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HSV XU6 blower loosing boost.. HELP!!

-sbxu6-

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hey guys i own a super charged hsv xu6... its been very loyal to me till i moved to qld from vic and i seem to be having problems for some reason i cant pull full 10 psi boost, its topping at 3 - 4, unless its colled then all good, got a new belt, new bearings, the shafts are clutch less so cant be that, if it was the blades on the charger it would change it would just be set on the boost how ever low...

now i was told it may be a waste gate problem??? they are gonna put it on the dyno to have a little look, then if thats the problem try and sting me 500 to fix it... now im very mechanicly minded, well fairly but never dugg this deep into a charger, so if thats the problem how can i find the waste gate my self and clean it, he thinks it may be sticking, web sites or images or steps would be great fellas... thanks heaps
 

HARVZ-6

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the "waste gate" hes refering to is the boost control valve.. on the passenger side of the charger theres a little black cylinder with some vaccum lines coming off of it.. on the bottom is a little shaft connected to a pivot on the charger.. make sure thats moving freely

but that shouldn drop the boost.. id be checking for gasket leakage

an you said unless its colled? do you mean when its cold it hits full boost?
 

chargedvx6

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Has any work being done on the car recently? It's unusual for a super 6 to loose boost just out of the blue. I'd definately be observing the boost bypass actuator on the charger next to the throttle body. With the car idling give the engine a few short sharp revs from the throttle cable arm and the boost bypass actuator should force it's arm all the way down onto the stop screw. Also check all the vacuum hoses in the vicinity, it's now out of the question for one to leak air. Just replace em with generic vacuum hose if needed
 

don0xer

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boost control solenoid could be the prob... its located on the back side of the motor under the U bend/throttle body, its a black box with 2 vacc lines coming off it... you can actually disconnect it and join the 2 vacc lines together iirc... might save you some dosh
 

Tsunamix

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At high temps, everything expands a little. So if something is expanding and your getting a pressure loss, I'd be looking at places where 2 different materials join or seal.

Copper expands more than steel, so ant place there is a copper gasket would be worth looking at. The other thing is right on the end of the blower snout. Rubber belts grow a little at temperature, maybe your simply getting belt slip. Check belt tension - You should be able to push it to the side by no more than a fingers width at cold. At hot, no more than 1.5 fingers width. If you can, tension it up. Another trick is to grab a piece of chalk and scribble over the ridges on the blower pulley. Chalk dust is quite abrasive, but soft. It will act as a gripping agent. If after a while you can still see the chalk marks, your belt is way too loose.

There the obvious things. I don't know how the blower seals are constructed on the L76 but they could be conceivably bleeding compressed air at temperature. Unlikely though.
 

-sbxu6-

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thanks guys, i will have a little look, see what i can see, no major work has been done other then new diff, it was hard to tell wen it started exactly, as i was living over seas for a little while. has 10 pound pulley but other then that nothing huge, i put a brand new pulley on yesty, and it only hit 3 at first but once it was warm it hit 10, so was wierd, then i turned it back of and back to 3 again... and yes when its cold it always hits 10, he thinks this part that may be sticking once warm any build up may be melting and causing the sticking problem, then wen cold its hard and no longer does it.... any more help im gonna try the first few ideas
 

-sbxu6-

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ok latest updates, i pulled the cover off and found the black box thing, but that seems to come all the way out, well most of the time, it doesnt seem to come fully out ever time i hit the throttle, but may just come half way, but i went for a drive to get it warm, pulled over had a look and same kind of thing, its not like it just comes out a little, so i played with a few lines gave it a few revs, and continued driving then i was hitting 7 - 8 pound, but after a bit back to 3, so im think maybe one of the lines that runs from the TB to the boost value then into the charger, if thats how it works..??? what do use think???
 

-sbxu6-

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PROBLEM NOT SOLVED, THOUGHT IT WAS, WENT GOOD FOR A WILE BUT IS BACK

i replaced the hose that runs from the plenium to the boost thing, which fixed it for a wile, but problem is back, i think it is a hode problem, but dont no were to get new ones from or which ones could cause this kind of problem
 
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chargedvx6

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Have you observed the bypass actuator on the side of the charger when you rev it? If the arm doesn't move all the way down to the stopper when you rev it that will be you prob. It is help on by 2 x 10mm bolts which allow for adjustment. Moving the actuator down will make it shut better if it isn't already.

What size pulley are you running BTW?
 

-sbxu6-

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yeah it seems to run most of the way not always fully, running 10 psi boost mate, it seems to always change boost now, im replacing lines now try and get rid of any other air leaks
 
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