Short trips in a turbo diesel OK?

But doest every trip involve the short bit at the start?

Just assumed as he said work was 5min away and referred to the motor not having time to warm up.

Yes sorry Exploder.... excuse my ignorance but how is it bad for an engine if it is not "warmed up" (which I think it would be after 5 minutes anyway) and then turned off.

I have heard storys about it being bad (in some way) for cars to be only driven for short periods of time (most of the time) but I thought it was either an old wives tale or was only relevant once upon a time i.e. not to modern car engines. What actually is bad about it for the modern engine?

Cheers
Greg

You will suffer from higher than average Corrosive wear, Can’t remember 100% but I think short stop start trips fulls under most manufactures supplementary service Plan basically change the oil at half the normal time.

Ok, yes diesel is more expensive, but a diesel can also run on Biodiesel which is substantially cheaper than ULP (petrol). I'm buying biodiesel for $1.10c per L at the moment, and I am running the same 1KZ-TE motor that a new Prado would have.

Corssion is not an issue with Biodiesel as there isn't any sulfur in it. And with the ULSD that is becoming (if it hasn't already) standard in Australia that issue is not so much of a biggy anymore either. The only real downside to the short trips (I do heaps of short trips, round the corner to mother in laws at least once a day which is only about 1km) is that the diesel engine is not as economical when cold and when I do heaps of short cold trips my fuel economy worsens substantially. Obviosuly the diesel burns better when the engine is at a good running temp of about 90c.

It's up to you, but personally if I owned a petrol (and I have previously) I always service them every 5000k's regardless of the fuel type.

It's up to you, the new VVTI petrols with the quad cams and 24 valves are insainly economical compared to the older type petrols and some fantastic economy figures are comming out from them, they also have plenty of power. The main difference I've notice in petrol vs diesel is sure the petrol has more open road power, but when you use it you pay for it through the nose. Diesel's will quite happily be flogged on the highway all day with a huge load, and yeah sometimes a nice long hill may knock you back to 100km's an hour if your fully loaded, but you economy is no different to normal.

So it's personal prefference. Do you carry a lot of weight is the first question I'd be asking, because that is where the main fuel savings of owning a diesel come into it, do you tow, are you going to tow? Diesel's do offer an advantage off road having the power down low, but conversly petrols will crap all over them once they get the revs up and get up to speed. It makes no real difference, some will excel in some areas and other will wipe the floor of them in others. It just depends what you are after.

Personally, after owning many petrols and now on my second diesel, I would take the diesel anyday, but that's my choice.

Yeah I normally use the "Idle Up" button, that brings it up to abotu 1200rpms, i need that to take the extra load of trying to charge two 100amp/hr batteries! ;-)

And yeah, it's a valid point about bleep people off around me, but I'll give you the tip, my engine running would be the LEAST of their worries if they were camped near me, that's why I camp AWAY from anyone else, defeats the point of bushcamping if there are other buggers sitting in your pockets and you can't listern to some music and have a laugh round the fire with your mates. (course others would disagree, that's why we do it!!).

Explorer
RE: the short trips are bad issue

Most of the engine damage is done in the first five minutes of it running.

If you drive from brisbane to sydney in one go that's 1000km. The engine only warms up once and is not lubrictaed only for about 5km of the 1000 km journey.

If you do 200, 5km trips, the engine is warmed up and then cooled 200 times over the same 1000 km, and is not properly lubricated for the whole 1000 km.

So you're always better off buying a car that has done long distance driving.

That's how I understand it anyway.

R.

Hi Guys,

Probably going to open a can of worms here, as this will challenge a lot of conventional 'wisdom', but...

How do you go about "warming the truck up a little first though"? By idling it for many minutes before starting to drive? Sorry, but that's not doing your turbo-diesel any great favours, IMHO. Long idling from stone cold is not the best way to warm-up any engine but it's particularly ineffective for diesels.

