'96 E300D, sluggish performance, unstable idle, noise
 

Just bought a '96 E300D (OM606 non-turbo).

Some small issues:

1. The car feels very sluggish. Yes, I know it's not a fast car by any means (I used to have a E250D!), but it feels too weak to have those 136 hp. Even going uphill on the highway at 60-65 mph demands "flooring it" to maintain speed. Fuel lines seem OK without bubbles.

2. Rattling noise on cold engine. Not valve lifters, it sounds a lot like the tensioner noise, but pushing on the tensioner using a screwdriver does not make much/any difference to the noise. Does the OM606 have the clutch alternator pulley that can cause noise too? The noise seems to go away when the engine warms up.

3. The car idles stable - but when the AC compressor is kicking in, it will surge for half a second before stabilizing again. Same goes if quickly giving the throttle a "blip" when it goes back to idle position.

Any advice for those three issues?

1 - Start with a new fuel filter.
2 - I think it has an over running pulley on the alternator. I replaced the one on my 98 E300 but don't remember the symptom.
3 - As long as it blows cold I would not worry too much about the a/c.

You can take the aux belt off for a short period, this will help pin down noise, as for lack of power could be many things - what is the milage?

The 96 E300D does have a clutch pulley. As for being sluggish, you might want to check the resonator flaps in the intake manifold to make sure that they are functioning correctly. Good luck!!!

I have the Bosch alternator, not the Valeo. When I check the part number for the Bosch pulley, it looks like a normal pulley - the clutch pulleys I find are all marked for Valeo and cost around $50 compared to $30 for the Bosch pulley. Do you know anything more about this?

There is a BIG difference in how the engine will idle without the proper clutch pulley installed.



The clutch pulley allows the alternator's heavy rotor to overrun, absorbing shock, each time the alternator cycles on and off (about 3 times per second). The result is smoother idle, no belt chirp, increased life of alternator, power steering pump, water pump, sepentine belt and automatic belt tensioner.