Welcome to our frequently asked questions about Turbochargers
Whats the difference between an external wastegate and an internal wastegate? And how do I choose which one to use?
Does my Turbo require an oil restrictor?
What is our 20 Point On Vehicle Turbocharger Health Check?
What is a REA (Rotary Electronic Actuator) and can it be repaired or replaced?
On a used vehicle is there any action we can take to prolong the turbocharger life?
Will Engine modifications and big bore exhausts improve my vehicles performance?
I have oil leaking from hoses and joints on my turbo. Is it due for service?
Why is my turbo noisy? It has a horrible screeching noise coming form it when I accelerate.
What do I need to do if my turbo fails?
Whats the difference between an external wastegate and an internal wastegate? And how do I choose which one to use?
Simply put, an external wastegate is fitted to the exhaust manifold bewteen the engine and the turbo and vents exhaust gasses away form the turbo to control the boost pressure before they reach the turbocharger. An internal wastegate in built into the tubocharger and uses a boost control actuator to open a (wastegate) valve in the turbine housing. Your turbocharger professional will guide you in the right direction when it comes time for choosing. An external wastegate is typically larger and allows more gasses to be vented away from the turbine rotor than an internal wastegate and is better suited to higher boost pressures and higher horsepower targets.
Does my Turbo require an oil restrictor?
Taken from Garrett's website. This is an accurate and detailed explination of where and how to use an oil restrictor in the supply line to your Garrett turbo. Other turbo brands use very similar technology and this can be used as a guide to answer the question for those other brands also.
PLEASE READ THIS CAREFULLY BEFORE RESTRICTING THE OIL SUPPLY TO YOUR TURBOCHARGER.
Oil requirements depend on the turbos bearing system type. There are 2 types of bearing systems. Traditional journal bearing and ball bearing. The journal bearing system in a turbo functions very similar to the rod or crank in an engine. These bearings require enough oil pressure and volume to keep the components separated by a hydrodynamic film. If the oil pressure or volume is too low, the metal components will com in contact causing premature wear and result in turbocharger failure. If the oil pressure is too high, leakage may occur from the turbocharger seals. With that as background, an oil restrictor is generally not needed for a journal bearing turbo (except for those applications with oil pressure induced oil seal leakage). Remember it is vitally important to address ALL OTHER potential causes of leakage first (e.g. Inadequate/improper oil drain out of the turbo, excessive crankcase pressure, turbocharger damage/wear/excessive mileage or past its useful service life etc...) and use a restrictor as a LAST RESORT. Restrictor size will always depend on how much oil pressure your engine is generating. There is no single restrictor size suited for all applications. Ball bearing turbos can benefit from the addition of an oil restrictor as, most engines deliver more pressure than a ball bearing turbo requires. The benefit is seen in improved boost response due to less windage of oil in the bearing. Oil pressure entering a Garrett ball bearing turbocharger should be between 40psi and 45psi at the maximum engine operating speed. For many common passenger vehicles, this generally translates to a restrictor with a minimum of 0.040" (or 1.016mm) diameter orifice upstream of the oil inlet on the turbochargers centre section. Again, it is imperative that the restrictor be sized according to the pressure characteristics of the engine to which the turbo is installed. Always verify that the appropriate oil pressure is reaching the turbo.
What is our 20 Point On Vehicle Turbocharger Health Check?
We have designed a 20 point check for your turbocharged vehicle to give you an idea of the "health" of your turbo and what you can do to prolong its life. Contact us to make a booking where we'll take approximately 15-30 minutes to cover all the ins and outs of your turbo. We'll provide you with a print out of the report so you can anaylise it or use it to promote the sale of your car.
What is a REA (Rotary Electronic Actuator) and can it be repaired or replaced?
Garrett by Honeywell have provided a REA Technical Bulletin explaining the issues surrounding REA's and SREA's. This bulletin explains why you cant replace just the electronic actuator on a turbocharger. Please read the bulletin here
On a used vehicle is there any action we can take to prolong the turbocharger life?
On imports just off the boat, look under the rocker cover. Usually there will be heavy build up of sludge. This is due to slow, cold running without regular lube oil changes. Do not to flush system (this will overload an already blocked filter causing the bypass to open and pass contaminants thru the whole system).
The best action is; as soon as able carry out a HOT oil and filter change, and again repeat the HOT oil and filter change within the first 500Km. Always use turbo-rated lube oil. For very contaminated engines this process may need to be repeated more than once.
Oil and oil filter changes in turbocharged vehicles should be carried out every 5000Km. Always check your air filter when you change your oil and replace it (or wash it, and re-oil it, if it is a washable type) if you are in any doubt.
Will Engine modifications and big bore exhausts improve my vehicles performance?
Many modifications to the engine will increase the performance of the vehicle above the factory specifications. These modifications will introduce greater stress on the turbocharger and may cause premature failure.