At idle, diesels are sucking in a cylinder full of cold air and injecting only a tiny squirt of fuel each stroke to keep it ticking over. The mass of air in the cylinders is very many times that needed to combust the fuel charge and the rest of the air absorbs much of the heat of combustion - so much that the exhaust gas temperature is well below 200 C, indeed below 100C for a couple of minutes.

The engine metal too is cold and is absorbing a lot of the heat of combustion. This is good as this is what we want to 'warm-up', but the quantity of heat available is so small that the engine will take a very long time to reach normal operating temperature. It's highly likely that it will NEVER reach normal operating temperature if the ambient temperature is low. [A couple years ago, on a 0C Alice Springs July morning, I drove to work at about 7:20. The gates were still locked so I sat in the car with the heater on. The temp gauge had only reached about 1/4 scale when I arrived. While I waited, idling, the temp gauge slowly fell back towards cold!]

So, during these minutes of idling, a significant bit of each small fuel charge will be condensing on the cylinder walls, diluting the oil film and eventually making it's way to the sump. The sooner we get these cylinders up to a reasonable temperature, the sooner we get to complete combustion and reduce this oil dilution. And the only effective way to do this is put some load on the engine - by driving it gently.

If you live in 50/60 km suburban/town roads, this shouldn't be a problem. Just give it, say, 30 seconds to get the oil circulating fully and then get going, using steady acceleration and moderate revs until the temp gauge is getting up towards 'normal'.

Now, this isn't possible for everyone. If you live on a 80/100km/h road and have to 'give it heaps' to get out into the traffic flow, then perhaps a couple of minutes idling might represent the best compromise.

But, IMHO, the 10 - 15 - 20+ minutes of idling that seem so 'essential' to caravanners who want to get on the road before 6:00am is definitely not doing their engines any favours and is probably shortening it's service life due to oil dilution.

I'll hop off the soapbox now...

Ian

My cousin is a very high up in the technical side of Honda (Aust), he has even done a little work for the Indy guys.

I am no expert but when a bloke of his caliber tells me that driving an engine (we are talking load any load ) cold it will reduce its life dramatically I sit up and listen.

He explained that if you could plug the car into a heating system during the shut down stage you would double the life, simple terms the engine components are not the correct size when cold among other things.

Have a look at taxis,(that would be a good Toyota taxi :-) they do over 500k without lifting the covers because they stay warm most of there life.

Any way I'm no expert but I do listen to them when they speak

Not on my soap box just talkin on level ground with ya, great day out side better go have a look at it :-)

Brett

Ian, that's a great description. I'm learning more and more about diesels as time goes on and I used to be one of those people that would run it for 10minutes in the morning before driving. I, however (like yourself) am not one of these people who says DON'T IDLE A DIESEL, lardy dary dah. I am in agreeance to the let it run for a minute or so and let the oil get out of the sump first for crying out loud! When it's really cold over here in Perth (which doesn't happen that often), I will let it idle for a few minutes, mainly because the oil's we use over here are for hotter climates and need a little more time to spread round the engine. I think a good practice is to start the car, then I put the kids in the car, strap them in, go and lock the house up and turn the alarm on etc, then go back to the car and drive at less than 2000rpms until my temp guage reads at least 80c. Of course excessive idling is sometimes required for me, ie when the power goes out, we run the house of the surf's pure signwave inverter so long idling is a pre-requestate of that and also the occasional 20minute run is required when bush camping for several days by ourselves. But after talking with some diesel mechanic friends of mine, they say Bah humbug, you're not going to damage your diesel idling it every now and then for those occasions, they say the only way you can Glaze a diesel is to do that for weeks at a time (like say a diesel genny might). They reckon even then the gennys they get in that have glazed up have done thousands and thousands of hours at low reves with NO other types of running at all. They were also describing to me how little a diesel fuel pump pumps at idle, it's quite incredible, they use bugger all at idle, but it makes sense as to why they take so long to warm up when you put that all into place.

