[Aragorn30d]

You can get coolant on the OBC, but afaik the diesel engines have no oil temp sensor fitted so theres nothing to give a reading.

[mob17]

Originally Posted by Aragorn30d

You can get coolant on the OBC, but afaik the diesel engines have no oil temp sensor fitted so theres nothing to give a reading.

+1

Only option is an aftermarket kit. There are some really good but expensive ones. Basically replace the oil drain plug with a temp sensor.

Are there any parameters on BMWhat that give you turbo temp or something similar? Apparantly there's some transmission temp paramers somewhere...

[KiwiRD]

The manual clearly says to start the car and drive off immediately. Obviously the idea is to be gentle until the oil has reached full operating temperature.

[Waspo]

This topic regularly makes an appearance several times a year on ALL Car Forums !!

I have yet to hear or read conclusive proof showing it is or it is NOT good to let your car run for X minutes/Seconds or drive straight off.

Personally i get in, if i am late i drive off, if i am on time i drive straight off, but not as fast, if i am early i set music/radio, switch on the heads up, put seat belt on and drive off........

I have owned 20-30 cars in my life and NEVER have i had an issue where i was told you should have driven straight off or you should have let the engine warm!!

[Sparky68]

No , i do however let it cool down at the other end of the 40 mile commute.

[HighlandPete]

Originally Posted by Waspo

This topic regularly makes an appearance several times a year on ALL Car Forums !!

I have yet to hear or read conclusive proof showing it is or it is NOT good to let your car run for X minutes/Seconds or drive straight off!!

It is more simply 'common sense' to give a cold engine a few seconds, before driving off. Oil takes a bit of time to fully get around the engine. If you've ever run an open engine, you'll appreciate how much time oil takes to fully flow back to the sump.

For most of us getting in, starting the engine and then putting your seat belt on and making any settings, is enough time before moving off.

There is strong opinion in the trade that allowing a turbo a few seconds while cold, is more important than the cool down, for wear in the bearings. Suggesting if we want to help longevity, a few seconds could be time well spent.

HighlandPete

[Waspo]

One word sticks out in your post Pete "OPINION"

No hard facts to change why i should not drive off straight away?

[djgandy]

Push button. Give it 5-10 secs, drive off. No point idling it in cold oil and that oil wont heat up quickly unless you drive it.

On way home I just ease off the throttle for the last mile or so. Best way to cool it is with all that air coming in the front.

[HighlandPete]

Originally Posted by Waspo

One word sticks out in your post Pete "OPINION"

No hard facts to change why i should not drive off straight away?

Opinion can be based on accumulated evidence, but not absolute, or definitive proof. (Remember the 'opinions' on smoking and health).

What is accepted is most engine wear occurs on cold engine start up, we can reduce that a bit with a little mechanical sympathy. That doesn't mean we go to extremes, just common sense, as we also know idling a cold engine is not a good idea either.

My father was an engine man, (diesel, petrol & jet engines) I simply use techniques he applied through 45 years of experience.

HighlandPete

[Waspo]

Originally Posted by djgandy

Push button. Give it 5-10 secs, drive off. No point idling it in cold oil and that oil wont heat up quickly unless you drive it.

On way home I just ease off the throttle for the last mile or so. Best way to cool it is with all that air coming in the front.

This!!!!!

[HighlandPete]

For those with autos....

An observation from using 5, 6 & 8-speed autos over the past 13-years. The few seconds wait before moving off from cold, besides the engine rpm stabilising, is the way the gearboxes also react to low rpm changes when moving off. Just a few extra seconds and the first change can be so different, rather than holding first gear to higher rpm, (even being a bit abrupt) it will change to second as a warm engine/gearbox.

More observable as ambient temperatures drop.

HighlandPete

[Aragorn30d]

The simple fact is idling a cold engine will cause more wear than driving it.

The oils thick and stodgey, cam lobe loadings are higher at low speeds, and by idling the engine it takes significantly longer to warm up meaning it ends up running for a much longer time with everything cold. The best thing for the engine is to get it up to temperature as quickly as possible (while being sensible ofcourse, full throttle out the drive would heat it up even faster but thats not going to be very good for it!), which means driving it and generating some real heat.

