JDM

..Just returned from dealer for an intermintent engine stumble. Car feels like it's running out of gas, but recovers quickly, and is fine. Transmission shifts funny from time to time, tech thinks it's all related. Say's MB has recently informed dealers that carbon is becoming a problem again. Decarbon service is $199.95, to be repeated as needed. Fuel pressure regulator in fuel filter still causes same condition, but not as much of a problem as previously thought.
Carbon cleaning is not done under warranty...FYI.

E55AMG99

How is carbon building up in the intake?

JDM

Apparently there is an ongoing argument between fuel manufacturers, and MB about how it occurs, but the info I got was that carbon builds up near the injectors, on tha back of intake valves, top of pistons, and near the end of the intake runners (piston side) Cadillac is having a hayday with carbon buildup too, has been for several yearas now. Fuel soaks into the carbon, and the car momentarily runs out of fuel.

JDM

I was fortunate not to get a diagnostics fee, as I am just out of warranty, but any of you that may be experiencing this, be aware that the cleaning could accompany a diag charge. $92 to tell you it needs a carbon service for $200. I'd talk to them about it to see if they can make the recommendation based on your description of the symptom, if you see what I mean.

JDM

......By the way, I checked out an E55 AMG while I was there, and holy smokes! that was a nice car...$95k though, manoman, it will be awhile before I could sink my teeth into one of those. Gorgeous cars, like super comfortable race cars....someday,...someday.... ... .. . .

E55AMG99

OK, these are the right places. For a minute I thought he didn't know what he was talking about.

Carbon buildup still a problem today only lessened by the more precise metering of FI and ECM. Some experience more problems with lower grade fuels. Go down to the local auto parts store and get some fuel system cleaner and dump it in the tank once in a while.

Jim Banville

"Sea Foam" from Napa

Jim Banville

http://www.superhonda.com/tech/carbo...nt_how-to.html

I used a can of this stuff in my old 126K mile 240sx. You'll have HUGE clouds of black smoke coming from your tail pipe as the carbon is released. I pulled the vacuum hose off of the brake booster and poured it down the tube as the engine ran. Some air has to go with the liquid or you will stall the engine. Have someone monitoring the throttle pedal to keep the car from stalling. No need to "rev" the engine as you work. Half the can goes into the engine, the other half goes in your gas tank.

Moviela

Since they charge $ 200. to change the oil at dealerships, I guess the same to spray a can of solvent into the intake, then letting it "soak" for three hours is not bad.

Since the "Rack Rats" (people who operate the gasoline distributors' tanker filling machinery) are now using upto 800 gallons of alcohol in an 8,000 gallon delivery, and using lousy products to claim "detergent" gasoline we need to clean the intake and cumbustion chambers ourselves.

http://www.redlineoil.com/whitePaper/15.pdf

Now comes the rub. Mercedes does not want any additives in the gas or oil. The Factory Approved Service Products booklet says so. Magically, however, for carbon deposits caused by poor quality fuel MB Part No. 000 989 25 45 10 can be added to gasoline if carbon deposits are encountered. I guess the solvent molecues have little three pointed stars on them.

DC sells a combustion chamber solvent to the dealers for about $ 8. a can. You spray the whole can of this foamy sutff into a hot engine while it is running. When the can is empty, you shut off the motor and close the hood. Then let it sit for three hours. When when you start the car there will be copious amounts of white smoke for several seconds, and you are good to go.

I have never found any of these methods to work very well. A head off through cleaning works, but is very costly.

RLE

On the other hand.....

My '01 C320 at the almost four years and 38K mile point got the de-carbon treatment at my dealer during it's last free service recently. Covered by the warranty.

The thirty year tech told me that the carbon was on the piston tops and is caused by the EGR and cannot be burned off by fast driving. At any rate, the idle is smoother now and it takes the throttle a bit better, despite the accursed electronic throttle.

