LINK TO VIDEO: https://*******/2IC0 - This is with the car in-gear (drive), but with parking brake applied.

Hi guys! New Mercedes owner here!

I've got an issue with my 89 190E 2.6L, and I was wondering if you guys had any idea what might be causing it.. It's RPM drops to about ~525 when you put it in-gear (drive or reverse). It goes up as you give it some gas, but as soon as you're stopped at a light or rolling under 5MPH, the RPM drops. To clarify, it's RPM shoots right back up to normal in neutral or park, or when you give it some gas.

Accompanied by the RPM drop is a moderately loud knocking/rattling sound.

Engine oil, transmission oil, coolant, and brake fluid are all clean.

My mechanic says I've got 2 small oil leaks. One from the head gasket and the other from the crank shaft seal. He quoted me $1500 to fix it.

I think it's a vacuum leak. He said they tried to find one, but they couldn't. Personally, I don't think they did a very thorough job. He also said the mixture is right where it should be, but for some reason he didn't recommend adjusting it.

I'm taking it back to him early next week, because he owes me some work.

I just bought the car about a month ago on Craigslist for $1,500. It's got less than 96k original miles on it, and is in pretty good shape overall. No paperwork on the car when I bought it, but it's got dealership service records in the book up to 50k miles.

So far I've got the following work done on the car:
New hood liner
Tune up (new plugs, rotor, distributor cap)
New serpentine belt
New cooling fan clutch
AC recharged

I was told the oil was changed (with regular) about a month before I got it. The previous owners sounded like they only put enough money into the car to keep it running. It's a shame, because it's such a beautiful car.

I haven't been very mechanically inclined up to this point in my life, but ever since I got this car I've been researching and learning more and more about this beautiful feat of engineering- With big help from this forum, thanks!

Side question: When I get my next oil change, should I opt for the synthetic oil instead of regular? Due to my small leaks, I was told using synthetic could actually make it "worse" -Is there any merit to this?

Thank you for taking the time to read my post and watch my video! I hope to hear back soon!

Best,
scoops190E

 

these old girls need thicker dino oil,i use 15 w40 diesel oil.Does your car have knock sensors?How old is gasoline?a lean condition can ause spark rattle too.hows water pump? all drive belts and parts.