The steps below help you determine if you need a new turbo boost on your car.
1. Is the Turbo Compressor Wheel Loose?
A loose compressor wheel is the first thing we recommend checking if you have low turbo boost. Before removing the turbo, test how loose the turbo compressor wheel is by grasping the center spindle with a pair of pliers (needle nose pliers work best in our experience). Start by gently pulling out and pushing in on the wheel. Now, try moving the compressor wheel from one side to the other and back. You should not experience any play, looseness, or wobble in either test. And the wheel should never touch the turbo housing body when moving it.
2. Do You See Oil on the Turbo Blades?
Excessive oil can build up on the turbine side of the blades, the compressor side, or both if you have a bad seal or gasket inside of the turbo. If you find excessive oil on either side of the blades you will need to replace your turbo.
3. Is Your Wastegate Stuck?
The wastegate is a valve that opens and closes to control the flow of exhaust to the turbine wheel in a turbo engine. The wastegate’s main function is to regulate the boost pressure in turbocharger systems. This regulation protects the engine and the turbocharger from too much pressure build up.
If the wastegate is stuck closed too much pressure will build in the turbocharger. This will cause the turbine to spin too fast, which will cause a huge increase in the car’s acceleration, potentially damaging the turbo and the engine.
When the wastegate is stuck in the open position, the turbo is not able to build or reserve any pressure. This will cause the turbo to not work at all, resulting in a very slow acceleration on your vehicle with no turbo benefits.
You can check the wastegate’s operation with a vacuum gauge. Make sure that the diaphragm is working freely, moving open and closed. If the diaphragm isn’t working or appears to be stuck, it is best to replace the entire turbocharger.
4. Is the Diverter Valve or “Blow-Up Valve” Working?
The diverter valve is designed to divert pressure when too much air pressure builds up in the intake. If the diverter valve gets frozen or stuck, the excessive pressure on the intake can damage the turbocharger.
If the diverter is broken or seized, it will cause low boost on the turbocharger.
5. How Are the Hoses on Your Turbocharger?
Now we need to break down the turbocharger a little more. Locate the hoses on the intake side and the pressurized side of the turbo are both tight and secure. Loose or disconnected hoses that lead to the intake or the intercooler will reduce boost.
When the turbine turns, exhaust gases get pushed into the compressor, past the turbine which then compresses the air and forces it into the intake. And that is how the turbo got its boost back… You should check the turbine for looseness, wobbles, or play. You should be able to see it, feel it, or hear it move. If your five senses pick up any movement, it needs to be replaced. (DIY Mechanic’s disclaimer – three of the five senses will do. There’s no need to smell or taste the turbo in this diagnostic step.)
Broken turbine blades van cause engine damage so if you see any broken blades, replace that turbine, asap. To check the blades on the exhaust side, remove the o2 sensor or the turbo exhaust pipe to get a clear look.
Also, check to see if the turbine is free and moving. If it is stuck, it’s defective, and replacing the turbo is really the only option.
If you see any contact marks on the intake from the turbine wobbling out of place, the turbo is defective and should be fully replaced.