Failures in the first hours of a new or overhauled turbo almost always have the same origin: the engine it was fitted to. Dirty oil, a coked feed pipe, a fragment left in the intercooler. The procedure below takes an extra hour of work and saves the turbo, the customer and the warranty argument.
First of all: why did the old one fail?
Look at the removed turbo and compare the marks with the 5 causes of failure. If you do not find and remove the cause, the new turbo will go the same way. Also check that the replacement turbo part number matches the application: two similar turbos can have different settings.
The oil circuit
- Change oil and filter, using oil of the specification required by the engine manufacturer.
- Replace the oil feed pipe. It cokes and narrows on the inside without showing outside; if it really must be reused, it has to be cleaned and checked.
- Check the drain: clear, without kinks and running downhill all the way to the sump.
- Check the crankcase breather: if blocked, crankcase pressure hinders draining.
- Use only new gaskets, the specified ones. Never sealant or paste on oil fittings: the excess enters the circuit and blocks the turbo’s own passages.
Intake and exhaust
- New air filter and a clean filter box.
- Clean hoses and intercooler: if the previous turbo leaked oil or broke a wheel, there is oil and debris inside. If the intercooler cannot be cleaned thoroughly, replace it.
- Exhaust manifold checked: no gasket residue or engine fragments.
- Exhaust, catalyst and DPF not blocked: high back-pressure raises turbo temperatures.
Fitting
- Fit the turbo without forcing fittings and brackets: stress on the housings causes leaks and cracks.
- Do not alter the actuator setting or the geometry adjustment: they are set on the bench for that individual turbo.
- Connect the vacuum lines or the electronic actuator connector carefully.
Pre-lubrication and first start-up
- Fill the centre housing with clean oil through the feed port and turn the shaft by hand before connecting the pipe.
- Where possible, crank the engine without starting it, for example by disconnecting the injector supply, until oil pressure stabilises.
- Start and leave at idle for a few minutes, without revving. Check for oil, air and exhaust leaks.
- Switch off, recheck the oil level and the fittings.
Test and handover
Read and clear fault codes, carry out any resets or learning procedures required by the manufacturer (for example on electronic actuators) and road-test the vehicle while checking boost pressure with the diagnostic tool. No real running-in is needed, but avoid full load for the first kilometres until you have confirmed everything works.
Frequently asked questions
Should the oil feed pipe always be replaced?
That is the recommended rule: carbon deposits form inside, reducing its bore, and they can break off and end up in the new turbo. The pipe costs very little compared with the turbo.
Does the intercooler need replacing?
Only if it cannot be cleaned thoroughly. If the previous turbo broke a wheel or leaked a lot of oil, fragments and oil left inside will be drawn into the new turbo or the engine: in that case, thorough cleaning or replacement.