I have an 08 E320 Bluetec, 77,000 miles. My car has the gummed up/carbon buildup on the intake manifolds as well. Here is the history:
1) Oil leaked from a deffective EGR membrane on the swirl motor, and fried it. I had it changed at the dealer ($1200) at about 70,000. Car had gotten a check engine light and the boost was restricted with poor acceleration (semi limp home mode). It was drivable, but not fun (0-60 would take forever and had to shift gears manually to get toyota prius acceleration).
2) Now, at 77,000 miles, the car has gone into limp home mode a few times very intermittently, without triggering the check engine light. Restarting the car clears the problem. Dealer quoted me $4300 to replace both intake manifolds. They do not want to clean them. They will replace the swirl motor under parts warranty, but will not cover any labor.
By the way, I use mostly speedway gasoline from NW Indiana, which does not have any biodiesel. Sometimes I put BP. The mechanic told me to stop putting speedway diesel and to put BP or Shell, as they are higher quality. Sounds like BS to me.
What do you guys suggest? Any hope that MB will step up and cover this repair, on a car with almost 80K miles. I bought this car for longevity, not to replace 4 yrs later.
08 E320 Bluetec
Mike, Indiana & Illinois are both selling the B20 deisel, your only fuel option is to find a station near you that is still selling the B5 (I found one and am only filling up there). The brand name makes no difference at all, it just has to be a B5 and unfortunatley the only person who can give you that information is the station owner. The people that work at the station usually dont even understand the question AND expect to pay a higher price for B5.
The only other reccomendation that came from a Merc Tech is to change the oil more frequently every 3K miles, using regular oil not synthetic. The excess fats that the combustion process does not burn go into the oil and it's the engine oil that is coating the intake manifold etc., according to him that is what the package companies that run Sprinters (same engine) are doing.
If we lived in a different State there wouldn't be a problem, only IN & IL enacted this B20 law to help the soy bean farmers and in doing so ruined are cars.
There is no chance that Mercedes will cover the cleaning costs, I already tried that and by the way if you buy a new Merc deisel in IL today they give you a special waver form to sign to completely clear themselves from any responsibility.
Either find a station with B5 or change the oil every 3K, after you have had the parts cleaned of the gunk it will hopefully then run for ever.
I now have 107K on mine and it runs beautifully but has never seen anything but B5 since I had the intake manifold cleaned.