OK, so the trouble never ends.....

Anyhow, i did a headgasket on this car two months ago. I have been noticing lately the following:

1-The rpm seems to fluctuate at idle when in P. it is more prominent when in drive while at a traffic light....

2-For the first few seconds after the car starts, it smells really bad. No smoke or anything, but the smell is strong from the exhaust. no oil dripping on the exhaust, no drips on the floor, i don't think this is burning oil smell either.,,,,

3-There is oil in my intake. i also found that my IAT sensor is covered with soot and oil. i did clean my intake really well when i changed the head gasket,,,seems the issue is back....

so are these issues related? I am very worried about the smell part the most. the car has a bit more oil than it should as i have not gotten a chance to take out the extra oil yet (it is at the full mark)....i also feel that he gas millage is not good.......

I am tired of this car already....any ideas?

thanks,

__________________
1993 300E, 2.8 M104 .....

If the IAT sensor is downstream of where the PCV system picks up it's air, the PCV system is your culprit.

__________________
A.S.E Tech A1,A6,A7,A8 & MVAC 609 + EPA 608

Unless stated otherwise, any question I ask is about my greymarket 1985 380SEL.

The IAT is exactly after where the intake tube crosses over the valve cover...the valve cover vents into the intake cross over tube rigth before the IAT ....i was not aware that these cars had a pcv system other than what i described. nothing is changeable or adjustable in that setup. am i missing something?

thanks,,

__________________
1993 300E, 2.8 M104 .....

If it's like any other engine with a PCV system, there's a spring-loaded check valve there somewhere that needs replacing.

If it's stuck open, it's pulling in oil-laden air from the valve cover or crank case. If your air flow sensor is upstream of the "tap", this is air that's not being accounted for by the ECM, which will cause driveability problems; and it'll screw with the PCV system itself.

Of course, you may not have a "proper" PCV system - I'm not familiar enough with MB engines of your vintage to say for sure...

__________________
A.S.E Tech A1,A6,A7,A8 & MVAC 609 + EPA 608

Unless stated otherwise, any question I ask is about my greymarket 1985 380SEL.

The vents in the top of the valve cover are the only PCV system i am aware of, they vent right into the crossover tube before going into the intake....(the tube is removed in this picture)

will this cause the rough idle and smell with the oil-covered IAT sensor?

thanks,

__________________
1993 300E, 2.8 M104 .....

A properly working PCV system vents pressurized air inside the crankcase due to blow-by, back into the intake system downstream of the airflow sensor. The highest flow is under low vacuum (high load). The "fresh air" supply which feeds the crankcase is usually routed from the air cleaner itself or from the intake tube upstream of the airflow sensor.

The pressurized air inside the crankcase would smell like burned oil or combustion gasses.

A sticking PCV valve would either be too open or too closed at idle or under load, which would cause driveability/idle problems.

If the valve is stuck closed, you'll get oil stains at the filtered air feed tube due to the positively pressurized air in the crank case, which is laden with oil, soot, acidic compounds, etc... but wouldn't necessarily cause poor idle - unless it coats your IAT sensor to the point that it can't take proper readings, or clogs the idle air bypass in the throttle.

If the valve is stuck open, you'll get excess un-metered air pulled into the intake downstream of the airflow sensor, which will cause idle problems - but you won't get any oil at the fresh air feed.

My guess is that it's sticking; it would explain all of your problems.

You should be able to check the PCV valve by shaking it. If it doesn't rattle, it's no good. If you can blow through it both ways, it's no good.

__________________
A.S.E Tech A1,A6,A7,A8 & MVAC 609 + EPA 608

Unless stated otherwise, any question I ask is about my greymarket 1985 380SEL.