Last night, I took my 1991 Mercedes 190e 2.6L on a test drive last night after finally installing all the body panels and fixing an oil leak. Made kind of a boneheaded decision before I took it out, We lost one bolt to the fuel distributor cap, but it seemed to be on therepretty tight with the two so we wanted to see if we could knock the bolt out of the engine bay by driving. We also had lost oil due to the leak, so then we put in some old, dark oil that was originally in the car.

We drove around with no issues for quite a while, but then after speeding up and shifting, the engine started shaking bad, it now shakes when driving, but shakes a lot worse while in idle. Everything connected to the engine shakes, and this isn't just some minor RPM vibration.

I know I've made some stupid decisions but please let me know any advice you have : (

 

Sounds to me like it might be a bad engine mount that needs to be replaced.

 

Thank you, thats kinda what I was thinking.

 

Sounds like you rushed this job in a major way. If it is shaking violently it is probably not firing a cylinder or two. See if this might be the case and make sure the sparkplugs are in the correct order and all firing.

Not sure what you meant by missing one of the FD cap bolts. Maybe a picture would help there.

 

Thinking about it more, it sounds like you might have multiple issues going on. See what improvement a new engine mount achieves. If there's no improvement with a new engine mount then it's likely a misfire as noted by dolucasi. I agree with dolucasi that you'll need to recheck your spark plugs to make sure you have them in the right firing order. Make sure that the spark plugs you're using are compatible with your car. W201s can be picky bout spark plugs. Also make sure that your spark plug wiring is in good condition with no fraying of the wiring and that all of the wiring connections are clean and tight. . You most definitely also need to change out that old dirty oil. Continuing to run your car with old, dirty oil is a recipe for more engine trouble. A loose distributor cap bolt running around your engine is also worrying. It could get into a wrong sport and cause some serious engine damage.