diesel question.

Submitted: Sunday, May 09, 2010 at 09:02
ThreadID: 78320 Views:5091 Replies:16 FollowUps:15
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hi we are now driving our first diesel, holden rodeo 06 dual cab td auto. read througth the manual and understand that we shouldn't start until the glow plugs light goes out. ok with that. management was talking with her girlfriend the other day, they also own a diesel. she said that we should wait a while before turning the ignition off to let the oil setttle in the turbo, or something similar, I am no mechanic. can someone enlighten me. coming from management and her girlfriend i suspect it is correct. they have never been wrong before... lol cheers...
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Reply By: dave-345 - Sunday, May 09, 2010 at 09:10

Sunday, May 09, 2010 at 09:10
Hi, I am a Mechanic and yes after a long drive on the freeway you should give you turbo a few minutes. This is because the turbine in the turbo can spin up to 25000 times a minutes to pump all that extra air into your motor.
Giving it a few minutes at idle gives the turbo a chance to slow down. If i was you i would have a turbo timer installed, this allows you to turn off the motor at ther key, but the motor will still run for a few minutes, then shuts down.
I hope this helps
AnswerID: 415927

Follow Up By: petengail - Sunday, May 09, 2010 at 09:23

Sunday, May 09, 2010 at 09:23
thanks dave exactly what i wanted to know. can you give me a rough indication of a price? also the wife sometimes hears a high pitched noise... i cant hear it because of tinnitis. would this be the turbo operating? cheers
FollowupID: 686032

Follow Up By: Member - Mark G Gulmarrad - Sunday, May 09, 2010 at 09:48

Sunday, May 09, 2010 at 09:48

this model is very popular and very reliable and easy to install,cheers.

Boggard turbo timer
FollowupID: 686035

Follow Up By: Member - Mark G Gulmarrad - Sunday, May 09, 2010 at 09:51

Sunday, May 09, 2010 at 09:51

forgot to add....just tell them your make /model and they will send you one to suit.Boggard make them to install yourself by just unplugging/plugging in to your existing wiring by the way of plugs(no cutting wiring etc).very simple and easy,cheers.
FollowupID: 686036

Follow Up By: dave-345 - Sunday, May 09, 2010 at 10:13

Sunday, May 09, 2010 at 10:13
Hi if the noise is under heavy acceleration then yes it would be, in relation to a price for a turbo timer, you will have to look into this yourself, as there are a huge range of different types and at different prices.
FollowupID: 686040

Follow Up By: howesy - Sunday, May 09, 2010 at 22:43

Sunday, May 09, 2010 at 22:43
Giving it a few minutes at idle gives the turbo a chance to slow down

Hmmm when I went to school I was told it was to bring the turbo's temp back down just that couple a hundred degrees or so.
Anyway no matter they have all given you sound advice after woorking it hard even 30 secs running will bring the temp down. It is particularly important in non water cooled turbos. Vote 1 the turbo timer.
FollowupID: 686139

Reply By: anglepole - Sunday, May 09, 2010 at 09:29

Sunday, May 09, 2010 at 09:29

Just how long you need to idle after a long run depends also on, is the turbo water cooled? Like the above suggestion a few minutes will be ok after a long highway run. Turbos get very hot being a part of the exhaust system

As far as the timer situation, you will find in some states of Aus it is illegal to run the motor with out a person at the wheel. Another issue that is often over looked with timers, the vehicle is easier to steal as timer wiring (start stop) in many cases is exposed to a would be thief.
AnswerID: 415933

Reply By: Maîneÿ . . .- Sunday, May 09, 2010 at 09:44

Sunday, May 09, 2010 at 09:44
I understand some vehicles may come with 'turbo timers' fitted, l'm going to Cape York in an '08 Mitsubishi Pajero which had one fitted when delivered new.

Maîneÿ . . .
AnswerID: 415936

Reply By: DIO - Sunday, May 09, 2010 at 10:40

Sunday, May 09, 2010 at 10:40
Turbo Timers are a great idea for anyone driving a turbo diesel at prolonged high speeds or sustained pulling with heavy loads. Think you'll find they are illegal in most States as it is an offence to leave a vehicle unattended with the engine running. Probably just as easy to sit in the driver's seat for an extram minute or two - a lot cheaper too.
AnswerID: 415947

Follow Up By: petengail - Sunday, May 09, 2010 at 11:30

Sunday, May 09, 2010 at 11:30
thank you all for your suggestions, i did have one more thought - i guess it dosent matter so much if i have just driven down to pick up the wife from work etc? 5 minute run, we are talking about as dio said prolonged high speeds or sustained pulling - not just normal running around... cheers and thanks
FollowupID: 686052

Reply By: Tonyfish#58 - Sunday, May 09, 2010 at 11:38

Sunday, May 09, 2010 at 11:38
Turbo Timer?

