Hello,

Wondering if anyone else does similar. 

 

I have a habit of letting my car idle for a few minutes at the end of the trip. It's so the turbo can cool off because there is a risk of it getting blocked by burned residue if the engine is switched off too soon. 

I've always driven tdi but been told this applies to petrol engines as well. Wondering how long should you leave it running for? Some days it's quiet, but some days you can almost hear a bang when the engine shuts off, even after a few minutes of idling. Am I damaging the engine? Should I let it idle longer? 

My car is a 2008  2.0 tdi pd engine and it's driven mostly on motorway but my driving can be quite intense. 

Just wondering how long it needs to cool off and if it's really a thing with these cars as I've heard even cylinders can become damaged on this car if I don't do this. I'm worried by the knocks and bangs I hear at times. 

Thanks 

Surely your intense driving is not much above 80 mph and the ambient temp not much over 25*oC even around Sunny South Ayrshire.

Your turbo deals pretty good with the car coming to a halt and you switching off the ignition without the need to sit idling,

 and the engine dealing with the cooling. You will hear the fan and pump when they are required.

Edited 19 April, 20215 yr by e-Roottoot

If it was a high powered sports car then maybe yeah. But your probably causing more heat in the engine bay sitting idling, not to mention just wasting fuel. Was it an old wife that told you to do this

47 minutes ago, Martini06 said:

It's so the turbo can cool off

Never needed more cool down on a TDi (any make) than a couple of minutes in a 30mph limit and manoeuvring. 

8 minutes ago, Kenny R said:

If it was a high powered sports car then maybe yeah. But your probably causing more heat in the engine bay sitting idling, not to mention just wasting fuel. Was it an old wife that told you to do this

Why is it people do it with their vw golf then 🤔 

It's an advice from a mechanic. 

 

7 minutes ago, KenONeill said:

Never needed more cool down on a TDi (any make) than a couple of minutes in a 30mph limit and manoeuvring. 

Couple of minutes is what it gets every time, but I don't like the knocks and bangs I hear at times, maybe just need to turn up the radio 😂

37 minutes ago, e-Roottoot said:

Surely your intense driving is not much above 80 mph and the ambient temp not much over 25*oC even around Sunny South Ayrshire.

Your turbo deals pretty good with the car coming to a halt and you switching off the ignition without the need to sit idling,

 and the engine dealing with the cooling. You will hear the fan and pump when they are required.

Speed varies, I tend to rev it a lot and I don't like driving at an established pace like a bus if that makes sense. But I've been told this applied even to old Passats, and you should lose speed a few miles before pulling up so turbo can cool down 😂

Edited 19 April, 20215 yr by Martini06

 

 

 

 

 

Modern engine cooling systems and oils have came on a long way from old school oils like Castrol GTX etc, when letting a turbo cool may have been relevant. 
 

3 minutes ago, e-Roottoot said:

 

 

 

 

 

Gotta love a VW! 

Having said that I'm absolutely delighted with my VRS 👌👌

10 minutes ago, Kenny R said:

Modern engine cooling systems and oils have came on a long way from old school oils like Castrol GTX etc, when letting a turbo cool may have been relevant. 
 

And I began my motoring adventures with the good old 1.9 tdi 😅 I may be stuck in the past 😂

Zeer goede meneer @e-Roottoot.

12 hours ago, Martini06 said:

I don't like the knocks and bangs I hear at times,

I don't like the sound of that either, but since I have no idea when they occur, I have no idea what causes them, just that I don't get this issue on VAG, PSA, Ford, Vauxhall or Rover group cars (and haven't in over 30 years)

16 hours ago, Martini06 said:

? Some days it's quiet, but some days you can almost hear a bang when the engine shuts off, even after a few minutes of idling

 

if it shudders to a halt or bang on engine shut down could point to issues in the anti shudder valve or DMF starting to age 

56 minutes ago, Gissin said:

if it shudders to a halt or bang on engine shut down could point to issues in the anti shudder valve or DMF starting to age 

Aww thank you! Any chance of having this checked at home? Car's literally just out of the garage. 

It has actually had a solid flywheel fitted in not long ago, so not sure this is relevant but being solid would it make it worse? 

Thanks 

I didn't think the 2.0 tdi was suitable for SMF conversion.. but yes, you will notice some more vibrations compared to the dual mass.

 

you can check the diaphragm on the ASV to see if it's split

2008 vRS - it's a 170 PD, engine code BMN,  then.  Has it had the dreaded inlet manifold flaps removed?  

 

If not, Darkside Developments are your friends.... https://www.darksidedevelopments.co.uk/products/ppd170-used-bkd-aluminium-inlet-manifold-conversion-kit.html

What about stop/start function. Does this compromise turbo cooling?

No. 

The stop / start was introduced by engineers who know what the engine requires.

  The fans and coolant pump works when required if the engine / cooling system needs cooling

when stopped & ignition off.

 

Low temperature differences between heating required and ambient temp, high load on the battery etc will disable / inhibit stop start.

A car with the engine / gearbox running within the normal operating temps even in summer does not disable / inhibit stop / start.

Edited 20 April, 20215 yr by e-Roottoot

1 hour ago, Gissin said:

I didn't think the 2.0 tdi was suitable for SMF conversion.. but yes, you will notice some more vibrations compared to the dual mass.

 

you can check the diaphragm on the ASV to see if it's split

Well it says so in the service book. Am I bad owner for not checking it myself 😅

1 hour ago, Schtum said:

2008 vRS - it's a 170 PD, engine code BMN,  then.  Has it had the dreaded inlet manifold flaps removed?  

 

If not, Darkside Developments are your friends.... https://www.darksidedevelopments.co.uk/products/ppd170-used-bkd-aluminium-inlet-manifold-conversion-kit.html

Nope, take it it's a disaster waiting to happen? Car's at 165k miles and keeps going

34 minutes ago, Martini06 said:

Nope, take it it's a disaster waiting to happen? Car's at 165k miles and keeps going

 

The flaps stick and break up and bits can get sucked into the cylinders.  Mine, in my '08 Golf,  were comprehensively knackered at 70k miles.  Also the bushes for the spindle in the ends of the plastic manifold wear and you get boost leaks from there.

 

Fitting the BKD manifold made my remapped car smoother, more progressive and a lot more economical.  If I kept it under 100 on long runs across country it would average 50 mpg. 

19 minutes ago, Schtum said:

 

The flaps stick and break up and bits can get sucked into the cylinders.  Mine, in my '08 Golf,  were comprehensively knackered at 70k miles.  Also the bushes for the spindle in the ends of the plastic manifold wear and you get boost leaks from there.

 

Fitting the BKD manifold made my remapped car smoother, more progressive and a lot more economical.  If I kept it under 100 on long runs across country it would average 50 mpg. 

Wow so it is a bit of a crap engine after all. I was warned not to get one but 😆 since I already got it.. It had already been mapped and runs perfect why part with it 🥰

 

Edit: and that's not my opinion, there are a few mechanics in my family, and they weren't impressed when I got this car. Their loss 

Edited 20 April, 20215 yr by Martini06

Yeah. ON the turbo cool down time. It applies to petrol an diesel, equally of course. 

 

There have been some advances like start , stop and secondary coolant circulation that help. But one principle stand true. It is not great to run the turbo car at 100% demand, pedal to the floor or high demand / revs,  and then immediately switch off for the reasons others in this thread have stated.

 

However, most people need to exit a motorway or A road, then drive some suburban roads, then their street, then their house, then switch off. This is ok IMO.