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Boost control valve testing

1381 Views 75 Replies 7 Participants Last post by  BobSaabit
I'm trying to troubleshoot low boost on my 2000 9-3 SE (b205r).

I've seen some contradictory information on troubleshooting. If I disconnect the electrical connector will the waste gate stay shut?

I'm Checking the bypass valve (B235R, B205L/R) – 9-3 2000 | SAAB Workshop Information System Online it talks about troubleshooting the Checking the bypass valve (B235R, B205L/R). Is this the vacuum operated part that actually connects to the waste gate via the pushrod?

I assume that if I disconnect the vacuum line from the part that actually connects to the waste gate via the pushrod that the waste gate that the waste gate will remain closed also.

Thanks,
Eric
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Discussion Starter · #41 ·
I'm going to look into the turbo, based on what I find there I may want to pressure test the system.

I've never done this before but based on some YouTube videos that I've watched I was planning to disconnect the snorkel from the air box and make a cap from PVC.to fit in it.

I'd then fit a Schrader valve in the cap and pump it up to 20 psi or so and see if I have any leaks. Are there any components that I should disconnect to prevent damaging?

I think some people run over 20 psi boost. I haven't found a max boost spec in the WSI, I guess it varies depending on octane, etc. I was thinking about 1 atmosphere (14.7 psi) would be normal? Base boost pressure is 6.5 psi.
 

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Discussion Starter · #42 ·
I'm going to look into the turbo, based on what I find there I may want to pressure test the system.

I've never done this before but based on some YouTube videos that I've watched I was planning to disconnect the snorkel from the air box and make a cap from PVC.to fit in it.

I'd then fit a Schrader valve in the cap and pump it up to 20 psi or so and see if I have any leaks. Are there any components that I should disconnect to prevent damaging?

I think some people run over 20 psi boost. I haven't found a max boost spec in the WSI, I guess it varies depending on octane, etc. I was thinking about 1 atmosphere (14.7 psi) would be normal? Base boost pressure is 6.5 psi.
In the first step of the WIS Checking the wastegate (B235R, B205L/R) – 9-3 2000 | SAAB Workshop Information System Online

It says:

Detach and move aside the bypass pipe with valve.

If I understand correctly, that's on the inlet side of the turbo. Any idea why they want you to do this? is it just to give you more room to work?
 

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Discussion Starter · #44 ·
Yes, just to give you room to work. It's the aluminum tube running from the bypass/recirculation valve to the turbo inlet pipe. There is a o-ring on the inlet pipe side.
I got the exhaust pipe off the turbo. The nut on the bottom was a real bear, badly rounded off. From what I can tell the wastegate looks good, like a healthy exhaust valve. I could spin it around. I tried feel it's seat and it felt okay. The turbine felt alright, spinning freely with no detectable end play.

I was kind of expecting some noticeable damage. I wonder what the loud whining sound and low boot could be due to. I think I'm going to need to do a pressure test.

I'll see if I can get some pict tomorrow.
 

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Discussion Starter · #45 ·
Yes, just to give you room to work. It's the aluminum tube running from the bypass/recirculation valve to the turbo inlet pipe. There is a o-ring on the inlet pipe side.
I got the exhaust pipe off the turbo. The nut on the bottom was a real bear, badly rounded off. From what I can tell the wastegate looks good, like a healthy exhaust valve. I could spin it around. I tried feel it's seat and it felt okay. The turbine felt alright, spinning freely with no detectable end play.

I was kind of expecting some noticeable damage. I wonder what the loud whining sound and low boot could be due to. I think I'm going to need to do a pressure test.

I'll see if I can get some pict tomorrow.
 

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Discussion Starter · #46 ·
I got the exhaust pipe off the turbo. The nut on the bottom was a real bear, badly rounded off. From what I can tell the wastegate looks good, like a healthy exhaust valve. I could spin it around. I tried feel it's seat and it felt okay. The turbine felt alright, spinning freely with no detectable end play.

I was kind of expecting some noticeable damage. I wonder what the loud whining sound and low boot could be due to. I think I'm going to need to do a pressure test.

I'll see if I can get some pict tomorrow.
The wastegate looks okay, but I think there's a part of a blade missing on the exhaust side of the turbine. I would think that would throw off the balance of my CHRA, but wouldn't think that would totally kill my boost. I have no boost and a loud whirring noise.