This has been said in the above post - I agree - If they were needed they would be fitted - I have never worried about a cool down time.

05-08-2009, 08:19 PM
hey turbo timers are good for race cars with big turbos fitted to them but lets face it how often does your daily driver hit temps where a turbo timer is required, i have owned turbo charged vehicles for 10 yrs now, i am a mechanic by trade and my 6 month old turbo diesel colorado is not getting one gees just lay off the right boot when you are a minute away from home, because lets face it you idle for one minute that is all fin and dandy cooling fans are kicked in but after that what happens cooling fans shut down then heat soak sets in and the temps rise again so you just wasted 1 minute of fuel idling-Cheers
AnswerID: 415952

Follow Up By: D200Dug- Sunday, May 09, 2010 at 11:44

Sunday, May 09, 2010 at 11:44
See below we posted at the same time :-)

I would ( and I am ) fitting a good after market temp gauge.

( Engine watchdog. )

If the engine is running hot then I will let it idle and cool down

I think it is better value for money.

FollowupID: 686056

Reply By: D200Dug- Sunday, May 09, 2010 at 11:40

Sunday, May 09, 2010 at 11:40
I have the 08 rodeo 3 lt TD and asked both my mechanic and the dealer about fitting turbo timers.

Both could have sold me a unit and both said on modern turbos they were not required.

Both also said glow plugs need time if the weather is really cold but in most parts of Australia this is not necessary.

I am just going on what I have been told !
AnswerID: 415953

Follow Up By: Member - Barry (NT) - Sunday, May 09, 2010 at 14:58

Sunday, May 09, 2010 at 14:58
Agree Doug you are on the money.
FollowupID: 686070

Follow Up By: D200Dug- Sunday, May 09, 2010 at 16:31

Sunday, May 09, 2010 at 16:31
YEA!!!! :-)

( does little victory dance )

now can you tell my wife i was right about something once please ? :-) LOL
FollowupID: 686083

Follow Up By: Member - Roachie (SA) - Sunday, May 09, 2010 at 18:33

Sunday, May 09, 2010 at 18:33
Okay, just so you have all the facts......

I used to own a Patrol with 4.2TD which used to get quite hot (coolant wise).

I won't bore you with a blow by blow of all the things I did, but a couple of them will be of interest to you (I hope).

I fitted (amongst other things), a Thermoguard EGT (exhaust gas temp) gauge with senders both before and after the turbo. I also fitted a reasonable quality coolant temp gauge (VDO) with the sensor in the top radiator hose.

After owning that vehicle for 6 years and having "studied at length" the various relationships between various components under the bonnet I can report as follows:

1) There is not necessarily any corrolation between coolant temps (as would effectively be measured by your proposed fitment of a TM2) and the temp of the turbo and/or exhaust gases. For example, if your vehicle's cooling system is in good condition, you could be flogging up a steep hill with a good load on and the coolant temp might not necessarily show ANY increase. However, the EGT gauge will quite easily rise from 350oC to 550oC in the space of 3 klicks; and that is perfectly normal and acceptable. On the other hand if the coolant system is blocked or has some other issue, it is possible to see the EGT gauge staying "normal" while the coolant temp could rise to 100oC (or above).

2) In 99.9% of situations, I noticed on the EGT gauge that even after having been driving for several hours at highway speeds (with say a EGT gauge reading of 550oC in the manifold or about 350oC in the dump pipe, below the turbo), that by the time I entered a town, slowed down to 60k/h for one of 2 klicks before pulling up for lunch or at a servo to get fuel (for example), the EGT gauge will have easily dropped to around 250oC (which is the temp at which I was happy to shut my engine down).

So, to conclude: by all means fit a TM2 (I have one on my Chev 6.5 V8 diesel's block). But, PLEASE don't automatically rely on it's reading to tell you what the turbo temp is. Secondly, I really don't think a turbo timer is necessary. As mentioned, in 99.9% of instances, even after a long highway drive with full load, the turbo will have cooled sufficiently by the time you pull up and want to stop. The only time I can think of that this wouldn't be the case is (for example) if you got pulled up by the cops (or because a kiddy was about to puke etc) right at the top of a large hill....your EGTs would be elavated above normal and it would be wise to allow the engine to cool down for a minute or so before shutting it off.

EGT gauge before turbo timer in my opinion.
FollowupID: 686102

Follow Up By: Member - Roachie (SA) - Sunday, May 09, 2010 at 20:01

Sunday, May 09, 2010 at 20:01
I forgot to add the most important reminder to any first time diesel owner (and forgive me, but I am not trying to be a smart arze.....)......

Please do whatever you think may be necessary to prevent the accidental filling up of the rigs diesel fuel tank with UNLEADED!!! Believe me, it is the most common (and extremely costly) mistake that is made by people who have owned petrols all their lives. Force of habit; you drive into the servo and without even giving it a second thought, whack in 80 litres of a diesel injector pump's worst enemy!!!

