Need opinion - Please read! Thanks...
 

I own a 1987 300E... I just purchased a new battery, new alternator... When I start my car, the engine shakes and there is a nasty sound; the engine feels like it is fluttering... a few minutes later when the engine warms up, everything is normal.

What do you guys think it is? Any suggestions? Thanks.

Was the engine doing the same sound BEFORE you installed the battery/alternator?
I wonder if the belt was routed correctly? or if the alternator pulley was damaged. Belt tensioner?

If the motor shudders when cold, and only when cold, then likely carbon in the cylinders could be the culprit. But I'm interested whether this problem began after your reported repairs...

Check the motor mounts. They will cause all kinds of noises. Also if it runs bad when first starting check the fuse in the OPR.

How is it shaking up today?

stan, what is OPR?

OPR, often called OVP relay = over voltage protection relay. (unless someone has a better anagram)

Joe,

There's a black plastic cover behind the battery (late 80's 300E, maybe others). It comes off easily. Once out of the way, you'll see the relay with a 10amp fuse on top of it under a clear plastic cover.

Hope this 10 cent fuse solves your problem.