Turbo blast

Clive Atthowe looks at a limping Mercedes

Published:  10 May, 2013

By Clive Atthowe

A customer booked a Mercedes E280 CDI in due to a lack of power and the engine management light coming on. After interviewing the owner, the full extent of this vehicle's history came out. This vehicle came to us with an unhappy owner who had already spent a large sum of money to try and resolve its issues - many new parts had already been replaced including air mass meters and a new turbo.

Initial assessment showed a fault code P2510 turbo actuator. The turbo actuator on this vehicle is electronically controlled and actuator tests via our Autologic tool revealed that it could function across its full travel.

Checks of the turbocharger actuator feeds, grounds and control initially seemed normal. After doing some research, which included consulting various wiring diagrams, I learnt that the feed to the turbo actuator is shared by the inlet port shut-off motor, situated under the turbo in the middle of the engine's 'vee'.

Stripping out the turbo to gain access to the motor revealed a poorly fitted air filter housing seal which had been allowing oil to leak into the motor which had damaged it.

With the turbo removed, we decided to check the exhaust manifolds for any signs of breaking up as this is a known issue on this engine causing damage to the turbo compressor. Three bolts sheared off in the exhaust which required drilling and repair however, the manifolds appeared to be OK.

A new inlet port motor was fitted and the turbocharger was refitted along with the existing exhaust manifold. As you might expect, we took extra care when fitting the air filter housing with a new seal to ensure no re-occurrence of the oil leak.

The conclusion was that the oil contamination of the inlet port shut off motor was causing it to draw too much current, hence the turbo actuator couldn't move at the same time. This resulted in a boost deviation and default running.

Although an expensive repair, the customer was pleased to have his vehicle back to normal performance.

It would have been typical for many technicians to simply replace the actuator as the DTC indicated such. As ever, former Top Technician winner Clive demonstrates the importance of checking and double checking the components in the chain to get to the root of the problem.

Apart from the hassle and inconvenience for your customer, if the car needs to come back to have the same fault rectified again after a short period, it is worth noting that turbo manufacturers won't honour a warranty claim for anything less than a genuinely faulty turbo.

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