Hi Brett & Jeff,

Brett, I have no argument with your cousin. Cold operation of an engine undoubted causes accelerated wear - that's well established. Taxis (and heavy trucks, marine engines, etc.) achieve their long service lives largely because of their very low ratio of cold starts to total kms travelled/hours run (and regular maintenance, of course).

What I was addressing is the best way to get an engine from stone cold to operating temperature. We mere mortals have no choice but to operate our vehicles with very many more cold starts Vs kms travelled.

I maintain that long periods of idling is not the best way, for any engine, petrol or diesel. And that long idling from cold is particularly ineffective and potentially damaging way to warm up a diesel due to the relatively small amount of available heat at idle and the subsequent probably of oil dilution. [For the record, I regard idling for more than about 1 minute from a cold start to be 'long'.]

I have yet to read a vehicle owner's manual that recommends long idling to warm-up. And every motoring organisation (RACx, NRMA, etc.) recommendation I've read suggests the "gentle driving soon after starting" method.

My Owner's Manual reads, under the heading "Driving - Petrol and Diesel Models",: "Warming Up. DO NOT warm-up the engine by allowing it to idle at a slow speed. ...it is advisable to drive the vehicle straight away...". [They are their block capitals by the way, not mine.]

So, perhaps you could check with your cousin and clarify what his recommendations are for getting an engine from cold to operating temperature, especially diesels, given that most of us have no choice but to operate our vehicles in this manner often?

Jeff, thanks for your kind words. You've raised another common 'urban myth'. That idling a WARM diesel for more than a few minutes is going to 'glaze the bores'. I've even read this as an argument against using a turbo-timer to allow the turbo bearing to cool down for a few minutes before shutdown. Regardless of the other pros and cons of turbo-timers, this is absolute rubbish!

As you rightly point out, glazing affects stationary diesels which are run at low load (not low revs) for very long periods - 100s or even 1000s of hours. Generator sets are governed run at the synchronous speed of the alternator they are driving, be that 1000, 1500, 3000 rpm etc. It's common practice to over-size these sets to cope with the "worse possible case load, plus a bit more". As a result, many station gen-sets for example, are run for years with no more than 10 to 30% of their rated load. This is when bores can get 'glazed' and excessive oil consumption results.

I'd agree with your diesel mechanics that idling your truck for 20 - 30 minutes for battery charging now and again will cause it no damage at all, PROVIDED it is at normal operating temperature first, not from stone cold! If you need to do this charging exercise while out camping (and I presume you'd only do this with due consideration to nearby campers), take the truck for a drive for 10 minutes or so first to get it properly 'hot', then come back and do you charging. If you need to do this regularly, perhaps a hand-throttle to run the engine at a 1000 - 1500 rpm 'fast idle' might be useful too.

Interesting discussion guys, thanks.
Ian

Oops, I posted my followup on the wrong section, Look above for my reply Ian! :-)

Hi Ian

My breif explaination of warm up could mean 2 mins or 30mins, I didnt explain myself.

My warm up is as long as it takes me to tie the shoe laces and lock the house door, a few mins at most and when I said cold I meant somthing like, just turn key and drive quickly of in normal traffic mode.

If I wanted to warm the truck at idle to operating temp I would have to wait a long time :-)

My operating manual states near the same as what you have written above although it does have a warning about not racing the cold engine. I remember reading it when I took delivery of the new truck. Wonder how many people actually read the operating instructions but thats another subject ........

Always all good info and I enjoy the read, raining outside today which is good the garden needed it.

Have a good day

Brett

its not necessary to idle down for normal driving. Are any vehicles fitted with a timer as standard???

I fitted a pyrometer when I had the turbo installed, I just look at the temp, and if it's below 200 deg C, it's ok to shut down. The problem is if you have the EGT up high, then a shut down stops the oil circulation through the turbo and that can stuff it up for you in a big way!