One of the most common modifications made to many vehicles is the exhaust system. A larger exhaust system (Big-Bore) is one of the cheapest and easiest methods of increasing an engine's horsepower. This reduces the exhaust gas back-pressure and allows an increase of gas flow across the turbocharger. The problem is the original turbocharger was designed to work on that engine with a known gas flow and backpressure. If the gas flow is increased the wastegate valve cannot spill enough of the gas flow and the speed of the turbine rotor shaft increases, resulting in an over-speed / over-boost situation. An overspeed will result in premature turbocharger failure. This will often be seen in the form of thrust bearing failure (overloading); Compressor wheel failure (over-speeding); Shaft breakages (pulse shock waves).
Other modifications such as computer chip enhancements can cause over-fueling, which may result in fuel still burning when the exhaust valve opens. This causes excessive thermal loading on the turbocharger. After market boost controllers and actuator bleed off valves by their very nature can allow over boosting (overspeeding), which will cause premature turbocharger failure.
Turbochargers NZ Ltd does not provide a warranty on any repairs and/or parts fitted to a vehicle with non-standard modifications made to the power plant.
I have oil leaking from hoses and joints on my turbo. Is it due for service?
One of the most common causes of turbo 'failure' is an oil leak from the turbo and/or air pipe work between turbocharger and engine.
Note that most engines vent from the rocker cover into the air intake line, which runs between the air cleaner and turbo.
Normally this complaint is not caused by the turbo but is caused by a blocked air cleaner or heavy breathing from the crankcase. Remove the intake line to the turbo. If there is oil inside the hose then the oil is coming from the breather.
If this type of leakage occurs and the engine is fitted with a charge air cooler the oil will block the air side of cooler and compound the problem. This must be removed and cleaned after the cause of lube oil contamination is corrected.
Why is my turbo noisy? It has a horrible screeching noise coming form it when I accelerate.
Turbochargers are often blamed for being noisy when in fact it can often be an exhaust gasket vibrating between 2 faces. The multi-layer steel shim type gaskets can, when a flange warps or becomes loose, vibrate between the clamped surfaces causing a screeching noise. This can be hard to diagnose, but will normally start abruptly under acceleration as the turbo boost pressure increases. As the boost increases so does the exhaust manifold pressure stressing the gaskets. If a manifold is warped or has a loose bolt/stud the pressure forces its way past the gasket causing it to vibrate. The biggest differences between a turbo whistle and a leaking gasket are: 1/ The noise starts abruptly if its a gasket or if its a turbo it will ramp up as the turbo spools up. 2/ If its a gasket leak it will most likely have a "buzz" to it where as a turbo will most likely have a smooth whistle. 3/ The exhaust gas leak noise is engine speed dependent and affected where the turbo whistle will change tune and pitch with load changes (even if the engine speed remains constant).
What needs to be done when a turbocharger fails?
The most important step, is to find the cause of the failure. There are many types of turbocharger failures and many different causes. If something acted on the turbocharger to cause its failure, the cause needs to be remedied before the repaired turbo or another one is fitted. Failure to identify the cause may lead to a repeat failure. Sending the failed unit to a turbocharger specialist for analysis and then discussing the failure with one of our trained technician can help point you in the right direction and get you up and running again.
Other things that should be inspected or carried out are listed below. This list is not a complete list as some engines have other components that may need to be checked also. This is intended to be a guide only:
- Take some time to inspect the air intake and exhaust systems to ensure they are in good condition and free from contaminates. If your turbo fails catastrophically, parts of the failed turbocharger can end up in the intake or exhaust system only to reappear after the new turbocharger is fitted. This will result in damage to the new unit.
- Change the oil in the engine and the oil filter(s). You may need to remove the sump to ensure all the material from the turbocharger failure is cleaned out. Remove and inspect the oil feed pipe and fittings for contaminants and restrictions. Take this opportunity to change your air filter as well.
- Inspect the intercooler for condition. There may be quantities of oil or parts from the failed turbocharger in the intercooler that need to be cleaned out. Check fir cracks or indications of leakage.
- If the vehicle has a catalyst or DPF (or both) in the exhaust system these need to be cleaned, regenerated or replaced to ensure correct operation and that they are not causing restriction.
- Check all intake pipes before and after the turbocharger for leaks, cracks or hoses that are failing.
- Check for exhaust leaks before and after the turbocharger and the condition of your muffler(s).
- Check the EGR (Exhaust Gas Recirculation) system for leaks and correct operation.
- Check the boost control system for correct operation. Many modern vehicles have ECU driven boost control systems. This also applies to R2S (Regulated 2 Stage) turbocharger installations.
- Check for correct operation of the AMS (Air Mass Sensor) or AFM (Air Flow Meter) and replace if it does not meet the engine manufacturers parameters. This is particularly important on systems with a Variable Geometry or Variable Nozzle type of turbocharger.
For any other matters, or questions relating to turbocharger failures, please contact one of the friendly team at Turbochargers NZ Ltd.
Correct diagnosis is important. If in any doubt, please contact us.
