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Finding a boost leak.

Joined
22 November 2004
Messages
631
Location
Atlanta
Hi guys,

I am currently trying to hunt down a boost leak in my bbsc system. I was planning on removing the intake from the sc to the throttlebody and pressurizing the system with say 5psi to see if I could find the leak.

However after talking to my local tuner he says that you cant do that because you cant get all the valves to shut.

I cant see what the valves being open would have anything to do with pressurizing the system? The air would just fill every pocket until the system was pressurized and if there was a leak externally through the hoses etc I should be able to hunt it down.

Am I missing something here?
 
If I understand your idea correctly, you are planing to pressurize the engine from the throttlebody throughout the intake, heads and so on. If my understanding of your idea is correct you will likely have an air leak through a cylinder that will have the intake and exhaust valves openned at the same time due to cam lobe overlap.
 
isnt it more likely for the leak to be upstream of the throttle body?
 
Hi bob, yes you are correct that is what I was planning on doing. I see what your saying but I didnt think that you could have both intake and exhaust valves on the same cylinder open at the same time?

Woody, as I understand it there is really only three major places directly relating to the sc that could exp a boost leak, The backing plate on the sc itself, the BOV, and the elbow connecting the sc to the throttlebody. So far I havent found any of those places to be leaking, thus I was intending on pressurizing teh system and see if anything else was leaking.
 
My setup is leaking at the Novi2000 -> Elbow connection. I can feel the air coming out of the 'slits' in the female side of the connection.
 
Pour/spray water with dish soap stirred in (but not foamy) around all the parts of the volute and connecting pieces. Fire up the engine and run up the RPMs to a few thousand. If you have foam start to form anywhere, you have a leak....
 
ALIENT said:
My setup is leaking at the Novi2000 -> Elbow connection. I can feel the air coming out of the 'slits' in the female side of the connection.

That seems to be the most common place for a boost leak as the edge of the alluminum elbow needs to be crimped down around the gasket. We resloved this problem by cutting the elbow at that end and using turbo connectors with clamps.


Armando
 
coldhammer said:
I am open to suggestions from anyone concerning a way to check this.
FYI, Depending on how you have your SC volute rotated, there is always one set screw that will allow air to excape. If you have a standard BBSC setup.... look behind the volute scroll where the screws lock it down to the gear body. I do not remember the size of allen head set screw, but they have a way of backing out..or into the volute. You can place your hand around the mounting bracket and feel the air pour out. Just put some red lock tight on it if you didn't loose it already.
 
I would recommend BLUE loctite, Red is pretty permanent, typically takes heat to get it loose, not good for disassembly of the volute later:).

JMO,
LarryB
 
MiamieNeSeX said:
That seems to be the most common place for a boost leak as the edge of the alluminum elbow needs to be crimped down around the gasket. We resloved this problem by cutting the elbow at that end and using turbo connectors with clamps.


Armando

I agree with Armando on this. With the normal elbow from the blower outlet to the TB inlet, it's very easy to cause leaks. I've taken it on/off so many times now I can normally reinstall without any issues, but it still gets a leak occasionally. I really hate that god damn elbow.

Make sure you put the rubber seal on the very edge of the blower outlet, then spray a small amount of silicone lubricant inside the outer lip of the elbow. Push the elbow over the rubber seal (it usually helps if you twist it back and forth) and try not to push the rubber seal too far back onto the blower housing.

If you have the elbow on as far as it will go, and the rubber seal in the rite place, you won't be able to see the blower housing through the slits in the elbow. Ofcourse, if you see that the seal isn't completey covered by the slits, you will have a big leak. You can still leak if it's barely covering it, because the blower housing gets really hot and the rubber seal will squish around causing leaks under high boost.

Also, I don't know about your setup, but I'm pretty sure mine came with a 'normal' industrial type hose clamp to secure the elbow to the blower housing (and to the TB). I've replaced all of them with the t-bolt type clamps which distribute the torque much more evenly around the joint, which is important when you dealing with a slotted elbow over a rubber seal.

I'd suggest removing your SC->TB elbow, and reinstalling it. That's most likely where your boost leak is coming from.

Cheers,

-mike
 
I did the soap trick and am indeed seeing air bubles coming out from the elbow at the sc end.

I pulled off the elbow twice and put it back on but i am still leaking air from around those slits. I looked at it and those slits run all the way down to the weld. I cant seem to get the rubber gasket to push up perfectly around inside of the elbow to form a good seal.

I think I am going to go with Armanods suggestion and saw off the lip and use some silicone couplers to join the pieces.

I have also uprgaded to the Tbolt a while back.
 
Larry Bastanza said:
I would recommend BLUE loctite, Red is pretty permanent, typically takes heat to get it loose, not good for disassembly of the volute later:).

JMO,
LarryB

Hey Larry, yes blue on the bolts that hold the Volute to the gear unit. I didn't trust the blue on the empty hole that leaks the air. This hole ie where the ALLEN screw would be installed from the PAXTON. It will backk out or in from the volute. SO, I wanted it to not back out at all. Do not use the red on the bolts.
 
I've been thinking about how to pressurize my system for awhile and although I haven't tried it yet my plan was to plug the exhaust at the muffler tips and feed air into my SC inlet. With an adequate supply (flow) of relatively low pressure air (about 15psi) I would expect to see about 2/3rds of that as actual pressure as there will be leaks past the exhaust manifold. At that point you can use soap, borescope, your hands or just a good ear to find any leaks. Just a thought. BTY, I've thrown all my $10 each "T" bolt clamps away for a good cheap set of stainless hose clamps. They create more localized clamping pressure than the fancy clamps and in my opinion for lower boost situations create a much better and more reliable/repeatable seal.
 
