I have a 1995 S500 with 200K mikes. The car began going into "limp mode". The dealer advised that this was due to sludge in the oil clogging up the oil pump and slowing it down. This slow down, in turn, impacted the timing and caused the car to enter the "limp mode."

The service advisor's advice was to get rid of the car ASAP. I thought it was interesting that the tech working on the car offered to buy the car from me and give me a "good deal" on it.

I took it to an independent merdedes mechanic and he stated his solution was a rebuild of the engine (can you say $$$$$). He seemed to believe that this was the only option available.

Am I crazy in thinking that maybe using a product like the Lubro Molly MotorClean to remove sludge inside the engine, removing the oil pan and header covers and cleaning everthing within reach without a rebuild might work?

Any thoughts, experiences or suggestions would be much appreciated. Thanks!

There have been many people with questions relating to "limp mode" problems, and none of the causes was due to sludge.

I'd get a second opinion very quickly.

Where do you live?

There are probably members on this site who can recommend a good independent shop.

You may also try the search function under limp mode and see what you get.

You may also search the good shops section and see if there are any recommendations on a shop in your area.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

I just noticed that you live in Dallas.

There are a good number of members here who live in Dallas.

Try e-mailing a member named LarryBible.

He lives near Dallas and is a looooong-term Mercedes owner.

He can recommend a good shop.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

My basic theory is to keep clean oil in it. That is change it (and the filter) when it gets dirty, which by your description may be every 3000 feet. The reasoning is you don't want to clean it too fast and loosen a chunk only to have it get stuck someplace worse (aka stroke.) Use diesel oil, its basically gas oil with more deteregent. An additional trick: after the engine has drained, pore a little clean oil in untill clean oil comes out, that will give you a little more cleaning.

You basically have a ruined engine so you won't lose much by experimenting.

Hey Mike The first thing you should do is have someone you trust remove the lower section of the oil pan ( an easy job for any mechanic with a pulse! ) and verify that the oil pump is indeed clogged. What exactly do you mean when you say "limp mode"? Do you mean the throttle feels funny and the ASR/ABS lights come on? Is the independant mechanic's advice based solely on the unverified "sludge" diagnosis? Did the service advisor think you should sell the car because it needs so much other work that it's not worth putting serious money into at this point? Every thing about your story sounds fishy to me so far. By the way, I've been a dealership MB tech for the last 14 years so I've seen the 140's from start to finish. Try and give me some more info and we'll see if we can keep you from getting jerked around.

Dunno about yours, but most Mercedes engines have oil pumps driven mechanically by the crank, so the dealer's theory is not making a lot of sense.

I mean, didn't anyone suggest an oil and filter change?

Here is some good advice on flushing:

Engine Flush Recommendations

I don't see what you have to lose by changing the oil and trying one or more flushes followed by oil changes. Moly is supposed to be a good product.

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

I had my oil pump on my s420 switched out at 40k miles and after that I began 1500 mile oil changes. In a couple of months, I'll go to 3000 mile oil changes. You must of not changed the oil often enough. What were the intervals in which you changed the oil.

A forum member who goes by Lebenz (Tracy?), posted in this thread:

Thoughts on 92 400E?

... that if you see sludge in a valve cover of an M119 (same engine family as yours), don't buy it.

Perhaps he can enlighten you on what's going on.

Click the email button at the bottom of his post to direct a message to him.

Sixto
91 300SE
87 300SDL
83 300SD

The engine has variable valve timing that is actuated by engine oil pressure. It may have sludge in the oil passage to the cam actuators. If so, and one is stuck, the engine management system would trigger a Engine Malfunction Light (check engine) and may go into limp in mode. The Dealer should have pulled the diagnostic codes and listed them for you. Lots of things CAN cause the limp in mode. Bad wiring harnesses are common. Sludged up engines are not.

STP sells an excelent engine flush product that works very well to remove oil sludge and varnish. Use it following the directions or even longer clean times--. Use it even 2 or 3 times in a row using fresh oil changes each time.

It will not harm any seals or other parts.

I've fixed lots of Check Engine lights caused by sticking cam timing actuators but I've never seen a limp condition arise from this. Mike, you need to get more information posted. I don't like the sound of all this sludge talk and I'd hate to see you waste good money due to bad advice from your mechanic.