1985 900 SPG - Saab 900 Bulletin Board - Saabnet.com

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1985 900 SPG
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Posted by SwedishDynamicsInc [Email] (#2304) [Profile/Gallery] (more from SwedishDynamicsInc) on Thu, 24 Jan 2019 11:08:12 Share Post by Email
In Reply to: Re: Valve Guide Seals or Turbo Leak?, Justin VanAbrahams [Profile/Gallery] , Mon, 21 Jan 2019 15:19:22
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Thank you for your post, and great to see you at TSN!

The Super60 compressor wheel is a larger trim than OEM, which may be more temperamental to turbocharger piston ring oil bypassing, especially at an engine idle condition. The turbocharger's larger wheel trim would be rotating at a slower shaft speed, at engine idle, as compared to an OEM turbocharger, and this reduces the oil consumption at the turbocharger journal bearings which leads to potential oil levels rising within the turbocharger's bearing housing. Any time the oil levels are allowed at the bearing housing may provide opportunity for piston ring oil seal bypassing at both the turbocharger oil seal locations. We have had reports of several customers reporting a need to increase the exhaust velocities into the larger turbocharger's turbine, hence increasing the turbine shaft rotation, and eliminating oil seal bypassing. Engine exhaust velocities may be increased by checking that there is no exhaust manifold restrictions, such as EGR "Bump" which should not typically be found on the 1985 engine. In many cases, a simple elimination of this restriction to exhaust velocities will speed the turbocharger turbine shaft speed, eliminating oil bypassing. Other areas of concern could be the exhaust manifold to cylinder head gaskets which have been known to shift over time, and may restrict the exhaust portal. The original sheet metal gaskets are typically elongated at the 8mm stud ports, which happens under thermal expansion.

Also, you could attempt to increase the B202 engine idle speed, which could address your conditions by means of a slight increase in exhaust velocities at the turbocharger, when at an idle condition.

Since the turbocharger used is a TB03 type, another likely method of addressing oil bypassing would be installation of the 360 degree turbine oil seal which will eliminate the standard gapped oil seal, and also provides a lifetime of service, and is the same seal which have been installed onto our T3/T4 hybrid for some time. Removing the turbocharger would be time consuming, and we are in hopes that your problems could be addressed by finding a method to increase the exhaust velocities, etc.

A last option would be via use of an oil inlet restrictor at the turbocharger oil inlet and may be fit into the two bolt flange gasket connection, although there will be minimal information relative to accomplishing this task. There have been several customers opting to install gasket with a reduced oil entry portal, or others have used mechanical/metal restrictors which will slow down the oil flow, especially at engine idle, thus eliminating oil bypassing at the turbine oil seal.

Again, great to see you at TSN, and please inform us as to your findings, when possible!




->Posting last edited on Thu, 24 Jan 2019 12:47:31.

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