Jim Banville

Several people on the other MB forum w/ the M271 engine have been getting misfires in #4 cylinder. Apparently there is a service bulletin to REPLACE the valves with a new design due to carbon build-up. Before I read about this, I noticed a lot of carbon build-up on my exhaust tip. I'm worried! I don't want anyone to take the head off my practically new engine! My car has about 2500 miles on it now. Has anyone else here w/ M271 noticed alot of carbon build-up on their exhaust tip?

mbbodytech

The bulletin actually has two procedures, depending on the condition of the vehicle. If there is only minor carbon buildup, there is a procedure for cleaning them that does not require the head to be removed. Only if there is severe cabon buidup would the valves be replaced.

Have the dealer take a look and see which category you fall under.

Jim Banville

How is just cleaning them going to keep it from happening again?

homer403

You might want to try http://www.redlineoil.com/products_fueladditives.asp as a preventive measure.

mbbodytech

I believe there is also a software update for the engine management control unit as well. It has been a while since I read the bulletin, so sorry that I left that out. Maybe I can look it up tomorrow once again and see exactly what it says.

tyro

Jim: I'm 100% sure your heads need to be removed

Jim Banville

Thanks!!!!!!!!! Looking at all that soot on my tailpipe made me think the car was running rich because it was still breaking in.

Capt Nemo o2

I got 6800 miles on mine and still get the build up, I dont think its excessive though, but that may just be because I had a '94 Jeep with the 318 small block and I'm used to carbon build up! If some one with a white car could chime in and tell us if there is any carbon showing up on the bumper, than that is excessive.

Moxxon

I have a lot of carbon on my tailpipe too, but I thought it was just normal. I wouldn't want anyone taking my engine apart either.....

tyro

I burnt my lips on my tail pipe.
I was confused.

rubenl

I too have noticed a sooty build up on my tailpipe...

Battery!

How do we find out about these bulletins? If there was a problem that was known with these cars, shouldn't something be sent to owners' residences explaining that it can be rectified at the dealer?

inFiniTE LooP

isn't the soot normal though??? is there anybody that hasn't been getting it?

nlpamg

damn man, this is starting to worry me too. where can we get the info on the bulletin? I know my dealer will probably tell me that there's no bulletin, so I'd like the bulletin number if you could get it. thanks!

mbbodytech

OK guys, here is the DTB #: P-B-07.61/46. The service advisor can look it up on Netstar.

Hope you can get it taken care of!

dmatre

Thank you for posting this DTB #.

I don't have the problem now, but it's nice to have the knowledge if the problem starts.

benz_og

Yeah man I have carbon build-up on the exhaust tips. I have a CPO. Can I get taken care of too. Because I just notice its build-ups. Also Can I just get new exhaust tips ? or is it a problem internaly ?

mctwin2kman

Carbon buildup is a normal occurance on the stainless tailpipe tip. Now if you are getting carbon buildup on your rear fascia then that I would say is a problem. As long as I have been around the car business I have seen carbon on exhaust tips. It is ther due to the combustion process. You should not however have excessive buildup. A little around the edge of the tip. You should see more discoloration of the tip due to heat than carbon. But it is normal for carbon to buildup. And it should easily wash off in most cases, if not get some Mother's!

On a side note my M271 engine has 38,000 miles of my hard driving and it has never once has a misfire on any of the cylinders.

Outland

This is a funny thread.

You guys don't occassionally get steam or water out the muffler do you...your engine is gonna blow for sure.

nlpamg

how would you know if it misfires? would you just feel a lack of power? or funny vibration/sound?

dmatre

If you have a misfire, typically you will know it.

The engine will run rough (will probably stumble), will be way low on power (25%), you may smell raw fuel in the exhaust, and the Check Engine light will come on.

When the Ignition Control Module failed on the wife's Passat (#2 cylinder dead), there was no mistaking that there was a serious problem.

southernjim

If you experience an engine mis-fire you would definately know it. Trust me, I am on my 3rd C230 Sport Sedan because of engine mis-fire problems with the first two. Read the thread "Am I the Only One..." to get all the details. Both my '03 and '05 reacted exactly the same way when the cylinder #4 mis-fired. The engine "stumbles" initially then runs extremely rough with greatly reduced power until the engine is cut off and restarted. The check engine light also illuminates and stays on.
This thread is the first I have heard of a "common" problem like this. Back in March, when I orginally posted my thread I did not get any indication of others experiencing this problem. Now I am curious to see if the '05 I picked up last week experiences the same problem. So far, the first 350 miles have been uneventful.

Jkw

I've had lot's of cardon on the tips, None on the Bumper (it's white), No engine mis-fires. I may try a fuel system cleaner.
Good Luck, Jkw