'86 560sel low oil pressure, idles rough
 

I just picked up an 86 560sel with 100k miles. The car has a bit of a burble when idling- almost as though it's missing, and the whole car shakes a bit. The car idles at 5-700 rpm. At higher rpm (over 1k), the burble seems to go away. the engine feels strong, the trans. shifts smoothly. I have not driven the car much as of yet.

I just noticed that the oil pressure is low. It idles at under 1 bar, and pushing the accelerator will bump it a tiny bit, but it still hovers below 1.

Oil levels look good.

Do I need a new oil pump? how much of a job is it to install one? I've done a few simple things like water pumps, etc, but never an oil pump in a Benz.

anything else I ought to look for on the 560? I assume that doing the timing chain would be pretty easy once things are apart and 100k it's about due for one, yes?

thanks!!

Before you throw parts at it measure the oil pressure to ensure the gauge or sender isn't reading incorrectly. You can tap into the port on the oil filter housing for the sender pretty easy. With the one piece oil pan, replacing that pump will be a nightmare with the engine in the chassis.

The idle problem is likely vacuum leaks. :rolleyes:

When buying a used 560 it's always a good idea to change the oil and filter and throw in a set of the RECOMMENDED plugs inspecting the old ones for signs of oil fouling. Use good oil with a quality filter as the M117 valvetrain wont tolerate anything less.

You'll also want to replace the little,plastic, cam oiler tube holder downer thingies before one comes loose, seizes the cam, and bends the valves.