Posted on 12/01/2006 5:49:41 AM PST by Red Badger
Tell that to people who bought GM diesels. there is no necessity involved. Truck engines are tougher because the market demands it and mileage isn't as important.
Mileage is more important to truckers than to JoeBob SUV drivers. Mileage is money in trucking. It just seems to consumers that truckers are unconcerned with mileage because big trucks get 6 to 7 MPG. Well, when you do the percentage improvement of getting a 0.5MPG improvement on a truck that is running 250K miles per year, that's a lot of fuel.
The trucking industry has been aggressively pursuing reduced fuel costs everywhere they can. After going to more efficient engines, like the Detroit Series 60's and their competition, the industry is now going after prolonged idling fuel consumption. It has been habit for truckers to idle their engines overnight in cold weather, because getting a big diesel started in temps lower than 10F is a bear. So more and more trucks are starting to put an "APU" on the truck -- these are very small diesel engine units that keep the big batteries charged, the sleeper and main engine heated and generate 12V and 120VAC for the sleeper compartment. They use very, very little fuel in comparison to idling a 400HP diesel engine overnight.
That's nice, but it has nothing to do with whether diesel engines are inherently more durable than gasoline engines. Small truck (gas) engines routinely get 200,000 miles of service.
Big rig diesel engines are built to be serviced and last forever. You can replace cylinder sleeves as well as pistons.
Uh... I really hate to burst your bubble, but hydrogen is going to turn out to be a huge scam and diversion from reality. Engineers know the truth about hydrogen and it isn't a fuel -- it is only an energy transfer mechanism.
As for hybrid vs. diesel economy -- that's misleading at best, and here's why: hybrids get their economy from using the electrical motor system for the stop-n-go driving in urban settings. On the wide-open road, I'll put an efficient diesel+manual transmission car up against any hybrid you care to name -- and the diesel will win.
And if you really want to win fuel economy awards, what you'd have is a diesel engine hybrid. The diesel could then run at it's optimum RPM all the time, and you'd get the best efficiency in an internal combustion engine available today. The hybrid drive system would give you the best efficiency possible in urban driving situations. You'd suffer a small percentage loss in wide-open, fixed-speed driving tho, but it wouldn't be as bad as what you'll see in a gasoline hybrid.
Or, if you'd like an easier bet, here's one:
I'll bet you $10 or a six-pack of beer that your Toyota salesman doesn't have an engineering degree.
Thanks for that very informative and thorough post!
Some diesels are inherently more durable, some aren't. Please don't get suckered into buying just any diesel because someone tells you all diesels are tougher than gas engines.
I've seen some real crappy diesel engine designs - they might have been heavy, but ultimately they were crap. There are good diesels and bad diesels, and good gas engines and crappy gas engines and how heavy they are isn't always an indication of how long they'll last.
I'll give you two examples: everyone thinks Cat diesels are great engines. And, for the most part, they are.
That is, until you've had a Cat 3208 V-8 diesel. What a piece of crap. After about 2,000 hours, every time you start the wretched thing, you're listening for those "expensive sounds" that tell you it is time to order a re-man.
Or, some people love Cummins engines. Cummins is a good engine manufacture. That is, until you've seen a Cummins 555, another V-8 with a short lifespan.
Most V-8 diesels aren't that good and don't live that long. "Real" diesels are inline 6's. The Navistar V-8 7.3L was an exception - it wasn't as good as an I-6, but it wasn't a complete piece of crap, either. So when Detroit keeps up their obsession with V-8's when they go to diesels, they're doing the consumer no favors whatsoever.
Some diesels used in pickups can only be dry-sleeved (like the Navistar) and some are wet-sleeve (like the Cummins B5.9's in Dodge's). Large diesels are almost all wet-sleeves, as you indicate.
In a gasoline engine, the engine I would love to have in a farm pickup is the old inline-6 Ford 300 cu. in industrial engine. It isn't pretty, but they last forever. I'd take it over most all other Ford engines.
BTW, IMO most of the improvement in engine lifespan in gasoline engines in the last 20 years has resulted from improvements in machining tolerances, coupled with the vast improvement in lubrication technology. Engine oils (good engine oils) have made huge strides in the last 20 years.
What most gasoline engine owners need to do is pay attention to what make filter they put into their engine. If they do, they'll get 200K (and more) miles. If the don't, they won't make more than about 100K. Little I-4's in Japanese 80's vehicles won't make it to 200K miles if they were used hard, even if well maintained. The Japanese used to design their engines to expect no more than about 120K miles of use.
On filtration: Here's a tip from a guy who goes through more filters and oil changes in a year than most engine owners will do in 10 years: Fram filters (the kind you see at Wally-World) are the biggest pieces of crap you could put into an engine. Any Fram filter -- just replace it with a better filter and you're doing yourself a favor. Wix, NAPA, Fleetguard, Baldwin -- any of these filters are good.
Fram is complete crap. Do yourself a favor and demand or use better.
Here's another tip for people serious about getting 200K+ miles out of any car (diesel or gas): take oil samples and send them into a lab. An oil analysis lab can spot engine problems in your used engine oil a long time before you notice outward symptoms. Things like bearing wear, leaking head gaskets, etc -- all can be spotted early with oil analysis.
