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-   -   Why do diesels shake?? (http://www.peachparts.com/shopforum/diesel-discussion/143054-why-do-diesels-shake.html)

Diesel Giant 01-19-2006 05:35 PM

Several factory. Odd number of cylinders, its a diesel, and a not very robust engine mounting system. After wrenching on these for some time, I really think the engine mounts are a joke. Go look at a Dodge Cummins powered truck, they have some stout mounts. I have NEVER had to replace one or even see one go bad.

Brian Carlton 01-19-2006 05:48 PM

Quote:

Originally Posted by Diesel Giant
............and a not very robust engine mounting system. After wrenching on these for some time, I really think the engine mounts are a joke.

The nature of the mounts dictates the problem. If you need a soft mount that isolates the engine from the frame, by definition it's going to take a beating. It's not easy to engineer a "robust" mounting system that is simultaneously "soft".

I'm not familiar with the Cummins, but, you can rigidly bolt a 6 cylinder engine to the frame and not feel much vibration from it.

intelligent 01-19-2006 05:54 PM

At Idle, with the stereo on you cant tell mine apart from a well tuned gasoline engine. It is perfectly still and idles softly.:) As a matter of fact, many people are shocked to learn that it is a diesel. Mine is a 6 cylinder though and has pretty good power. It will GET UP AND GO when I want it to and then you'll hear it. I hate to sell it because it is so perfect and one rarely gets lucky to find a car and the engine in such pristine condition but I would really like to have a 1999 S500.:greedy:

Diesel Giant 01-19-2006 05:59 PM

The Cummins is not a rigid mount, but the mounting system is a very heavy duty unit, but does have a rubber isolator just like the mercedes. I think the way the load is spread out from the engine side on the Mercedes is not adequate. The rubber could be just as pliable but maybe a different compound.

Brian Carlton 01-19-2006 06:01 PM

Quote:

Originally Posted by Diesel Giant
The Cummins is not a rigid mount, but the mounting system is a very heavy duty unit, but does have a rubber isolator just like the mercedes. I think the way the load is spread out from the engine side on the Mercedes is not adequate. The rubber could be just as pliable but maybe a different compound.

I agree with you there. The load is very concentrated on a narrow portion of the rubber and the longevity is not present. But, the mounts are not costly and, usually, are not that difficult to change........especially with a lift.

Diesel Giant 01-19-2006 06:04 PM

Brian,

How the heck do you reply so fast?!:eek:
Does your computer "ding" when someone makes a post?

Yes the mounts are cheap, but I like the idea of never having to change them or mayby only once in the cars life. I remember that when I sold my '73 Camaro it still had the original mounts. I like that.

Brian Carlton 01-19-2006 06:57 PM

Quote:

Originally Posted by Diesel Giant
Brian,

How the heck do you reply so fast?!:eek:
Does your computer "ding" when someone makes a post?

Yes the mounts are cheap, but I like the idea of never having to change them or mayby only once in the cars life. I remember that when I sold my '73 Camaro it still had the original mounts. I like that.

I just sit here and wait for you to post........Russell.......didn't you know??:D

For sure........never changing them is less costly than changing cheap mounts!;)

Diesel Giant 01-19-2006 06:59 PM

Yea I thought so.:P

You must be in the computer field and able to be available so quickly. I use to but no no more. I have 2 more quarters till I get my refrigeration diploma, then off to the races.

Brian Carlton 01-19-2006 07:16 PM

Quote:

Originally Posted by Diesel Giant
Yea I thought so.:P

You must be in the computer field and able to be available so quickly. I use to but no no more. I have 2 more quarters till I get my refrigeration diploma, then off to the races.

.........no computers for me.

.........check the profile.........it's just slow around this time.;)

TheDon 01-19-2006 07:34 PM

ive always wondered why big rigs shook when they started up.. its cool seeing a big 15 foot thing shake like a dog starting up.. heh i rember playing with my toy trucks as a little kid .. id have a whole truck stop and all.. fuel depot.. diesel 1.10 a gallon and id pretednt to start them up .. make them shake a little and stuff..


i love it how my diesel shuts down.. it gives a nice little shake..

86560SEL 01-19-2006 08:38 PM

Agreed! I had a 1981 Toyota Cressida 4dr sedan with a 2.8L inline 6-cylinder. The engine was as smooth as silk. Even when it blowed a head gasket and was running on 5-cylinders, it was still smooth. :D

What a car it was. Too bad the head gasket went. I gave it to grandpa- he knew a guy that was going to repair for him at a low rate, but the guy never did it. Grandpa did not need the car, so he sold it to his neighbor for $200 who was going to repair it for his granddaughter. She got into some mischief and he sold it from under her.

I have no idea where the car is now.


Quote:

Originally Posted by Brian Carlton

A six cylinder in-line engine is perfectly balanced. Doesn't matter if it's gas or diesel, they run perfectly smooth due to the inherent design of the engine.


Jim H 01-19-2006 09:13 PM

Quote:

Originally Posted by TheDon
ive always wondered why big rigs shook when they started up.. its cool seeing a big 15 foot thing shake like a dog starting up..

Somewhat Off Topic, but Harley V-Twin engines shake like crazy from torque pulses.

Old British vertical twins, ditto. Sometimes the front fender would be a blur at idle, there was so much movement. The, with added rpm the torque pulses would change frequency and the bike would seem smoother, for a bit, until at maximum revs the handlbars would seem to get as big as the big end of a baseball bat.

123c 01-19-2006 10:55 PM

Quote:

Originally Posted by Wasuchi
Some 4 cylinders are smooth, like a lot of Subaru engines. But then again they aren't inline engines either, they're a boxer or oposing design.

My Subaru Engine is very smooth, no vibration at all, with 200,000 miles, and original motor mounts...

braverichard 01-19-2006 11:13 PM

Quote:

Originally Posted by Brian Carlton
Exactly. They need very good isolation mounts if the four cylinder is not going to be felt by the driver. Personally, I've observed that the newer Camry's and Accords do a fantastic job with this.

Very correct on this. I have driven the newer (2002 and later) Camry with both engine options and couldn't tell the difference. Test details by Consumer Reports later revealed to me that Toyota has mastered NVH control so well that its four cylinder engines are as smooth as the six cylinder engines! These guys are amazing in their never ending fights against NVH.

Diesel Giant 01-20-2006 05:28 AM

Big rigs are different. They are inline 6 cylinders, but they have a HUGE amount of mass to get moving compared to our cars.


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