Viewing 40 posts - 81 through 120 (of 131 total)
  • Diesel Vs Petrol
  • stumpy01
    Full Member

    5lab – Member
    I disagree. DMF, DPF and so on have no relation to whether a car is

    a) serviced
    b) ragged from cold
    c) correct spec oil

    as above, no dpf in an ’06 Octavia 1.9 TDi.

    Servicing can identify wear etc. early that may prevent catastrophic failure of parts.
    I have been told that PD engines are quite sensitive to the correct oil being used, hence my comment about correct spec oil. Do you not agree that correct spec oil & frequent changes will help prolong the life of an engine?

    What are the “and so on” bits that you refer to?

    Anyhoo – I have mine serviced regularly, make sure the garage use the correct oil & don’t rag it from cold. It’s lasted 173k miles with no diesel engine specific parts failing apart from a £50 hose mentioned above (that any car with a turbo will also have)……it’ll probably fall to bits on the way home, now I have typed this…

    cookies
    Full Member

    now its £1100 for an EGR. Mine’s elctrical and so shonky that Fiat make you buy a wiring loom to go with it, with the possibility of a remap….

    stumpy01
    Full Member

    ^^^ oof!

    I thought £500 for a new air con compressor was a lot to fork out!

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    5lab
    Full Member

    Servicing can identify wear etc. early that may prevent catastrophic failure of parts.
    I have been told that PD engines are quite sensitive to the correct oil being used, hence my comment about correct spec oil. Do you not agree that correct spec oil & frequent changes will help prolong the life of an engine?

    What are the “and so on” bits that you refer to?

    don’t get me wrong, servicing is a great idea, as is using the correct spec of oil, however lots of people have problems with modern diesels which servicing wouldn’t fix, such as

    Clutch
    DMF
    DPF
    Injectors
    Turbo seals (the bearings will last longer with regular servicing but not the seals)
    anything related to a sensor going wrong
    some muppet putting petrol instead of diesel in

    The only thing regular oil changes do really help with (other than the turbo bearings mentioned above) is bore wear on the engine. This is still an issue on higher milage (150k+) cars, but for most cars other stuff causes the death of the car prior to this becoming a factor..

    mboy
    Free Member

    completely agree, but in the same light, I don’t think its fair to compare that car to a modern petrol either. in the 90s you needed a similar engine to give you that power in petrol – the volvo 850 (non turbo) got about 160bhp from a 2.4l engine, and averaged ~25-30mpg.

    Volvo’s have always been lazy, torquey engines. Most other manfucturers 2 litre 16 valve engines were pushing out roughly 150bhp since about 1994. My old 1998 Pug 306 GTi-6 had 167bhp! So I’m gonna stand by my original comparison.

    5lab
    Full Member

    but if you’re cherry picking like that, the very engine you have put out 180hp in some states of tune (72bhp/litre) which isn’t that far off what most diesels do today. Hell VW had a mk5 golf with *half* that much power

    verticalclimber
    Free Member

    use a quality de coke agent 1-2 times a year(forte recommended by MOT stations), will help stop egr coking + use decent fuel cheap ones have very little detergent in.

    Grimy
    Free Member

    A lot of modern diesels suffer from intake manifold failure, or more specifically, the swirl flaps get bunged up and fail.

    All this euro 4 shizzle has resulted in the inert exhaust gas, which is rich in carbon, being recirculated through the EGR and intake manifold to reduce the combustion temerature and thus the amount of nitrogen oxide. This is all good, but not when the manifolds also full of oil vapour from the heavy breathing they do. Flour and eggs / oil and carbon, same effect.

    Regardless of driving technique, they can, and more often will eventually bung up. If its not the EGR that fails, its the manifold swirl flaps that just cant open any more for the wall of crud behind them. Depending on the car, its then a new intake manifold as they snap the plastic link arms that connect the flaps. Either way, it can be a very costly repair, and its very very common.

    Im sticking with petrol for now. You can pick them up a lot cheaper than diesels and they’re just less risky if your on the second hand market.

    If I was buying new, and with a waranty, then shifting it on after 3 years, then a diesel may make more sense.

    molgrips
    Free Member

    Regardless of driving technique, they can, and more often will eventually bung up.