A suggestion would be to place a red plastic tag on the filler cap with the word DIESEL. As I said...WHATEVER IS NECESSARY....JUST DO IT.

FollowupID: 686117

Follow Up By: D200Dug- Monday, May 10, 2010 at 19:21

Monday, May 10, 2010 at 19:21
Just out of interest I re read the owners manual for the rodeo last night and there was no mention of any cool down period for the turbo under any conditions.

There are a lot of warnings and safety things included but no mention of a cool down period being required.

If I have done a long hot run I will let it idle before turning it off and I don't see a turbo timer doing any harm but I think on modern turbos they are not as necessary as on earlier versions.
FollowupID: 686242

Reply By: Lex M (Brisbane) - Sunday, May 09, 2010 at 11:52

Sunday, May 09, 2010 at 11:52
Rather than a turbo timer with all the possible illegality problems, your money would be better spent on an Ehaust Gas Temperature gauge (EGT) which lets you see when you need a cool down time as well as other useful information.

AnswerID: 415956

Reply By: Mudripper - Sunday, May 09, 2010 at 13:12

Sunday, May 09, 2010 at 13:12
I don't know if this is of any importance, but you did mention glow plugs. I have an 04 model Rodeo and there is a glow plug indicator light in the tacho face that comes on when the glow plugs are working (cold engine). I used to think that the light indicates the duration of time that the plugs come on for. But I was wrong. The light only comes on for 2-3 seconds, but if you listen carefully you will hear the glow plug relay turn off after about 8 seconds. Then after the engine is started, they will come on again for another 20-30 seconds. Well that's Tasmanian temperatures anyway. So I fitted a Narva LED pilot light in the cab and wired it to the glow plug rail (the metal strip that connects all the plugs together. Now I can see what the glow plugs are doing, not having to listen out for a faint 'click'.

Re the turbo cooling period, follow what others have mentioned here. Even though the turbo would be water cooled (if you look you'll find oil pipes and cooling hoses going to and from the turbo housing). I always let mine cool off after towing or coming off the highway.

It might also be a good idea to fit (or to have fitted) a turbo boost gauge. I fitted mine recently and bought the gauge from Supercheap (Calibre is the make). All parts are included (vacuum hose, wiring, brass tee piece). I had to buy the gauge cup separately. By fitting one, you can see what the turbo is doing and may be able to detect any faults (like vacuum leaks) in the future. Mine runs about 12-13 PSI max.

Of course there is a multitude of accessories to fit like EGT gauges, Scan gauges etc. They're always there if you want them (and if you can find the money, though it is cheap insurance).

Hope this helps.

AnswerID: 415967

Reply By: Wilko - Sunday, May 09, 2010 at 13:53

Sunday, May 09, 2010 at 13:53
Hi Petengail,

I've got a turbo timer on my rodeo and IMHO its a good idea. It idles for a set period of time (I set mine for 1 min) then turns it self off.

It prob is illegal but most of the places I go you don't need to worry about the boys in blue, Theyd be several hundred km away.

Dont worry about waiting till your glow plug go out on the dash unless it really cold.

Older diesel you would have to wait for them to go out but not the modern ones.

Cheers Wilko
AnswerID: 415970

Reply By: Member - Barry (NT) - Sunday, May 09, 2010 at 15:10

Sunday, May 09, 2010 at 15:10
This is a bit like holden/ford or tojo/nissan arguement ie not many facts but "preferences".

Here's my "preference",,, do what manufacturer recommends FULLSTOP.

UNLESS you have specialised knowledge of EGT & pressure and cooling rates of turbos and housings, many posts are pure guesses,,, well intentioned probably but guesses,,, ie time to set turbo timer or when is one needed.

Glow plugs issue is really simple,,, if you crank engine and it starts like normal you don't need to use glow plugs. If it takes time to start on cold morning ie say 5 secs cranking I suggest you use them.

Years of experience with dieles with and without turbos and glow plugs give rise to my opinions above.

Old Deutz diesels on cold morning we would leave glow plugs on (manual switch) while cranking for 30-45 seconds on cold Melbourne morning - it was the beast at the time.

More modern diesels don't need glow plugs as much as they did say 30 years ago, and some diesels (by design) will never need glow plugs BUT they may need "winterised" diesels etc etc to ensure clean start and no frozen fuel.

Hey we are in Aust not antarctic.

I rave a bit sometimes but hopefully this makes sense to most of us.

cheers Baz
AnswerID: 415983

Reply By: ChipPunk - Sunday, May 09, 2010 at 15:26

Sunday, May 09, 2010 at 15:26
Turbo-timers evolved before water cooling etc to ensure turbos they didn't bake.
Water cooled turbos solved much of that. So did improved lubrication, materials, design etc.

