Turbocharger heart attack caused by lack of lubrication

Turbochargers are tough nuts—even under the most extreme conditions, these technically complex components provide excellent performance. Shaft speeds of over 300,000 rpm, exhaust gas temperatures of over 1000°C, and charge air pressures over 2.5 bar are completely normal values. A modern turbocharger needs to withstand these strains for many years and thousands of kilometers.

But the life of a turbocharger hangs by a silken thread: its thin oil feed line. Although it is typically only a few millimeters in diameter, it is extremely important. Any congestion here can have disastrous consequences. If we compare the turbocharger to a human heart, the feed line is like an artery. A human heart is supplied with blood, and in a vehicle the turbocharger is supplied with engine oil. If the line is blocked, then an infarction will occur in both cases.

Turbo heart attack risk—watch out for constricted feed line

Hot spot—the oil feed line runs directly over the hot exhaust side.
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1. Deposits

The effects of aging and heat cause coke deposits in the infeed and throttle the flow rate to the turbocharger. Eventually, this minimal lubrication is no longer enough—the bearings start to seize up.

Therefore: always replace the line when replacing the turbocharger, and be sure to replace any missing or loose insulation.

2. Kinks

Flexible oil lines, especially, will become kinked sooner or later. This plastic deformation can never be restored to its correct shape. Here again, this causes bottlenecks in the supply line.

Therefore: be sure to replace bent or kinked lines

STOP! Do not use any sealant. The gasket provided for this purpose is fully sufficient.
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3. Gaskets

Liquid sealants are an absolute no-go for turbo repairs. They can clog the infeed and block the fine oil holes in the bearing housing. Anyone who uses this sort of sealant for installation must have sprung a leak themselves!

Therefore: use only the gaskets provided—and nothing else

Loss of pressure is deadly to turbochargers

Deposits clog the intake screen on the oil pump.
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Like the crankshaft, the pistons, the hydraulic followers, etc., the turbocharger needs a certain oil pressure. It can only work properly with engine oil that is under pressure. A lubricating film forms between the shaft and the plain bearings, on which the shaft basically “floats.” There is essentially no wear because the two parts of the bearing do not make contact with each other. Failures in the oil supply make themselves known in the turbocharger first, because it is the weakest link in the oil circuit. Other bearing points are not under as much load and especially are sized much larger. If the oil pressure fails under full load, it takes only a fraction of a second for the turbocharger to blow out. The most common causes are defective oil pumps and blocked control valves, which adjust the oil pressure to the engine speed ( see TM 04/2016).

Therefore: check the oil pressure and the amount of oil delivered; also check the pressure under various load conditions

A “sick” environment damages the “healthiest” turbo

Culprit: when the particulate filter is full, life is difficult for the turbo.
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Lack of lubrication can occur even with a clear oil feeder line and perfect oil quality. Namely, if there are problems in the engine environment of the turbo, for example, if a diesel particulate filter (DPF) becomes clogged. Because the saturated DPF generates such high back pressure, the exhaust gases no longer flow freely out of the engine into the DPF. As a result, they seek the path of least resistance—which is through the turbine side of the turbocharger and back to the oil pan. On the way, they pass through the turbine-side radial bearing and force out the vital oil film. This causes inadequate lubrication, the bearing components make contact, and the shaft starts to seize and ultimately locks up. (More information here: “When the turbo won’t charge” and TM 03/2016)

Therefore: always check the amount of buildup in the particle filter and regenerate or replace it as needed

Dangerous for turbochargers: bad oil

Oil quality plays a crucial role today. Especially in modern diesel engines, special additives are required. Without these additives, expensive engine damage can occur. Cleaning additives are also added to the oil. They prevent oil carbon and other residues from accumulating, or break them down. The turbocharger is the first to suffer from any scrimping here. Low-quality or old oil can cause increased oil carbon buildup. These residues then act like abrasives on the radial bearings of the turbocharger—wear increases tremendously.

Therefore: always make the customer aware of the importance of high-quality engine oil

  • Residue can also block the oil pump control valve.
  • Turbine wheel with heavy deposits. Bad oil tends to carbonize more quickly.
  • Left: Radial bearing with wear caused by dirt Right: New bearing

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