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36

Inside the car: Manual: Check the manual for the service history. Was it services regularly at a authorized dealership? Ash tray: Smells like cigarettes? The previous owner was a smoker, dealbreaker for me personally. Interior: Does the amount of wear correspond with the expected amount of wear for a car of that age and mileage? Trunk: Spare tire ...


36

Torque is the name of the game. High torque is needed to move heavy loads. If comparing a gasoline engine to a comparable diesel engine the diesel will always have higher torque. The higher torque comes from the need for a higher compressing ratio needed for compression ignition. To achieve the higher compression ratio a longer stroke is required. The longer ...


17

These are things I check before buying a car (in addition to Alex's advice): Make sure it has radiator fluid (at a proper level). If the radiator fluid is empty, it probably has a radiator leak, they probably have not been watching it, and the engine probably has heat damage. The thermometer won't work without radiator fluid so they won't see that the car ...


17

A major, but often overlooked, reason for the dominance of gasoline engines in passenger vehicles is the need for diesel engines in heavy vehicles. A given quantity of crude oil, depending on its composition, will yield a given quantity of diesel, a given quantity of gasoline, a given quantity of candle wax, and specific given quantities of other petroleum ...


15

To OP’s main question: “Why do heavy vehicles almost always use diesel engines?” Answer: Cost and dependability. Diesel engines are significantly more expensive, but have lifetimes many times greater than gasoline engines. For a commercial vehicle that is on the road all day every day, it adds up to big savings because of the better fuel efficiency and less ...


14

You "can" use diesel in a gasoline engine. In the sense that it will run, but it will run poorly and smoke A LOT. But the problem with gasoline in a diesel engine is that diesel engines rely on diesel to lubricate various components (diesel is an oil). If you put petrol through these components, it washes away all the lubrication and will cause them to ...


12

The recall is not to remove the cheating logic; it is to actually make the engines meet emissions requirements so they do not violate the law any more. From Autoblog's initial article on the scandal: Volkswagen intentionally installed software in nearly a half-million diesel vehicles that helped the cars evade substandard results on emissions tests, the ...


11

I'm surprised this has not been mentioned. Have a compression test performed on the engine. This will expose many major engine problems like head gasket leaks, damaged valves/valve lands or rings. It is a simple, inexpensive test that can save you from some of the most expensive repairs a vehicle may need. I would consider a compression test absolutely ...


11

It's a Diesel, which means that you usually have a high detergent oil in an engine that dumps combustion by-products like soot into the oil as part of its normal operation. Given the age of the vehicle I'm not surprised that the oil has noticeably darkened after 10 miles - one of the older Diesels I owned a while back did that during the time it took to run ...


11

I have both a 2004 Bora TDI (Jetta Mk4 in the US) and a 2012 Mk6 TDI Golf. When either of these cars requires it's warm up system, it will automatically switch it on for the time it needs. This is signified by the glow plug light illumination on the dashboard: Once it's up to the temperature it requires, the light goes out and the car can be started. I ...


11

I would say there are two major reasons. First, the seals and o-rings used in diesel engines can't tolerate the chemical composition of gasoline. They are designed to tolerate the chemical composition of diesel only. Second, the kind of pressure needed to inject diesel can't be tolerated by gasoline. The Chevy Duramax diesel engine has 23,000 PSI in the ...


10

A glow plug is essentially a resister and is tested the same way: Disconnect wire to the plug. Remove the plug. Clean the thread of the plug to make for a good test connection. Use an ohm meter to check the resistance between the thread and the connector. Resistance should be below 6 ohms or so. It may be very small (under 1 ohm). High resistance or ...


10

As an everyday buyer you won't be interested in the high performance end of diesel or petrol, so here goes: Diesel engines typically rev lower and have more low speed torque - so you are less likely to stall off the line, for example. Petrol engines usually rev higher and get more power at 3-4 thousand revs Diesel seems to be getting more expensive - ...


10

The only two stroke diesel i'm aware of is the Detroit diesel. The Detroit diesel does use forced induction but not in the way that you think. From your description it sounds like your describing a two stroke gasoline engine. The engine draws in air into the crank case. Then compresses it and shoots it into the combustion chamber. This setup works well ...


9

Despite any opinions of safety it seems that gas tanks are manufactured to not accept more than 95% of their total volume because of regulations. Here is a quote from the US Department of Transportation Federal Motor Carry Safety Administration Regulation 393.67 Subpart E. (12) Overfill restriction. A liquid fuel tank manufactured on or after January 1, ...


