The cylinder head on early builds of the M271 causes exhaust valves to stick, guides/springs to wear, and carbon to build up, resulting in mis-firing.

The fix at the dealer is a new cylinder head.
Apparently the exhaust valve on the new head is smaller to avoid this problem.
I would like to know if this is the only reason to replace the entire head.

I know dealers typically don't "rebuild" parts, they just replace. I'd like to have the head rebuild by an independent garage, so I'm interested if there's anything else different about the cylinder head that gets replaced.

I have an early 2003 M271, and recently blew the head gasket. The only head gasket failures on the M271 are related to this issue. I won't know till a shop pulls the head, yet all the symptoms are the same.

 

could this issue cause your car to shake when idling?

 

Hey Kris, you are actually at an enviable point. You could get a light port and polish done by a competent machine shop then have it put back on....You would be the first.....Hint-Hint!

E

 

Yes. Do not keep driving it, get it to a shop. My mistake was keeping driving it and I blew the head gasket, it seems some are able to fix this with a "carbon flush", yet don't ask me what that is.

 

Do you think a competent garage should be able to rebuild the existing head (provided its not warped badly)? I'm scared that replacing just the head gasket will only lead to the same problem down the road, I want to know why the cylinder head failed in the first place.

LOL at this point I just want the car back to 100%, after the following issues I'm hesitant to dump anymore money into fixing it:
- fuel pump replaced (warranty)
- end-links replaced, twice (warranty)
- thrust/control arms replaced (warranty)
- front bearing repacked (warranty)
- AC condenser replaced (out of warranty)
- $12 hose replaced (out of warranty)
- leaking cam sensors replaced (out of warranty, money wasted on MAF and both O2 sensors chasing problem)
- front ball-joint replaced (out of warranty)
- head gasket blown (out of warranty)

If I did a port and polish, I would take the time and bore the TB and port the SC, yet I don't want to spend any more money fixing this car.

 

so doing a carbon flush might be a solution to my car? if i have that same problem?

 

Get out of my thread :p

Seriously, take it to a garage or the dealer, it'll cost a $100 if you're out of warranty yet they'll diagnose what is wrong.

A carbon flush, from what I understand, removes all the excess carbon that may be causing the valves to stick. Its still a design flaw, excess carbon should not build up if the valves seal properly. My suggestion would be if this is the problem, and a carbon flush fixes it, sell the car and move on, or start saving for when you'll have to do the same repair I am.

 

Can't the heads be cleaned simply by, say, a day or so of spirited driving?

 

Yes and no.

An "Italian tune-up" of driving the car hard to clean out some carbon works, likewise fuel additives to clean carbon work as well. They both loosen large chucks of carbon, not exactly what you want sucked into the piston chamber, yet overall not entirely harmful to the engine.

The problem is excessive carbon build up cannot be cleaned this way.

I'd advise anyone with a 2003 or early 2004 M271 to check their spark plugs.
- If they are burnt, its indicative of running too rich and that will build up carbon faster than normal.
- If they have white spots it might be a sign of leaking coolant, get a compression check.

Its not expensive, and perhaps early M271 owners should adopt the practice of getting a compression check regularly to ensure the valves are sealing and the head gasket isn't leaking.

 

Kristen are you still around? Did you get the cylinder head machined and working? I have an 2003 c230k coupe that bucks like a bronco idling in parking lots, and don't want to spend the $6k the dealer wants on a new head, esp since I've dumped thousands into the car in the last year already. Want it working so I can sell it for full KBB value. I'd love to hear from you! Or anyone! Stupid M271.

 

I just replaced my head about a month ago. Got it from http://mercedesengines.net/. They were great to deal with, and it was only about $750.
Pretty easy swap too.

 

That looks great hogger! Mine would be $1200, but that's over half of what I was quoted by MB and a friend. Did you do the work yourself, I'm curious?

 

Yes I did. My timing chain stretched and bent valves. Ended up being cheaper and easier to just replace the whole head.

 

That member is listed as "Banned" so doubtfully they'll chime in.

There was a post on here detailing the new valve part #s as Mercedes did redesign the valves on later models to provide more clearance. Good luck finding it, I barely remember it existed.

Perhaps Glynn can provide some part numbers as that's his knack.

 

I think his name was Mike at Metric Motors, he knew of the valve and spring update, and his heads have them.
$1200 is their web site price. They also sell on eBay. Here is their listing.

 

Seems like a lot of people have been getting banned lately!

 

Ah, I see they are banned. Great. Must've talked trash about german engineering too much. I was just talking to Mike and he seemed pretty aware of the changes and that they're confident they've fixed them. We shall see. May try a few other things first. I've loved my car, but man are these things pricey when out of warranty. Acura was nothing like this.

 

To you, perhaps. This is the thing with individual experiences. My 05 C230 has 135,000 basically trouble free miles on it now. My 2002 Acura TL which I purchased in 2005 with 33,000 miles (for over $20k and with a clear history, CPO) and washed my hands of in 2007 at 76,000 was a complete freakin' nightmare. It managed to go through three transmissions in its two year stay with me, along with basically every other part aside from the engine needing replaced. The entire dash had to be replaced because it warped in the sun, the front leather seats and seat heaters had to be replaced due to extremely premature wear, the whole Bose sound system (every component) was replaced at less than 40k, the engine mounts were replaced at less than 50k, the rotors warped every few months, the windows and sunroof arbitrarily stopped working, etc. Everything was warranty but still, I spent two years worth of weekends at an Acura dealer.

I was at my wits end with that POS in March 2007. I was driving to Atlanta one Saturday night about 1am back to my now-ex's place. I was doing about 78-80mph on I75S when all of a sudden the transmission SLAMMED down from 5th gear to 2nd, causing the front wheels to momentarily lock and the engine to over-rev. This was transmission number 3 for me. I traded it shortly thereafter.

Mercedes is not perfect and I'd be equally as frustrated as you with my car if it were giving me those problems, but Acura is not a knight in shining armor either. From 1998-2006, Honda/Acura basically were unable to design an automatic transmission that didn't fail prematurely. At least Mercedes learns somewhat quickly.

The 2005 cars should be fixed. But they're designed for the gasoline of Europe, not America. And driving the M271 hard sometimes is necessary for its overall health.

 

What about fixing the 2003? I wish there was an alternative owners manual that came with an MB -- German cars don't like U.S. gas, drive car hard, etc etc. Your Acura experience (LB) is so entirely different than mine, my wife's, and my parents' (4 cars between us). I just dumped some Techron in my car, but I don't hold out much hope as I try to avoid a new cylinder head.

 

It's funny, you try to go back to see why they were banned, and you don't find anything. Well, "Kristen" was spending alot of time in Offtopic.
Lots of trash spoken there.

People have good luck with Seafoam cleaning up the carbon and restoring compression.

 

I normally wouldn't advocate seafoam, but at the point where you're facing down a four-figure repair bill, what do you stand to lose? I'd try anything. Techron, seafoam, Italian job..

I attribute my pleasurable ownership experiences with the C230 to this forum. Had I not registered as soon as I bought the car and remained active to this point, there are things I wouldn't know. I wouldn't ever have thought I needed to replace the timing chain. I wouldn't have known that I needed to install adapters to stop oil leaking into the wiring. I wouldn't have known that the transmission fluid is, in fact, not lifetime fill. My car likely would have had a lot more problems had it not been for MBWorld's collective knowledge.