    I took mine off my 1.9 TD to clean it, convinced it’d be clogged. After 180k miles there was a flim of soot on the inside. I was surprised.

    Anyone know why a simple valve being blocked would result in a £1100 repair bill?

    Dolcered
    Full Member

    [/quote]I was getting 21/22MPG on a run but since the EGR blew coming back from France its only doing 18MPG. A new EGR and service is £900.

    Why do EGR’s keep failing….

    dunno, but ive had two go, one on 2.0L petrol A3 (300quid thank you very much) one on a 1.6D Volvo C30 (free under warranty) both cars went at just under 3yrs old as well.

    Grimy
    Free Member

    Anyone know why a simple valve being blocked would result in a £1100 repair bill?

    Daft money I know but thats what it can cost. On a 1.9tdi vauxhall for example, if the swirl flaps break, you need a new manifold, £££, usually a new egr too, £££. To do the job, you need to remove the timing belt and fuel pump and all the ancillerys around them. Then there’s the gaskets and labour, £££.. soon adds up at a dealer.

    donsimon
    Free Member

    It’s pretty good though I’d go for an auto as the manual cen be a bit snatchy on pull away. Otherwise, car is smooth, economical and in normal guise, 180bhp so plenty powerful enough. For long term ownership, it has chain driven cams rather than the belt replacement job required on the 2.5L@ 80k (IIRC). That’s an expensive job on the 2.5L.

    I had mine chipped though and there’s loads of grunt whilst returning the mpg’s above. I didn’t fancy the 3.0L for the extra power as it only came in 4×4 mode and for 99.9999% of my driving, 4×4 is irrelevant.
    cheers boblo. 🙂

    Inbred456
    Free Member

    Have a mondeo mk3 tdci 130 estate 2004. Pre 2005 cars use the ford puma engine. Chain driven cams no dpf fitted. Garrett turbo tested to 150k+. DMF clutch kits are amongst the cheapest to replace 500 quid approx. I was advised by a mate who runs a fleet of different cars to allow turbo to cool for a minute before turning off ignition and use decent quality fuel not cheap supermarket stuff. This is to protect the fuel pump from wear. Oil is changed every 10k or per year what ever comes first. Low sulphur fuel eats fuel pumps and wears injectors. A fuel pump failure will make everything else look cheap by comparison. On a brighter note just drive them and enjoy them!

    mastiles_fanylion
    Free Member

    ? The Puma never had a diesel variant ??

    1.4, 1.6 and 1.7 petrol (the latter being the Yamaha engine). The 1.4 was soon retired as it was pointless.

    Inbred456
    Free Member

    Not the little hatch, puma is also the code for the ford 2.0l tddi and tdci chain cam engine. Also known as the ZSD engine.

    soops
    Free Member

    I have just bought an X reg golf SDI estate, and driving it back from Yorkshire at 80-85mph i got 402 miles out of £50 worth of fuel. Alot better than my 318i BMW used to do. Bonus! 😀

    molgrips
    Free Member

    You managede to get an SDI Golf up to 85mph? I’m impressed.

    nickf
    Free Member

    My very heavy 4×4 does 30mpg, which is acceptable though not great. It’s a diesel, and the characteristics of the engine suit the car – the petrol version I tried was gutless in comparison, which is probably why Land Rover stopped making it.

    For all of the anti-diesel sentiment being expressed here, I’ll say this: in the last 200k miles I’ve done, almost exclusively in diesels, I’ve not had a clutch failure, a DMF/DPF problem, a turbo failure…nothing.

    What I have had is suspension problems (BMW 530D, but common to all E39 5-series), rear transmission issues (Volvo XC90, common across the range), and failed electronic parking brake (Passat, again unrelated to dieselness). I’ve also needed discs and pads – diesel cars tend to be heavier, so they wear the brakes more – and, on the Passat, shock absorbers. Probably unrelated to being a diesel, but the additional weight might have taken its toll.

    Land Rover and Passat are each on around 140k at the moment, no plans to change them out for a while yet.

