak and cant find it :wack:. YOu can pressure test the system with not a lot of work.