I was driving two friends yesterday who berated me about leaving the engine ticking over for a while at the end of a fast journey.
I explained that turbos produce substantial heat while driving, and if one turns off the engine immediately at the end of a trip, this residual heat will boil the oil in the turbo system, leading to a build-up of carbon particles that can cause corrosion and premature engine wear.
I always allow the engine to cool down by leaving the engine running for a couple of minutes at idle.
I added that one should never blip the throttle before turning the ignition off - which was met by laughter!
I was berated for being "Obsessive" - but I am comfortable & confident that I am following best practice, but was surprised that one senior JLR driver & the driver of another turbocharged diesel car were both so ill informed.
NJSS
NJSS
16th Nov 2021 8:23 pm
teddy
Member Since: 22 Jul 2017
Location: suffolk
Posts: 72
I remember the Park Lane JDM importers telling my parents to not go from hard driving to engine off straight away in the WRX they bought. They had about 1mile single track road to their house to it worked perfectly as a "cool-down" before switching off. I try to go very easy on the last couple of miles home, in the same way, I don't boot it straight out the box in the mornings (even with the FBH doing it's thing!)2010MY Disco 4 HSE in Ipanema Sand over Almond.
It's got THE rear diff.
16th Nov 2021 8:45 pm
s60r
Member Since: 14 Mar 2021
Location: West Sussex
Posts: 287
Yep... I agree with you NJSS... was always taught the same.
Besides... why else would "Turbo timers" exist.A mod a week until I have nothing to improve or add.
16th Nov 2021 8:54 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4626
I remember when turbo's were first introduced to production cars, and there was a very large warning sticker on the dash from some manufacturers. This entailed a warning that the engine must be left to idle for 5 mins after a journey to prevent damage to the turbo. (Toyota Camry turbo diesel springs to mind)
Back then the mainstream multigrade oil choice was 20w/50, 15w/40, 15w/50, and the all new 10w/40.
Synthetics hadn't been invented yet, and so it was risky to switch off a hot engine with a turbo as the oil in the turbo could burn causing damage after the next start up.
I see nothing wrong with allowing your engine to cool if it has been run hard such as a motorway.
Although, I would have thought modern synthetics would be well capable of dealing with such issues.
For me, it's more important to always run the engine up to full temp before switching off again. Oil in a ICE needs to reach a certain temperature before it begins to mist and become fully effective. So it's really important to avoid short journeys where the "mist effect" will not occur. However, this "mist effect" is less of an issue with diesels as they tend to have cylinder spray jets to offset cold running conditions, as well as piston cooling in hot conditions.yµ (idµ - eAµ) ψ=mψ
16th Nov 2021 8:54 pm
Oxford-boy
Member Since: 07 Sep 2015
Location: Oxford
Posts: 1061
My 1993 Subaru Legacy Turbo estate (Subaru Lunacy turbo..) did indeed have such a sticker.. It was a phenomenal car for an estate... It remains one of the best cars I have owned for the stage of life I was in (2 young kids). Supreme acceleration wedded to permanent 4WD.Jim
2014 Discovery 4 XXV SDV6 Causeway Grey
2016 Discovery 4 HSE Lux SDV6 Loire Blue - now gone
16th Nov 2021 9:52 pm
Nick H
Member Since: 25 Feb 2013
Location: Southampton
Posts: 659
Another 'obsessive' here MY16 Landmark - Yulong White
MY10 HSE - Stornoway Grey
17th Nov 2021 9:55 am
Trailered Movements
Member Since: 16 Jan 2020
Location: East/West Sussex Coast Borders
Posts: 1198
Friend collected his new to him BMW 63 something or another, anyway a turbo diesel, and his first turbo car.
Driving home down the M6 he pulled into the services for fuel, got on the pumps and just shut it down.
Strange heat cracking type noises as he filled up, went to pay for his fuel, came back and started it.
Masses of smoke and horrible noises.
It cost him half of what he had paid for the car to have it repaired at BMW.
Any engine deserves a bit of a warm down, but with turbos, it's a must.
