should i let TDI cool down

[fahafiz]

i have a tdi 90.... should i let the car warm up before driving it and then let it cool down before switching it off?... cos i used to do this with a petrol turbo car... is it the same with diesels?

 

[ChrisUK]

You should do really, but in reality, how many people actually do ?

 

[BCM]

used to have a derv mate, always let it settle for a wee min, just puts my mind at ease!

 

[Blue Monday]

You should do really, but in reality, how many people actually do ?

Plenty of people do, there was a recent theread on this and the majority did.

Only needs 1 minute poss 2 or you can do the cool down for the last 5 minutes of the journey.

 

[RobM]

You should do really, but in reality, how many people actually do ?

Every owner should do if they drive a turbo car. If they don't, it's either through a lack of knowledge or ignorance to be honest. I'd like to think that any owner who knows what they should and shouldn't be doing would treat their car accordingly.

The turbo needs time to cool and for oil to keep moving through the system to aid this, which doesn't happen if you just switch off the engine after a hard drive. What will happen, though, is oil will dry in your nice, expensive and very hot turbo which can cause all sorts of unwanted problems later in the life of the car.

 

[ChrisUK]

Would 1 minute be sufficient though? I'd expect it would take longer than that to cool down ?

 

[fahafiz]

ah cool... i never let the car cool down but now i will hopefully...

 

[TimBarratt]

Seriously though, how can you not let it cool down. What i mean is the majority of people in the UK live in residential areas where the speed limit is 20/30 mph. Therefore for the first/last few minutes of your journey you have to be taking it easy.

 

[TimBarratt]

I tend to settle for a couple of minutes of careful driving, preferably under 2000rpm to keep it off boost (figuring that if I'm still moving then there's cooler air being forced through the engine bay anyway), then I normally let it stand for 60 seconds or so on the driveway while I get out and grab my stuff out of the boot or whatever.

Surely though the best thing to do is drive it gentle so cold air passes through the engine and as soon as you pull up turn the engine off. If you leave it running there wont be any cold air passing over the engine so it wont help. The fans still work with the engine off.

 

[jamesy]

i don't understand this cool down process? never heard of people cooling the engines down before switching off

 

[BCM]

I tend to settle for a couple of minutes of careful driving, preferably under 2000rpm to keep it off boost (figuring that if I'm still moving then there's cooler air being forced through the engine bay anyway), then I normally let it stand for 60 seconds or so on the driveway while I get out and grab my stuff out of the boot or whatever.

pretty much exactly what i do!

 

[MDS]

When in doubt.... do with a TurboTimer.

 

[ChrisUK]

I get you now !!

Never let it idle on the drive, but I do have an easy 5 mins at the end of each journey

 

[TimBarratt]

Really? Don't think I've ever noticed any fan noise after I've switched the engine off, even over the past couple of days which have been quite warm in Derbyshire.

Yep they do, either you have to have been driving it very hard or it has to be a very hot day.

 

[itsmefishy]

Its not cooling the turbo down, its letting the turbo wind down. The turbo's vein is like a big fan which obviously runs on bearing which are lubricated by engine oil, if you turn the engine off without letting it wind down, then the turbo continues to spin with no oil feed, thus starving the bearing causing excessive wear.

 

[Art0ir]

I very rarely drive full pelt anyway, most of my driving is mpg influenced would usually change around 2000-2500rpm rather than revving the life out of the engine so doubt I would really need to?

 

[Chester]

There's no need to go through a 'cool down' process on a TDi. They don't have anything like the amount of thermal problems that a petrol turbo engine has. So no, a 10-20 second spool down is all that's needed as the turbo still spins at 125K RPM, and faster under load.

There's practically no way to drive a TDi off boost either, without coasting, but then even gentle acceleration into a side road or cul-de-sac will make a TDi's turbo spin-up.

All that said, I always give it 10 seconds minimum to let the turbo spin down.

Incidentally, if the car is left idling for over a minute or two, the turbo starts howling again. It's definitely ECU controlled and a quick tiny blip of the throttle stops it. Is the intention to lean out the exhaust gases or something?

 

[JamJay]

Apparently driving a turbo car from cold, gently, is a better way of warming it up than just sitting there waiting for 5mins as it pumps the oil round the system.

 

[Dyscontinued]

According the the manual you should turn it on and drive off straight away.

 

[joely]

I always warm/cool the engine...

But, doesn't the LC & LCR oil pump continue to run after the engine is switched off??? I’m sure I have read that somewhere and I also have experienced ‘something’ running (not the fans!) when it has been a hot day and I’’ve stopped after a spirited drive.