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I"m not clear on how to take off inlet pipe. It appears that I'd need to disconnect the bypass pipe and disconnect the hose clamps at the top and bottom. What is the fitting to the left of the solenoid valve in this picture:
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You can just pull out that pcb banjo bolt. Copper washer top and bottom.

The stock bypass valve - the one on the charge air hose with the single vac line - probably won't hold 20 psi. 16 is OK.

Yeah, that turbo exhaust wheel is done. Is there serious play in the bearing? I'm also wondering where that chunk went. Run a compression test.

But you're right - that much missing blade would not seriously affect boost.
 

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Discussion Starter · #49 ·
I'd think on the exhaust side that it would probably be in the catalytic converter. I'd think if the inlet side is okay my engine didn't likely eat anything. A compression test might be good to do as a sanity check.
 

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I'd think on the exhaust side that it would probably be in the catalytic converter. I'd think if the inlet side is okay my engine didn't likely eat anything. A compression test might be good to do as a sanity check.
Oh yeah, I shouldn't post before coffee.

But a dry/wet test would be good; cold and hot if you can swing it.
 

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That turbo is done for... It will be out of balance and wobbly. There will likely be future destruction. You definitely need to check the inlet side. Something caused that. A missing blade will definitely affect boost... It's a hole for exhaust to go through that doesn't spin the impeller.
 

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That turbo is done for... It will be out of balance and wobbly. There will likely be future destruction. You definitely need to check the inlet side. Something caused that. A missing blade will definitely affect boost... It's a hole for exhaust to go through that doesn't spin the impeller.
It will affect boost, but not enough for his level of low boost.

But I too am more concerned about why. Bearing check needed.
 

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It doesn't matter... That turbo is done for... Pull it out and replace what's broken... Hopefully just the CHRA. If you continue to run it it will wobble, blades will impact the housing, and you will send shrapnel throughout the engine. I would not start that motor one more time, personally.

It's definitely possible that what you're seeing is the result of something wrong on the compressor side that caused wobble and broke the exhaust impeller off on the housing.

You have less than base boost which means either the wastegate is open (you said it's not) or there is an intake leak preventing you from building boost or the turbo is damaged. We already know the latter is true.

Another possibility here is an intake leak, which caused a turbo overspeed, and that's what wrecked the blades. Pulling the inlet side off will tell you more, but you might as well pull the whole turbo off since you cannot continue to run it anyway.
 

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Discussion Starter · #57 ·

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They're referring to an o-ring that is at the turbo end of the aluminum bypass pipe. It's part # 7987415. I've never replaced one. They don't seem to get abused. If you're ordering other stuff from e-saab and are already paying shipping, they're cheap enough .You could use something generic.

#35 here: 7987415 by OES | Bypass Hose O-Ring

You will need the manifold gasket for the turbo. Part # 9113937 9113937 by OES | Turbo to Manifold Gasket

There's an oil connection on the bottom to drain back to the pan. It's a pipe that has two bolts on the turbo side and plugs into a hose that goes into the oil pan. Part # 55563093. 55563093 by OES | Turbo Oil Return Gasket

On the other end of that pipe is a hose that connects to the pan. Be nice to it, they are no longer available.

You might also want a pair of washers for the banjo bolt that attaches to the intake pipe. 8124158 by OES | Gasket Those are either 12mm or 14mm simple copper crush washers and again, you can use generic if you can find them locally.
 

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Discussion Starter · #60 ·
They're referring to an o-ring that is at the turbo end of the aluminum bypass pipe. It's part # 7987415. I've never replaced one. They don't seem to get abused. If you're ordering other stuff from e-saab and are already paying shipping, they're cheap enough .You could use something generic.

#35 here: 7987415 by OES | Bypass Hose O-Ring

You will need the manifold gasket for the turbo. Part # 9113937 9113937 by OES | Turbo to Manifold Gasket

There's an oil connection on the bottom to drain back to the pan. It's a pipe that has two bolts on the turbo side and plugs into a hose that goes into the oil pan. Part # 55563093. 55563093 by OES | Turbo Oil Return Gasket

On the other end of that pipe is a hose that connects to the pan. Be nice to it, they are no longer available.

You might also want a pair of washers for the banjo bolt that attaches to the intake pipe. 8124158 by OES | Gasket Those are either 12mm or 14mm simple copper crush washers and again, you can use generic if you can find them locally.
The WIC says to change the oil prior to changing the turbo, any idea why?
 
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