M130 (Zenith) Vibration

[OunooiZA]

Hi All,

New to the forum and needs some assistance, if possible.

So long story short, I bought a 72' W114 230.6 Auto that had blown the motor. She was then fitted with a rebuilt W108 280s with the dual Zenith carb setup. She runs beautifully, and starts easily hot or cold.

BUT, the engine has a vibration which I cannot get rid off (almost like a misfire). I've done the following:

- Changed the coil
- Changed the ballast resistor
- Gapped the plugs
- Replaced points
- Replaced condenser
- Adjusted the timing (She seems happiest at around 8 degrees)
- Replaced all vacuum hoses
- Adjusted idling (Which helped)
- Replaced engine mountings
- Replaced the gearbox mounting
- Replaced subframe mountings

She happily cruises at 120km/h without missing a beat, don't use oil or coolant.

Any pointers or advice on what else I could possible check?

[stickandrudderman]

I once had an engine that vibrated terribly. Turned out someone had fitted the wrong flywheel.....

[OunooiZA]

Flywheel is what came out of the W108 with the engine, so it should be the correct one.

[Peter]

Other options that you didn't mention but probably have looked at:
the pulleys, the v-belts, alternator, air conditioning compressor and the correct mounting of the alternator and air conditioning compressor bracket.

Loose bolts of the A/C compressor mount caused severe vibrations in my car.

[OunooiZA]

Thanks Peter, the car doesn't have AC.

What should I look out for on the Alternator mounting/setup?

[Peter]

I would run the motor at different RPMs and then feel "old fashioned" by hand.

If the alternator vibrates, it may be due to the bearings or (mounting) bracket. But v-belts and pulleys are also suspect. If all is in order and the engine still vibrates and the ignition timing is correct, check the compression per cylinder.

[roymil]

 for a very short time you could just remove all the belts and then start it up to see if the vibration changes or goes away.   Of course, you don't want to do that for more than a few minutes since the water pump would be disabled, but a couple minutes should be long enough to feel a difference if its due to any of the rotating accessories. 

[ja17]

Determine for sure if it is an engine misfire or a real vibration. Pull the plug wires one at a time. If you find that one or more make no difference, then it is most likely a engine miss and not  a balance Problem.

[cfm65@me.com]

Ounooi, Check daai balancing disk voor op die krank.

Years ago, a friend bought a 280SL with a 220SE engine. The 280SL/M130 engine was in pieces in the trunk. After the original 280SL engine was rebuilt and refitted in the Pagoda, it had a bad vibration.
I was asked to take a look and found that during the swap, the 220SE balancing disk was accidentally fitted to the 280SL engine.
Regards
Chris
Cape Town

[OunooiZA]

Thanks guys for all the insights.

I will have a look at them all this weekend.

Another question:
Is the rubber damper on the front of the crank balanced unique to that specific engine?

[OunooiZA]

Vehicle doesn't have AC or Power steering (I do have a complete power steering system that will be fitted later)

What should one look out for on the Alternator mounting brackets?

[OunooiZA]

Very good idea, I will try it as the car only has one v-belt powering the alternator and waterpomp.

[OunooiZA]

Thank you, I've done that and makes no difference, other than the engine running worse when each lead plug is pulled. So I think I can eliminate an actual misfire.

Plugs, leads, condenser, points, coil and resistor have all been changed as well which made no difference to the vibration.

[rwmastel]

Thank you, I've done that and makes no difference, other than the engine running worse when each lead plug is pulled. So I think I can eliminate an actual misfire.

Plugs, leads, condenser, points, coil and resistor have all been changed as well which made no difference to the vibration.

If you are going to reply to a series of messages with your own series of messages, it might help to use the "quote" button so people can see what specifically it is that you are replying to.