Was just wondering is it still good practice to let a truck engine idle for a couple of minutes before you switch it off in order to let the turbo cool down??
A lot of firms nowadays always instruct drivers to switch an engine of straight away when they stop and to avoid excess idling in order to save fuel but I remember an old boss of mine always telling me to keep an engine ticking over for 2 or 3 minutes especially when running heavy in order to avoid wear on the turbo.
Is this still good practise on todays truck engines to idle for a couple of minutes before switching off or only relevant to older vehicles??
I do it out of habit. It used to wind up the driver trainer at maritime. But these big firms with that attitude buy new and replace at 2 years old. They never suffer the problems down the line
I do it and I always will. Good practice IMO
I would say its still a good idea nowadays. Not just about the cooling down though either. When you think a turbo spins at thousands of RPM, and the bearings have a film of oil pumped through, what happens when the engine stops? The turbo will still be spinning at a fair rate, but no fresh oil is being pumped around as the pump is driven by the engine. So the shaft wears quicker. Sitting idling gives the turbo a chance to spin down prior to the flow of oil stopping when you turn the engine off.
As said above, the large fleets changing units every couple of years wont be fussed as they’ll have got shot of the problem before it even starts so they might as well play the fuel saving card.
What annoys me more is drivers who get in a truck with low air levels and just plant their foot to the floor to build it up.
Yep, allow it to warm up and allow it to cool.
Not changing my good practices to suit a fad, next week it’ll be another fad and the fashionistas will just have to be disappointed again when that one doesn’t get my undying admiration for innovative thinking either.
Save a cupful of fuel and eventually bugger the turbo, thats good economy for you.
Just look at your turbo pressure just before your stopping … you shouldn’t be really be using it should you if your driving with carev
Yep ! As above, always let it slow down on Tick over & Never- Never Rev the nuts out of a cold engine ! Grrrrr !
I do it. I have always done it. and a MAN without a turbo is like a dog without a bone 
However modern practice and advice is to start the engine and drive straight off without letting them tick over for half an hour.
Once upon a time it was considered good practice, a few seconds would be sufficient on a modern engine the turbo fan rotates on tick over anyway and the improvement in lubricants means there is no need.
There is also no need for the engine to be run from cold before use, an engine has to be loaded before it heats up idling won’t do this, gentle acceleration will.
mike68:
Once upon a time it was considered good practice, a few seconds would be sufficient on a modern engine the turbo fan rotates on tick over anyway and the improvement in lubricants means there is no need.There is also no need for the engine to be run from cold before use, an engine has to be loaded before it heats up idling won’t do this, gentle acceleration will.
Yea but-
all the oil is in the sump in the morning, so a couple of minutes on tick over will get it splashing around the top of the engine, before putting her under load !
martinviking:
mike68:
Once upon a time it was considered good practice, a few seconds would be sufficient on a modern engine the turbo fan rotates on tick over anyway and the improvement in lubricants means there is no need.There is also no need for the engine to be run from cold before use, an engine has to be loaded before it heats up idling won’t do this, gentle acceleration will.
Yea but-
all the oil is in the sump in the morning, so a couple of minutes on tick over will get it splashing around the top of the engine, before putting her under load !
That is the advantage of modern lubrication, it doesn’t all run down to the sump, the bearings are still coated and protected even after being stood still for 12 hours, plus engineering tolerances are much more precise. But yes. I agree that two minutes is not excessive, start it up, ■■■■ on the wheel, count your tyres, done (y)
It’s not just the turbo to cool,on a ■■■■■■■ it’s the water too,if you don’t they will hydraulic when you come to restart,some say its the liner seals ,other say its the head gaskets ,I have heard its fuel running in ?if I don’t leave mine 5 full mins it will clunk and won’t turn straight away.
As most are variable geometry type now it makes no difference as the turbine/compressor spindle is rotating at nearly the same speed at tick over as when its under load its just not doing any work.
Dirty oil and air do far more damage than shutting the motor down too early.Diesel turbos down run all that hot anyway.
