As turbochargers can spend at over 240,000 rpm and have to endure temperatures of 950°, oil leaks can lead to very expensive repairs. The turbocharger relies on a thin film of oil that lubricates the bearings on the turbine shaft. This oil is kept in place by seals at each end of the turbocharger, behind the turbine and compressor wheels of the bearing housings.

The seals are not like normal oil seals, but are more similar to this brings. They need a positive air pressure inside the compressor and turbine to keep oil lubricating the bearings and preventive seeping into the end housings. A restriction on the inlet side will create a vacuum that will pull oil pasta seals at the compressor and housing. If the engine idle for long periods, the Turbo will rotate at very low speed with correspondingly low air pressure. The resulting vacuum will cause oil to seep into the turbine housing. Any of these situations will result in insufficient oil reaching the turbine bearings.

So what causes oil leaks at the compressor end?

• A blocked or restricted air intake filter
• A locked or restricted air intake pipe or hose
• Air leaks on intake hoses or at the intercooler

And what causes oil leaks at the turbine and?

• A leaking exhaust system
• A leaking EGR system

What would cause oil leaks at both ends of the turbocharger?

• Any restriction in the oil drainpipe from the Turbo to the engine
• A restriction in the engine breather
• Physical damage to the Turbo is rotating parts, and excessive bearing clearance
• Repeated hot engine shutdowns, leading to carbon deposits building up in the centre housing
• The incorrect Turbo being fitted

To prevent turbo failure caused by oil starvation

• Ensure there are no blockages or restrictions in the air and oil systems
• Ensure the run, no leaks and exhaust system