Engine vibrates but runs really good - PeachParts Mercedes-Benz Forum

michaelwoodcock · #1 08-05-2012, 11:05 AM

Hey guys, I'm not sure what the problem is. The engine seems to run perfect. It has no hesitation, maybe just a slight bit sluggish off the line but I can't tell for sure as it runs the best the car ever has while I've owned it. I did a diesel purge, valve adjustment, new air filter, new air cleaner mounts. the vibration got reduced significantly with new air cleaner mounts & the valve adjustment (did them both at once) but the vibration is still there. I am assuming it could very well be my left side engine mount, or engine shock, maybe my injectors need to be rebuilt, any ideas? also the primary fuel filter has air in it all the time, possible cracked hose?

michaelwoodcock · #2 08-05-2012, 11:20 AM

forgot to mention it smooths right out once I get going

psaboic · #3 08-05-2012, 11:28 AM

I would lean toward engine mounts. Not to hijack the thread, but I have a similar issue with the engine. At 1800 -1900 RPM, it feels like I have an out of balance tire. I speed up or slow down and the vibration goes away. I haven't looked into it yet but I'm thinking valve adjustment (it is due) or possibly injectors

Fulcrum525 · #4 08-05-2012, 11:59 AM

At 246,000 miles I'd second the engine mounts but if you do the job replace both at the same time.

sixto · #5 08-05-2012, 01:18 PM

The shocks have no bearing on engine vibration at idle. Their job is mostly to subdue the engine's wag when you shut if off.

If you have the old style lift pump, make sure the plunger is secure; that is, threaded into place.

Do you have an updated rack damper?

Sixto
87 300D^2

michaelwoodcock · #6 08-05-2012, 03:26 PM

Sixto,

Old style lift pump, plunger appears secure. I do not have an updated rack damper, think this may be part of the problem? I had adjusted mine earlier back when I had bad air cleaner mounts, should I try again or just order a new one?

Thanks,
Mike

sixto · #7 08-05-2012, 03:44 PM

I had similar symptoms when my old style lift pump plunger backed out, that's why I suggested it.

I replaced the silver rack damper for a gold one for the heck of it. The difference in spring pressure was dramatic but it didn't make a difference in my car that was idling smoothly in the first place. I'll defer to the experts whether this is a wise thing to do but you might turn the damper further to see if it makes a difference. IIRC idle speed drops with too much damping. The point of the exercise though is to see if the existing damper can get idle to drop. If not, it might be too tired to do a proper job. Count turns to you can get it back to how it was.

Sixto
87 300D^2

Zacharias · #8 08-05-2012, 10:12 PM

Can you describe the vibration a bit more? Is it generalized through the car or just through one area?

michaelwoodcock · #9 08-06-2012, 12:48 AM

The vibration is mostly noticed in the headlights moving up & down, and the hood vibrating. But there is a transmission of vibration into the whole body of the car. You can feel a slight vibration from the drivers seat. When stopped, if I put the car in park the vibration lessens. Once I get going above 5 mph or so the vibration is completely gone and the car drives perfectly.

Cheers,
Mike

Pabster · #10 10-20-2012, 09:20 PM

I had a similar problem with the 1997 E300D when I first bought it. At a stop or in neutral, the car vibrated like it had a 8.0L racing engine in it that didn't like to idle and wanted to run hard.

I knew it was an air leak since it didn't vibrate like this when it first started up, but began after the car engine was at 80c. At 80c, it didn't respond well when giving it gas and it would sort of "chug" its way to getting up to speed regardless how much I pushed the gas pedal.

This took care of it:

1) Replaced all fuel lines in engine area as the older ones were hard and discolored.
2) Cleaned out the intake manifold, ugly job!
3) Replaced cracked and beat up oil breather fittings into intake manifold
4) Replaced crushed washers and rubber o rings on the fuel delivery valves.

Then the big "idling" vibration went away and the car is instantly responsive when I push on the gas pedal.

I hope this helps.

Pabster

mach4 · #11 10-20-2012, 10:28 PM

I'll be watching this closely, as I've got the same issue... vibration between 1500-1900 rpm, mostly under power, then smooths out really nicely. Had a significant idle vibration that new motor mounts took care of but didn't help the starting up vibration.

nscarr · #12 10-21-2012, 12:00 AM

I've had recent experience with vibration / shaking issues, and I found the intermediate shaft to be bad. I would definitely pull the vacuum pump and check the timing device for play--only takes an hour and a new gasket. Pull the timing device in and out, shouldn't be more than 0.12 mm (thanks to Diesel911, see http://www.peachparts.com/shopforum/diesel-discussion/258062-second-vacume-pump-help-trip-toronto-3.html)

Diesel911 · #13 10-21-2012, 12:28 PM

I had shaking that got worse after the Engine was hot and at idle speedl ran OK after at higher speeds..

1st I bougth a new Governor Idle Damper Pin but it was minimal in helping

Raising the Idle speed within the upper normal rang, Adjusting the Valves and rebuilding the Injectors took out the bulk of the shaking.

New Motor Mounts and Transmission Mounts took away some more shaking. This is not a recommendation but believe it our not I have URO Motor Mounts for 5+years. I have Lemfoerders to replace them when the time comes.

I had a small Air Leak and replacing the Fuel Inlet Took care of that. The Car came with a new style Hand Primer so I did not haveto replace that. If you replace it get only a Bosch one not one of the Copies.

After doing all of the above stuff I found that the Rack/Governor Damper Pin was able to remove some additional shaking.

So there can be a bunch of cuses for the shaking. Most people start with the free or cheapest stuff first.