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Discussion Starter #1
Hi, I have an 03 Passat 1.8t (everything stock) and I've been going crazy over this boost leak. I finally decided to plug the output side of the turbo and pressure test there. It seems there is air leaking into the engine block from the intake side of the turbo (I could feel air pressure coming from open end of throttle body). Also, I could hear oil dripping when I applied air pressure which leads me to believe a seal is broken and air is escaping through the oil line. Before I get a new turbo, I just wanted to confirm that this is the case.
 

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You would need pull and plug the PCV from the intake tract. That allows air past the rings and maybe through the oil seal in the turbo.
 

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Discussion Starter #3
You would need pull and plug the PCV from the intake tract. That allows air past the rings and maybe through the oil seal in the turbo.
Yes, that was already done, the only line the pressure is going into is the turbo inlet.
 

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So you pressure tested the turbo? Hopefully you did not damage the seals. Did you pressure test the turbo outlet hose to the throttle body? That's the most likely source of a leak apart from the non-one-way valved hoses attached to the manifold.
 

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Discussion Starter #7
So you pressure tested the turbo? Hopefully you did not damage the seals. Did you pressure test the turbo outlet hose to the throttle body? That's the most likely source of a leak apart from the non-one-way valved hoses attached to the manifold.
From most of what I've seen, people include the turbo in pressure testing.The turbo itself would only hold 1-2 psi so I'm thinking there's probably an issue there. When accelerating, I'm reading a peak boost of 8 psi followed by a consistent 2 psi. I will do more testing on the rest of each section this weekend when I have time.
 

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Are you loosing any oil? The turbo should hold higher as most people test to 15psi or so. I've only tested mine once as I had a V6 for a 10years in between the turbo engine. 8psi is good, but it should not drop that low until near redline.
 

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Are you loosing any oil? The turbo should hold higher as most people test to 15psi or so. I've only tested mine once as I had a V6 for a 10years in between the turbo engine. 8psi is good, but it should not drop that low until near redline.
I don't seem to be losing any oil
 

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With the engine running, you would not have a boost leak inside the turbo as the oil pressure is higher than the boost. Since you are not loosing oil, the turbo seals are good.
 

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Discussion Starter #11
Well I think I found the issue. Everything held boost downstream of the turbo so I did some looking around on the turbo itself. Previous owner or someone must have messed with the wastegate adjustment and put it back wrong. Both nuts were tightened together on the end of the rod with the wastegate lever just balanced on the end of it, stuck always-open. Also, pressure testing wasn't working because the diaphragm in my diverter valve was leaking air into the intake manifold (I had plugged up every other outlet). I put everything back together late last night, so I'll do some test driving today.
 

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I am surprised you had any boost at all with that wastegate setup. Hopefully it all works now.
 

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Discussion Starter #13
Everything seems to be working fine now, holding 12 psi steady. Just waiting on the new diverter valve so I don't blow out the turbo. In other news, I just bought a 2015 passat and plan on selling this one.
 
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