I decided against a timer, mine is a manual and therefore I like to park it in first gear.... it's just a easy to wach the EGT gauge!

Just my opinion

Cheers

Brian

out of curiousity, who recommended the 200 degrees in particular?
And if the manufacturers dont bother fitting them after the hundreds of thousands of km's testing and spending hundreds of millions of dollars on development then warranting it for 3 years and 100000km, why would anyone think they were NECESSARY (as opposed to desirable)

Having said that, they do no harm and if they make you feel better and you can afford it, why not??

Same as basically no manufacture fit’s Oil or Volt’s gagers anymore they prefer to fit a idiot light instead, it’s cheaper and easer. As well as how they highlight everything under the engine bay with yellow caps that’s important, why because the general public know f-all about engines.

Why did they get rid of Auto transmission dipsticks because the dipsticks owners were poring engine oil into the transmission thinking it was going into the engine, never mind that big cap on the rocker cover that say’s OIL.

Keep em fat dumb and happy, Why do CAT and alike have just about every gage know to man hanging of there engines because they allow you to very quickly check if everything is as it should be. (:

Cat and those sort of engines are operated by people are trained in their operation or at least their monitoring, such as truckies, marine engineers etc.
I didnt know they had got rid of auto dipsticks, how do you check the levels?
Still doesnt address the issue though, a car with a 100,000 km warranty could reasonably expect to started and stopped between 1000 and 50000 times during its warranty. If manufacturers thought it was going to be a prob, surely they would do something about it??

You don’t generally only if a leak is suspected, the level can be checked the same way as a Manuel transmission.

If Nissan had fitted an EGT and a Boost gauge to the 3Ltr Patrols it might of alerted some owners that something wasn’t right before it went bang.

It isn’t necessary to have these gaugers but it’s nice to be able to have a quick glace down and see that the Oil pressure, Charging system, Cooling are all operating in acceptable limit’s as well as the EGT and Boost levels are all acceptable and not waiting for a little red light to tell you that a system has failed and you are now up a well know creek.

Maybe they feel that by displaying a lot of gaugers it will intimidate some buyers.

Who knows, IMO the basic 6 are Fuel, Oil, Temp, Volt’s, Tacho and speed

Some good optional additions would be Fuel pressure, Oil temp, EGT and Boost

fisho64
My mechanic said in his opinion 200 deg C was a safe enough temp to shut the engine down.... so that's what I do. I keep an eye on it whilst driving, it amazed me how quickly engine temps rise and fall, the thing is I didn't want to risk over heating it.... with the trailer on and going up a steep climb, it's not long before the pyro is around the 600 deg mark...I can see how easy it would be to really overheat one of these engines if you weren't careful.

Cheers

Brian

Personally I idle ANY engine down if it's just been flogged, especially on a hot day.

Let's put the turbo aside for a second and ask what happened to the head temp why you turn a hot engine off. It goes up. Why? Because the coolant has stopped flowing through the motor. My turbo timer is a basic altroncs job with a couple of mods, but basically it has a 70c temp switch screwed into the heat sheild on the exaust manifold. So a short low load (slow) trip to the shops and back won'y set of the turbo timer, but if I flog it to the shops it idles until the temp goes below 70c or 2minutes (whichever is sooner). 2 Minutes of idling a diesel will use absoluatally bugger all fuel, and as it won't idle it when the engine is cold (previous conversation with Ian) it won't do any harm, so why the hell not let the cooling system get that extra bit of heat through the radiator and out of the block, let the turbo and oil all cool. Why not!

