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Mounting turbo
Checklist

When installing a new / different / used turbocharger, there are some things that are important to keep in mind. If the Old Turbo has broken down, you must first know why this has happened. Otherwise there is a great risk that the same thing will happen with the new turbo.

Before mounting

  • Clean the air filter box, if any
  • Clean or replace air filter
  • Check intake ducts for leaks
  • Is the oil in the pipe old? replace this. It is not possible to clean.
  • Clean crankcase ventilation and check / upgrade this for free flow
  • Change engine oil and oil filter

Mounting

  • A new / used turbo must always be lubricated with oil so it has an oil film immediately at start-up.
  • If a journal bearing turbo is fitted, make sure that the full oil pressure is available from the engine main supply.
  • If a ball bearing turbo is fitted, make sure that an oil restrictor is fitted
  • Use new steel gaskets - not gasket on tube
  • Do not use threaded tape on the oil in adapter
  • Drizzle in oil in the turbo's oil inlet before starting up

Start-up

  • Buil up oil pressure before starting the engine
  • Check for leaks at idle

Troubleshooting

No / low charging pressure
Air leakage
Open / loose wastegate
Wastegate control does not work
Vacuum leakage

Exhaust smoke
- Too much oil in the turbo part due to different reasons
Too high oil pressure
Poor evacuation / oil return
Poor crankcase ventilation
Wrong angle on oil return

Oil in pressure pipes
- Too much oil in the turbo part due to different reasons
Too high oil pressure
Poor evacuation / oil return
Poor crankcase ventilation
Wrong angle on oil return

 

 

Common causes of turbo failure

 

Backpressure
Exhaust back pressure approaches or becomes greater than the engine boost. This can result in uneven loading on bearing surfaces and make lubrication of the turbo bearings more difficult. If the back pressure exceeds the charging pressure, the turbo will wear prematurely and in the worst case break.

Crankcase backpressure
High crankcase pressure is common in tuned engines. This high crankcase pressure counteracts the turbo's return flow of oil back to the engine. The oil return does not work with any pressure but only flows back to the engine and therefore it must be free flow without crankcase pressure that counteracts the return flow.

If you have high crankcase pressure, the oil can not evacuate the turbo the right way through the oil return, but is then pushed out through gaskets and ends up in pressure pipes, inlet pipes and out into the exhaust housing and results in all of these cases with extra exhaust fumes/smoke from the exhaust. Also called blue smoke and oil smoke as the oil eventually makes its way through the engine.

Oil return dimension
As already mentioned above, the turbo's oil return does not work with pressure but should only have a free flow to the engine. Therefore, it is important to have a properly dimensioned oil return as the oil can flow freely back to the engine. In the case of a journal bearing turbo, this is especially important as there are large amounts of oil to be evacuated. This is also important with a ball bearing turbo, but then you do not need to have as large a return line.

If you fail when dimensioning the oil return, you get the same consequential error as with too much crankcase pressure.

Oil return angle
Excessive inclination of the oil return causes the same problem as at high crankcase pressure and too little oil return as the oil cannot flow back to the engine efficiently enough.

Oil feed dimension
Journal bearing turbo
A Journal bearing turbo must have an oil supply from the engine main line as it needs to have oil pressure. This can be compared to the engine crank and rod bearings which also need pressure to maintain an oil film between fixed and moving parts.

Ball bearing turbocharger
A ball-bearing turbo should not work under pressure. It should only be dripped with oil so it is lubricated. It must not have oil pressure. Therefore, an oil restrictor is mounted on a ball bearing turbo.

A ball-bearing turbo that get to much oil will get the same error as with high crankcase pressure and incorrectly dimensioned oil return.

Debris in oil
That debris in oil would destroy the turbo and not the engine bearing may sound unbelievable, but this is more common than you think. This is due to various reasons.
One - you have thread tape / seal on your NPT thread on the oil supply so the thread sealant get into the turbos bearings.

Two - The turbo bearing is much more sensitive than the heavy bearings in the engine. The turbo is very precise and the slightest deviation can cause problems.

Three - When manufacturing the oil supply hose, there is another source of error as to why debris can end up in the turbo.

Debris in the oil damages the bearing. Usually so the oil can take a different path than through the oil return with a leak that is similar to a high crankcase pressure. The lubrication of the bearing can also suffer as the oil pressure is not maintained as oil can leak several ways.

Oil pressure
Too low on oil pressure causes a journal bearing turbo to break down fairly immediately as it needs proper oil pressure. This also applies to a ball bearing turbo, but it should not have pressure but only drops that ensure that the bearing is lubricated. Regardless of which turbo you have, you must ensure the correct oil pressure and then adjust this if you have a ball bearing turbo.

Debris in intake air
It is often difficult to keep completely clean when assembling car parts and in this case turbochargers and inlets. However, it is absolutely necessary as debris that enters the inlet pipe when the turbo spins can cause major damage to the compressor wheels with consequent faults such as imbalance and oil leakage. This sometimes leads to turbo failure.

Excess rpm
If the turbo RPM exceed max recommended both the turbine blade and the bearing part are damaged.