please refresh me

lexi · Unread post by **lexi** » 26 Oct 2010, 12:07

I have always read that leaving a turbo engined car running on tickover for long periods does it no good. If peeps have heard likewise what are the exact technical reasons for this?

Is it true?

citronut · Unread post by **citronut** » 26 Oct 2010, 13:04

i dont know about that but they do say to let the engine tick over for a few sewconds before switching it of, for the TURBO's benafit

regards malcolm

andmcit · Unread post by **andmcit** » 26 Oct 2010, 13:51

Totally agree with Malcolm here; the turbo at idle won't be heated or
stressed so the oil feed to the bearings will be fine. Where the turbo takes
a hit is at start up with cold oil/engine and before giving the turbo an
exercise it's always preferable to get the temperature to a running/optimum
level even with more modern synthetic oils etc. After a hard run allowing
the engine to momentarily idle is good practice to dissipate the latent heat.

Andrew

lexi · Unread post by **lexi** » 26 Oct 2010, 15:41

Would it have been because of the CAT? . I do remember when getting my first turbo diesel reading this in a publication......it would have been a car mag or even the manual ?

andmcit · Unread post by **andmcit** » 26 Oct 2010, 18:36

Not sure TBH. I would add, just ignoring the turbo for a second and letting
an Activa TCT idle for a while will have a harmful effect on the wallet...

Unread post by **CitroJim** » 26 Oct 2010, 19:28

andmcit wrote:I would add, just ignoring the turbo for a second and letting an Activa TCT idle for a while will have a harmful effect on the wallet...

But not half as much as a dead turbo will though...

Citroenmad · Unread post by **Citroenmad** » 26 Oct 2010, 21:17

andmcit wrote:Totally agree with Malcolm here; the turbo at idle won't be heated or
stressed so the oil feed to the bearings will be fine. Where the turbo takes
a hit is at start up with cold oil/engine and before giving the turbo an
exercise it's always preferable to get the temperature to a running/optimum
level even with more modern synthetic oils etc. After a hard run allowing
the engine to momentarily idle is good practice to dissipate the latent heat.

Andrew

This is something i have always believed too.

Running a car on idle will not damage the turbo, but running on idel after a run will help the turbo cool.

pug_owner2002 · Unread post by **pug_owner2002** » 26 Oct 2010, 21:23

I managed to kill the turbo on my old 306 Dturbo.
When I had it reconditioned the company advised that I let the car idle for a little while once I'd pulled on the drive after a run. before it died I used to drive it as normal and park up & turn off.
Must be some truth in it as a few sporty turbo cars have turbo timers that will automatically turn the engine off x amount of minutes after parking (saves you hving to hang around if your brave enough to leave it).

addo · Unread post by **addo** » 26 Oct 2010, 21:40

It's about heat transfer.

The paralytic converter dosn't come into it; that's a fairly tough piece of kit until it starts failing - then they can come apart in chunks.

What the idle down does, is allows heat to be purged from the hottest parts (like the turbo) via exchange with the cooling media (oil, water, air) without a load existing on the motor.

This prolongs oil life, and as a "knock-on" effect, the life of oil-fed bearings. A degrading oil may restrict its passageways, and cause untimely failure of the related parts.

Citroenmad · Unread post by **Citroenmad** » 26 Oct 2010, 21:44

addo wrote: and cause untimely failure of the related parts.

This seems to be getting more common on more modern diesels, which seem to have very small oil piping to the turbo.

addo · Unread post by **addo** » 26 Oct 2010, 21:49

I know in country areas here, the police pursuit cars can have oil-related problems.

The routine is still a bit like Mad Max - let the offender whoosh by as viewed from their hidey-hole, then jump in the car a minute later and thrash its ring to catch up. Unsurprisingly, this gets the whole motor almost red-hot.

Then, whilst nicking our hapless driver, the car is left running, frequently with large electrical loads (aircon, comms gear, lights) and it never can cool down properly. Top ends really suffer as a result.