M103 - combustion chamber cleaning by water - PeachParts Mercedes-Benz Forum

glpro160 · #1 11-08-2010, 09:02 AM

Guys,

My M103 produces pinging sounds when under high load, e.g. passing or hard acceleration. I suspect there's carbon buildup in the combustion chamber and it should be cleaned. Some suggest using water can do the job. They advice to spray water into the throttle body while letting the engine at about 2000rpm.

Has anyone of you done it and what is the result? Does water do any harm to the mechanics of the engine?

oldsinner111 · #2 11-08-2010, 09:41 AM

Old cars you could.You want to mist the water in,like steam.Better to purchase water injection kit.Add methonal for more power too.

ILUVMILS · #3 11-08-2010, 12:12 PM

Chevron Techron, or GM top engine cleaner is the way to go.

Rahulio1989300E · #4 11-08-2010, 02:06 PM

Could give Seafoam a try, I would not mist 100% water into the engine... even if you go overboard by a bit, you could hydro-lock the engine.

Hit Man X · #5 11-08-2010, 04:05 PM

I read a thread on Bobistheoilguy.com that someone broke down Seafoam... surprise, surprise... it was mostly water with some petroleum crap left over from the refining process.

You can run simply a vac line between the intake manifold and cabin, the one just below the throttle body should be fine, and slowly induce a bit as you drive down the freeway.

I would probably put in a higher octane fuel and do some 'spirited driving' for a while to help blow the top end out. I have no knock in my 300SEL on 87 fuel.

Chas H · #6 11-08-2010, 05:13 PM

I have done it many times back with older Volvos. I used a sponge and squeezed a small amount of water into the intake while running the engine at about 2K. Works quite well.

glpro160 · #7 11-09-2010, 08:20 AM

Thanks all for your input.

Those familiar with M103 will know that that you can't spray water into the TB directly as access to the TB is blocked by the MAF. I unplugged the vacuum line to the Ignition Control Module and put it into water. The result is not desirable. My M103 still has some sound when accelerated brutally. I don't think it is preignition but carbon buildup on the pistons and get contact with the valves head and makes noise. Other than that, I have a moderate engine vibration at idle, the plugs look very good.

I experienced this with my motorcycle. My mechanic opened up the cylinder and made carbon buildup removed. The irritating sound was then gone.

Maybe some specialty agent is needed. I can't get seafoam over here.

RBYCC · #8 11-09-2010, 08:29 AM

Quote:

Originally Posted by glpro160

Thanks all for your input.

Those familiar with M103 will know that that you can't spray water into the TB directly as access to the TB is blocked by the MAF. I unplugged the vacuum line to the Ignition Control Module and put it into water. The result is not desirable. My M103 still has some sound when accelerated brutally. I don't think it is preignition but carbon buildup on the pistons and get contact with the valves head and makes noise. Other than that, I have a moderate engine vibration at idle, the plugs look very good.

I experienced this with my motorcycle. My mechanic opened up the cylinder and made carbon buildup removed. The irritating sound was then gone.

Maybe some specialty agent is needed. I can't get seafoam over here.

The M103-12V doesn't have a MAF ...possibly you mean the air valve assembly ?

glpro160 · #9 11-09-2010, 08:54 AM

I meant Mass Air Flow sensor, the plate that controls the fuel quantity injected according to amount of air drawn in by the engine.

jhodg5ck · #10 11-09-2010, 11:03 AM

That's the air metering plate...

On older/high mileage/loaded up engines I use water to clean them out w/ Good results.

Get car up to full operating temp, I use a water bottle w/ a small hole poked in the cap and work the stream/RPM's so the car just has a Touch of roughness while running. Do not cut rpm's till the engine smooths/works through the water that's in the system.

Always change the oil afterwards, it will be Black as Night!!

Jonathan

Ivanerrol · #11 11-09-2010, 06:56 PM

Subaru's don't like carbon buildup.
Subaru include a carbon clean every other time the car gets serviced.

You can get a Seafoam "equivalent" from a Subaru dealer.

mak · #12 11-10-2010, 09:42 PM

JCwhitney has a water injecting kit for engines .maybe someone has tried it.
mak
103 300se

Duner · #13 11-10-2010, 10:08 PM

I have used water to clean carbon deposits in another brand. What I did was feed water under vacuum metered by adjustable valve. I like to use 3-4 quarts of water in 250 miles or so. It does clean things up for certain.
I have a section of clear plastic hose so I can see what is going on and I shut it of when parked as I have to mount the water bottle rather high and I don't want water siphoning in with engine off.

Can't Know · #14 11-11-2010, 03:34 AM

I was in a Pep Boys recently and saw an aerosol can of Seafoam with a u-bend attachment and tube designed to fit at the intake seal downstream of the MAF. I read the can, it's designed for combustion chamber cleaning. Something like run engine to operating temp, fit the attachment, start it, run to 2,000 rpm and instill half the can, then shut it off and remove, reattach intake seal, etc. and let sit for some period, the run again later. Seems like it would be worth a try before water experimentation, which can be unpredictable to say the least.

glpro160 · #15 11-11-2010, 08:29 AM

I already tried the combustion chamber cleaner hoping it would solve the mild vibration at idle issue but sadly it didn't solve.

I tried these:

- changed injectors
- changed cap and rotor
- tightened all vacuum connections
- cleaned combustion chamber

they don't solve my problem.

A guy on this forum commented that rough idle is by nature to CIS systems. (Mercedes (and BMW) straight sixes have a rough idle "by design"?!). I mostly agree with him. What do you all think?