MySwag.org The Off-road Camper Trailer Forum
General => General Discussion => Topic started by: MarkVS on February 17, 2015, 09:27:27 AM
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Being the mechanic novice that I am, I was looking up the basics on how diesel engines work as opposed to petrol.
One of the things that I couldn't quite work out, is why there is so much talk about diesel engines lasting so much longer than petrol.
Why do they ? what is do different ?
Is it something as simple as the fact that diesel engines are unlikely to do as many 'rev's over their life....or being a slightly simpler motor, less that can go wrong....or..they would have better heat dissipation so they don't run as hot so last longer ?
Any mechanics that fill the understanding gap..
Mark
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Stronger block and internals to handle the compression
Less moving parts asa it relies on compression to go so there is no ignition system to speak (apart from glow plugs to start it)
However this is old school diesels modern CRD is now as complex as petrol with the same lifespan
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Stronger block and internals to handle the compression
Less moving parts asa it relies on compression to go so there is no ignition system to speak (apart from glow plugs to start it)
However this is old school diesels modern CRD is now as complex as petrol with the same lifespan
Thanks for that..so it is as simple as I thought..simpler motor, bigger engine block etc = longer life.
Thought I might be missing something.
Thanks
Mark
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only if they're looked after :)
they get most power at lower rpm = less revolutions over its lifespan = less wear and tear
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Traditionally diesels were plonkers with low revs and lots of torque. They would just idle along doing the heavy work or pulling large loads. They mostly had a wide torque curve, as opposed to peaking at high revs like their petrol equivilants.
But now, not so much. Many diesels are turbo charged, some with two turbos. Think with modern diesels, a lot of the old longevity arguement has gone out the window.
KB
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Traditionally diesels were plonkers with low revs and lots of torque. They would just idle along doing the heavy work or pulling large loads. They mostly had a wide torque curve, as opposed to peaking at high revs like their petrol equivilants.
But now, not so much. Many diesels are turbo charged, some with two turbos. Think with modern diesels, a lot of the old longevity arguement has gone out the window.
KB
:cup: :cup:
I have been holding back from commenting on this topic, but KB has pretty much nailed it. :cheers:
(Had I commented, GG would have moved it to the Daily Rant thread, and most here would hate my guts, FOREVER !! ;D )
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Had I commented, GG would have moved it to the Daily Rant thread, and most here would hate my guts, FOREVER !! ;D
Mate, I enjoy reading your posts/replies. I learn something most times or get a laugh, sometimes both. Don't ever be afraid to post your opinions, they mostly make sense :cheers:
KB
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but KB has pretty much nailed it. :cheers:
The diesel lasting longer thinking comes from industrial and marine engines mostly, heavy vehicles to.
Cars with small diesels, different story.
Then to add confusion, high speed marine diesels last no where near as long as medium or low speed.
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:cup: :cup:
I have been holding back from commenting on this topic, but KB has pretty much nailed it. :cheers:
(Had I commented, GG would have moved it to the Daily Rant thread, and most here would hate my guts, FOREVER !! ;D )
He has indeed.
Now we'll just have to find some other reason Shane...... ;D ;D ;D
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Petrol washes the oil off the cylinder walls promoting wear but diesels are only compressing air until diesel is injected on the ignition stroke, plus diesel is just thin oil so has better lubricating properties than petrol.
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Mate has a petrol 80 series still going strong with 550ks on it
Swannie
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Diesel engines generaly have alot lower compression witch I guess has a bearing on longevity but a badly maintained diesel is destined to fail prematurely well before a badly maintained petrol.
My 80 series has done about 350k and still strong as an ox
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^^^^
I think you mite be slightly wrong there. ;D
Diesels usually have compression ratios of 16:1 and greater.
http://auto.howstuffworks.com/diesel1.htm (http://auto.howstuffworks.com/diesel1.htm)
:cheers:
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and most here would hate my guts, FOREVER !! ;D )
Ah don't let that stop you,coz we will anyway ;D ;D ;D ;D ;D ;D ;D ;D ;D
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:cup: :cup:
I have been holding back from commenting on this topic, but KB has pretty much nailed it. :cheers:
(Had I commented, GG would have moved it to the Daily Rant thread, and most here would hate my guts, FOREVER !! ;D )
Dont pick on me just because I drive one of those twin turbo jobbies, I had no choice in the matter, it made me do it ;D
The dark side has it's ways
GG
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They truely would be a good thing, if they had spark plugs, an ignition system and ran on petrol >:D
#tractorengines :-*
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The diesel lasting longer thinking comes from industrial and marine engines mostly, heavy vehicles to.
Cars with small diesels, different story.
Then to add confusion, high speed marine diesels last no where near as long as medium or low speed.
There's a boat that's powered by two Prado D4D engines. And we all know that stands for D4Detonation. ;)
(Yes I drive a D4D)
http://m.drive.com.au/motor-news/its-a-toyboata-20141015-116fgl.html (http://m.drive.com.au/motor-news/its-a-toyboata-20141015-116fgl.html)
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I reckon if you had both diesel and petrol of roughly the same capacity kept both serviced prior to service intervals and had working conditions the same, you will probably find the life span on both be pretty close the same.