    Unless you’re doing a lot of miles, the price differential may not make it worth it, but given the distances the wife and I do, and the loads carried, diesel just makes more sense for us.

    soops
    Free Member

    molgrips – 91mph flat out on the flat! 🙂

    mboy
    Free Member

    Well we can end the argument, cos on Thursday I pick up my new car and it runs on…

    LPG

    Win/Win

    😀

    nedoverendsmole
    Free Member

    My B5 tdi passat has done 254k miles on its original engine and gearbox. It never returns less than 55mpg and usually does 65mpg on my daily commute, the best ever brim and brim tank mpg being 85mpg over a 30 mile b road commute. In hard times I have run it on cheap pure veg oil. I see deisels being ragged through the gears everyday (as a pedestrian, try and cross the road near any busy roundabout or junction) in pointless drag races to 40 mph, the driver no doubt drunk on excess torque.

    flow
    Free Member

    Well we can end the argument, cos on Thursday I pick up my new car and it runs on…

    LPG

    Win/Win

    For over a year I did a 160 miles commute to London everyday in an LPG converted 1.7 Vauxhall Combo (Corsa) van. A tank of fuel didn’t last very long (MPG is awful) but because its cheap to buy it works out slightly better than petrol, but not as cheap as diesel. The prices have changed now though so its probably all different.

    What car is it?

    mboy
    Free Member

    My B5 tdi passat has done 254k miles on its original engine and gearbox. It never returns less than 55mpg and usually does 65mpg on my daily commute

    I had two… The first returned 45mpg average, sold it 10k later to get a higher horsepower version (90bhp in a 1.5 tonne saloon was just so weak!).

    Bought a 110bhp estate, it averaged only 41mpg… For 3k miles, (from 121,000 to 124,000) before it blew up! Dropped a valve into a piston, blew the injector out the head, smashed the turbo to pieces etc. The car had a full VW Service History and only 2 owners…

    When it comes to VW’s, don’t always believe the hype! Though to balance this out, my MK3 Golf TDi was the cheapest car I’ve ever had to run, did over 30k miles in that in 18 months and it never missed a beat…

    For over a year I did a 160 miles commute to London everyday in an LPG converted 1.7 Vauxhall Combo (Corsa) van. A tank of fuel didn’t last very long (MPG is awful) but because its cheap to buy it works out slightly better than petrol, but not as cheap as diesel. The prices have changed now though so its probably all different.

    What car is it?

    Boring old Mondeo… Still, 38,000 miles, FSH, aircon and heated seats and the LPG tank, all for 900 quid can’t be bad can it! Combined MPG is quoted at 36 for it (it’s a 1.8 Zetec), so if it does 30mpg on LPG (to be expected) I’ll still be a happy bunny as it’s only 68.9p round here.

    flow
    Free Member

    Sounds good mate. Doesn’t seem that long ago that petrol was that price per litre!

    Think LPG when I was using it was just under 40p/litre, thats gone up a fair chunk too.

    Robbing bastards

    molgrips
    Free Member

    LPG

    Win/Win

    No.. petrol hybrid win/win!

    flow
    Free Member

    No.. petrol hybrid lose/lose!

    Diesels are more economical, produce less pollution in the manufacturing process, are faster, and have more torque.

    molgrips
    Free Member

    Lolz, that old chesnut again.

    Show me a decent sized automatic family car with 140bhp, 89g/km CO2 and very low NOx and I might be impressed. I’d definitely be surprised, mind 🙂

    nedoverendsmole
    Free Member

    Bought a 110bhp estate, it averaged only 41mpg… For 3k miles, (from 121,000 to 124,000) before it blew up! Dropped a valve into a piston, blew the injector out the head, smashed the turbo to pieces etc. The car had a full VW Service History and only 2 owners

    I must have bought the only good one, clearly

    flow
    Free Member

    89g/km CO2 and very low NOx

    Nowhere did I say anything about that.

    automatic family car with 140bhp, 89g/km CO2 and very low NOx

    What hybrid has that?

    mboy
    Free Member

    Sounds good mate. Doesn’t seem that long ago that petrol was that price per litre!

    I passed my test at 17 in 1997, petrol was cheaper than 68.9p per litre round here back then.

    I remember absolutely brimming my 106’s tank after letting it run just about dry, and I managed to squeeze all of £32 of petrol in it! And that £32 would last almost 400 miles, despite me caning the knackers off the little car everywhere!

