Turbo Failure 101

What causes failure and how do I maintain my turbo?

The number one cause of most turbocharger failure can be traced back to the engine lubrication system.  The turbochargers bearings depend on a constant flow of clean oil to function properly.  Several factors can lead to the break down of the oiling system - including lack of maintenance, improper oil or filter, severe driving conditions, or in most cases simply the age of the vehicle can all contribute to degradation of the turbochargers oil supply.

 The bearings in 90% of all production turbochargers are journal bearings (bronze bushings) that when pressurized with oil create a hydro-dynamic film between the turbine shaft and the journal bearing. This oil film supports the turbochargers rotating shaft allowing it to spin free with minimal resistance.  The tolerances between the journal bearing and bearing housing are very tight so any contaminants held within the oil will cause damage and service issues if not corrected.  The best defense you have against oil borne contaminates is a very strict maintenance schedule.

Regular oil and filter changes are critical to the life of the turbo.

The following are examples of carbon buildup due to infrequent oil changes or improper oil type:

 

 

 

 

The other key factor is engine heat, unfortunately all late model gasoline turbocharged engines suffer from a condition called "heat soak". Heat soak is caused by improper service intervals, low coolant no coolant, low oil level, no oil. Heat soak causes oil to cook into the engine components leaving unwanted deposits in vital areas of the lubrication system. These deposits restrict the oil flow to the turbocharger and in some cases will starve the turbocharger during heavy load conditions. Heavy foot or performance drivers should allow the engine to idle for 1.5 minutes before turning off the engine or purchase a Turbo Timer to have the engine turn off automatic.

The following are examples of heat induced failure:


 

 

 

Another condition we see regularly is foreign objects or a "UFO" entering either side of the turbochargers rotating components. Foriegn objects can come from the air filter system, or through the turbine inlet coming out of the engines combustion chamber.  Compressor Side: Servicing your air filter should be take dead serious, be sure to thoroughly inspect the entire system for loose connections, loose debris, nuts/bolts/ clips ANYTHING that might accidentally enter fall past the air filter housing during the air filter service.  Compressor wheels are made from cast aluminum, cast titanium or billet aluminum and in most cases extremely delicate. Leaving debris inside the housing can cause an immediate catostropic turbo failure. Turbine Side: Its not uncommon to find turbine wheel damage caused from internal engine component failure. Components like engine valves, melted pistons, spark plugs, glow plugs, exhaust manifold deterioration, turbine manifold deterioration will cause turbine wheel failure.

The following are examples of turbine foreign object or UFO damage:

 

 

 

 

Turbocharger over-speed aka Overboost is not straight forward to diagnose and should be investigated prior to any replacement turbochargers being installed. All turbochargers have an efficiency level or boost pressure that is pre-determined in most cases by a spring tension wastegate actuator. The wastegate actuator regulates the wastegate or door allowing it to open and bypass the turbine wheel to keep specific pre-set boost pressure.  If there is a leak between the compressor outlet, intercooler and the engine intake manifold consistant boost pressure will be difficult for the turbocharger to maintian and the waste gate will remain closed. Even a small leak can cause the turbo to work 30% over its efficiency level, great care should be given to the charge pressure system and or intercooler system.

The exhaust system after the turbocharger needs regular inspection.  Increased back pressure due to clogged or damaged catalytic converters, resonators or mufflers will decrease the exhaust flow out of the engine and will also raise the temperature inside the turbochargers exhaust housing, both of which contributes to oil coking and also raises the risk of gasket failures or cracks in the exhaust manifold and turbine housing area.  Usually this occurs in older or higher mileage cars.  10 years or 100,000 miles is an average life span of most modern exhaust systems, beyond this replacement is in order.

What are the symptoms of a turbocharger that needs rebuilding or servicing.

Power Loss: Most drivers are familiar with thier car or truck and its power, sound and fuel economy. Drivers that experience minor power loss over a short period should have the vehicle or machine inspected before the power loss becomes a major power loss. Major power losses can be a 50/50 gamble, either there is a big break in the intercooler charge system or the turbocharger completely failed.

Turbocharger Noise: whistling, police siren are all signs of a turbocharger that will need immediate service and or replacement depending on the damage. Typically a turbocharger will have a crisp consistent sound that will not deviate with linear engine speed. Turbochargers that sound like a dentist drill are typically worn beyond service limits.    

Black or Gray Smoke: Turbocharged gasoline engines with tail pipe smoke at any time should service the turbocharger immediately. The diesel engine shares similair trait's with the gasoline engine but will require a more in depth investigation to determine the cause of tail-pipe smoke.

What determines if a turbocharger is able to be rebuilt?

If the major parts of the turbocharger are in rebuild-able condition, the work will be performed for the price quoted. If the turbocharger has items that are non-rebuildable the price will be plus these additional items. In most cases we will have replacement options as well as new options available for most turbo models. Thiss will help you save money and also contribute to the “Going Green” recycle and reuse philosophy of the rebuilding process.

Once your turbocharger arrives at our shop, it will be visually inspected and a full inventory record will be made to ensure all of the turbocharger and other fittings, brackets etc. will be returned to you. The turbocharger is then disassembled and inspected. Following this you will then be contacted with the condition of the turbocharger as well as a preliminary estimate. Once we receive your approval to continue the service, the turbocharger component pieces will be fully cleaned and all critical measurements will be taken, and any machine work will be performed. At that time all of the rotating parts of the turbo will be dynamically balanced and all of the new bearings, seals, o-rings will be prepped for assembly. The end housings will be sand blasted and coated to prevent corrosion where needed, the waste gate actuator will be tested and ultimately everything will be assembled in a clean room environment to guarantee the highest quality service we can provide. Your inspection fee is applied to the service of the rebuild.


 

 

 

 

What is involved when I install my new or rebuilt turbocharger?

Aside from the actual act of removing and re-installing your turbocharger, there are a few things that will need some extra attention. Since most turbocharger failures result from oil issues, we require that the entire oil feed line system be replaced with new parts at the time of turbo replacement. If left uncorrected, oil coking, or carbon build up within the oil line passages create blockage and also a potential contamination issue. Changing these lines and fittings will ensure that the highest quality of oil is delivered to the new turbocharger. Your oil and filter will also need to be replaced, again to ensure high quality unrestricted flow of clean oil to the new turbo.

Other items you will need to have available will be any gaskets for the exhaust manifold to turbine housing, turbine housing to down pipe, oil return line flange, any water line copper crush washers as well as any rubber coolant lines that might be in the proximity of the turbocharger. Not all turbos will have these gaskets, so be sure to ask us what you might need to complete your job.

Copyright 2012 All Rights Reserved - Tri-State Turbocharger Service