I just bought a 94 f250 7.3 idi with a factory turbo. I was told the turbo does not work so I got a good deal on the truck. It does not whistle and I do not feel any boost. How can I test it and what should I look at to fix it. I did take the air inlet duct off and checked the fan. It was clean and moved freely.

 

I dont know how much you know about the turbocharger. What it is , is two opposing fans connected by a commn shaft. The exhaust drives the turbine side of the turbo, which will spin the compressor wheel because they are both on the same shaft. If there is no drive to the compressor side of the turbo, I would suspect the turbine fins are off OR the exhaust pipes from the manifolds to the turbine side of the turbo are out, worn or leaking.
What do you see when you remove the intake hose and start the engine? Can you see the compressor (fan) spinning? Is your truck equipped with an intercooler? If so equipped, I would suspect the hoses are dried out and leaking or the intercooler has holes in it. If there is no intercooler and the compressor is spinning, I would suspect the seal on the top of the intake manifold is blown out. Can you describe the way the turbo gets the air into the intake manifold? Are there any extra lines or hose or piping? When you took hold of the compressor wheel, could you move it - spin it - does it wiggle a lot up and down or in and out? There will always be a slight movement in the compressor wheel, but very slight. Also, the shaft between the turbine wheel and compressor wheel may be broken.
Let us know what you discover. DONT STICK ANYTHING ESPECIALLY YOUR FINGERS INTO THE COMPRESSOR WHEEL IF IT IS SPINNING. And dont put any rags into the opening while is spinning.

 

Other than stated above, you could simply install a boost gauge and see what you get.

Les

 

thats what i did with mine. I was having the same problem mainly because you can't hear it. the little actuator the passenger side of the turbo is the pressure feed wastegate actuator. when the turbo spools up, the pressure in the hose connected to the actuator forces the diaphragm (sp) to move the long rod connected to the turbine housing. this allows the wastegate to limit the amount of boost the turbo makes. I put a "T" fitting in the pressure line and then ran a boost/vaccuum gauge into the truck and went to drive it. the only time mine made the full 7psi of boost was under wide open throttle. other than that i got about 4psi at half throttle or more. I still couldn't hear the turbo though. i was also going to try removing the pressure line and capping it off to let the turbo run full capacity and see what kind of boost it makes. i haven't gotten a chance yet though because of heart failure. (in the truck that is)

good luck. If its bad, there is one on ebay right now for 500 dollars.

 

BTW. i will try to post some pics when i get home.