Dave2011 Discovery 4 Commercial SDV6 (Gone)
2010 RRS TDV8 (Gone)
1980 OBLIC 4.0ltr Range Rover (went a long time ago)
17th Nov 2021 11:00 am
forest66
Member Since: 04 Jan 2021
Location: Lymington
Posts: 84
before i retired in the lets 90s my garage (a indy landrover spesh) was next door to uk turbos a recon firm (gone now) i fitted all the turbos for them when customers brought their cars in,
yes there was a 30 sec rule and the owner would site oil delay in every court case he was in (most Thursdays) and always won the day
so yes they are correct, it went that when starting up let it tick over for 30 seconds and when stopping let the turbo spool down and tick over for 30 seconds , the owner said u should do this on every trip, the turbos would run out of oil while still spinning down or when starting there was oil delay,
it was the petrol turbos that would be affected most, cause they were higher revving
its good practice to obey the 30 second rule ot longer on any cold engine with or without a turbo most engine ware is cause at start up i let mine warm up a bit before i drive off
17th Nov 2021 11:31 am
pko
Member Since: 06 Apr 2006
Location: usually in the pub
Posts: 398
I have the new petrol engine in my RR Sport HST, & when starting from cold the engine goes straight to 1500 rpm where it stays for a few seconds before dropping to normal tickover. I was always led to believe that this was a big no when starting a cold engine, but obviously technology has moved on.never drive faster than your guardian angel can fly
current motor RRsport hse
prev. cars TD5
3 Ford Explorers
2 Ford Mavericks
Sierra 4x4
17th Nov 2021 12:44 pm
robpenrose
Member Since: 12 Jan 2016
Location: Surrey / SW London
Posts: 2136
So how do modern turbos and stop start work then? Do they have something in place to protect turbos?
Current: D4 HSE
Previous: BMW Z4M Coupe
Previous: Land Rover Defender 90 CSW Td5
Previous: Land Rover Discovery Td5 ES
Do they have something in place to protect turbos?
I don't think so, Stop/Start is to meet emission requirements. It cannot be good for the engine, turbos, starter motor etc...
This is why I disable S/S on my D4.
NJSS
17th Nov 2021 5:05 pm
sasdiscos
Member Since: 22 Feb 2013
Location: Northants
Posts: 886
Yea right.
Millions of cars out there that have never been cooled down prior to switch off and suffered no ill fete.
I used to do it when I had my cosworth but now I know better it doesn’t bother me. Think of all the cars and all the different driving styles.
Any damage would be very negligible.
I used to work at Denso in Coventry and they did many tests for this very thing. They had a bmw on test for 2 years prior to a new engine release.
Never once suffered a failed turbo, in fact, I was told it was bullitproof, on a side note, the funny thing was they had to run the engine on a test bed, but keep the car and it’s electrics connected. They punched a hole in the wall and extended all the cables.
After 3 years of running the engine flat out and many many stop starts, the engine went back in the car with 0 miles registered. One of the bloke brought it from the company for 1000 quid and it’s still running 6 years later.
He can never sell it on though. It has to be scrapped when he is finished with it.
Steve.You remind me of a younger me, not much younger mind...perhaps even a little older!
17th Nov 2021 9:58 pm
jenseneverest
Member Since: 12 Jun 2017
Location: somewhere
Posts: 760
yup I agree
Turbo's and oils have come a long long way in the last 2 decades. We have stop / start Cummins with variable geometry turbo diesels at work, that are still on original turbos, with 350k + miles on them. The VGT actuators (and starter motors) fail frequently but not the turbo core.
17th Nov 2021 11:57 pm
DN D3 Decade
Member Since: 24 Jun 2006
Location: W.London.
Posts: 2293
Keep doing the same NJSS, those friends of yours have probably never had to fork out for the actual costs of running a JLR vehicle, and have no conception of such. The likes of you or I would be concerned about this, not necessarily ‘obsessive’ though…. …. D3 owned from new, P017 brake recall, BAS FBHIC, new FBH, LR013487 oil pump, new water pump. RRS front lower suspension arms. New suspension compressor/ relay. New Denso alternator. CuNifer rear brake pipes. New GKN rear propshaft. New HPFP belt & tensioner. New A/C Condenser.NO WARRANTY for many many years.
1. Warm up gently until up to operating temps. No, that's not when the temp indicator goes to the middle, you will need an EMS or Gap tool/similar to work out how far/long you drive until the engine oil gets there. For example, in my Puma, the coolant indicator gets there in about 4-5km, but going by the EMS, it's more like 10km.
2. Cool down the turbos after a long/hard run. I usually reduce speed about 1km from my destination and just dawdle there. And by the time you've gathered your keys, wallet, sunglasses, shopping, etc., the turbos have cooled down enough.--
2010 Defender Puma 90 + BAS remap + Alive IC + Slickshift + Ashcroft ATB rear
2015 Range Rover Sport V8 Supercharged
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