Diesel Engine Relax

[stouricks]

I cannot find how to post directly into the Motoring Forum, please move this.

 

Just had some guys drive from Bkk to my home, 400km, to deliver things. On arrival they left the engine running, and I asked them to turn it off.

They said that after such a long trip they had to let the engine 'relax'. Is this necessary or bu..s.it?

Edited October 1, 2020 by metisdead
ALL CAPS removed from topic title.

[Kwasaki]

Yeah some people do it, good for the turbo, you can a delay on engine cut out even after ignition keys are taken out and truck is locked.

[jastheace]

yeah, as kwasaki says. good to let the turbo cool down with engine at idle for a minute or so. especially if the turbos been used a lot. a 400km journey at full pelt, and you'll only be a few minutes, leave engine running. have heard a proper term for this, don't think it's 'relax' though, unless franky's on his way to hollwood?

edit. i just googled it and it's called 'turbo cool down'.

Edited September 28, 2020 by jastheace
addendum

[JAS21]

In some handbooks I have seen that it says to run engine at idle for a period before stopping engine.

 

But the engines in Hybrid/PHEV’s where even when driving at high speed will shut off if you release the accelerator. So one would hope that they are designed to do so. 
 

The type of oil used in turbo charged cars is clearly important.

[Jitar]

Idling hot turbo charged engines for a few minutes at start and stop is a good idea.  It was more critical with older design turbo's, with turbo timers being fitted to many trucks and heavy equipment to improve turbo life.  Newer design turbo's with water jackets are less susceptible to damage so the cool down period has reduced and not always recommended by OEMs now.  

[Don Mega]

Yep every morning and night.

 

work commute is 100km each way on the motorway and each end of the commute I let the rig idle for 5 mins and then leave the bonnet up.

[mistral53]

Yes - it is complete BS. As has been pointed out, the place you would benefit some is when e.g. getting gas on a German autobahn, after having hounded the car at 250 km/h for as long as the gas lasted.

Assuming you do not live in a rest area on a German autobahn but a couple km from said exit, the turbo cooled way down. Moreover, Diesel engines run at much lower temperatures than gasoline engines, so there is even less of problem. And last but not least, engine oils used in modern engines are mostly of the synthetic variety, their tendency to coke is far lower than the mineral oils of yore. BTW, really high stressed turbos are water cooled - but that does not apply to the average pick-up truck in Thailand.

[KeeTua]

1 hour ago, mistral53 said:

Yes - it is complete BS.

Complete BS? Apparently you know more about the workings of a Vigo D4D  engine (diesel) than Toyota's engineering department. Cool down idle times are clearly stated in the owners manual for my pickup. If using synthetic oils its arguable that this is not necessary but why take the chance.

 

Owner's manual recommends after driving:
80 km/hr idle 20 seconds
100 km/hr idle 1 minute
over 100 km/hr for long distances idle 2 minutes
Around town no idle time required

 

[mistral53]

4 hours ago, KeeTua said:

Complete BS? Apparently you know more about the workings of a Vigo D4D  engine (diesel) than Toyota's engineering department. Cool down idle times are clearly stated in the owners manual for my pickup. If using synthetic oils its arguable that this is not necessary but why take the chance.

 

Owner's manual recommends after driving:
80 km/hr idle 20 seconds
100 km/hr idle 1 minute
over 100 km/hr for long distances idle 2 minutes
Around town no idle time required

 

All you did is confirm my argument - or are you traveling at 100 km/h up to your driveway?

 

And as for stopping at a gas station on a highway - read my comment again: from the time you get off the highway to pull up to a pump, you are very close to the 1 minute mark, too. But was not the question of the OP - it was the distance traveled, not the speed, which was claimed to be the reason for not shutting off the engine.

 

That a manufacturer would want to protect himself to not incur warranty claims, and bakes in some extra safety is just prudent.

[Lacessit]

This is Thailand, get used to it. Today at the Big C, I parked next to a Toyota Hilux with its engine running. Window tint was so dark it was impossible to see inside. However, I saw the owner come back to the pickup with a trolley full of shopping. I can only speculate the engine was left running to keep the aircon going, so he had a nice cool cabin to come back to.

[transam]

21 hours ago, KeeTua said:

Complete BS? Apparently you know more about the workings of a Vigo D4D  engine (diesel) than Toyota's engineering department. Cool down idle times are clearly stated in the owners manual for my pickup. If using synthetic oils its arguable that this is not necessary but why take the chance.

