Stop/start turbo damage.
 

Hi,

I bought a 2014 S60 D4 r-design a couple weeks ago then found this site. Car is great and the site is a great place for information.
Something's been niggling me about the stop/start function on the car though. I've always been of the opinion that to safeguard against damaging the turbo it is wise to let the engine tick over for a little while to let the turbo slow down while the oil is still flowing. If for example you have just come off the motorway and the car has to stop for whatever reason and the engine cuts out because of the stop/start function is this not going to cause premature wear on the turbo? Have manufacturers found a way round this problem or is it best to simple turn this function off when leaving motorways etc?

Thanks in advance for any advise.
This is my first post so I hope this is in the right place.

Andy.

I think you can trust the engineers on this one

The Stop/Start uses a plethora of conditions to know when it is safe to stop and start the engine automatically, and you can bet that hot engines / hot turbos are not safe to shut down, therefore I'd hazard a guess that the stop / start system will be inhibited if engine temperature is outside the 'box' of nominal operating temperature.

Likewise too flat a battery, too low a fuel level, too low a temperature, engine not at nominal temps, vehicle not stationary, brakes pedal not pushed, etc etc etc - lots of conditions have to be satisfied for stop/start to do its thing.

The waiting for the turbo to stop and cool is an old wives tale from the 1980's ,modern turbochargers are watercooled so run at a greatly reduced temperature for it not to be a problem .. The older turbos would glow red hot after hard use of the turbocharger ...

Thank you both for your reply. That makes a lot of sense and has put my mind at rest.

Andy.

The advice to allow a turbocharged engine to run for a few minutes after stopping from a fast run was to protect the oil in the turbo being "cooked" and solids building up in the turbo oil galleries and bearings. Such solid deposits would eventually block the oil flow and ruin the turbo. This was much more of a risk 20 or more years ago when mineral based oils where much more common and even then it only really affected petrol engine cars where the heat energy in the exhaust gases is much higher than on diesel powered cars.

Far from being an old wives tale, it was a problem recognised by Volvo who fitted electric auxiliary water pumps to some petrol turbo models in the 80's and 90's that would continue to pump coolant around the cooling circuit of the turbo for 30 seconds after the engine was stopped or until such time as the turbo had been cooled to a pre-determined level (coolant leaving turbo < 90 deg C) if that was longer than 30 seconds.

On modern diesel engines with synthetic oil it's not an issue you need worry about. Turbo chargers are much better designed and cooled now.

what i meant that to read was , that today it is an old wives tale , which was relevant in the 1980's . It was a long day :-) Turbochargers on volvos from the beginning in 1982 have always been utterly reliable and long lasting , even with old fashioned oil and with or without electric pumps ( 400 turbo ) which circulated coolant around the head after switch off .

My neighbour always insists on driving his turbo diesel away as soon as it starts even when cold, I cannot see that being a good idea, still. Not entirely on topic, sorry, just wondered.

I think Clan covered this some when and that it was better overall for the entire engine not to let it idle when cold.

All engines warm up quicker under load
You only need to ensure the oil pressure has come up to normal pressure before you drive away.
Of course, taking it easy until the engine is warm is always a good idea

And, if you have a diesel preheater (I do), running it when it is less than around 10 deg C outside always helps the engine warm up faster.
In cold weather, especially in sub-zero temperatures, it makes a huge difference in engine warmup time and also cabin warmup time :)