    I remember when I first saw LPG available for cars (probably a while after it was actually available) and being gobsmacked you could fuel a petrol engined car for 28.9p per litre!

    molgrips
    Free Member

    automatic family car with 140bhp, 89g/km CO2 and very low NOx

    What hybrid has that?

    Prius, last time I checked.

    FunkyDunc
    Free Member

    “1.4, 1.6 and 1.7 petrol (the latter being the Yamaha engine). The 1.4 was soon retired as it was pointless.”

    The 1.4 and 1.7 were all the same Yamaha engine block (not sure about the 1.6, in fact the smallest was the 1.25 (although not used in the Puma)

    5lab
    Full Member

    petrol hybrid co2 is heavily weighted by the urban figure (which is very high). On motorways, the prius is just a slippery-shaped 1.5 petrol, which doesn’t have particularly shining results. If you drive on motorways a lot, a similar powered diesel (for instance, a golf dsg) would probably be more economical. if you drive in town, the hybrid has the edge

    Best of both worlds is diesel hybrid. Pug have one in a big 4x4ish thing that puts out 200bhp and does <100g CO2. impressive.

    molgrips
    Free Member

    On motorways, the prius is just a slippery-shaped 1.5 petrol, which doesn’t have particularly shining results

    Got evidence for that? Cos I have 80,000 miles of evidence 🙂

    It’s a lot more than just a slippery 1.5 petrol. Don’t claim stuff you don’t know about 🙂

    Some stuff I remember reading:

    – It’s very slippery indeed, the slipperiest production car (at least it was, may have changed may not)
    – Engine is a pseudo-Atkinson cycle which has a longer expansion stroke than compression, resulting in more recovered energy
    – On previous US models it pumped hot coolant into a thermos to keep it warm
    – Current engine has a coolant circuit that goes through the exhaust near the engine so it heats up really quickly to improve cold start economy.
    – The engine has no drive belts – everything’s an electric motor, so no parasitic drag
    – The transmission whilst being like a CVT works completely differently, and can mimic a huge range of gears. Even in mine I cruise at less than 2krpm.
    – Even on motorways it recovers energy going down hills and when lifting off. So not just like a normal petrol.

    65-70mpg is normal for a new model Prius afaik, which is reasonably similar, perhaps a little more than a Bluemotion Passat, but it’s petrol so has lower C02, burns more cleanly and no heavy oils need to be cracked to make the fuel.

    Having said that I like the Pug – although it doens’t need 200bhp and surely to goodness if they put the same powerplant in a smaller aero car it’d be more efficient still? I didn’t think diesel hybrids were much of a goer because many of the advantages of diesel are mitigated by the hyrbid petrol system (pumping losses for instance) but they seem to have figured it out. Apart from the NOx emissions and so on.

    stumpy01
    Full Member

    Some stuff I remember reading:

    – It’s very slippery indeed, the slipperiest production car (at least it was, may have changed may not)
    – Engine is a pseudo-Atkinson cycle which has a longer expansion stroke than compression, resulting in more recovered energy
    – On previous US models it pumped hot coolant into a thermos to keep it warm
    – Current engine has a coolant circuit that goes through the exhaust near the engine so it heats up really quickly to improve cold start economy.
    – The engine has no drive belts – everything’s an electric motor, so no parasitic drag
    – The transmission whilst being like a CVT works completely differently, and can mimic a huge range of gears. Even in mine I cruise at less than 2krpm.
    – Even on motorways it recovers energy going down hills and when lifting off. So not just like a normal petrol.

    So how much of this is a direct result of it being a hybrid and how much of it is just clever technology to further increase efficiency? (not that there is anything wrong with that).
    Why can’t most of that be applied to a ‘normal’ car? And what would the result be?
    It can’t be too hard to make a normal car as aerodynamic (so long as people will accept the shape), fit skinny tyres, recover heat/KE & use it effectively, rather than wasting it etc.

    I wonder how many more mpg my Ibiza would manage if it had skinnier tyres and a more slippery form. It only sits at 1800rpm doing 70mph.