Now, letting it tick over for 15seconds to let the RPM's stabilise is isnt a huge issue and isnt likely to cause any issues, idling it for 5 minutes or more however is where you probably start causing issues, especially if your doing it every day. The worst thing being when folk start their engine in the dead of winter and leave it ticking over for 15mins for the car to defrost while they have their breakfast.

With mine, i start it and drive off. I have to reverse out the drive anyway which is done with minimal load and so the cars probably been running for 15 seconds or more before it actually gets driven away regardless. In winter, i start the car then get out and clear the windows. That usually takes a minute or two, but usefully allows the car time to clear the inside of the windscreen to actually enable the car to be driven away.

For cooldown it really depends what you've been doing. Normal driving, then it just gets turned off. You typically spend the last few minutes of any journey at low speed and low load anyway, navigating around a carpark or residential estate. If i've been giving it the boot then i'll try to give it a couple of miles low load driving to cool everything down before parking up.

I once recall (in my old car, petrol turbo) driving quite briskly (not flat out, but not hanging around either) up a glen road to my mates place, parking in his drive and shutting the engine off. It was dark, and when i got out i could smell burning oil so popped the bonnet. Peered in to see the turbocharger glowing a very distinct red color! I immediately went and restarted the engine and let it idle for 5 minutes, by which time the red had faded away! The burning smell was a leaking rocker cover gasket and completely unrelated to the turbo, but just shows how hot things can get without you realising it when you dont drive sensibly for those last few minutes.

[Fundguy1]

Originally Posted by Sparky68

No , i do however let it cool down at the other end of the 40 mile commute.

How do you let it cool down And why? It's not a horse. Idling heats.it up. Moving cools it down. Turning it off let's it cool down. This isn't the 60s driving Hugh cubic v8s with junky oil and belt driven oil pumps. Again, 210,000 in this car, another 800,000 in others. Never warmed up. Never hears of "cooling down". I lived in the northeast and now Florida. Not one issue ever from just jumping in and flooring it every time and the parking it, turning off, and savoring the smell of the hot tires and brakes. The only real thing you're doing is killing your gas mileage. Silly people.

[jackstrath]

As others stay start it and go just taking it easy, thermo expansion is this uncontrollab issue here , don't go hammering it from cold as you will do damage (how much I guess depends on how tight the tollarances are in the engine)

As for cool down , just take it easy for the last mile if thrashing it , again it lets everything cool at a more normal rate together , turbos will be fine , they are water cooled these days so no real issue like old oil cooled only turbos
People don't realise how stupid they look sitting with there crosa vxr sitting on its turbo timer "cooling down" lol Iv yet to see water temp drop doing this unless the fan is going

[SteveC]

Originally Posted by dest

I simply don't understand why people let cars idle after an average drive. If you pull up and have a hot engine, what is idling it going to do? Make it even hotter!

The rationale is to keep oil and water circulating so it transports away heat. In older turbo engines it was important after full speed autobahn drives to keep oil flowing though the turbo bearings and let them cool down. If you didn't the hot bearings 'cooked' the oil in the bearing housing, ultimately causing bearing failure.

As you say, there's no reason to cool down a motor after a steady 'average' drive

[Sparky68]

Originally Posted by Fundguy1

How do you let it cool down And why? It's not a horse. Idling heats.it up. Moving cools it down. Turning it off let's it cool down. This isn't the 60s driving Hugh cubic v8s with junky oil and belt driven oil pumps. Again, 210,000 in this car, another 800,000 in others. Never warmed up. Never hears of "cooling down". I lived in the northeast and now Florida. Not one issue ever from just jumping in and flooring it every time and the parking it, turning off, and savoring the smell of the hot tires and brakes. The only real thing you're doing is killing your gas mileage. Silly people.

