Ever wanted to own a turbocharged car, but never knew the right questions to ask? Turbo Technics have put together a buyer’s guide. You don’t have to be a mechanic, but if you can take someone along with you, it does help.
Here’s what you do …
First check under the bonnet (hood). Check the following …
- Engine oil condition. Black oil suggests poor maintenance.
- Service history. Very important, especially for a turbo engine.
- Receipts from previous turbo repairs. Proof of a reputable service history.
- Aftermarket turbo remanufacturer’s name plate. Has the turbo been replaced before and by whom? Be suspicious if the repair was not carried out by a reputable company.
- Oil leaks around the turbo. Signs of a poor turbo rebuild or a worn turbo.
- Heat shields loose around the turbo. Sign of a recent replacement turbo.
- Painted exhaust turbine housing. Could be trying to hide a poor quality turbo repair.
- Water staining around the turbo bearing housing. Leaking water connections.
- Alignment of hoses and connections. Poor alignment indicates a badly repaired turbo.
- Non-genuine hose clips. May indicate poor workmanship.
- Bleed valve on actuator hose. Turbo has been operating at a higher boost pressure that it was originally designed for. This may have damaged the turbo.
- Dump valve. Indicates that other engine modifications may have been performed.
- Replacement actuator. Uprated actuators are fitted to operate at a higher boost pressure. This may result in turbo damage.
- Grip marks on actuator rod. Signs of a recently increased or reduced boost pressure adjustment or problems with the turbo.
- Air filter condition. Signs of oil staining on the air filter may indicate engine wear.
- Split compressor intake hose. Unfiltered air entering a turbo will cause damage to the compressor wheel.
- Exhaust leaks. An incorrectly serviced engine can run weak, causing excessive heat build-up in the exhaust. This leads to warping and cracking of the exhaust manifold and turbine housing.
- Non-genuine oil filter. A sign of cost-cutting when servicing a car.
- Retro-fitted boost gauges. Cars fitted with a boost gauge tend to have had the boost pressure increased.
- Compressor wheel lift. Movement of the turbocharger’s rotating shaft (up and down) is an indication of turbo bearing wear.
- Rubbing compressor wheel marks. If you can get the owner’s permission to remove the air filter hose, check signs of the rotating compressor wheel making contact with or rubbing the housing. This indicates excessive wear in the turbo bearings and means a turbo rebuild is imminent.
- Actuator hose cracked or split. This will cause over-boost.
- Intercooler damaged or split. This will cause low boost and a loss of power.
- Rubbing or split Intercooler hoses. This will cause low boost and a loss of power.
- Oil feed hose leaking. May lead to turbo oil starvation and eventual failure.
- Oil drain hoses squashed or bent. Restrictions in the turbo oil return will lead to leaking turbo seals and blue oil smoke from the exhaust.
- Breather hoses squashed or bent. Restrictions in the breather pipes or hoses may cause blue oil smoke from the exhaust.
- Breather system “one-way” valve sticking. Can cause blue exhaust oil smoke.
- Uprated or non-genuine exhaust system. Reducing the exhaust back pressure with a free-flow exhaust system can cause oil leakage from the turbo oil seals, leading to blue exhaust oil smoke.
Next comes the road test. Check the following …
- Whistling noise on acceleration. Turbo imbalance or air leak.
- Rubbing noise on acceleration. Turbo bearings badly worn.
- Poor performance. Low boost caused by defective turbo, wastegate mechanism or air leak.
- Too much performance. Over boost may be due to an incorrectly adjusted or defective wastegate.
- Hesitation – violent. This condition can be experienced when accelerating hard. The boost pressure exceeds a nominal value, leading to over boost (a safety cut out switch). The problem may be caused by a defective wastegate.
- Hesitation – holding back. Engine mixture weak, or air restriction.
- Pinking or detonation under load. Incorrect ignition setting, poor quality fuel, excessive boost pressure or a poorly maintained engine.
- Blue smoke under hard acceleration. Engine wear or defective breather system.
- Blue smoke under deceleration. Engine wear.