After any excessively taxing drive, varying cool-downs may be required - eg, the exhaust before parking on grass; the brakes to prevent fusion; etc.

Turbo timers are usually added by blingsters or those that misunderstand their use & history.

But a turbo timer should be a limited theft issue since the vehicles should normally locked & secured, and the timer SHALL cut out - it cannot be extended.
Since normal securing for me means leaving my manual box in gear, I have no use for any similar timer.
AnswerID: 415985

Reply By: gbc - Sunday, May 09, 2010 at 16:00

Sunday, May 09, 2010 at 16:00
Unless you drive an overboosting zd30 hand grenade, there is NO reason to put a turbo timer on a standard vehicle - they cannot get hot enough to warrant it.

AnswerID: 415988

Follow Up By:- Sunday, May 09, 2010 at 18:51

Sunday, May 09, 2010 at 18:51
Not correct, the ZD30 (even the Series II GU) dont run a high an EGT as 1HZ cruisers anyway, but the first ZDs that have gained notoriety dont need turbo timers.

Also Series II and CRD ZD30 have water cooled GT2052V turbochargers so they dont need them.

The Series III and Series IV ZD30s (also Series II with replacement S3+ turbos) with oil cooled GT2052Vs will benefit from a turbo timer.
FollowupID: 686105

Reply By: Sand Man (SA) - Sunday, May 09, 2010 at 17:09

Sunday, May 09, 2010 at 17:09
I have never given this issue any thought at all.
There is nothing in the owners manual suggesting a "cool down" period.

Perhaps the Turbo's in current turbo diesels have bearings designed to negate the need to have an "idle" stage.

In any case, turbo timers are illegal in most States to my understanding.



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AnswerID: 415993

Follow Up By: Member - Roachie (SA) - Sunday, May 09, 2010 at 20:09

Sunday, May 09, 2010 at 20:09
G'day Bill,

I don't believe the actual turbo timer is illegal.....it is the act of leaving a vehicle running and not being at the controls which is illegal. If (for example) you wanted to fit a turbo timer just to be safe (in case you accidently turned the key to OFF when the turbo had just finished a particularly hard stint), then there would be no issue with that. It's just that you're SUPPOSED to sit in the vehicle until the engine stops idling.

BTW, most turbo timers I'm aware of actually have a over-ride button, so that in the event that you have just driven to the shops and want to stop and get out straight away (knowing that the turbo is only luke warm), then you can switch off at the key (engine will still be running), then press the OFF button on the turbo timer and engine will cut out immediately.
FollowupID: 686118

Reply By: Lex M (Brisbane) - Sunday, May 09, 2010 at 17:23

Sunday, May 09, 2010 at 17:23
When all else fails read the handbook - mine says

"Normal city driving - idle time not necessary

High speed driving 80Km/h - about 20 secs
100 Km/h - about 1 minute

Steep mountain or continued driving above 100 Km/h - about 2 min.

Never turn the engine off after a heavy load. This may cause severe engine damage."
AnswerID: 415995

Follow Up By: Fatso - Thursday, May 13, 2010 at 21:11

Thursday, May 13, 2010 at 21:11
G'day Lex
From memory that is what my Hilux handbook said.
FollowupID: 686710

Reply By: Peter_n_Margaret - Sunday, May 09, 2010 at 19:04

Sunday, May 09, 2010 at 19:04
I have an exhaust pyrometer fitted to the OKA.
Exhaust temperature can vary from 100c or less to a tad over 500c and bears almost no relationship to coolant temperature whatsoever.
I wait until the exhaust temp is below 200c before shutting down. Sometimes that is as soon as I pull up, sometimes it can take 3 or 4 minutes, depending on what the engine has been doing.
As I understand it, above that temperature there is a risk of cooking the oil in the turbo.

OKA196 Motorhome.
AnswerID: 416011

Reply By: Thermoguard Instruments - Thursday, May 13, 2010 at 20:18

Thursday, May 13, 2010 at 20:18
Hi Petengail,

As you are new to diesels, may I suggest you had a look at this article: "Why Diesels are Different". There are also several follow-up articles in the "Technical" series on turbos, intercoolers and diesel injection.

I urge you to follow the advice of the earlier posters who advise following (a) the manufacturers' recommendations about turbo cool down (most handbooks I've read do recommend it) and (b) those who have actually measured the temperatures involved, rather than those who, from a position of technical ignorance, advise "it not necessary anymore" to justify their own impatience to look after their engines.

I can confirm from actual measurement that it does take a lot longer than the time to coast to a stop from highway speeds for turbo bearing temperatures to drop to a point where I'd like to turn off and subject the oil remaining in the turbo bearing to a very severe 'baking'.

Hope this helps and that you enjoy lots of satisfying kms from your 'new' diesel.

AnswerID: 416583

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