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Cannot Boost Over 10psi

nisskid

By nisskid,
in Engines & Forced Induction

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nisskid Grand Master

nisskid

Posted
Posted

hey guys, after a recent track day, i went to check my pneumatic boost controller and noticed the bolt in the end of the controller had actually come out and was chilling down in a crevis in the engine bay (lucky as fark), anyway put it back in and tried it in a few positions, but didnt seem to go above around 10psi which is around stock in my car, as in that is a bout what id get if i just ran a vacuum line straight to the actuator without the bleed.

now only can think of one main thing:

when the bolt has come out, a small component has come out with it, i think it has a ball bearing and spring or something in it?? this is the controller here im talking about: http://www.skylinesaustralia.com/forums/go...ntr-t73375.html

a few things to know:

it has recently had a new dump put on where it has a screamer for the wastegate, cant see how it would affect it.

the turbo is a stock R33 one on an RB20, using an RB20 actuator.

besides that i have nfi what ive done since the last time it was boosting up around 12-13psi as its been a while (was turned down a while back, also had to go through regency etc etc)

so yeh, any suggestions? is it possible for some components to fall out if the bolt isnt in screwed in?

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https://www.sau.com.au/forums/topic/238331-cannot-boost-over-10psi/
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RBwhatever Veteran

RBwhatever

Posted
Posted (edited)

you've lost the ball bearing that goes under the spring and bolt. The ball bearing is the valve. Without it, its just a direct connection to the actuator, hence 10psi because its a 10psi actuator.

Also, this particular MBC doesn't bleed.

Edited by KeyMaker
DrewII Community Regular

DrewII

Posted
Posted
you've lost the ball bearing that goes under the spring and bolt. The ball bearing is the valve. Without it, its just a direct connection to the actuator, hence 10psi because its a 10psi actuator.

Also, this particular MBC doesn't bleed.

x 2

the ball bearing is so tiny you would never find it anyway.

im selling one in parts for sale section if ur interested

nisskid Grand Master

nisskid

Posted
  • Author
Posted
you've lost the ball bearing that goes under the spring and bolt. The ball bearing is the valve. Without it, its just a direct connection to the actuator, hence 10psi because its a 10psi actuator.

Also, this particular MBC doesn't bleed.

thanks mate, that's what i thought i was, going by a bloke in that thread it was around 7mm in diametre so ill try and grab a BB and see how it goes. is that all, any other components that could have come out?

Keeper Experienced

Keeper

Posted
Posted

a spring will be between the ball bearing and the screw, too strong tension and the boost will be too high, too soft tension and fully wound in the boost controller wont do a thing, too big a bearing it wont fit in the hole, too small and it wont close up the gap inside.

crap pic hopefully gets the rough idea

post-20826-1222956173_thumb.jpg

nisskid Grand Master

nisskid

Posted
  • Author
Posted
a spring will be between the ball bearing and the screw, too strong tension and the boost will be too high, too soft tension and fully wound in the boost controller wont do a thing, too big a bearing it wont fit in the hole, too small and it wont close up the gap inside.

crap pic hopefully gets the rough idea

post-20826-1222956173_thumb.jpg

haha interesting, always thought it worked differently. so yeh guess the spring would have had to of come out for the BB to have. mm reckon ill take the thing out and go round to a few places and match the parts. cbf sourcing out a new controller as i need it by next sat.

Keeper Experienced

Keeper

Posted
Posted
haha interesting, always thought it worked differently. so yeh guess the spring would have had to of come out for the BB to have. mm reckon ill take the thing out and go round to a few places and match the parts. cbf sourcing out a new controller as i need it by next sat.

thats only my understanding, maybe in more sane hours someone else can confirm thats basically how they work, i opened a mates up by accident once by unscrewing it too much and thats the order of things inside it.

R34GTFOUR Mentor

R34GTFOUR

Posted
Posted

the picture you drew is exactly how a manual spring and ballbearing type bleed valve works. Theres only one other type of manual bleed valve that i know of and its just like a "tap", same principle as a water tap. The sping type are much better as far as manual controllers go.

i would just go to any performance shop and just get a new turbosmart bleed valve, it cant be much more than 100bucks, if no good go to repco and they'll have something, someone will have one in stock. You'll spend all afternoon going around trying to get the right parts for the current bung one.

bubba Grand Master

bubba

Posted
Posted

Just spend $30 and get a new Turbotech mbc. I wouldn't bother trying to source new parts as there was probably a fair bit of thought gone into springs specs and I guarantee you won't be able to get one the same as the one you lost.

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