Can air enter the fuel delivery system? - Page 2 - PeachParts Mercedes-Benz Forum

123 300D driver · #16 11-07-2003, 01:52 PM

Marshall,

No, the valve-adjustment that I did had no effect on my random missing problem at cold startup. This problem is random...first it misses a few times after starting, then about 3 sec later it misses (one power stroke) again and about 4 sec after that it misses again...and so on until after about 20 sec it no longer misses.

Adusting the valves had no effect (worsening or improving) on the random missing problem, but it does idle a bit smoother than before overall.

I am convinced that there is air getting in there somehow, because the missfire seems so sudden (the engine makes a real lurch when it happens and there is no resulting smoke because of it).

I can live with this problem, but I am just puzzled by it.

Gary

#17 11-07-2003, 03:42 PM

The most common source of air is a bad hand pump! Pump you hand primer and if it leaks at all - REPLACE it! There are other potential air sources (leaky fuel lines or connection to the filters/tank etc.) but they usually leave drippings on the ground.

Marshall

123 300D driver · #18 10-21-2005, 01:51 PM

I solved my random missing or sputtering engine problem recently. A new timing chain and tensioner did the trick. The old tensioner still seems OK tho.

My old chain was stretched about 9 degrees which would make the injection late by about 4.5 degrees. After replacing the timing chain the engine:

1.) never misses or sputters any more,
2.) idles smoother and a bit faster,
3.) emits less visible smoke at ALL times,
4.) has a bit more power, and
5.) has a bit better fuel economy.

I didn't have to touch the pump timing and I am assuming it has never been adjusted. What got me motivated in replacing the timing chain was a ticking sound coming from the camshaft sprocket area while idling. This turned out to be the timing chain master clip link amost completely failed. I think the ticking sound was the master link flopping around the various sprockets at each revolution. Only the center link was still in there holding the chain together.

If anyone is interested, I still have the old chain and I could post a pic of it.

boneheaddoctor · #19 10-21-2005, 02:08 PM

Quote:

Originally Posted by 123 300D driver

I solved my random missing or sputtering engine problem recently. A new timing chain and tensioner did the trick. The old tensioner still seems OK tho.

My old chain was stretched about 9 degrees which would make the injection late by about 4.5 degrees. After replacing the timing chain the engine:

1.) never misses or sputters any more,
2.) idles smoother and a bit faster,
3.) emits less visible smoke at ALL times,
4.) has a bit more power, and
5.) has a bit better fuel economy.

I didn't have to touch the pump timing and I am assuming it has never been adjusted. What got me motivated in replacing the timing chain was a ticking sound coming from the camshaft sprocket area while idling. This turned out to be the timing chain master clip link amost completely failed. I think the ticking sound was the master link flopping around the various sprockets at each revolution. Only the center link was still in there holding the chain together.

If anyone is interested, I still have the old chain and I could post a pic of it.

Sounds like you narrowly avoided an impending disaster...