    5lab
    Full Member

    It’s very slippery indeed, the slipperiest production car (at least it was, may have changed may not)
    – Engine is a pseudo-Atkinson cycle which has a longer expansion stroke than compression, resulting in more recovered energy
    – On previous US models it pumped hot coolant into a thermos to keep it warm

    the idea of coolant is that, once the engine is up to temperature, it isn’t kept warm, so this wouldn’t help on a motorway drive

    – Current engine has a coolant circuit that goes through the exhaust near the engine so it heats up really quickly to improve cold start economy.

    again – useful for short jouneys, not great for long ones as the engine is already hot

    – The engine has no drive belts – everything’s an electric motor, so no parasitic drag

    but it does have much more drag on the altenator, as the alternator has to power all of the electric motors which drive the air con, pas pump, coolant pump and so on. The lack of belts is more a design feature of allowing the car to be run whilst the IC engine isn’t, rather than an efficiency design in itself (converting motion to electricity then back to motion is a pretty wasteful process)

    – The transmission whilst being like a CVT works completely differently, and can mimic a huge range of gears. Even in mine I cruise at less than 2krpm.

    cvt can manage infinate gears. Sadly, its less efficient in its transmission of power than a regular gearbox, which is why its never caught on – the inefficiencies of the cvt outweigh the efficiency gains by running the engine at the optimum rpm. cvt cars have been around for years and years – the prius uses a different form of CVT to allow the hybrid drivetrain to run at an indipendant rpm to the IC engine

    – Even on motorways it recovers energy going down hills and when lifting off. So not just like a normal petrol.

    there’s very few (if any) motorways this is applicable in a prius, as the drag caused by the energy recovery reduces speed pretty quickly – so the amount of energy recovery on zero throttle is very low (early priuses were modified to reduce this drag (and the amount of power recovered) on zero throttle as people didn’t like the way the car slowed down so much). The prius can only ‘gain’ power in a situation where a normal driver is using the brakes.

    this can be pretty much summed up by the fact that a prius can only do 76mpg extra-urban, wheras a volvo s40 (which looks, to my untrained eye, like a less slippery shape) can do 86mpg on the same test.

    flow
    Free Member

    automatic family car with 140bhp, 89g/km CO2 and very low NOx

    Prius, last time I checked.

    LOL!

    Try 76 bhp, 104 g/km, 0-60 in 10 months, and a top speed of a whopping 106mph!

    VW Golf Bluemotion is quicker, better looking, less CO2, has 30 bhp more, a ton more torque, 10 mpg more efficient on the combined cycle, and cheaper tax.

    5lab
    Full Member

    LOL!

    Try 76 bhp, 104 g/km.

    0-60 in 10 months, and a top speed of a whopping 106mph!

    Golf Bluemotion is quicker, better looking, less CO2, has 30 bhp more, a ton more torque, 10 mpg more efficient on the combined cycle, and cheaper tax.

    that is the old prius, not the latest one, and that bhp is only the IC engine, wheras on a hybrid car you really need to include the whole drivetrain (98bhp for the IC engine and 36 for the electric). the golf is 74mpg combined, which is higher than the prius, but you’ll probably find it has less torque through the rev range, not that its really relevent to an automatic (as the prius is)

    flow
    Free Member

    Err he is on about the 1.5

    The interior of the new one is nice, very futuristic.

    molgrips
    Free Member

    Try 76 bhp, 104 g/km, 0-60 in 10 months, and a top speed of a whopping 106mph!

    Yeah.. as above check your facts before lolling.. 76bhp is indeed the petrol engine, all in it’s about 110bhp ish from memory, bout the same as the Golf than which is it bigger. 0-62 is 10.9s for the Prius and 11.3s for the Golf so ya boo sucks. Worth noting that you always get the maximum hp when you boot it becaues of the CVT effect, unlike a car with gears where you are not always at max hp.

    Also there semes to be some trouble getting the govt figures from the Golf, but I can verify that it’s rather easy to get the govt figures from the Prius. In the summer, at any rate. Not really possible in the winter.

    Btw why is a top speed of 106mph ever possibly a problem outside of Germany? Seriously, are you like 12 years old or something?

Viewing 40 posts - 81 through 120 (of 131 total)

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