why no boost?

[pointynoggin]

Just breaking in a new rebuild with a Giles pump and a boost controller.

I can't get the boost over 10psi, it runs up and stops dead at 10-11psi. Even if I open the waste gate to atmosphere.

I have disabled the BOV with a bit of wood dowel and a cork in the line.

The pump is a bit smokey and EGTs can climb past 1200F.

Am I missing anything?

[theman53]

I would think the overboost protector or the BOV as you called it is still funtioning.

[Baron VonZeppelin]

I tend to agree with TheMan53 on that.

I just crank that screw all the way down tight on the OBP - on my cars and the ones i service (TD's) - and still get 12-13 boost. And they don't fall off flat when they get there.

[pointynoggin]

I get what you mean by 'fall off flat'.

I'll check it again.

[745 turbogreasel]

Rev it higher
And maybe cap the WG tube instead of venting.
Exhaustectomy recommended.

[pointynoggin]

I put a longer dowel in the hole and cranked it where I can feel it deforming the valve.  Should be tighter now, see how the drive to work goes tomorrow.

Is it possible to control boost pressure when the waste gate is disconnected?  Is it better than a bleed type controller?

[bajacalal]

Exhaust and make sure there aren't obvious boost leaks. The BOV where it mates to the manifold is a good place for one to occur.

[CrazyAndy]

What everyone else said, and also maybe something along the lines of this:
http://www.vwdiesel.net/forum/index.php?topic=18289.0

[theman53]

I put a longer dowel in the hole and cranked it where I can feel it deforming the valve.  Should be tighter now, see how the drive to work goes tomorrow.

Is it possible to control boost pressure when the waste gate is disconnected?  Is it better than a bleed type controller?

I don't know what you are saying, but maybe. You can build things so that you can control boost, but stock I don't think so other than how you are doing it. My suggestion is get a manual ball and spring boost controller and put that in the hardline on the wastegate and eliminate the BOV as you have called it. The BOV will continue to function and you will loose boost with the wastegate disconnected to open. That is what it was designed for, to open if the wastegate wasn't functioning, hence overboost protection name. VW saw it pointless and later manifolds do not have it at all. I welded mine closed.
Saurkrat would take the set screw of his K24 all the way down flush with the jam nut, not any more than that, and the wastegate will hold it right at 25psi at that point. Somewhere in between maybe good for you.

[CrazyAndy]

I put a longer dowel in the hole and cranked it where I can feel it deforming the valve.  Should be tighter now, see how the drive to work goes tomorrow.

Is it possible to control boost pressure when the waste gate is disconnected?  Is it better than a bleed type controller?

I don't know what you are saying, but maybe. You can build things so that you can control boost, but stock I don't think so other than how you are doing it. My suggestion is get a manual ball and spring boost controller and put that in the hardline on the wastegate and eliminate the BOV as you have called it. The BOV will continue to function and you will loose boost with the wastegate disconnected to open. That is what it was designed for, to open if the wastegate wasn't functioning, hence overboost protection name. VW saw it pointless and later manifolds do not have it at all. I welded mine closed.
Saurkrat would take the set screw of his K24 all the way down flush with the jam nut, not any more than that, and the wastegate will hold it right at 25psi at that point. Somewhere in between maybe good for you.

I think this links is somewhere else on the site, but this guy made a great write-up on ball-and-spring MBC's.
http://www.gusmahon.org/html/boostcontrol.htm

Scroll down a little until you see stuff about brass pipe fittings.  He includes McMaster Carr PNs and everything.  This is what I'll be making for my own car.

[rodpaslow]

I had a T3 that with no boost line connected to it, would open at 10-12 psi no matter what.  I think the spring in it was wore out and it would open regardless at that psi (I had the overboost thing in the intake plugged).  So I actually had to thread a bolt into the plate that covers the wastegate on the T3 so as to hold the valve closed.  It would then climb up to about 20 psi at higher revs.  My VNT I have on it now is no comparison.  The t3 would start boosting at about 2500 rpm.  The vnt starts almost immediately climbing with engine revs.

[pointynoggin]

still stays at 10-11psi.

it is a T3 aswell.  I will change the over pressure valve o-ring if that doesn't work i will try with the waste gate line plugged.

if that doen't work \i will have to tap the plate.  can that be done in place?  My studs are very rusty, I don't want to take it apart.

[pointynoggin]

changed the over pressure valve o-ring - no change.

Disconnected the waste gate, now boost peaks at 22psi!!

I don't know why the boost controller didn't work.  It is one of the generic ebay ones.  I didn't use the tee that came with it, maybe it doesn't work with out the tee?

[R.O.R-2.0]

changed the over pressure valve o-ring - no change.

Disconnected the waste gate, now boost peaks at 22psi!!

I don't know why the boost controller didn't work.  It is one of the generic ebay ones.  I didn't use the tee that came with it, maybe it doesn't work with out the tee?

bet it rails alot better with 22psi eh?!

[pointynoggin]

it goes now pretty good, after ~17psi I don't feel much change in power.  i notice that the EGT drops when the boost hits which is nice.