9

Given two engines of similar weight, both operated at their respective optimum efficiency (i.e. maximum mechanical work done per unit of chemical enthalpy in the burnt fuel), you will end up with similar fuel consumption for either engine type. But a Diesel engine will generally offer slightly more power out of this, by giving more torque; that's how it's ...


7

Another difference is that the diesel engines cost more to produce and to maintain. So the diesel version is almost certainly more expensive to buy than the equivalent petrol car, and it usually costs a bit more in servicing. So the rule of the thumb is to buy diesel if you're going to drive more than ~10000km per year or so, depending on fuel costs, taxes ...


7

Be aware that a diesel head gasket is not necessarily a job for an amateur. It is generally not as straight forward as a gasoline engine head gasket. You may need special tools that many amateurs lack -- a torque wrench, for sure. Be sure to consult a repair manual for your particular engine. Some VW diesel engines will have multiple head gaskets ...


7

Most modern diesel engines (ie: engines after mid-80s) require some electricity to run because they are electronically controlled. This is due to computers controlling the fuel charge and monitoring of the engine itself. Without this, the diesel engine has no control. They also require electricity to power the primary fuel pump, to move the fuel from the ...


7

Several reasons: First: Diesels have a very simple operation which is basically more air, more fuel = more power. On gasoline engines you have to worry more about running too lean, too hot, having incorrect timing. And, you generally already have enough air. You run at higher RPMs and suck in more air. Gasoline is much more volatile than Diesel. It burns ...


7

It sounds like you already know why a gasoline engine keeps the fuel/air ratio as close to the stoichiometric ratio as possible, but just for the sake of information for anyone else: The stoichiometric fuel/air ratio is the amount of oxygen required to burn all of the gasoline completely. A "lean" burn leaves some oxygen leftover and a "rich" burn means the ...


6

Besides the weight, be sure that you buy oil with one of the "C" codes in the service symbol. The top half of the ring should say "API Service C-something". Update: The Logo looks like this one:


6

In short, diesel engines tend to be more reliable and more robust. They're also far more fuel efficient than their petrol counterparts. Also, diesel engines may be down on power but what they lose in power they make up for in torque. Torque is more noticeable in an urban environment because of the stop and go nature of traffic. You need quick acceleration ...


6

By far the most common cause of failure of the gasket is overheating. So why would it overheat? Check for coolant leaks in the following engine gaskets water pump radiator pipes Also check for oil leaks or low oil - these can have knock on overheating effects. Check your radiator isn't full of sludge - that could be a cause of the problem, or it could ...


6

You can run gasoline in a diesel motor, but it causes problems. As mentioned elsewhere, when you compress the fuel/air mixture enough, it gets really hot then ignites. With diesel, this is ok, because the fuel burns (relatively) slowly, so it doesn't need to be timed very well. Gasoline, on the other hand, burns really fast. If you consistently ignite the ...


6

Non-turbo diesels lose less power in the Rockies At least according to the SAE J1349 standard. (Calculations shown below). Assumptions Dry air pressure in the Rockies = 90 kPa ( at 3000 ft) Absolute Temperature = 277.15 K ( 4 °C ) This allows us to compute the two quantities, A & B, that are used to determine the correction factors ...


6

Since the diesel has no physical throttle, power is controlled by limiting fuel. Air is always available so any unintended, un-metered fuel will cause the engine to increase rpm and power output. The most common sources are blowby oil and oil leaking from a worn turbocharger, these then pool in the intake manifold. This engine oil gets pulled into the engine ...


6

tl dr: By adding a throttle plate, it creates the vacuum needed to draw in gasses from an EGR valve. Since diesel engines are designed to run lean, they don't need throttle plates to run. They utilize the amount of diesel fuel needed to keep the engine running and to provide the work needed to do the job required of them. One of the inherent issues with ...


6

DEF Diesel Exhaust Fluid is a Urea based fluid that is added to the exhaust ahead of a thermal reactor. Its purpose is to reduce the amount of NOx (nitrogen oxides) in the exhaust. It works as a fuel. NOx is reduced only in rich mixtures. Diesels run lean at all times and therefore have little extra fuel in the exhaust. While the lean combustion mixtures in ...


6

Renault are developing a small 2 stroke diesel with turbo and supercharger. It's name is the Renault 'Powerful' see for example - http://www.enginebuildermag.com/2014/12/renault-unveils-two-storke-twincharged-diesel-two-cylinder/



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