I asked Ron Borsbroom who is head of DAF engine design about this at the launch of the MX-11
truckingtopics.co.uk/dafmx-11euro6.html
What he said was this was good practice when the first turbo engines came out, because they had been designed as non-aspirated engines originally and turbo lubrication and cooling was marginal.
Over the years it had become less critical because of developments in turbo design, lube/cooling and oil quality.
His advice with modern engines (Euro 4 5 and on) was that you only needed to idle the engine if the truck had been working really hard with the turbo ‘singing’ just before you came to a stop, and then it was only necessary for a minute or less.For normal driving, where you might turn off the motorway and drive along an access road before slipping into a loading bay, it wasn’t needed.
Also, it was best to give the engine a bit of work to do as soon as you could after starting: it actually helped it get up to temperature quicker. Cold idling meant condensation and unburned fuel in the engine and exhaust system.
Bear in mind that modern truck oils are often 10W-40, rather than the 20W-50 that was used years ago. They flow twice as fast at cold temperatures, but are also engineered to ‘cling’ better to components at the top of engines. Modern ohc engines have a very fast high-pressure feed to the head, you don’t have to wait for the oil to ‘work its way up’ any more.
He said operators shouldn’t choose trucks that were too powerful for the job at Euro 6 because the engines and exhausts needed to get hot to work properly. Scania also takes a similar view.
martinviking:
mike68:
Once upon a time it was considered good practice, a few seconds would be sufficient on a modern engine the turbo fan rotates on tick over anyway and the improvement in lubricants means there is no need.There is also no need for the engine to be run from cold before use, an engine has to be loaded before it heats up idling won’t do this, gentle acceleration will.
Yea but-
all the oil is in the sump in the morning, so a couple of minutes on tick over will get it splashing around the top of the engine, before putting her under load !
I would lose my bonus if it showed on iso track I had been ideling, we even have to build air pressure up and turn it off half way through.
I drove a bus with a ■■■■■■■ L10 in it once and there was a sticker in the cab from ■■■■■■■ saying that the engine should not be switched off after running under full load until it had been idling for 2-3 minutes. Possibility of early turbo failure was the stated reason.
The local bus firm around here would appear to still be using the L10 in some of their buses.
I think provided you are not thrashing the motor just before you stop and don’t thrash it as soon as you start it from cold, it should be enough to slow the turbo or warm the motor through before it has to start working hard.
Ive always let the turbo cool down=never had one break on me.
GasGas:
I asked Ron Borsbroom who is head of DAF engine design about this at the launch of the MX-11truckingtopics.co.uk/dafmx-11euro6.html
What he said was this was good practice when the first turbo engines came out, because they had been designed as non-aspirated engines originally and turbo lubrication and cooling was marginal.
Over the years it had become less critical because of developments in turbo design, lube/cooling and oil quality.
His advice with modern engines (Euro 4 5 and on) was that you only needed to idle the engine if the truck had been working really hard with the turbo ‘singing’ just before you came to a stop, and then it was only necessary for a minute or less.For normal driving, where you might turn off the motorway and drive along an access road before slipping into a loading bay, it wasn’t needed.
Also, it was best to give the engine a bit of work to do as soon as you could after starting: it actually helped it get up to temperature quicker. Cold idling meant condensation and unburned fuel in the engine and exhaust system.
Bear in mind that modern truck oils are often 10W-40, rather than the 20W-50 that was used years ago. They flow twice as fast at cold temperatures, but are also engineered to ‘cling’ better to components at the top of engines. Modern ohc engines have a very fast high-pressure feed to the head, you don’t have to wait for the oil to ‘work its way up’ any more.
He said operators shouldn’t choose trucks that were too powerful for the job at Euro 6 because the engines and exhausts needed to get hot to work properly. Scania also takes a similar view.
This 100%
I had very similar advice from other manufacturers when doing an economic driving course, the days of letting the turbo cool are long gone, but as was told it is something that seems to have passed into drivers mythology and been accepted as fact by the guys out on the road, they all agree that in the morning getting the engine upto optimum operating temperature as soon as possible is ideal, and that wont be achieved by idling the motor “to lubricate the turbo” to use his words, “fire her up and get going its the best thing for her”