Is this excessive carbon buildup? M103 - PeachParts Mercedes-Benz Forum

ps2cho · #1 03-13-2014, 01:13 AM

I am replacing a leaky head gasket and noticed that it looks like a lot of carbon buildup considering that I drive probably 70% freeway miles on the car. 147k miles.

What do you guys think?

This year I replaced the idle air hoses and all rubber vacuum components.
Last year I replaced plugs/cap/rotor on the ignition-side and the o2 sensor.
2 years ago I had the fuel distributor and eha rebuilt and matched and injectors replaced. fuel filter replaced last week (it was a little overdue). Fuel pumps are original. Duty cycle fluctuates around ~48%

I am getting about 20mpg average fuel economy.

Some photos from today:

Stretch · #2 03-13-2014, 05:55 AM

It has been sucking oil - look at the intake manifold it is wet.

That's the source of the black stuff.

Could be crank case breathing system error or valve stem seals.

As you have the head off check to see if there are shadows on the walls of the cylinders - if there is a lot of blow-by the crankcase breathing system could be struggling or the valve stem seals could be struggling and in that way the oil could be being forced into the intake.

What does the exhaust manifold look like - any evidence of oil there?

ps2cho · #3 03-13-2014, 11:54 AM

Valve stem seals were done 60k ago...I don't think they should be leaking.

What should I check on for the crankcase vent?

Did not find any oil in exhaust manifold...FWIW my valve cover gasket was leaking for a while and I found oil in my spark plug holes...so maybe it was from there?

Cylinder walls looked normal...

gerryvz · #4 03-13-2014, 12:35 PM

What about your valve guides? Were they also done 60K ago?

ps2cho · #5 03-13-2014, 01:01 PM

Yes. Had the head skimmed and rebuilt at a shop.

Stretch · #6 03-13-2014, 01:15 PM

If you google "M103 crankcase ventilation" you will come across an online FSM with a description of how it works.

I think I need to make one thing clear - the oil / fluid in the intake manifold doesn't come directly from valve stem seals. A sealing problem in the cylinder raises crankcase pressure which can force engine oil into the inlet manifold / air filter etc because that's the "environmentally" friendly thing most designers do with crankcase fumes => burn 'em.

I've just remembered on my W201 (with M102) that the fuel tank fumes are fed through a carbon filter system that ultimately goes to the intake manifold (for burning) too. It is therefore worthwhile checking to see if this dampness is oil or fuel based.

I suspect oil - but I could be wrong.

gerryvz · #7 03-13-2014, 02:56 PM

I've never taken an engine apart that didn't have oil residue (wet or dry) in the intake. In fact, when I just did my M104, there was actually a small pool of oily goo collected in the bottom half (aluminum) of the intake manifold. It wasn't much (perhaps a couple of teaspoons or tablespoons) but it was clear that this was crankcase blowby oil and fumes that had collected over a long period of time. I didn't let it bother me, and there was no evidence of any issue with crankcase ventilation. It's the nature of the beast.

You can clearly see the "moisture" in both my M117 and M104 (along with the small pool of blowby oil/goo in one M104 photo).

Again, what I see in your photos is totally normal for an engine with some miles on it.

Cheers,
Gerry

gsxr · #8 03-14-2014, 11:25 AM

Those piston tops are normal. Any engine you take apart that has more than a few thousand miles it, will look like that.

Stretch · #9 03-14-2014, 01:12 PM

Sorry to be a pain folks - I still think there's too much wetness on the intake manifold - whatever...

MAVA · #10 03-14-2014, 06:07 PM

Quote:

Originally Posted by Stretch

Sorry to be a pain folks - I still think there's too much wetness on the intake manifold - whatever...

Sorry guys, I side with stretch.. The plugs say so-even 60k mileage plugs do not look like that..

Martin

gsxr · #11 03-14-2014, 01:15 PM

The intake manifold carries PCV vapors. There will always be oil present in the intake. Period.

"Too much" is measured by oil consumption over thousands of miles when driving the car, not looking at the engine taken apart. When it starts sucking down a quart of oil every 1000 miles, or 750 miles, or worse... you have a problem.

Stretch · #12 03-15-2014, 07:41 AM

Quote:

Originally Posted by gerryvz

+1

[IMG]http://*********.com/forums/images/smilies/bar-b-q.gif[/IMG]

Nice GIF - provides a good analogy => you need a lot of heat to burn off grease / oil

As I asked earlier - what's the exhaust manifold like?

If that is getting gunked up with goo too then the oxygen sensor will probably start to struggle and the catalytic converter will get less and less effective and eventually you'll end up with annual emission / exhaust gas check test failures.

Whilst you could argue that all old cars end up with this trouble and that "they all look like that" it doesn't mean it is "normal" - you might say it is "commonly found" - but that doesn't mean it is OK.

I consider it to be a point of concern.

DieselPaul · #13 03-14-2014, 01:18 PM

Out of curiousity why did the headgasket let go again after only 60,000 miles?

gsxr · #14 03-14-2014, 02:28 PM

Quote:

Originally Posted by DieselPaul

Out of curiousity why did the headgasket let go again after only 60,000 miles?

+1. What were the symptoms last time, and this time?

ps2cho · #15 03-14-2014, 10:06 PM

Both gaskets were leaking oil out of back corner
Both were Victor reinz. I hope that the Genuine MB is superior.

Replacement was a success including teplacement of the broken valve spring.
Will post photos later and update. Prior I was losing a quart every 2 weeks of oil onto the garage floor. Was sick of it.