OK so i have thus far found two boost leaks. One is at the seal that joins the volute to the elbow. Not a big leak but leaking nontheless. I plan on cutting off the lip of the elbow and using a turbo coupler to join it.

The second leak was the hole chudson mentioned. At first I couldnt tell if it was coming from there or somewhere else so i just started spraying water around the general area till the air started blowing the water sideways.

So I have indentified two leak sources so hopefully once those are addressed i have boost back.

As to what mark was saying about pressurizing my system I had thought about capping off the exhaust as well but then like he mentioned you could lose air from exhaust leaks etc. and I didnt want to go through all that jsut to find out i was leaking air faster than i could hunt for the problem heh.

Stay tuned....
 
I have run into a problem. I tried to insert a new set screw into the mounting hole that is exposed.

However there is not enough clearence there to actually fit the screw straigh into the hole.

This raises a question, if i cant get the screw in then i cant see that it could have fallen out from the outside. That means that it must have fallen inside the volute. If so could that have damaged the turbine blades somehow?

THe really big question now is how do i remove the supercharger so that i can plug that hole up. I boght the car with the supercharger already on it so I have no instructions for anything.

Can anyone point me in the right directon for this?
 
Remove the blower by removing the 4 allen bolts closest to the blower holding it to the drive, then remove the blower mounting bracket which is attatched with 3 bolts to the top of the tranny. You might have to use a chisel to loosen the allen bolts as they tend to tighten up pretty good. Once you have the blower/bracket removed it is pretty straight forward to replace the set screw.

Armando
 
MiamieNeSeX said:
Remove the blower by removing the 4 allen bolts closest to the blower holding it to the drive, then remove the blower mounting bracket which is attatched with 3 bolts to the top of the tranny. You might have to use a chisel to loosen the allen bolts as they tend to tighten up pretty good. Once you have the blower/bracket removed it is pretty straight forward to replace the set screw.

Armando
Armando is correct. You can also if you have long arms remove the Actual head unit from the bracket. MAKE SURE THAT DRAIN LINE ALWAYS FLOWS DOWNHILL NO MATTER HOW YOU DO IT!!!! You then can access the hole very easy to put the screw back. I thought mine went inside of the volute. 9-10 they back out per PAXTON/vortech.
HTH
Charles
 
You can loosen the four small bolts that hold the two volute clamps if you're patient with a small 7/16 or 11 mm wrench and a 1/4 drive universal socket. You only have to loosed them a little to be able to rotate the volute the small amount need to get that screw in. You also have to remove the discharge elbow, b ut you said you were taking that off anyway

HTH,
MB
 
Ahhh the hits keep on coming. So I tried to just loosen the 4 bolts that mark talked about however i cannot get a wrench to one of them to loosen it up.

So I tried taking off the 4 allen bolts that connect the drive shaft to the blower unit. And wouldnt you know it the top two allan bolts were stripped by someone.

So now I am wondering if anyone has any suggestions how to remove these bolts. Since the bolt heads are smooth and rounded I have nothing to latch onto to remove it. Since its the top two bolts they are pretty small and I am hestiant to try and drill them and back them out.

Any suggestions?
 
coldhammer said:
Ahhh the hits keep on coming. So I tried to just loosen the 4 bolts that mark talked about however i cannot get a wrench to one of them to loosen it up.

So I tried taking off the 4 allen bolts that connect the drive shaft to the blower unit. And wouldnt you know it the top two allan bolts were stripped by someone.

So now I am wondering if anyone has any suggestions how to remove these bolts. Since the bolt heads are smooth and rounded I have nothing to latch onto to remove it. Since its the top two bolts they are pretty small and I am hestiant to try and drill them and back them out.

Any suggestions?

Use a dremel with a small grinder attachment (if you don't have a dremel, just use a corse metal file). Grind one of the edges flat. Use a center punch and a malot and smack it a couple times. This should get it loose enough to turn with a pair of channel locks or pliers (you might want to grind a little edge on the opposing side of the bolt as well, to have something to grab onto.)

I had the same exact problem, only the stripped bolt was my own fault, and it was one of the driveline cover bolts.

-mike
 
If all else fails buy a LEFT HAND twist drill to use for drilling the bolts out. The left hand spiral of the drill will be trying to unscrew the the bolt as you are drilling. Be sure you are runing the drill in reverse when drilling with a left hand drill bit. It is often unnessary to use an easy-out sice the bolts often unscrew themselves during the drilling process. These drill are available at most mill supply stores. This is the process we always use when we must drill out broken studs or bolts [as long they are right hand thread].
 
OK so I tried a dremel that didnt seem to work for me in the end I just hammered a torx bit into the hole and was able to remove it that way.

So on to the next thing. I have now removed the 4 allen head bolts that connect the drive shaft housing to the the blower. I have removed the bolts holding the blower to the blower support that is bolted to the tranny.

However when I try to pull out the blower the end of the drive shaft that connects to it will not come out. How is the shaft connected to the blower? Does it just get pushed into the center or is there some sort of retaining clip or screw there?
 
So in the end I completely removed the entire supercharger setup. Removed the blower from teh driveshaft housing replaced my setscrews reconnected everything and started it up.

Now i am having some god awful vibration type of noise coming from the driveshaft. I loosened the blower end again and tried to retighten everything but the noise continued.

I do notice that under boost the noise dissapears almost. but then as soon as you let off the boost the noise is back.

When i removed the unit I only removed the blower end from the shaft housing. I did not remove the rest of the driveshaft from its housing.

Any ideas?
 
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