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#tractorengines :-*
Yep. Ideal when travelling and towing further than around the block.......
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They truely would be a good thing, if they had spark plugs, an ignition system and ran on petrol >:D
#tractorengines :-*
TD42 started as a Forklift engine :)
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TD42 started as a Forklift engine :)
And that's where they should have stayed >:D (Never have seen one in a forklift, heaps of 25/27's though)
The TD42 wouldn't be a bad thing, if it was direct injection, didn't split bores, didn't blow head gaskets, didn't cavitate the timing cover away, or the water pump, didn't crack heads, didn't pull head bolts and ran on petrol >:D
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And that's where they should have stayed >:D (Never have seen one in a forklift, heaps of 25/27's though)
The TD42 wouldn't be a bad thing, if it was direct injection, didn't split bores, didn't blow head gaskets, didn't cavitate the timing cover away, or the water pump, didn't crack heads, didn't pull head bolts and ran on petrol >:D
Isn't that a 186 red motor?
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ambivalent
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Well I reckon it's more to do with what they are used for. Until recently, diesels were most often found running trucks, tractors, generators, locomotives or boats. They would usually run around the maximum torque point, run for days or months without stopping, maintain constant revs and temperature, and not get thrashed. Petrol engines often had a very different life with frequent stops and starts, cooling down at night, and revving hard right through the range when in use. Perhaps if they were operated in the same way as a diesel they might last almost as long.But I know next to nothing about engines.
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Old school diesels were usually long stroke, low revving engines that spent most of their life at less than 3000rpm.
New common rail diesels are shorter stroke, and higher revving. Essentially they are made now to match the performance of petrol engines. They are also more complex now with fuel systems running at very high pressures and more things that break. There isn't much difference in the expected life of the two types of engines these days.
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hi all. son has a petrol gas Datsun has 400000 on clock it gets treated like Shit but is serviced regularly
enjoy 4b
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There are quite a number of people on Subaru fora who have over 400,000 kms on their original petrol donks. Specifically the EJ series engines, but others as well. Many of these are well looked after, but used hard.
My '93 Subaru Impreza had around done 236,000 kms when I traded it in. During a 4,500 km roundtrip to Brisbane in 2011, it used no measurable quantity of oil or water and the ambient temperature was around the high thirties to mid forties on most travelling days. My right foot is far heavier than my left ;D. For much of its life, I drive it like I stole it, as the car was heavy, the engine gutless and the gearing and tune all wrong, I spent a lot of time revving its rings off ... It had an EJ-18 engine (1800 cc), and weighed nearly 1200 Kgs tare. The only engine repair in its life with me was a new water pump at around 210K kms.
Ask someone who has had to replace their diesel particulate filter for around $4000 about the reliability of what I call "consumer diesels" (to distinguish them from things like the 3 cylinder GM diesels in our farm tractors).
It is my understanding that the DPF in modern heavy diesels is separate from the catalytic converter, and is designed to be easily removable and cleaned. With consumer diesels they are part of the catalytic converter, and are a throw away item.
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I would have thought that the longevity of most modern diesels would still be better than modern aluminium block engined petrol engines? A well maintained cast iron block engine can be repaired unlike a modern aluminium block engine. The aluminium block engines, no matter how well maintained will generally have a shorter life span due to corrosion in the water jackets eventually killing the block.
Just look at engines from vintage cars as a good example, how many of them are able to be totally rebuilt using the original block and head when there are aluminium components, like the head? Not many, unless original parts are available.
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However this is old school diesels modern CRD is now as complex as petrol with the same lifespan
yep - 'when I was a lad' diesels didn't have any of this - or glow plugs - diesels were diesels. one tugboat I worked on went for years flawlessly - but when they go, they go.
I also find diesel driver tend to be more sedate (did they have any choice...?) - I drive my petrol pajero like a diesel and it's still pretty much much as it was when I bought it barr the traditional mitsubishi worn valve guides- first timing belt was changed at 270000km and only then because the water pump went
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Was it an NL 3.5 l petrol ??? ??? ??? :cheers:
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My wife's 2008 lancer has done about 260,000 without any problems, we've had it since new. Regular servicing every 15-20k. My petrol jeep has done 180,00klm without a hiccup though it's a cast iron pushrod, with regular servicing. Diesel or petrol look after them and they'll look after you, though i probably wouldn't buy a modern diesel as i've had such good runs from petrol.
cheers
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Was it an NL 3.5 l petrol ??? ??? ??? :cheers:
why, yes it is - how did you know...?
(smokes and clatters back out again...)
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I loved the old Detriot Diesel but they liked to drink the fuel >:D
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Brett B
The Old DD did do the job , & yes sucked the juice , but they did the job >:D
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Our 3.4L petrol 90 series Prado has over 340,000km on it and going just as strong as the day we got it (@140,000km), serviced every 10,000km and only takes around 5L of oil (I think the diesel is double that amount and needs it every 5,000km). Our mechanic says that's nothing as another customers 90 has over 500,000km on his and it too is running fine. They don't have the low-down torque of a TD although I think the 4.0L in the 120 Series is pretty torquey at low revs.