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Thread ID: 67054	2006-03-15 19:12:00	Diesel Car - Yes or no?	Mike (15)	PC World Chat

Post ID	Timestamp	Content	User
438391	2006-03-16 02:54:00	I wouldn't touch a 2 . 4L turbo with a barge pole . They have a habit of cracking heads, you'd be far better off with the 3 litre version . I've put 50,000 km on my Surf in the last 17 months and it still runs as sweet as the day I bought it (100k when I got it) . Just keep up with the servicing . Great info from Surfer Joe . :thumbs: OK . . . . anecdotes? I got anecdotes! Owned a 1982 General Motors Pontiac Grand Safari 9 Passenger Station Wagon . . . . the biggest and heaviest passenger car made for a few years (6,275 lbs, without passengers) and it had the worst engine in public opinion that ever existed: The (so-called) worked-over 350 DX Oldsmobile gasoline-to-diesel conversion engine . This is the one that gave GM a bad eye for total failures and disasters that also poisoned the public opinion for Americans about diesel engines even until today . OK . . . I got 486,000 miles on it on a single engine (although 3 sets of head gaskets), one rebuilt injection pump (I worked in a Roosa-Master pump shop at the time and did it myself along with rebuilding the injectors once in all that mileage), and I built a transmission once . It towed a 38 foot long travel trailer weekly for the years of 1985 to 1992, and even a couple of times after that . When not towing anything, the A/C running and cruising at mostly 10 to 15 over the speed limit (55 at that time), it got 41 miles to a gallon (US), and while towing it got 30 . When I gave it away to the son of a friend, it had 486,000 miles (US) on it and it was getting a little weak by then . Never had a major breakdown . . . never blew the engine up . . . but I did have to replace the head gaskets a couple of times . . . . small price to pay I think .	SurferJoe46 (51)
438392	2006-03-16 03:02:00	As far as fuel mileage..diesels do it better...they are more efficient with the fuel they get because of the higher compression and the fact that the fuel still expands as the piston travel to the bottom of the stroke...not like gasoline that "snaps" off and the piston just coasts the rest of the way after a small explosion.nah not by a long shot. while deisel and petrol have different burn rates its not as much difference as you make it seem. deisel "push" just the same as petrol, all depending on the design of the motor. Take this little test: Grab hold of the exhaust manifold of a diesel engine that has run for at least 15 minutes at idle...uncomfortable, but you will not lose any skin over it or suffer too much from heat....then grab the manifold of a gasoline engine run the same time...if you can get near to it...it will burn your skin off clear thru to the bones and there's no mistaking that it is a lot hotter than a diesel's. Why? Heat conversion efficiency, that's why. The heat was used propelling the engine, not being pumped out the exhaust as waste heat...and wasted dollars as that is just fuel getting dumped into the atmosphere. as a general rule deisel make max heat at max fuel input, petrol is hottest when its leanist (ie idle). you also need to factor in that the deisel pumps more air through than a petrol (both at idle), a deisel has a lot more cooling air running thorugh it than a petrol, so the motor is cooled more and the heat is spread out more over the larger amount of air. a petrol has a smaller amount of air to handle the heat so that little bit of air coming out is alwasy going to be hotter. Gasoline has to fire the plugs BEFORE top-dead center, to make sure the fuel will be burning by the time the piston starts down; diesels inject the fuel a few degrees AFTER top-dead center to push the piston more efficiently... ...remember we are talking glorified heat pumps here...that's what an engine really is. actually deisel engines can also fire before TDC. actuall timing comes down to flame speed which is a factor of head design and type of injection. mind you some engines are retarded and under fueled for thermall load reasons as well, it also depends on if its forced induction or not.	tweak'e (69)
438393	2006-03-16 03:06:00	Just looking through this thread, I note that no one has raised the issue of environmental friendliness (or rather the lack of ) and the antisocial nature of these trucks for personal use. Unless you have an off road use for one why would you buy one - they're more expensive to run and maintain that a similar sized car or wagon. If you buy one make sure you get it for a very good price as they're getting harder and harder to sell, especially the older ones as you seem to be considering.	dvm (6543)
438394	2006-03-16 03:07:00	You are thinking of non OHC actually Sb0h is correct. the 2lt motor (thats model number not engine size) has a history of cracking heads, comman fix is to use the 3L (model number)heads . the motors are OHC. the non OHC ones where early to mid 80's. however if properly looked after (and the coman faults fixed) they are good for 400,000 kms without a problem.	tweak'e (69)
438395	2006-03-16 03:18:00	Just looking through this thread, I note that no one has raised the issue of environmental friendliness (or rather the lack of ) with older vechiles its a liitle tricky . while petrol has some bad emmisions, deisels are extreammly bad at makeing NOX . new deisels have EGR systems to reduce NOX ouput . however older vechiles, such as that surf, the EGR systems are often the casue of the vechiles problems and are commanly removed . also of that age all NZ assemabled vechiles never had EGR systems anyway . petrol may be better but also at that age, NZ never had cat convertors (it reduces emmisions) and most imported ones are stuffed and often removed . don't forget something like 75% of emmisions come from the manafacture of the vechile .	tweak'e (69)