 

Owner's manual recommends after driving:
80 km/hr idle 20 seconds
100 km/hr idle 1 minute
over 100 km/hr for long distances idle 2 minutes
Around town no idle time required

 

So why does a Vigo handbook quote idling times at shutdown, quoting advised idle times for a given speed used before shutdown...?

[Don Mega]

1 minute ago, transam said:

So why does a Vigo handbook quote idling times at shutdown, quoting advised idle times for a given speed used before shutdown...?

because its an old truck with old technology requiring old ideal's.

[transam]

4 minutes ago, Don Mega said:

because its an old truck with old technology requiring old ideal's.

No, 2015 isn't old, or is it to you.?

The turbo is not water cooled, it relies on the oil pulling heat away as the turbo slows, which in itself takes quite a while.... 

[Don Mega]

3 minutes ago, transam said:

No, 2015 isn't old, or is it to you.?

 

20 year old engines, hardly new are they !!

[transam]

1 minute ago, Don Mega said:

20 year old engines, hardly new are they !!

Your point is....?

[Don Mega]

Just now, transam said:

Your point is....?

because its an old truck with old technology requiring old ideal's.

[transam]

5 minutes ago, Don Mega said:

because its an old truck with old technology requiring old ideal's.

Perhaps you should read the thread title again chap......????

[Don Mega]

3 minutes ago, transam said:

Perhaps you should read the thread title again chap......????

Perhaps you should not ask questions you won't like the answer to, Bro.......????

[stouricks]

On 9/28/2020 at 9:46 PM, Kwasaki said:

you can a delay on engine cut out even after ignition keys are taken out and truck is locked.

Please tell me how. When I turn the key to the off position the engine stops.

[transam]

I have answered the OP's question. ????

 

And just for you..Upto 2015 Vigo ....Turbo care, idling....

Normal city driving.......Not needed.

Highway driving 80km/h.....20 seconds.

                       100km/h.....60 seconds.

              Above 100km/h....120 seconds.            

 

 

                       

[transam]

2 minutes ago, stouricks said:

Please tell me how. When I turn the key to the off position the engine stops.

Aftermarket add-on...

Look at my post above...

[Don Mega]

3 minutes ago, stouricks said:

Please tell me how. When I turn the key to the off position the engine stops.

You fit a turbo timer.

 

 

 

[stouricks]

6 minutes ago, Don Mega said:

You fit a turbo timer.

 

 

 

After 8 years and 200,000km with no problems, I shall not bother. Thanks for the info.

[Don Mega]

7 minutes ago, stouricks said:

After 8 years and 200,000km with no problems, I shall not bother. Thanks for the info.

Whilst I do let mine idle for a few minutes after a high speed run down the motorway (force of habit owning turbo cars over the past 20 years) it really is not needed on modern day diesels.

[transam]

17 minutes ago, Don Mega said:

Whilst I do let mine idle for a few minutes after a high speed run down the motorway (force of habit owning turbo cars over the past 20 years) it really is not needed on modern day diesels.

Think I would rather check my handbook before making assumptions...????

[Don Mega]

Just now, transam said:

Think I would rather check my handbook before making assumptions...????

As should every owner.

 

My manual does not instruct me to idle the vehicle after a high speed run but I do.

[Kwasaki]

59 minutes ago, Don Mega said:

As should every owner.

 

My manual does not instruct me to idle the vehicle after a high speed run but I do.

I don't know if its mentioned in my Isuzu manual either, It's just something recommended by diesel turbo engineers as it keeps the turbo in a better longer life condition.

[Don Mega]

1 minute ago, Kwasaki said:

I don't know if its mentioned in my Isuzu manual either, It's just something recommended by diesel turbo engineers as it keeps the turbo in a better longer life condition.

Its not just turbo diesels but all oil cooled turbo's and the reason to do it is to keep the oil flowing as the turbo cools down otherwise that bit of oil in the hot turbo can get cooked which is not good for the lifespan of the oil and also the possibility it can then damage the turbo.

[transam]

Just now, Don Mega said:

Its not just turbo diesels but all oil cooled turbo's and the reason to do it is to keep the oil flowing as the turbo cools down otherwise that bit of oil in the hot turbo can get cooked which is not good for the lifespan of the oil and also the possibility it can then damage the turbo.

Thought you said only on old rides....????

[Don Mega]

8 minutes ago, transam said:

Thought you said only on old rides....????

Yes, recommenced for old rides some even mention it in the owners hand book.

 

modern technology and modern oils it is not as critical, thats why its not mentioned in the owners manual..... well not my Ranger one anyways and neither the Nissan pickup I just sold and from what Kwaksaki mentioned most likely not the Izuzu one either.