Incomplete Combustion - PeachParts Mercedes-Benz Forum

Jmana · #1 03-04-2007, 04:48 PM

I am having an issue with my 300D that is causing terrible incomplete combustion. It has terrible grayish white smoke at idle, and the exhaust smells horribly like unburned diesel. It gradually began doing this. The engine also nails terribly especially when in gear at a stop. I replaced the chain recently, and I think this all started about 2 months after replacing it. The engine runs much smoother on vegetable oil for some reason. I am thinking that maybe an injector or two is clogged. There is a noise at the rear injector that sounds like someone trying to suck the last bit of soda out of a straw, is that a sign of a clogged injector? It also began getting hard to start, and also began having no power, to the point were I was afraid of somebody rear ending me. So I took off the ALDA, and this solved the power issue, but it now smokes even worse, and has terrible mileage. What could the issue be?

#2 03-04-2007, 05:24 PM

Check your injection timing.

Jmana · #3 03-04-2007, 07:41 PM

I had checked the injection timing when I put the new chain on, and it was right on. Do they go out of whack after a few months?

#4 03-04-2007, 07:44 PM

The can may have fully seated itself or "broken in" after the first few hundred miles.

psfred · #5 03-04-2007, 10:57 PM

Check valve and injection timing -- it should not jump injeciton timing, but if it was set and the bolts aren't tight there is no reason to assume it would not change.

However, this being a 603, are you using coolant with no obvious leaks? The head cracks easily on this engine, and they also blow head gaskets, and one place that goes is the compression ring on the rear cylinder.

Your symptoms are low compression, or very early (not late) injection timing.

If you have sucking/blowing noises on the rear, I'm betting on a head gasket -- usually you get oil leaking out under the chain tensioner and at the right rear corner, too.

I just replaced mine.

Peter

dannym · #6 03-05-2007, 10:29 AM

I agree with the injection timing.
The chains are designed to break in. That's why you have different specs on chain stretch for new and old chains.

If the you or the PO retimed the pump with the old chain it will more than likely be out of time with the new chain.

Did you check for a woodruff key when you put the new chain in?

Did you replace the guides too?

But then again I had some of the same problems you described when my tank vent clogged. Does your fuel cap suck when you take it off?

Danny

Jmana · #7 03-05-2007, 09:21 PM

My car doesn't lose any antifreeze, so I don't suspect a bad head or gasket. The injection timing being off due to a newly installed chain breaking in does make sense. I really don't have time to pull the fan off and get everything lined up in order to check the timing again, but I was thinking that if the chain stretches, then the timing should be retarded, right? So I suppose I could just go straight to advancing the injection timing to see if it makes the smoking stop. But that's where the problem is, I cannot find a definitive answer on how to adjust the injection timing for the 6 cylinder. If I want to advance it slightly, how do I go about doing this?