Why is that? It would seem to go against what I have been taught.
There's a lot of wear and stress on everything from the cylinders to the bearings when engines are constantly accelerating and decelerating.
Why is that? It would seem to go against what I have been taught.
Just how do these machines endure this and some of them for several thousand hrs ....???
You are spot on with the relative strength of diesel engines to gas. A small displacement 4 cylinder diesel will weigh as much as a v8 gas engine. All that rigidity has to help.The carbon in a gas engine is abrasive, adding to engine wear.
Additionally due to compression ratios typically twice as high as gas engines, engine components must be built much stronger. This rigidity of components contributes to less engine wear
All this said, I still agree with the oil change nature of this thread. I am an oil change fanatic. I always pull the drain plug when the engine is completely warmed up and let it drain overnight. Those last few drops are the gunkiest of what comes out. I have achieved very good engine life from my engines which have always had such frequent changes using my extreme method.
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The good ol' days are right now.:thumbsup:
You are spot on with the relative strength of diesel engines to gas. A small displacement 4 cylinder diesel will weigh as much as a v8 gas engine. All that rigidity has to help.
Don't forget that 98% of engine wear comes from dirty air and not dirty oil. (and most dirt in dirty oil is from the air) Sure, lubricants are important, but not like clean air. If you pull the air filter out and run 2 hours in a dusty environment the engine is shot. But you can run with old oil indefinitely as long as the level is kept up. Compare air filter tech from the 60's and 70's when engines started to smoke at 70k and were shot at 100k with modern filters in cars that go 2,3 and even 400k miles.
(I have suspicions about the accuracy of your statement on carbon being different in a gas engine from a diesel. That's never ever been brought to my attention before. Do you have any details on it? If it really is correct, I'd like to understand it)
Yes, they sure are. Or as a buddy says, "They don't make them like they used to -- Thankfully"
The difference in gas engine and diesel engine byproducts of combustion is quite obvious to the naked eye. Take apart an engine of each category and examine everything. The carbon in a gas engine is solid and dry. The "carbon" which is not really carbon in the diesel combustion process, is an oily goo. It's quite easy to see which one is significantly more abrasive.
As far as modern engines vs the older engine wear goes, the single most important improvement that is the most responsible for today's long engine life is fuel injection. With the old carbureted engines, raw fuel found it's way to the cylinder walls during cold start up. This fuel washed the oil off the cylinder walls. Sure, today we have better lubricants, better engine construction and better machining processes, but FI is the biggest factor. The lack of a choke in a diesel engine along with the fact that diesel fuel is an oil as opposed to a solvent is one of the factors that has always led to longer diesel engine life.
Todays automotive gas engines come VERY close to the longevity that automotive diesel engines have enjoyed for decades.
Interesting observations. I have taken apart a lot of gas engines (hundreds) and dozens (maybe more?) diesel engines. Can't say that I've reached the same conclusions as you. Poor condition diesels suffer from a lot of carbon build up. I've only seen the oily residue on ones that have injectors with worn nozzles or low pop off pressure. Other than those, the carbon residue on diesels was typically worse than on gas engines.
Have you much experience looking at engines from the pre-unleaded fuel days? Your observations may not be the same with them. I remember in '78 or so taking apart my first un-leaded fuel engine with 100k miles and being shocked at how spotlessly clean it was. The older leaded fuel used to really gum up and make a mess where the new unleaded keeps everything really nice.
You may be right on choke equipped engines, but they went the way of the dinosaur when the carburetors went extinct. However, the longevity of the last 10 years of so of carburetor fed engines was on par with the FI fed engines of the day. I'd still put faith in improvements to air cleaner tech as one of the more important aspects of engine longevity.
What's the real reason? Dunno. It's probably 100 different little things that all together have made the big improvements over the past 35 years. There have been many changes from air filters, oil quality, fuel, FI, etc etc etc all of them together have sure made cars reliable!