438396	2006-03-16 03:36:00	Just looking through this thread, I note that no one has raised the issue of environmental friendliness (or rather the lack of ) and the antisocial nature of these trucks for personal use . Antisocial - well, my personal view of many 4x4 and SUVs is that many urban drivers are "compensating" for something (a gross generalisation, I grant you) . Those that genuinely use them for off-roading purposes or for transporting over-size loads are the exception, but my experiences from Auckland, Wellington, Palmerston North, suggests that most people don't need the extra size . They make it very difficult for other drivers to see around, particularly when an SUV is parked close to kerb corners or when they are turning right at an intersection . I know from personal experience that many people drive their SUVs like cars, and the results can be quite dangerous . People will rail against the injustice of such a generalisation, and cite their freedom to do what they want . But then they always will . . .	Lizard (2409)
438397	2006-03-16 03:51:00	Antisocial - well, my personal view of many 4x4 and SUVs is that many urban drivers are "compensating" for something (a gross generalisation, I grant you). You are SO right there!!!!!!! :thumbs:	personthingy (1670)
438398	2006-03-16 03:59:00	Antisocial - well, my personal view of many 4x4 and SUVs is that many urban drivers are "compensating" for something (a gross generalisation, I grant you). . I wasn't going to expand on my view as some time ago I nearly got my head bashed by a bloke in one of these trucks who had muscled his way into a car park in front of me by my suggestion that the size of his useless truck was in inverse proportion to a certain part of his anatomy. The speed of my retreat may have got me into the Games 100 m dash.	dvm (6543)
438399	2006-03-16 07:06:00	nah not by a long shot . while deisel and petrol have different burn rates its not as much difference as you make it seem . deisel "push" just the same as petrol, all depending on the design of the motor . as a general rule deisel make max heat at max fuel input, petrol is hottest when its leanist (ie idle) . you also need to factor in that the deisel pumps more air through than a petrol (both at idle), a deisel has a lot more cooling air running thorugh it than a petrol, so the motor is cooled more and the heat is spread out more over the larger amount of air . a petrol has a smaller amount of air to handle the heat so that little bit of air coming out is alwasy going to be hotter . actually deisel engines can also fire before TDC . actuall timing comes down to flame speed which is a factor of head design and type of injection . mind you some engines are retarded and under fueled for thermall load reasons as well, it also depends on if its forced induction or not . Damn! I just love it when somebody comes up for air and tries to espouse flamefront propagation and stoichemetric values with me . . . let's go at it! Modern engines, gasoline, have wonderful little things called oxygen sensors that are really part of a series of devices that are designed to maintain a 13 . 7:1 air-fuel ratio (AFR) no matter what the rpm, load or air temperature or airflow . Your arguement of "lean" hold no water at all . . . unless you want to digress to 1960's technology with carburetors and non-'puter controlled combustion processes . Modern engines, and now even diesels have CPU's that monitor at about 33khz ever sensor and feedback operated device on the engine, controlling the shift points of the transmission, idle speed, fuel mixture, air density factors (altitude and barometric values), throttle position, coolant temperature, pre-cat oxygen values, post-cat values, exhaust temperatures, accessory load, event and duty cycle of the injector(s), ignition timing (individually on each cylinder, as well as the injector for each cylinder too . Bang! Dead thought that gasoline engine run lean at low flow times . The only diesel engines that inject fuel before tdc are old hot-bulb types . . and they are usually found in stationary use engines like oil-water pumps or slow operating (less than 300 rpm max) behemoths that are obsolete by now in advanced civilizations . The latest vestage of cross-injected engines were in the 1940's or so, although a few still exist in vehicles that amazingly run and run . . . . these shot the fuel across the top of the piston as it rose to apogee and as the fuel was directed into a pre-combustion chamber, it was allowed to cook-off there until the piston dropped a little, opening the chamber to allow the fuel to then enter the swept area of the cylinder, pushing the piston down the rest of the stroke . Diesels can indeed have the timing advanced too far and actually get before tdc . . . but they have a propensity to run backwards (Macks and Detroit Squeezers are notorious for this), and if left in gear and accidently bumped, can fire backwards and ruin the engine because the oil pump runs backwards and starves the bearings and journals . . etc . I have had a driver or two come into the shop complaining that his exhaust is coming out the air cleaner . . . . and he has 13 speeds reverse and 3 forward . . . exit one engine! It's not pretty . Short report of the diesel timing statement . . . Yes, there are some that were designed to run that way (BTDC) . . . but in reality, the actual expansion of the fuel wasn't allowed into the chamber until the piston was well on it's way south and would not damage the rods, rings and cylinder walls . These engines are almost all in museums and they are all very low speed anyway and not really fit for modern propulsion . Doubly so if the engine was 2-cycle . Now . . the heat thing: diesels DO NOT control or modulate the intake of air . . OK, an exception to the rule is the Mercedes Benz diesels . . they use a butterfly in the intake of the plenum . . . but this is just a noise abatement device . Diesls do not have intake vacuum that can be put to use as a modulated gasoline (and M/B diesels) to use for accessory devices like divertor doors and power brakes and vacuum modulators for transmission shift values . Any vacuum a diesel vehicle requires usually comes from an auxillary vacuum pump that is probably belt-driven or even camshaft driven . In all theory and application of air:fuel ratios, we understand that if there is uncontrolled air allowed into a combustion chamber and yet a very small amount of fuel is allowed in, then we are speaking of a very lean running condition . This would be the situation if we drilled many large holes into the intake manifold of a conventional gasoline engine while it was idling . It would not survive if much uncontrolled air entered at all . . . it would die for lack of sufficient fuel to support combustion . Now, your "lean" idle condition would be correct if we are only talking about a gasoline engine . . but as I am speaking diesel here, and the fact that diesels do not modulate the air intake and that indeed there is scant little fuel injected at idle . . . it blows your lean-idle idea totally away . . . diesels are subject to the same laws of thermodynamics as gasoline or gunpowder engines . Dead bang wrong there . The thought you had about diesel and gas being only slightly different in therms and BTUs is wrong . If gasoline were subjected to 22:1 compression ratios, it would almost instantly destroy the engine . Volitility and vapor pressure values are off the page when compared to each other . Dead . Bang again! The very fact that diesel can keep detonation from happening at those compression values indicates the . . . let's use octane here, although there are a lot of other factors involved . . cetane, pentane, heptane . . etc . . . etc . . . . . these are properties that gas does not have . The stoichemetric values for diesel compared to gas are very very different . . . starting at the therms, viscosity, specific gravity and vario-compressability . Using your points and your arguement then, a diesel would be running at near 100000:1 AFR (air/fuel ratio) at idle and therefore be so hot that it might be incandescent . It just ain't so . They idle . . I have seen them do it, for days at a time and they don't get hot at all .	SurferJoe46 (51)
438400	2006-03-16 07:27:00	Just looking through this thread, I note that no one has raised the issue of environmental friendliness (or rather the lack of ) and the antisocial nature of these trucks for personal use . Unless you have an off road use for one why would you buy one - they're more expensive to run and maintain that a similar sized car or wagon . If you buy one make sure you get it for a very good price as they're getting harder and harder to sell, especially the older ones as you seem to be considering . (I swear I am gonna get off my soapbox right after this post . . . for a while anyway! :rolleyes: ) There is another cottage industry that is fueled by the "obvious" soot and dirty exhaust of those damn ol' diesel engines . BAH! Here's the real poop . Diesel exhaust is full of nasty things that are indeed dirty looking . Let's look at these nasties a little . The most obvious part is the smoke . . . . dirty rotten smoke . It's the long chains of carbon molecules that get forced together at high pressures and temperatures . Here's the neat part . They are quite harmless to your lungs or much anything else of yours that you treasure . Unless one has a hobby of placing their lips on tailpipes and inhaling massive doses of exhaust (ANY exhaust, not just diesel), ingestion of these long molecules is something your lungs can handle quite well . . . if not totally inundated by them . The carbon chain is so big that your cilia in your lungs can actually discharge the junk and get it out of your body very well . The largness of these molecules makes it easy . Another point . . . these molecules are food for a very interesting bacteria . The very bacteria that eat all the rubber dust from your tires (ever wonder where your tires go when they are wearing out?) also feast on the exhaust of diesel engines . I am not pressing for a "Feed the microbes" awareness political rally . . . just that the same little bugs eat the diesel that you see as soot . So . . . it's not the stuff you can see . . . (it's pretty harmless on a large scale) but the stuff you cannot see . The nitrous oxides and the perchlorates and the stannous fluoride of the catalytic convertors on gas vehicles, the sulfur dioxide from the same cats (as well as cheap fuel for diesels) are the real culprits . Please tilt at the right windmill . . it ain't the soot that's killing you . . . it's the stuff that lays close to the ground and tastes like you've been sucking on (insert your favorite coin of the realm here) . Nitrous oxide is the worst of them all . . . it causes many deaths due to respiratory failures and asthma, bronchitus, heart conditions and oxygen deprivation in children . Next we'll work on the sulfur and the weird chemicals that the companies inject into the fuels to "stretch" them out and in essence make a lot more money at your expense . MTBE's are a good example . . . they are banned here as they found out that it gets into the water supply (wells, water table) and pollutes the drinking water . Don't get me started on methanol or alcohol additives . . . . that's a two-soapboxer! [stepping off for the night . . . you are warned . . . . . . . . . . . I get very loquacious on this stuff]	SurferJoe46 (51)
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