The main goal of the turbo is to increase power, therefore, when a frisky engine suddenly becomes dried, then in most cases a turbine is to blame (but not always). The most frequent symptoms of turbine disease: power loss, boost pressure, turbine noise, increased oil consumption and oil -fledged fumes, black smoke on diesel engines.
The easiest way to diagnose a turbine is to measure vacuum pressure. If the indicator does not show a normal increase in full gas pressure (usually from 0. 63 to 0. 98 AT for many turbines), it will be better to prepare for the repair or replacement of the turbine. But keep in mind that excessive reverse pressure often occurs due to clogging of the catalyst.
Pay attention to the work of Westgate. If the WestGate does not move, there will be superfluous pressure and detonation. But if it does not completely close, exhaust gases will pass by the wheel of a turbine and a turbocharger will not develop a complete speed. Try to turn off the WestGate to check its closure.
On cars that do not have a turbine control devices, you can get a boost pressure pressure by connecting a vacuum manometer to an intake manifold.
One of the most common reasons for the insufficient performance of the turbine, the development of the shaft bearings. Turbines rotate at speeds that often exceed 100 thousand revolutions per minute. If there is a gap in the shaft bearings, the shaft will vibrate.
The best way to check the bearings, remove inlet or exhaust air pipelines from the turbine to look inside. Any sign of contact of the impeller with the case means that the bearings are developed and the turbine must be replaced or restored. You can also twist the impeller with your hand to feel how the turbine rotates. If the impeller does not rotate freely, it is necessary to repair.
Among other problems of a turbocharger, these are cracks, dents or growths, and / or “erosion” in the turbine blades. The turbine is very sensitive to balancing. Most turbocompressor impeller impressors are confused with an accuracy of 0, 001 gr.! The imbalance will not allow the turbine to reach a maximum of revolutions per minute and eventually break the bearings of the shaft. You will not be able to balance the impeller, so if there are any signs of damage, damaged parts must be replaced.
To check the gaps in the bearings, there is no need to remove or disassemble the turbine. You can put a wire or something like a match (but there is an indicator) in an oil canal and observe the displacement of the indicator up and down while you will rotate the turbine. Up and down the shaft of the movement should be no more than 0. 07 to 0. 15 millimeters. Do not forget to look inside the body to check the oil of the oil on the shaft or housing.
You still need to check the presence of oil in any half of the case. The shaft seals at both ends of the shaft hold the oil. Oil leaks are more often found on the compressor side.
Oil leaks can also be caused by blockage of the oil return channel. If the oil is present in both cases, but the turbine does not show signs of a breakdown, just clean the oil return channel and check it for obstacles with a hard wire.
Diagnostics of troubleshooting.
If the turbine does not work, you must remove it, regardless of what you are going to do, replace or restore it. You need to determine the cause of the breakdown so that this does not happen again. First, this is a check of the state of the shaft bearings. Bearings, as a rule, are worn out or problems with oil, oil starvation or cooked.
Deep grooves or spot corrosion of the supporting surface indicates dirty oil, possibly due to insufficient oil filtration. Check the oil filter. As soon as the filter is clogged, the bypass valve opens and the unfiltered oil enters the turbine and other parts of the engine.
If the bearing is covered with black oil crust (coke) inside the bearing housing, then this indicates a large temperature. The bearings are cooled by oil, and at normal operation temperatures it does not heat up to cause coking. But when the engine is turned off, the temperature can rise to 300 -350 degrees inside the case. The oil is oxidized and forms a coke, which then acts as an abrasive. The use of high -temperature or synthetic oils, the installation of auxiliary oil radiator, as well as oil replacement every 5000 kilometers will help to avoid hair clipping. In turbines with water cooling, coking is a lesser problem, provided that the oil changes regularly, and you use the right oils. So if you find a coke inside the case, it is better to check the coolant hoses.
Molten bearings indicate oil starvation. Check the level of oil, oil leaks, the oil channel between the turbine and the engine, oil pressure. Oil fasting can be avoided by allowing the engine to work at idle for a minute or so.
The following to pay attention to, to the condition of the compressor and impeller of the turbine. Cracks may be the result of metal fatigue, curved or damaged blades can be caused by extraneous objects, unfiltered air entered the system. Check the air filter.
Finally check the condition of the body. It will be required to replace when detecting defects in the case. Beware of cheap buildings from ordinary cast iron, it should be made of nickel alloy for resistance to high operating temperatures.
Capital repair of the turbine.
To restore the turbine, you need to clean it. The most difficult thing is to clean the body. Do not use sandblasting cleaning.
The shaft can be washed in the solvent. If the surface of the shaft bearings are not perfectly smooth, rounded, you need to replace the shaft and impeller of the turbine.
Dirty impeller can be cleaned with a solvent and a wire brush. Do not use abrasive materials. Do not try to straighten the impeller shoulder blades. This will only weaken them further, as a result of which they can come off at high speeds. Curled shoulder blades violate the aerodynamics of impeller, reducing the efficiency of pumping, so always change the impeller that does not have perfect blades.
The worn -out turbine shaft can sometimes be restored by the shaft point and the installation of large -sized shaft bearings, or by increasing the shaft with solid chromium and processing it back into the initial size. The bore and the use of large -sized bearings is cheaper than chrome, which, if not everything is done correctly, will exfoliate and break down again.
When assembling a turbine, cleanliness is necessary. Any dirt, sand or garbage can cause future breakdowns. The bearing of the shaft must be lubricated with oil, and are checked for proper fitting and alignment. It is necessary to make sure that the shaft rotates freely and does not concern anywhere. It is recommended to finally check the gaps with a set of indicators before installation.
After restoring or replacing the turbine, replace the oil and oil filter, check the air filtration system for leaks or blockages, and roll oil into the oil supply channels before starting the engine. Disconnect the ignition coil and spin the engine from 10 to 15 seconds to fill the turbine lubrication system.