The only reason I posted to this thread is that some years back my brother bought a GM truck with one of those V8 diesels. He did the oil analysis route, the whole nine yards, and it fell apart in 50,000 miles.
My only point is that the word diesel doesn't automatically mean durability.
There is a type of filtration that is becoming more popular called "bypass filters" that can make diesel engine oils last much longer. It could also be used on gasoline engines, too.
Here's the background (folks, tell me to shut up if I'm borin' ya all to tears here).
The typical oil filter on an engine is called a "full flow" filter. Inside that filter, there is a bypass mechanism to allow the oil to keep flowing through the filter if the filtration media (typically folded/pleated paper) becomes clogged. These types of pleated paper filters will catch all particles down to about 30 microns in size.
Bypass filtration is where you have a filter that catches substantially smaller particles, but you can't push the full output of the oil pump through the filter. The filter can permit only a small amount of the oil flow through it, so there is a bypass valve in the filter mounting mechanism to allow the rest of the oil to go around the filter. These filters can catch particles as small as 10 microns, in some cases even smaller, and really keep the oil much, much cleaner than a "full flow" filter.
Some newer bypass filtration systems can catch particles down to 3 microns. Now we're talking seriously clean oil coming out the backside of that filter.
JR Simplot Company has a rock phosphate mine up in Wyoming. They run lots of equipment, powered by diesels, just as you find in any mine. Most diesel engine manufactures have warranties guaranteeing that the customer, with a verified and company-approved maint schedule, will get "X" hours on the engine before needing an overhaul. Simplot was guaranteed 12K hours on some of their diesels, but was getting less than 8K hours on their engines.
Anyone who knows anything about JR Simplot knows he's not a man to allow nickles to drop through the cracks. Simplot Company demanded the engine companies pick up the warranty rebuild on these engines.
So Cat (one of the companies finding their warranty period was not being met with proper maint/oils/filters) made a study of the situation: instead of using full-flow filtration in the oil, and conventional filters in the fuel/air/coolant on these engines, they put on the highest-restriction/smallest-particle filtration they could. They wanted to filter out everything larger than 3 microns from getting into that engine.
Engine life suddenly jumped to over 20K hours, with no other changes.
This is why I highly recommend people run the best filters they can find/afford in their cars if they want to keep them a long time. It makes a huge difference.
With this level of filtration technology starting to find its way into truck fleets, the fleet operators aren't changing their oil every 5K to 10K miles any more. They're pulling off the bypass filter cartridge, then they add a half gallon or so of oil to make up for what was lost in the filter. (most big diesels use between 5 and 10 gallons of oil -- not quarts, gallons). When they change the filters, they pull an oil sample. The oil sample results tell the fleet mechanics whether the oil needs to be changed.
In some newer truck engines, they no longer change the oil at all. They change only filters, and the engine burns a little bit of engine oil all the time by injecting the engine oil into the diesel fuel. You load up a reserve tank of new engine oil every so often, and that gets metered into the crankcase as the used oil is metered into the fuel intake. This keeps the additive package up to snuff and gets rid of the used oil disposal problem. Burning used engine oil is an EPA-approved disposal method for engine oils.
Ah -- I see. You're 1000% right, of course. That GM V-8 350 was a roaring piece of crap. Put American consumers off diesels for the next 30 years.
Thanks! That question was asked of me by a poster today, so I'll be glad to pass along the info!.........
See Post #48 for filter info......
Don't expect the same from Honda, Nissan and Toyota engines. GM, Chrysler and Ford must compete with high quality engines of their own or 3rd party............Cummins, Detriot Diesel, etc........
Part of the high cost of diesel in the US is probably due to the fact we use diesel oil from fractional refineries to produce gasoline. Diesel is cheaper to produce, but demand for gasoline takes up part of the diesel supply. More folks buying diesel would reduce cost.
Also, we've recently switched (Oct 15th) to Ultra Low Sulfur Diesel, so supply is probably still ramping up.
Finally, we are in winter, and diesel is being bought for home heating oil.
You remember those 350 ci "diesels" that GM made? What piece of Murtha that was.
Almost as much as their 4-6-8 engine. Another GM wonder.
I was thinking of trading my Corolla for a VW TDI back when I was driving more than 20,000 a year for work. But then diesel was also substantially LESS expensive than gasoline at that point. Yesterday, I happened to notice that diesel (the new ultra low sulphur stuff) was almost fifty cents a gallon more expensive than gasoline!
Mark
Could you add me to your list.
Godspeed, The Dilg
And I believe that the regular maintanance it more expensive for diesels. For instance, don't you need to use special oil for diesels? And due to the higher compression ratios, isn't oil fouling a bigger issue for diesels than gasoline engines? So you need to be sure to have more frequent changes?
Mark
Rachel's cute, but I've had enough of the "Eeee Veeee Ohhhh Ohhhh" and it would be a bad thing to be around her the next time she said it... On the other hand, I'm in love with Giada and Sandra Lee! Wow! Too bad they're all married :-(
Mark
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.