I am informed that just switching it off after a spirited drive is not good for the turbos

[AceOnShake]

RTFM! It even states in the winter months as well no need to warm it up just keep the revs below 3k

[tc535i]

Originally Posted by Sparky68

I am informed that just switching it off after a spirited drive is not good for the turbos

not on our cars

if the car determines you still need cooling, the pump will continue after the car's shut off since it's electric instead of belt driven

some turbos are oil cooled and could sieze if you didn't idle for a bit afterwards, which is why turbo timers were used

[HighlandPete]

Let's keep "idling time" in the context of the OP's original comment. I don't think anyone is talking of long idling times for 'warming' an engine, or extended cooling periods in normal driving.

Originally Posted by Rory

Just wondered if you guys are as mechanically paranoid as me lol

I always let my turbo cars like 335i warm up for at least a minute before I drive off, I like to hope the oil will get around the turbos a bit before they spin faster.

I drive it gently until up to temp as well.

After a drive I let it idle for a minute or 2 to cool. So far it's served me well on all my turbo cars

Also keep in context the OP is running a petrol engine, many on here are using diesel engines where turbo temperatures are not as hot, or critical, due to EGT running at lower values.

Years back many petrol turbo installations in the UK got a bad name due to premature failures, many due to coking of bearings through hot running and failure to cool them down after hard use.

We've moved on, but there are still simple procedures recommended by the industry, even for diesel turbo installations.

Take the following from a respected engine maker, Cummins. Their advice on operating procedures to reduce issues with turbochargers. In part suggests...

Good operating practices
Operators and owners can help themselves to get maximum service life from their turbochargers if a few good practices are followed:-

Start Up
When starting the engine use minimum throttle and run in idle mode for approximately one minute. Full working oil pressure builds up within seconds but it is useful to allow the turbocharger moving parts to warm up under good lubricating conditions. Revving the engine within the first few seconds of start up causes the turbocharger to rotate at high speeds with marginal lubrication which can lead to early failure of the turbocharger.......

Shut Down
Before shutting your engine down, let the turbocharger cool down. When an engine runs at maximum power/high torque, the turbocharger is operating at very high temperatures and speeds. Hot shut down can cause reduced service life which is avoidable by a minute or two of idling. Most mobile equipment applications include an adequate cooling period during parking or mooring procedures.

Simple and sensible 'common sense' advice. Just remember operators will be looking to get at least 500,000 miles from the engine without issues, not popping turbos like we do in car engines.

HighlandPete

[jackstrath]

Yeh but I'm near in certain Cummings turbos are all just oil cooled , the turbos in the petrol and derv cars are water cooled , a turbo charger be it on a petrol or derv is going to be equally as critical, you boot a 335d for a period of time I bet you the turbo core temp will be near the same as a 335i

But like I said its thermo expansion that's the issue , I don't know how tight the engines are but Iv done damage to my race engine (marking the skirts on the pistions) due to my revving the car when to cold

Common sense is the big thing here , you don't wake up in the morning and go straight for a flat out run , neither does your engine

[AWSAWS]

Start it, drive off.

Park it, walk off.

Have faith that BMW have learned something over the years. The car and the technology within it are a lot more advanced than you seem to realise.

I live at the top of a massive hill so my car doesn't get a near idle last leg of the journey. The only benefit for a few seconds of idle at the end are to make sure your AFRs return to normal so that you don't leave any more unburned fuel in the system than is necessary.

When I leave my car in a hot state, I hear the pumps continuing to flow coolant to protect the components.

[HighlandPete]

Originally Posted by AWSAWS

Have faith that BMW have learned something over the years. The car and the technology within it are a lot more advanced than you seem to realise.

If BMW had a better reputation for 'solid' engines, maybe.

BMW engines are not necessarily fragile, but do have weaknesses. The N54 being a prime example.

Many of BMW's decisions are not made for longevity, service intervals being one point of debate. 'Sealed for life' another.

Such failures as the N47 timing chains, is it use, servicing, poor design? Whatever it is, a bit of mechanical sympathy can only be for the good.

When more engines exceed 200,000 miles (even 100,000) without incident, I'll have more faith in BMW's decisions.

HighlandPete