You've got trouble; your engine still runs, but something's amiss in your turbo system and your wallet is about to go into shock. Your car is laying down a smoke screen that would make James Bond envious, and there's a screech coming from underhood that makes the hair on the back of your neck jump to attention. This is big and bad.

It's critical to take quick action because identifying the gremlin early can limit the damage to the turbo system and your wallet Ive compiled this troubleshooting guide to help you zero in on those gremlins. The first thing I recommend is determining whether the problem is engine or turbo related. Use common sense. If you've been cranking up the boost 3 psi a day and/or running at WOT for minutes at a time, internal engine damage can explain many of the symptoms listed in this story. A leakdown test on the engine will confirm or deny the source of the problem. If you are sure it's the turbo system, remember the conditions when the problem surfaced and follow the guidelines listed below.

LACK OF POWER
EXHAUST OBSTRUCTION: In this scenario, an exhaust obstruction creates a restriction, which doesn't allow the turbo to function properly and less boost equals less power. The most probable obstruction point is the catalytic converter, which can be overheated by the turbo. Severe overheating causes the inner matrix to melt down. Additional ramifications of this condition include excessive heating of the turbine side of the turbo. This over-spinning and trial-and-error tuning can contribute to the breakdown of the cat. The heat was so intense the turbine housing can cracked at the waste-gate flapper valve seat.

Clogged air filter
Check, Clean, Replace

Obstruction between the compressor and manifold
Find, remove obstruction

Air leak between compressor an mainifold
Check connector hoses, clamps

Exhaust Obstruction
Check manifold, Catalytic converter, Muffler

Exahust leak
Check manifold, wastegate flange

Lack of fuel pump/Injector capacity
Ensure system is working properly and provides adequate volume

Poor Camshaft Timing
Check, Adjust to spec

Blow By/Worn PIston Rings
Check, replace, rebuild

Hurt engine internals
Check valves, rods, pistons

Damaged Turbo
Check bearings, clearances, wheel

SMOKING (BLACK)
BLOW-BY /WORN PISTON RINGS. HURT ENGINE INTERNALS: These are leading suspects in engines that run stock internals. Tuning can play a role in hurting internal parts but often it comes down to the engine component's ability to handle the kinetic energy produced by a boosted engine. Trying to push 350 whp through parts designed for commuting duty will only be endured for so long. Were you revved on, accepted the invitation and now your engine is smoking? Look to these areas. Think of it as an opportunity to upgrade to billet rods and forged pistons. Blow-by can be caused by exceedingly high cylinder pressures that compromise the piston rings, oil starvation that causes cylinder wall/piston ring damage and poor assembly. What happens is oil is able to get past the rings and into the combustion chamber. This can cause smoke while also robbing power because oil is in the air/fuel mixture and vital compression is lost.


Obstruction between filter and turbo
Find, remove obstruction

Air leak between compressor and manifold
Check conector hoses, clamps

Exhaust obstruction
Check manifold,Catalytic converter, muffler

Exhaust leak
Check manifold, wastegate flange

Lack of fuel pump/injector capacity
Ensure system is working properly and provides adequate volume

Poor Camshaft timing
Check,adjust to spec

Blow by worn piston rings
Check, replace, rebuild

Hurt engine internals
Check valves, rods, pistons

Dirt caked on compressor wheel/diffuser
Clean W/non caustis cleaner, soft brush, change oil/filter

Damaged turbo
Check bearing Clearances, wheels

EXCESSIVE OIL CONSUMPTION

COKED BEARING/SHAFT IN TURBO CENTER SECTION: Blow-by is a leading cause of oil consumption, but oil can also be lost at the turbo. Coked bearings are the result of a wicked one-two punch. The jab is allowing oil to be contaminated; the right cross is hot turn-off. The dirty oil causes accelerated wear at the bearing. This wear is compounded by hot turn-off, which is simply blasting the last mile to your house and shutting off the engine. With no cool-down time, the heat contained in the bearings and on the shaft cook the oil residue. This creates an imbalance and, over time, the bearings become compromised and oil escapes from the turbo. The cure is regular oil changes— 2,000, to 2,500 miles—and the use of a turbo timer.

Clogged air filter
Check,clean,replace

Obstruction between filter and turbo
Find, remove obstruction

Air leak between compressor and manifold
Check conector hoses, clamps

Obstruction of oil drain line
Clean, replace oil line

Obstruction in crankcase ventilation system
Ensure proper ventilation

Coked bearing/shaft in turbo center section
Change oil/filter overhaul turbo

Blow by worn piston rings
Check, replace, rebuild

Hurt engine internals
Check valves, rods, pistons

Dirt caked on compressor wheel/diffuser
Clean W/non caustis cleaner, soft brush, change oil/filter

Damaged turbo
Check bearing Clearances, wheels

OIL LEAK (COMPRESSOR SEAL)

DAMAGED TURBO: The most likely cause of oil leaks at the seal is a damaged turbo, namely the bearings. Excessive bearing wear can allow pressurized oil in the turbo to be to be pushed by the bearing and around the seal. On the compressor side, the oil is pushed into the engine and burned, resulting in smoke and a drop in power. If you have easy access to the intercooler, simply removing the inlet pipe and checking for oil residue will confirm the problem.

