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Location:
Perth
Registered:
September 2003
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Re: inspecting a GT30 turbo?
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Fri, 05 December 2003 01:21
 
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try and 'wiggle' the shaft. there will be a small amount of movement even in a new one, but if you can make the wheel touch the compressor or exhaust housing then it's stuffed. if any oil comes out of the core's banjo fitting, check it to see if it has been running on clean oil. if the oil's dirty in the core, let it go.
check for cracks around the clamp fittings, wastegate flap in the exhaust housing and flange bolt holes (where it bolts to the manifold). also check for leaks.
check the blades as well, both compressor and exhaust. look for hairline cracks around the base of the 'fins', this is a sign of overspeeding from excessive boost. it 'shouldn't' happen on a steel turbine, but it has happenend. also look for pitting in the fins as well, a sign that the engine and turbo have sucked grit/sand/small rocks/fingers in it's lifetime thru being driven without a filter.
whether it labels the A/R on the compressor or not is up to either the brand, if it's been machined off (for polishing) or just plain removed for aesthetics.
most GT30s should be in the 0.66 - 0.70 range though, otherwise it'd be a pretty poorly matched GT30! and yes it should be the same bolt pattern as a GT35.
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