Engine Cool Down / Idle

[Guest Close Guest]

Correct, and this I knew. But I dont see how it answers the question about if he should idle down?

Seems to be a lot of answers going totally off topic from some posters lately. :x

And you have never got to the end of a conversation and wondered how it started?

No it doesnt answer the question directly, but its hardly"totally off topic" when their still talking about turbos and how they cool down.

Calm down!!

Should I let it cool down / idle for longer period

Was the question, I dont see how bleating on about a Mercedes or not adding any input to the above question answers this or has any relevance?

Sure its water cooled like a million other turbo cars, "BUT" should he idle it down is the topic of relevance.

[Stitch Junior Member Find all posts View Profile Close Stitch]

Ahhh Turbo timers.....set and forget. If stopping after a stint of high speed / load driving, I set the timer to 3 mins. Had Timers to all my old Turbo Diesels in the past, never had turbo probs.

[Hubble80 Member Find all posts View Profile Close Hubble80]

I have gotten myself into the habit of leaving the car running and getting everything (wallet, phone etc) out and ready to go before switching off.

If on holidays with the wife she wants the engine (A/C) running so she can fix her hair in the vanity mirror!!! That gives the engine enough time!!!

[Chippy Addicted PP Member Find all posts View Profile Close Chippy]

If on holidays with the wife she wants the engine (A/C) running so she can fix her hair in the vanity mirror!!! That gives the engine enough time!!!

Isn't that expensive on fuel ??? .......
leaving the car running for 90 minutes, or so, every time you pull up :lol: :lol: :lol:

Cheers
Chippy

[Steve & Sandra Senior Member Find all posts View Profile Close Steve & Sandra]

What harm does it do to let it cool down for a minute? When i was an apprentice it was somethiing we had instilled in us no matter what engine turbo or not it is good practice to allow a hot engine to cool down.

cheers

Steve

[Guest Close Guest]

Idling Down the Prado after long drives and 'Turbo Timers'

Hi bettsy, this may or may not be of help and I will try to explain it as simply as possible. :?

Turbos are used to create 'boost' which will force more air into the engine during the 'intake' cycle of a 4 stroke engine.
But they operate on a common shaft that goes through the 'cartridge' (centre section of the turbo) and directly connects the impellor (usually alloy wheel on the intake side) and the turbine (steel wheel on the exhaust side).

While there has already been mention of the 'heat saturation' suffered by engines after shutdown and this should be taken into account, the main issue you should be concerned with is 'lack of lubrication' to the turbo bearings after a 'good' drive, and this is where the idea of idling vehicles with turbos down after hefty drives originated.

These shafts commonly sit inside of 'solid' brass bearings, and 'float' inside of them on a film of engine oil created by oil pressure while the engine is running.
Basically, the more power you demand from the engine (accelorator), or the more load you put on the engine (caravans, boats, bullbars, roofracks, hills etc), the more air the engine requires, thus more boost is made, and ergo, the turbo spins A LOT faster.
Turbos can spin at over 22,000 rpm under full engine load and boost! :shock:

So say for example, if you were coming home from a day of fishing or water sports with a 5-6 metre boat on the trailer out back, family in the car, and you had three turns to make within 200 metres, then you will be constantly under full load and acceleration at the end of your trip, using close to maximum boost, thus the turbo will be spinning, regardless of what engine rpm is. because due to today's computer controlled engine management systems, they can control turbo 'fins,' injection timing and length to also create more boost (power)!
In these cases, I would recommend a 'Turbo Timer' which actually keeps the engine running after you cycle the key to the off position for a selectable amount of time (usually 1,3 or 5 mins) and it shuts the engine down after.
With a comparatively 'cheap' investment, you can save an enormous amount of money in engine and turbo damage through repeated shutdowns with the turbo still 'spoolin'!

Now during the normal operation of a diesel engine, boost is only created when three factors are present - fuel is not restricted, air is not restricted, and there is 'load' on the engine.
If the vehicle is fairly stock standard, and your trip home is relatively flat, and you don't have any steep roads to climb on your routes, and you are not towing anything, then it is safe to say that you will not require an 'idle down.'
But even if you only do the earlier story occasionally, I would recommend a Turbo Timer. Because if you can picture a steel shaft spinning at 12,000 rpm (conservative), 'floating' on a film of oil and all of a sudden that oil is removed, then that spinning shaft falls onto the brass bushing and continues spinning metal to metal until all inertia is lost. Even if this happens once, the damage is done and it will only be a matter of time until failure!

Your query is a hard question to answer, and with out knowing the layout of your surrounding home area or your specific situation, it is hard to make a hard and fast recommendation! But as a general rule of thumb, use 1 min to allow the vehicle idle down after easy, short drives, 3 mins to let it idle down after long drives with little load, and 5 mins after long drives with high loads.
The only hard advice I would pass to you is to talk to a reputable performance engine specialist in your area, and if possible, one that deals with the D4-D power plants regularly. They can talk to you about your needs and if needed, you requirements.