Driving around town in cool weather it's probally not neccessary and most of the time you do have to slow down before you stop, but you watch people thrashing it up and down sand dunes and then go STOP for smoko. ARRRGH, poor engine!

quote
"If Nissan had fitted an EGT and a Boost gauge to the 3Ltr Patrols it might of alerted some owners that something wasn’t right before it went bang."
unquote

EGT and boost gauge would not tell you anything to do with the nissans problem, which I understand is/was to do with poor under piston oil cooling.
EGT gauge mainly monitors the operating conditions as regards turbo. Exhaust valves will rarely fail on a non turbo engine due to hot exhaust temps unless pump timing is a mile out.
Boost gauge is of no practicle use to the everyday driver, if turbo fails there will be a radical loss of power and copious amounts of black smoke, a more graphic illustration of a problem than a gauge most people dont understand.

having said all that, once again I repeat, turbo timers and idling down certainly dont do any harm. so if it feels good, do it!

Do you have a point to prove against me LOL?

From what I have read some 3Ltrs have Over boosted and caused hoses to blow of the turbo and so forth A Boost gauge would of alerted the owners that the turbo was over boosting.

Over boost an engine and risk damaging it, Boost gage = One risk eliminated.

Holing a piston, over fuelling could of played a part in this.

An EGT gauge could of alerted you to this also. 2 risks are eliminated.

Lack of lubrication, well it was argued a wile ago that oil contamination was a contributing factor too, Oil starvation to a piston would also leave other symptoms in the cylinder Bore have never heard anyone mention stuff like that.

Anyhow I am forgetting what point I was trying to make or if I was trying to make one at all LOL, you feel, the extra gaugers are not a necessity I will agree with you there. But I like to have a few extra gaugers just so I know what the engine is doing that is all I.E Oil, Volts, temp, tacho and fuel Which are fitted on my car anyway.

Oh, I was only referring to fitting an EGT Gauge on a Turbo engine not a a N/A.

I agree, the more guages the better, however I'd like to point out that CAT, Komatsu and the like have more monitoring computers, alarms, dials, lights and guages than you could poke a stick at, and the "boneheads" that drive them are not "trained" in anyway to know what's going on, that's why they have two ways. BEEP BEEP BEEP, FAULT 9654 is about all they get when something craps it'self, then they are supposed to shut the machine down and call the service guys. (weather that happens or not is another thing completley of course!).

True that the guys you are talking about arent trained but those machines are serviced daily (dump trucks etc I assume). Truckies and fisherman do have some understanding of how it works. Fisherman need a basic engineering ticket if they dont have an engineer aboard.

Exploder, I havent heard of that being the problem with the 3 litre's. If so then you are correct. But my understanding of the problem causing the engines to blow on a regular basis was that the under piston cooling sprays were inadequate and misdirected, causing piston failure. In this case EGT and boost will tell you nothing til too late.
I hadnt heard of them overfueling, being electronic there would be a serious problem for that?

I thought the same, my patrol is 10000km services, check with Toyota.
Paul.

depends on how long you intend to keep it, I've kept he last two vehicles for 10 years or more, oil is cheap compared to engines, suburban driving is far harder on an engine than distance travelling, I'd still change at 5k especially as our diesel still isn't as good as it could be.

Hi Mark,

You raise an interesting point. There's really two events here: the actual 'cold start-up' and 'warm-up'.

The problems of metal to metal contact due to lack of an oil film is the 'cold start-up' problem. This can and is addressed by modern oil technology: techniques/additives to maintain an oil film even when the engine has been cold for some time and very low cold viscosity oils (10W, 5W and even 0Wxx oils, etc.) which get flowing very quickly after start-up.

So, we've hit the starter, the engine is running at idle and the oil pressure warning light has gone out almost straight away, signifying that oil pressure has been established. Now, unless I'm very much mistaken, it's pretty safe to now assume that within a couple of seconds all engine surfaces are going to have their oil films in place (can any automotive/lubrication engineers confirm/deny this?)

We are now in the warm-up phase - getting the engine metal and coolant system up to normal operating temperature in a manner which will minimise further wear. My comments on this are further up in this post.

Thanks,
Ian

thats pretty true Ian, last part of the engine to get oil is the valve train/topend. On some engines it can take up to a minute or more to get it up there to all points, so I guess on an overhead cam motor that could be a worry, depending how long it has been sitting