We carried out an Independent Inspection Report back in 2015 on a customer's remanufactured turbocharger. The turbo had been purchased from a well known company, but due to hearing horror stories about remanufactured VNT turbos the customer wanted us to check the unit over before it was fitted to their vehicle. The findings were as followed:




 REG NUMBER: Unknown

 MAKE & MODEL: Seat Leon

 TURBO PART NUMBER: 724930-0005



 TURBO SERIAL NUMBER: Unknown (Illegible)

XXXXXXXXXXXXXXXX requested Turbo Dynamics Ltd to undertake an inspection of the turbocharger (overhauled and purchased elsewhere) prior to it being fitted to the vehicle. The turbocharger was delivered to Turbo Dynamics Ltd in a built, complete condition as ready for fitment to a vehicle. There was no paperwork relating to the turbocharger (measurements, balance specification, etc) included with the unit.

VNT Mechanism

The first test undertaken was to check the actuator calibration and the flow of the VNT mechanism. This is done using a Turbo Technics VTR machine.


Starting with the ‘Van Flow Setting’ columns the first thing the machine does is flow air through the VNT mechanism. This should fall around the 100% line although there are lines above and below this indicating the tolerance. As can be seen the flow was not only outside these lines but it was also off the scale. Due to the flow test being failed a pressure test was not undertaken.

The machine also checks and records the actuator travel. As can be seen from the graph on the bottom right the actuator did not have the required travel and so this test was also failed.

In order to examine and test the turbocharger further the housings and actuator had to be removed. Seeing as the VNT mechanism was already out of calibration removing the housings will not affect the turbocharger as, at this stage, it was clear the unit should not be fitted to a vehicle.


When the actuator was removed it was found that the turnbuckle rod end was not being locked by the top nut. In fact, the only thing preventing the top nut spinning was the paint applied by the reconditioner. If it’s not locked off against the rod end the nut serves no purpose.



Axial and radial measurements were then taken from the turbocharger's CHRA (Centre Housing Rotational Assembly) and recorded below. These were within specifications as would be expected of any freshly overhauled turbocharger. 






0.004” Max



0.020” Max

When examined closely neither the compressor wheel retaining nut (nosenut) nor turbine wheel showed any sign of high speed balance correction (material removal) leading us to believe the CHRA was not balanced.


At this point the CHRA could have been put on one of our high speed VSR balance machines however when we inspected the turbine housing fine particles of what we believe to be blast media were present in the manifold ports leading us to question if the whole turbo had been properly cleaned. Not wanting to risk putting a contaminated CHRA on our balance machine we decided not to check balance the unit.


The image above shows one of the manifold ports of the turbocharger. A clear witness line can be seen within the port where one of our engineers ran his finger into the port to show the presence of a contaminant. Whilst this is unlikely to get into the engine directly from the ports any contamination within the CHRA itself would be picked up by the oil and could lead to accelerated wear to the turbocharger or other engine parts.

Upon inspection it had also been found that the location pin designed to ensure the turbine housing and bearing housing alignment is accurate had been removed (see image below). Whilst not a major issue if set up correctly even a 1 degree discrepancy in this angle can lead to problems with the VNT mechanism calibration.


Other Comments


There is a lot of damage to the ID of the compressor cover inlet fitting – this is clearly as a result of a turbocharger failure previously. Whilst the damage is unlikely to be affecting performance it looks unsightly.


It is our opinion that the turbocharger, as supplied, is not in suitable condition to be fitted to a vehicle. This opinion is based on the following;

- The VNT mechanism and actuator are incorrectly calibrated meaning problems would likely occur once fitted. These problems could include poor / erratic performance, boost/flow related fault codes, reduced power.

- No signs of any balance correction on the turbocharger nor is there any paperwork to suggest balancing has taken place. If unbalanced long term reliability of the turbo will be compromised.

- Contaminant present within the manifold ports. This could well be present to other areas of the turbocharger but it would require complete strip down in order to confirm this.

The turbocharger can be reassembled to the condition it was delivered if required. Further images can be supplied upon request.

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