Obstruction between filter and turbo
Find, remove obstruction

Obstruction at exhaust manifold
Find, remove obstruction

Obstruction in muffler/ exhaust system
Find, remove obstruction

Obstruction of oil drain line
Clean, replace oil line

Obstruction in crankcase ventilation system
Ensure proper ventilation

Coked bearing/shaft in turbo center section
Change oil/filter overhaul turbo

Dirt caked on compressor wheel/diffuser
Clean W/non caustis cleaner, soft brush, change oil/filter

Hurt engine internals
Check valves, rods, pistons

Damaged turbo
Check bearing Clearances, wheels

SMOKE (BLUE)

OBSTRUCTION OF OIL DRAIN LINE:. The oil return line is susceptible to clogging or becoming kinked-When this happens, the bearings become oil starved, paving their road to doom. I can't tell you how many limes I've heard people say they got a bad turbo only to get another and see smoke shortly after installation. What they think is a had turbo inevitably turns out to he an oil line problem. The cure? Check the line whenever the opportunity arises. If a turbo fails, replace the oil return line when you replace the turbo. It should be noted that poor crankcase ventilation can lead to a lot of smoke and is an easily correctable condition.

Clogged air filter
Check,clean,replace

Obstruction bewteen compressor and manifold
Find, remove obstruction

Obstruction between filter an turbo
Find, remove obstruction

Air leak between compressor and manifold
Check connector hoses/clamps

Obstruction of oil drain line
Clear/replace oil line

Obstruction in crankcase ventilation system
Ensure proper ventilation

Coked bearing/shaft in turbo center section
Change oil/filter overhaul turbo

Blow by/worn piston rings
Check, replace, rebuild

Hurt engine internals
Check Valves rods, pistons

Dirt caked on compressor wheel/diffuser
Clean W/non caustic cleaner, soft brush,change oil/filter

Damaged turbo
Check bearings, clearances,wheels

OIL LEAK (TURBINE SEAL)

OBSTRUCTION IN CRANKCASE VENTILATION SYSTEM: A damaged turbo is the leading cause here as well but venting problems at the crankcase can also mean trouble. Crankcase ventilation is a tricky proposition. The effects of improper ventilation can differ from car to car. Buick Grand Nationals are especially temperamental in this area, while other cars can endure improper ventilation up to a point. Pass that point and the results can be anything from puffing smoke to oil loss.

Obstruction of oil drain line
Clear/replace oil line

Obstruction in crankcase ventilation system
Ensure proper ventilation

Coked bearing/shaft in turbo center section
Change oil/filter overhaul turbo

Blow By/worn pistons rings
Check, replace, rebuild

Hurt engine internals
Check valves, rods, pistons

Dirt caked on compressor wheel/diffuser
Clean W/non caustic cleaner, soft brush, change oil/filter

Damaged turbo
Check bearings, clearances,wheels

WHINY TURBO NOISE

DIRT CAKED ON COMPRESSOR WHEEL/DIFFUSER: A noisy turbo is a turbo in trouble. The sound in question is usually caused by either an oil-starved bearing nearing its failure point or wheel-to-housing contact Oil starvation can usually be traced to low oil level, oil pump failure or oil return Line obstruction. While it's true that bearing failure can Lead to an imbalance, sometimes the imbalance is on the wheel itself. Din can become caked on the compressor wheel, causing an imbalance and wheel-to-housing contact This is actually a "best-case scenario" because if caught quickly, the situation can be rectified without a major turbo rebuild. The cure is simple: Remove the dirt, remove the imbalance, silence the turbo.

Obstruction between filter and turbo
Find, remove obstruction

Obstruction between compressor and manifold
Find, remove obstruction

Obstructed intake manifold
Find, remove obstruction

Air leak between filter an turbo
Check connector hoses/clamps

Air leak between compressor and manifold
Check connector hoses/clamps

Exhaust leak
Check manifold, wastegate flange, turbine outlet

Dirt caked on compressor wheel/diffuser
Clean W/non caustic cleaner, soft brush, change oil/filter

Damaged turbo
Check bearings, clearances, wheels

CYCLIC TURBO SOUNDS

OBSTRUCTION BETWEEN FILTER AND TURBO: This kind of turbo sound is a repeated cycle of sounds. It's more of a sound of air rushing than a scraping or squealing sound associated with bearing failure or wheel-to-housing contact A cyclic sound can be traced to a foreign object in the intake tract generating vortex or oscillating effect While the blockage can cause an interruption of flow (and loss of power] or a surge effect on the bearings, the big danger is the FOD (Foreign Object Damage) that will occur if the object makes its way into the compressor housing.

Obstruction between filter and turbo
Find, remove obstruction

Dirt caked on compressor wheel/diffuser
Clean W/non caustic cleaner, soft brush, change oil/filter

great write up as usual man, definetly some good info here. i will have to read this more thouroughly this weekend.

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Thanks