Now, while the engine is at normal operating temperature, leave the engine idling for 10 minutes. Check the following …
- Blue oil smoke at idle. Defective turbo seals, excessive bearing wear, defective breather system or restricted turbo oil drain system.
- Black smoke at idle. Worn diesel injection pump or injectors or excessive over-fuelling.
- White smoke at idle. Engine damage, cracked cylinder head or head gasket failure. Very rarely caused by a damaged turbocharger.
Congratulations. If all the tests above checked out OK, then your probably reaching for your cheque book now, but before you do, read the Turbo Technics guide to owning a turbocharged car.
Your turbocharger is engineered to match the specific requirements of the engine it is fitted to. Each is dependent on the other to maintain optimum performance. Don’t think of the turbo as a bolt-on accessory, rather as an integral part of the engine. The turbo’s requirements are similar to the engine’s, except that the turbo is less tolerant of neglect or poor maintenance. It is, therefore, essential that scheduled servicing, using good quality parts, is central to caring for your turbo.
In many instances Turbo Technics receive turbochargers which have been mis-diagnosed as having a turbo problem, when actually the turbo is not at fault. Incorrect fault-finding is often caused by a lack of product knowledge. Many contributory items around the engine bay can trick the unsuspecting into believing the turbo is the culprit, when in fact it is not. Unfortunately, if the real problem is not diagnosed before a replacement turbocharger is fitted, the problem still exists!
We have a saying at Turbo Technics which goes “Turbos don’t die. They’re killed”. A turbo can be killed in many ways, but the most common causes are :
- Lack of lubrication.
- Contaminated oil.
- Foreign object damage.
Lack of lubrication is self explanatory, but not always quite as obvious as sometimes thought. The turbocharger is lubricated using engine oil. It is carried from the engine’s main oil gallery via either a steel or flexible pipe connected to the top of the turbocharger. One of the most common causes of oil starvation is due not to the turbo, but because the oil pipe or hose becomes restricted or blocked. This will result in the turbocharger seizing. It follows that, if a turbo is replaced, the oil supply line should also be replaced at the same time.
As it is the oil from the engine which also lubricates the turbocharger, engine oil must be replaced at regular intervals using good quality oil. Poor quality oil can sometimes lead to carbon deposits forming inside the turbo. These contribute to restricting the oil flow to the turbocharger’s bearings, resulting in failure. Should the engine develop a problem which leads to metal particles being introduced into the oil system, they become known as contaminants. In some instances work carried out on an engine can also dislodge very small particles of dirt or carbon. If these particles are not collected by the engine’s oil filter, they will enter the turbocharger. Turbocharger bearings can have as little as half the working clearance of that of an engine’s bearings. Therefore, very small contaminants in the engine oil, which would have otherwise passed through the engine’s bearings without causing concern, may lodge in the turbocharger’s bearings, resulting in bearing failure. With such small working clearances, it becomes clear why cleanliness, when working on a turbocharged engine, is so vital.
Foreign object damage results in either the air intake “compressor wheel” or exhaust “turbine” wheel being damaged. The former is often caused by someone accidentally leaving a nut or other foreign body in the air induction hoses. In the latter case, this may be caused by part of an engine component, such as a piece of valve, exiting the engine in rather a hurry! In both cases it results in severe turbocharger damage instantly.
Turbochargers are simple in operation, but manufactured to precise tolerances as fine as 1/1,000,000 of an inch. Turbo Technics balance and test every single turbocharger many times, including final assembly. Designed by Turbo Technics, the balancing methods and procedures are unique. Without them, no turbocharger can be balanced to the ultra-fine tolerances required for today’s high speed turbos. It is now common for turbochargers to spin up to 150,000 rpm. That’s approximately 25 times faster than most petrol engines rev at the red line! Sophisticated machinery and highly-trained factory staff ensure that the highest standards are always maintained. For these reasons, Turbo Technics is acknowledged as the leading remanufacturer of high-speed turbochargers.