I have recently switched to Shell 89 octane mid-grade on the advice of my dealer and it looks like fuel mileage has improved. One tank is no test so I will just see how it goes. About eight cents per gallon cheaper. Eight cents here, eight cents there, pretty soon........

mleskovar

Air cooled engines have this problem in a big way but this is the first I've heard of it in modern cars. There has to be a reason why everyone isn't experiencing this. Maybe driving style? Excessive idling during warm up? Constant stop and go when engine is cold? All my cars in the past 25 years ran clean, no hesitations, no power reduction from new, very little oil usage, gas mileage remained the same, all past 100K miles. Or is this a very recent (within the last year) condition that we can now look forward to?

E55AMG99

You are right about cool temps causing more problems and how that should not be an issue in modern cars. My guess is that poor quality fuel with little detergent additives are to blame more than anything.

RLE

<< You are right about cool temps causing more problems and how that should not be an issue in modern cars. My guess is that poor quality fuel with little detergent additives are to blame more than...>>

You are right about detergents except that this was supposedly solved twenty years ago. And it isn't a question of air or water cooled, particularly. In the early eighties all of the gasoline producers cut down or removed the detergents from their product in an attempt to save money. This was very well known at the time. Audi, for example, would do a carbon removal (walnut shell blasting) one time for any 5000 owner. BMW did the same as did Mercedes who didn't publicize it. My own '85 190E got the treatment (warranty) which pepped it up considerably. Porsche pretended the problem did not exist,of course, leaving the customer to find a solution. I had my 944's combustion chambers walnutshell blasted and it felt like it gained 15HP. There is a machine specifically for this procedure.

I was shown an a 911 intake valve that had so much carbonlike muck built up on the backside that there was nearly a straight line from the guide to the seat. Of course, this increases valve weight which leads to failures.

And my carboned-up engines were not poking around town at 2000 rpm like some diesel powered conveyance.

Detergent packages were "improved" when GM threatened the oil companies that they would start specifying which gas to buy in their owners manuals.

I could go on...........

RLE

<, Now comes the rub. Mercedes does not want any additives in the gas or oil. The Factory Approved Service Products booklet says so.>>

Bosch, on the other hand, has recommended Techron to keep injectors clean and deposits at bay. No more than twice per oil change, to quote two Bosch field reps.

I have used it many times and even used it in my diesel, now long gone.

mleskovar

I have 'decoked' several motorcycle engines and it required removing the head and valves. It was also fairly easy to remove the exhaust headers and carburetor(s) and look down the sparkplug hole to see the buildup. Some searching on the net gave varying opinions (surprise!) on when to do it with car engines. Some advised not to do it at all with older (150K miles+) engines. I'm leary about pouring a chemical so caustic that it will soften carbon deposits into my intake....what will it do to seated rings or other softer metals? How could you tell it was necessary on one of our engines?

RLE

<<metals? How could you tell it was necessary on one of our engines?>>

While replacing the lifters, the exhaust rockers and both camshafts, the dealer tech pulled a plug and checked the combustion chamber with a borescope. The decoking was covered by the warranty using MB approved materials.

The tech told me that the carbon buildup is cause by the EGR and is unavoidable.

mleskovar

[QUOTE=RLEWhile replacing the lifters, the exhaust rockers and both camshafts.[/QUOTE]
Wow, what was the cause of those being replaced? So you think it ran better because of the carbon removal and not the parts replacement? What's up with that?

RLE

<< Wow, what was the cause of those being replaced? So you think it ran better because of the carbon removal and not the parts replacement? What's up with that?>>

I commented to the tech that I thought the valve train was noisier than normal and he said some are noisier than others. He later changed his mind and said he was going to replace the lifters and the exhaust rockers. He also said that if he saw any "dithering" marks on the cam lobes (not uncommon. apparently) that he would replace the camshafts.

The result of the decarbonizing was a much smoother idle.
The parts replacement quieted the engine down considerably.

BTW, this car has 38000 miles and has had a Mobil 1 0W40 oil change each 5000 miles.

I think this kind of service may be because I have been a customer at this dealer since 1973 and have purchased five new cars from them. Soon to be six, perhaps. And, the ability to walk into the shop and speak directly to the tech is invaluable.

All in all, even considering an occasional glitch, I am well satisfied with the service at Phil Smart MB in Seattle.