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I have a 1986xr7. She's still pretty stable but she's making this god awful "siren" sound, upon acceleration. She shifts fine so I don't think it 's the tranny. But that's how loud it is. People think they're getting pulled over. Quite embarresing. I've been told multiple times that it's my turbo but I've got no clue as to where I'm looking or what I'm looking for.???? Any suggestions?
 

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Contributing Sr Motorhead
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I had your car's cousin (85-1/2 T-bird Turbo Coupe). Yes, it is probably the turbo gone bad. If you look at the passenger side of the engine, you'll see a rounded appendage attached to the exhaust. That is the turbo.

A turbocharger is a turbine that is spun by the exhaust gasses passing over the exhaust side of the turbo. That is connected to an inlet turbine by a shaft between the two. That way, when the exhaust spins one side, the inlet side is turned, thereby forcing air under pressure to the intake manifold. This compression of the inlet charge is what is forced into the cylinders and produces more power than a non-turbocharged engine of the same size.

The turbo turbine spins at a very high RPM, spinning faster and faster as more exhaust pressure is passed over it. The downside is that since that turbine shaft is turning so fast, and is being heated at the same time by the hot exhaust, it tends to 'cook' the oil that is lubricating the turbo shaft bearings. When the oil cooks, it forms ash which gums up the oil passages to the bearings and then the turbine bearings fail. Now you have to replace the turbo.

A rebuilt unit will cost in the neighborhood of $500, not counting labor to replace it. The turbo in my T-bird went at 48,000 miles the first time, and was starting to show signs of needing replacement again when I gave the car away with 92,000 miles. It also needed struts, shocks, bodywork, etc. To me it just wasn't worth spending $1500 or more to fix a rusted out car so I gave it to a coworker who just got out of the service and needed a car.

Ok, what you need to do is take the air cleaner element off and start the car. Listen to the open duct that goes to the turbo. Listen both at idle and blip the throttle a few times. If you hear a jingling or whirring coming from the inlet duct, your turbo is shot.
 
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