:lol:

[bettsy Junior Member Find all posts View Profile Close bettsy]

Thanks Darwinite and others for the advice.

I have got in the habit of letting in idle for a minute to 2 after a drive on the highway, and more when I have towed.

Only reservation I have in relation to the truno timers is concerning the non use or remote locking which has been discussed in other related posts.

Regards
Craig

[ntp Addicted PP Member Find all posts View Profile Close ntp]

Re: Idling Down the Prado after long drives and 'Turbo Timer

Hi bettsy, this may or may not be of help and I will try to explain it as simply as possible. :?

Turbos are used to create 'boost' which will force more air into the engine during the 'intake' cycle of a 4 stroke engine.
But they operate on a common shaft that goes through the 'cartridge' (centre section of the turbo) and directly connects the impellor (usually alloy wheel on the intake side) and the turbine (steel wheel on the exhaust side).

While there has already been mention of the 'heat saturation' suffered by engines after shutdown and this should be taken into account, the main issue you should be concerned with is 'lack of lubrication' to the turbo bearings after a 'good' drive, and this is where the idea of idling vehicles with turbos down after hefty drives originated.

These shafts commonly sit inside of 'solid' brass bearings, and 'float' inside of them on a film of engine oil created by oil pressure while the engine is running.
Basically, the more power you demand from the engine (accelorator), or the more load you put on the engine (caravans, boats, bullbars, roofracks, hills etc), the more air the engine requires, thus more boost is made, and ergo, the turbo spins A LOT faster.
Turbos can spin at over 22,000 rpm under full engine load and boost! :shock:

So say for example, if you were coming home from a day of fishing or water sports with a 5-6 metre boat on the trailer out back, family in the car, and you had three turns to make within 200 metres, then you will be constantly under full load and acceleration at the end of your trip, using close to maximum boost, thus the turbo will be spinning, regardless of what engine rpm is. because due to today's computer controlled engine management systems, they can control turbo 'fins,' injection timing and length to also create more boost (power)!
In these cases, I would recommend a 'Turbo Timer' which actually keeps the engine running after you cycle the key to the off position for a selectable amount of time (usually 1,3 or 5 mins) and it shuts the engine down after.
With a comparatively 'cheap' investment, you can save an enormous amount of money in engine and turbo damage through repeated shutdowns with the turbo still 'spoolin'!

Now during the normal operation of a diesel engine, boost is only created when three factors are present - fuel is not restricted, air is not restricted, and there is 'load' on the engine.
If the vehicle is fairly stock standard, and your trip home is relatively flat, and you don't have any steep roads to climb on your routes, and you are not towing anything, then it is safe to say that you will not require an 'idle down.'
But even if you only do the earlier story occasionally, I would recommend a Turbo Timer. Because if you can picture a steel shaft spinning at 12,000 rpm (conservative), 'floating' on a film of oil and all of a sudden that oil is removed, then that spinning shaft falls onto the brass bushing and continues spinning metal to metal until all inertia is lost. Even if this happens once, the damage is done and it will only be a matter of time until failure!

Your query is a hard question to answer, and with out knowing the layout of your surrounding home area or your specific situation, it is hard to make a hard and fast recommendation! But as a general rule of thumb, use 1 min to allow the vehicle idle down after easy, short drives, 3 mins to let it idle down after long drives with little load, and 5 mins after long drives with high loads.
The only hard advice I would pass to you is to talk to a reputable performance engine specialist in your area, and if possible, one that deals with the D4-D power plants regularly. They can talk to you about your needs and if needed, you requirements.

:lol:

Helluva first post! Another Top End PP member... hurray! :wink:

[Golly Advanced Member Find all posts View Profile Close Golly]

Re: Engine Cool Down / Idle

City driving with the mrs doing her shopping is ok to switch off straight away ?
Hope so... :shock:
I thought if it had a intercooler you didnt need the timer..... am I wrong ? ops:
Great site this for learning the ropes... :mrgreen:

[Hornet Junior Member Find all posts View Profile Close Hornet]

Re: Engine Cool Down / Idle

Still beats me: if it is so important, how come it is not a standard equipment in D4D?
Cost cutting at its best?
:evil:

[chester Advanced Member Find all posts View Profile Close chester]

Re:

I have gotten myself into the habit of leaving the car running and getting everything (wallet, phone etc) out and ready to go before switching off.

If on holidays with the wife she wants the engine (A/C) running so she can fix her hair in the vanity mirror!!! That gives the engine enough time!!!

Yep same here i find with the roadhouse stop and by the time you fart around it easily chews up 3 or 4 mins