Frequent basic checks around the area of the turbo can prevent problems developing at a later date. Check for oil leaks and split air hoses, and rectify problems when they are noticed. Although, at an early stage, some problems may appear minor, they can lead to more serious problems later. For instance, if unfiltered air is allowed to enter the turbocharger through a split hose, this can cause rapid wear to the turbocharger’s compressor wheel. Also, keep an eye on oil lines and the engine’s crankcase breather system for cracked or split hoses. The way in which fumes are evacuated from a turbocharged engine’s crankcase is critical to the turbo’s long term reliability. If this ventilation system were to become restricted or blocked, it could lead to the turbocharger smoking, especially whilst the engine is idling. If in doubt, replace breather hoses and breather valves before condemning the turbocharger.
If a turbocharger fails and requires a replacement, under no circumstances replace it with a turbo of a different type or part number. Although from the outside many turbochargers can look very similar, and may also be of the same model type (such as a Garrett T3), with very few exceptions, internally they will be very different. The variations may include different internal diameters within the exhaust turbine housing, different grades and strengths of individual component materials, different size compressor wheels, different spring rates to operate the wastegate, and different type oil seal arrangements inside the turbocharger bearing housing. The effects of fitting the incorrect type turbocharger to an engine can include loss of performance, high fuel consumption, high oil consumption or, in some circumstances, complete failure of the turbo, leading to engine damage!
Whenever an engine’s specifications are changed, the turbocharger specifications must also be carefully considered. For example, if a car has been chipped, overbored to a larger capacity, or the camshaft changed, the effect of these modifications will undoubtedly affect the turbocharger. Quite often, if overlooked, the turbocharger’s service life can be cut prematurely. Bleed valves can be used to increase the boost pressure, but again, the turbo will be on borrowed time in many instances. The solution is a replacement turbocharger that is designed to take into consideration the modifications that have been carried out on the engine. These turbochargers are called hybrid turbos and are developed using experience in designing competition turbochargers for our customers throughout the world. Turbo Technics’ hybrid turbochargers cover a wide range of common cars in various stages of tuning. For example, a Stage 1 hybrid turbo may be advised on a modestly upgraded or chipped car, whereas a stage 3 hybrid would be fitted to a highly modified engine. To fit a stage 3 hybrid to an engine with little or no modifications would not be beneficial. No additional power would be released – only poorer turbo response, with increased turbo lag! To understand and interpret which would be the ideal hybrid turbocharger for any different combination of engine tune takes experience. Turbo Technics revel in the opportunity to match turbochargers exactly to a customer’s road or competition car so that optimum performance is realised.
Useful tips when driving any turbocharged engine, whether it be petrol or diesel, are to always allow the engine to warm-up fully, until the water temperature gauge reaches normal, before full throttle is used. Try to plan the end of your journey sympathetically. Don’t use full throttle or allow the engine to labour during the last few miles. This will prevent excessive heat build-up within the turbo when the engine is turned off. Also, when coming to a standstill, try to leave the engine idling for a few extra seconds to allow the heat to decrease. Never rev the engine just as the ignition is turned off. Remember the turbo spins at a far greater speed then the engine, but is lubricated with engine oil. Once the engine stops the oil supply ceases. In reality, none of the above traits will cause a turbocharger to fail immediately, but repeatedly over a long period, they could reduce the life of your turbocharger.
If it becomes necessary to seek advice about a turbocharger or a turbo-related problem, always rely on a professional. Turbo Technics are the UK’s leading turbo specialist, and are acknowledged as one of the most experienced turbo design companies in the world. Within the U.K, we have authorised appointed dealers and fitting centres to advise customers with turbocharged cars on a wide variety of questions and issues relating to owning and running a turbo car. As turbo specialists, replacement turbochargers are fitted by those who have a thorough understanding and experience in this field.
It cannot be stressed too much how important it is, when purchasing a replacement turbocharger, always to choose the top brand name – Turbo Technics. Consider this. As with so many things in life, quality costs, and there are sometimes cheaper turbos for sale. Without the safeguard of using a Turbo Technics turbocharger, you run a serious risk that your short-term saving may turn out to be a long-term nightmare.