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Since 95 percent of turbo failures are caused by issues, other than the turbo itself, it’s important to determine why it failed, and fix it, before a new one is fitted. If not, the replacement unit could fail too, costing you, and your customer, more time and money. Leading turbo manufacturer, Carwood, explains all you need to know about oil starvation, a common cause of turbo failure.
What is oil starvation?
With modern vehicles demanding the power output of larger engines, but with the economy of smaller ones, today’s turbochargers operate at over 300,000 revs per minute and close on 1,000°C temperatures. This puts a huge strain on the engine oil, the turbo’s lifeblood. So, if its supply is restricted, even momentarily, it can cause catastrophic damage to the bearing systems, destroying a turbo within a matter of seconds, and in severe cases, the engine.
What causes oil starvation?
low oil levels
incorrect grade or degraded, high-mileage, contaminated oil
short frequent journeys or repeated hot engine shutdowns causing carbon build up – this can block oil galleries
hard acceleration from cold starts not allowing sufficient oil to circulate
carbon deposits or other contaminants in the oil supply lines
a bent or kinked oil feed pipe
a damaged, clogged or poor-quality oil filter
failure to prime the replacement turbo with oil during installation and before start-up
engine left idle for extended periods, especially in cold weather
incorrect or worn oil gaskets.
What are the signs of oil starvation?
oil warning light illuminated
reduced fuel economy.
poor engine performance – unable to reach full boost pressure
engine overheating from increased metal-to-metal contact
different or excessive noise from turbo
black exhaust smoke
blue discolouration of the shaft journal surface as a result of increased friction and heat
transfer of bearing material onto the shaft
wear to the inside of the journal bearings causing the shaft to become out of balance
broken/snapped shaft due to prolonged excessive heat
loose or missing compressor wheel nut following shaft seizure
excessive wear to the thrust bearing due to friction with collar
discolouration of and scoring to the thrust collar
staining to thrust pad due to excessive heat.
How to prevent oil starvation
check that the air induction system is clean and object free
inspect all pipework for wear and tear – clean and/or replace
always fit new oil feed and return pipes when replacing a turbo
never bend or use excess force when fitting a new feed/return pipe – torque tighten at both ends to VM spec to avoid leaks
ensure that the oil is at the optimum level
use fresh oil and new OE-quality oil and air filters, as per VM
only ever use new, OE-quality gaskets, seals and fitting kits
prime the new turbo with the correct grade oil before fitting
when starting for the first time, crank the engine 10 x 1 seconds or for 10 seconds, without starting, to lubricate the components
once started, allow the engine to idle at tick over for a few minutes before revving to enable full oil pressure build-up
never use silicone on oil gaskets
How to resolve oil starvation
check and clean the entire oil supply system – replace components where required
fit new VM spec filters, gaskets and oil supply pipes
flush and change engine oil with the right grade and quantity
conduct an oil pressure test to identify any issues and check it’s supplying full pressure.
Whilst this advice, may add additional expense to your customer’s bill, it is far more cost and time-effective than having to fit another turbo, and potentially an engine, when they return with the same issue soon after.
For further support and advice, call Carwood’s turbo technical hotline on 01623 867966. Or for more on its range of OE-quality, competitively priced remanufactured turbochargers and accessories, visit www.carwoodecat.co.uk.
Autotechnician is a magazine published nine times a year, delivering essential information to independent garage owners and technicians in the UK. Delivered both digitally and in print, autotechnician provides readers with technical, training, business advice, product and news, allowing our readers to keep up to date with information they need to run and work within a modern workshop.