95 E300D, swapped out my driver's side motor mount today, vibration got a lot worse - PeachParts Mercedes-Benz Forum

Texasgeezer · #1 01-24-2018, 08:31 PM

Put in a Lemforder brand motor mount today for the mount that showed wear. New mount only about 3/8" higher than old one taken out ( when compared out of the car ).

Vibration is a lot worse at idle - low rpm's with new mount. Smooths out as rpm goes up.

My old original mount was Boge brand. Mileage less than 70,000. Passenger side shows virtually no wear.

What would y'all do? I don't like the idea of swapping out with different brands, but that might be necessary.

Texasgeezer · #2 01-24-2018, 08:38 PM

Forgot to mention, I've recently replaced fuel lines, shut off vacuum valve, tensioner assembly, and alternator pulley with one way pulley.

A couple of delivery valves are seeping a little fuel. Haven't done that yet because I can't remember who I loaned my new torque wrenches to. Will probably have to buy a new one. I have 4 others but don't trust them for proper torques on the injection pump delivery valves. From what I've read, even new ones are off by a good margin, but they are typically better than hand tightening.

Is there a chance the delivery valves might be causing some idling shuddering?

Diseasel300 · #3 01-24-2018, 08:59 PM

Leaking delivery valve holders can potentially cause idle issues, though the O-ring part is not on the high pressure "delivery" side of things.

How old are your injector nozzles? If the pop pressures are off or if you have a poor spray pattern, you can expect a bit of roughness, especially at idle.

Compression? A cylinder imbalance of >25PSI can contribute to rough/lopey idle. The bigger the imbalance, the more roughness you can expect.

Don't forget that it's an IDI diesel, it's just gonna do what it's gonna do. A perfectly smooth idle probably isn't a realistic expectation. Believe it or not, the fuel you're running can affect the idle quality.

Texasgeezer · #4 01-24-2018, 10:18 PM

I think what bothers me most and makes me suspect the new mount is before with the original mount there was minimal vibration at idle. Now the car shudders along with the engine and the noise is much louder. Before at idle I could hear just the normal engine sounds, now with the new mount I hear the vibration/shuddering.

I guess I'll do the delivery valves. After that if the shuddering still occurs I'll re-install the old mount. If it gets back to minimal noise and vibration I'll try another brand, probably Mercedes or Boge if available.

Any other thoughts on this problem?

Diseasel300 · #5 01-24-2018, 10:37 PM

What kind of vibration are we talking about? Is the engine idling nice and smooth and you're just getting the vibration of the cylinders transferred to the chassis? Or is there an irregular rocking or lurching to it?

If the latter, there's likely a combustion imbalance at the root of the problem. A fresh engine mount is fairly stiff in comparison to the old one and will transfer a rocking motion better to the chassis. The engine mounts in these vehicles is designed to restrain the engine and isolate vibration from reaching the chassis. They're NOT designed to isolate a rocking motion. They will damp it, but not prevent it.

t walgamuth · #6 01-25-2018, 10:31 AM

If your mount is letting the engine go metal to metal the sound and feel will be like a jackhammer hitting your car frame. Maybe you need to change the other mount. You should be able to do a visual inspection and verify if you have metal to metal.

tjts1 · #7 01-25-2018, 10:44 AM

This can happen when replacing 1 of 2 mounts. Do both sides. The passenger side mount gets most of the abuse.

ROLLGUY · #8 01-25-2018, 10:58 AM

Quote:

Originally Posted by t walgamuth

If your mount is letting the engine go metal to metal the sound and feel will be like a jackhammer hitting your car frame. Maybe you need to change the other mount. You should be able to do a visual inspection and verify if you have metal to metal.

The mounts for the W210 chassis are way different from a W123, and don't suffer the same fate of eventually getting metal to metal. The vibration could be just from being new, and will soften up over time. Not the same thing, but could have the same affect: I put new 300D mounts in my 240, and the engine vibration was transmitted throughout the car at idle. I suspect the mounts for the 5 cyl are much harder than those for the 4 cyl. Or it could be that they too will soften over time.

Phillytwotank · #9 01-25-2018, 05:42 PM

Also, a good or bad mount can’t reliably eyeballed with these types of mounts. It’s got fluid in the inside and that can be all gone without changing what the mount looks like on the outside.