Rosco - Bris. replied:

Tell him to stick to his day job.

Davoe replied:

he is kinda right. for combustion deisals rely on heat and compression so if you use your 4.2 diesal like mums hyundai and drive the kids 400m to school then let it cool down before driving it 1k to the shops at midday then pick the kids up at 3 etc etc then it will be continually be driven around at below optimum engine temp and combustion will not be perfect which creates more soot in the oil which is not good for optimum engine life. long runs are best for diesals with a bit of "work" thrown in. As for thrashing them - they are rev limited but thats probably not ideal either. Me? I ride my bike around town as much as possible and save the diesal for trips as much as possible (just my opinion based on my limited mech knowledge)

Member - Mick S (QLD) replied:

Marcus.
Whilst it's true that diesels like to be worked, the old "drive it like you hate it " philosophy dates back to the GM & Rootes 2 strokes of the '50s & '60S . Modern diesels have quite different torque characteristics and thrashing the pickhandles out of them will produce nothing but excessive fuel use and premature failure.
I agree your mate should keep his day job.
Cheers.
Mick.

Truckster (Vic) replied:

He was only correct in stating that lots of short runs are not good for diesels. They carbon up if you like, and a good long run every few weeks is always good.

Try it, you notice a difference after month or 2 of city work, go for a long run..

Twigiee replied:

Marcus,

Heard this opinion much in the past, actually my uncle is a farmer and he once connected a plough to his hilux and run around the paddock for a few hours to 'clean out' his glazed up deisel!

I'm not sure what's the best solution for a 1hd-t which are known to have big end problems.

Twigiee

Big Trev replied:

Firstly, I have been a heavy vehicle driver trainer since 1987.

Secondly, tell your friend to stick to what he is qaulified to do: "Fix 'em".

Thirdly, get out the drivers handbook from the glovebox and read up up on what the manufacturers say.

Aas previously stated the vehicle should be driven to get the best fuel consumption, horsepower and torque. Normally, that is shown on the tacho by a highlighted area, depending on the vehicle that is around 2000-3000 rpm (as a rough guess).

"Driving them like you hate them", is just that, hating them, and I am sure you don't hate your's. Diesels were never, ever designed to be driven like that. That term came from having uder-powered engines in trucks, and the feeling that drivers had to rev thebleepout of them to get them to work. It is an ignorant approach.

You may be succesful in finding out the optimum engine rev range (or performance chart) by having a search around the web site of tour 4X4 maker.

2ndLow replied:

Didn't believe diesel need to work hard. But after consulting some instructor in TAFE, my mate next door (a diesel mechanic) and other source i started to believe. But I was still not convinced until I experieced this myself. I used to drive it for less than 15 mins everyday. Just enough to get it warm up.

About a year ago, engine started to build up some tapping noise. It sounds like tappet but it is much slower than real tappet noise. The sounds even more distinct when under load. Also lack of power.....
Try everything.....use good grade engine oil (CI-4), Fleetguard filter, breed fuel system, injector, adjust tappet ......still same

Finally, after a long hill climb up a trek reving constantly above 3500 rpm (3900 rpm is max limit) for like 1-2 min in High Country...........no more tappet sounds.....regain more power....... now sounds sweet~~~

My engine is TD42....with 360000k on it..........

So just to share my experience on a diesel engine

Muddy 'doe (SA) replied:

My service manual says to change the oil every 5,000 kms unless I am driving the vehicle in harsh conditions. It lists several harsh conditions (dusty, freezing, towing) and also lists "repeated regular trips of less than 8 km" in which case it says do the oil change at 2,500km.

I live 3.1 km from work and quite often go out at lunchtime to shops and errands within about 4 km so the turbo-diesel does lots of short trips. I try to make sure I do at least a 40 to 50km run on the weekends just to get things flowing for a while at good engine temp even if it just an excuse to go for a drive!

As for driving it like u hate it, I agree with above that that only applied to older underpowered units. I try to keep mine in the economical powerband around 1500 to 2500rpm where all the torque is available without thrashing it. If I rev it out round town all it is doing is making noise!

I bought it for reliability and torque on long trips and off road and better fuel economy (although the 4.0 petrol is not too shabby in that department!). I find is cruises very comfortably at 110kph at just under 2,000 revs in 5th.

Muddy 'doe

Andrew replied:

Hi Marcus

Diesels like to be loaded (not overloaded) They do not like long periods at very light load (such as idling) or lots of high revs.
If you like to use revs then buy a petrol engine.

You can tell the guys who drive on the governer, they're the ones with all the black smoke pouring out the back.

When lightly loaded deisels tend to glaze up the bores which leads to oil consumption problems and compression blowby because the rings don't seal properly any more, hence the comments about loading her up to deglaze the bores (only works sometimes.
Jiggers like fire tankers which can spend all day idling while on a fire line have been known to suffer badly from this problem.

Line haul trucks have never heard of it because they are running reasonably (sic) loaded all the time.

Diesels are best driving using the engines torque band as previously suggested. Thats when they give their best life and economy.

regards

A

joshinthecity replied:

What a shame then that Nissan have seen fit to give a 3.0 GU TD a 2900rpm 110k/ph cruise. ( in manual form )

Insane.

Josh * Just back from the snow *

Mikef_Patrol replied:

My 2c

I run mine (Series 3 3.0L Nissan manual) generally between 2,000 and 3,600 RPM. Max torque to Max Power. (Actually, that is probably more like 1700 to 3,250 most of the time).

Slightly bigger tyres will lower the revs at 100 a bit Josh. Mine does about 2700 now (265/75/16). The auto does ~2100 in O/D at 100.

When towing our van at 100, the slightly higher revs make the job easier on the car, doesn't lugg all the time. I keep out of 5th below 80 as well, so as to not strain the 5th gear. All too easy, just have to learn how to drive the particular vehicle. They are all different.

MikeF

Bros replied:

marcus,
Got a HJ 75 2H. Done 334,000 km.
Give it plenty.
Sometimes flat or close to it for hour or two (after market cruise), especially travelling south from North Queensland against 15/20 knot headwind.
Had the rocker cover off the other day to check the valves and was surprised to see no gunk. Could see the metal. Had petrol cars in the past so gunked up you could not see any metal.
Change oil and filters every 5,000 km. Take for a 100k run regularly.
Do whatever suits you, because after all you are the one using and paying.
This is my opinion only and no correspondence will be entered into.
Regards,
Bros.