Old engines vs new

Why does an older enginr(class 8 diesel) vibrate more than a new(newer) motor, same manufacturer?
i.e. what changes are happening as an engine ages/wears
that increases vibration/shake?
thanks gary
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Better motor mounts - and truck shock absorbers?
If nothing else, less wear on the rings and better valve adjustment.
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Ignition might be less effective on older engine (missing "bangs" leading to more shakes)? Something out of balance? I had a blade come off the fan at speed on a truck once - the resulting vibration was astonishing.
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wrote:

I would first investigate everything that surrounds the engine, for poor damping and resonance.
i
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Probably several things , like motor mounts, cab mounts and such. The fuel injection system has a lot to do with it. With age the injectors and the fuel pump wear. The cylinder balance changes and you have irregular fuel outputs to each cylinder. New engines which are more stringent emission wise are new and have more exact fuel outputs , thus a smoother engine. Once had a new Mack exhibit right front tire imbalance. Replaced tire and rotor. Nothing helped. Around 45 mph the truck would start vibrating. Pulled injection pump and the fuel balance was off. The engine would rock in it's mounts giving you the sensation the right tire was bad.
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A newer computerized diesel will have better fuel metering and atomization. Also, tighter injection timing. Not to mention better engineering of the engine mechanicals, better balancing, etc. No mystery. JR Dweller in the cellar
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Have to agree here diesel computer controls are dam good today, the after market chips/sensors that bolt onto modern truck diesels will pump up the power of stock trucks alot. You can get some BIG power gains with chips/sensor upgrades. This is common on the smaller trucks but I am sure the larger trucks are using tight controls also, all in an effort to save fuel. 1 MPG gain would mean a shit load of money to a big fleet.
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snipped-for-privacy@hotmail.com wrote in news:nr6l42dk9piggu2iph2vtpks8ofqqjd92q@ 4ax.com:

Much tighter tolerances on the parts, including balance influencing issues such as piston and connecting rod weights and clearances. There has been a large jump in injector technology, meaning better atomized fuel. The EPA regulations have required a change to a much higher compression ratio, and this has resulted in basically a brand new design of the engines from the ground up. In order to take the increased loads, all the other parts of the engine have to be beefed up, which damps vibration. Gone are the aluminum pistons with a cast ring insert, replaced by, at first a 2 piece steel/aluminum skirt piston combination, and as the latest round of EPA tightening came into effect, an all steel piston. There is another round of EPA tightening due this year, which will require changes beyond that as the diesel manufacturers again bump compression ratios in order to clean up exhaust emissions.
The side benefit to all of this, is a more powerful engine that uses up to 20% less fuel than it's predecessors.
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Think about 20% fuel savings. In todays world that is a great selling point.

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My dad's 63 190d had (from memory) a cr of 21:1. Are today's diesel engines any higher?
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Yup. But, I am not sure of the exact number. The change to a special steel alloy was to prevent melting of the piston at the much increased compression ratios.
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diesel
steel
Steel pistons ? - that's a new one for me !
AWEM
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Andrew Mawson wrote:

Looking at the caterpillar site their engines seem to have around 17-18:1 but they're also turbocharged.

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Yup...been that way for a few years. Like I said, at first it was a 2 pc steel crown with an aluminum skirt. Now they are 1 pc steel.

Yes, and they run quite a bit of boost.
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Anthony wrote:

Seems rather obscene to say the EPA is driving such improvements(?)
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to 20% less fuel than it's predecessors.

Nope..tis the fact of the matter.
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snipped-for-privacy@hotmail.com wrote:

Electronic Fuel Pump instead of mechanical ? New Dodges have that and are quiter than their older counterparts,
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wrote:

Totally different fuel system: High Pressure Common Rail - the same basic system used on the Navistar [Ford] and Isuzu [GM] light diesels and not applicable to the engines used in a Class 8 [Peterbilt, Kenworth, Volvo, Freightliner] truck.
Carbon buildup, ring wear [non-uniform compression loss], uneven rod bearing wear, bad valve timing from extended Jake-brake use ... any/all could be factors in addition to motor-mounts and, even, front shocks.
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