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2000 mercedes c240
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16 Posts
Discussion Starter #1
Hi, i feel like my c240 has a mind of its own. my car runs great, but sometimes (only sometimes) when Im driving on the highway and I go into the passing gear it shoots out a cloud of smoke. it doesnt do it all of the time and it seems to only do it when im going highway speeds. for instance today i was driving and i had the cruise on. i started going up a hill so the car had to kick into the passing gear. when it did it shot out a cloud of smoke and the check engine light turned on. the code came as a misfire on cylinder 1. it almost seems like my car is sucking oil into the intake or something. i replaced the valve guide seals and it got better, but it still does it occasionally. Im afraid for the worst (a burnt ring) but i was just curious if anyone has had this problem or any clues what it could be. any help would be great.
thanx
 

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CLS550 Master Lease, 1990 300zxTT, 2000 camry
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361 Posts
I remember about a year ago a guy in our shop had the same problem. He ended up having to replaced the head because there was a crack around the valve seat. Dont know if that is your problem. His was blue smoke, is your blue black or white?
 

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2000 mercedes c240
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16 Posts
Discussion Starter #3
I remember about a year ago a guy in our shop had the same problem. He ended up having to replaced the head because there was a crack around the valve seat. Dont know if that is your problem. His was blue smoke, is your blue black or white?
its white smoke. also, i checked the head gasket and its fine. a head huh! that sounds cheap :) wait :( haha.
 

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2004 C230 Kompressor Sport Coupe
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1,903 Posts
Just on a whim, swap the coils around. That's probably not it, and I would suspect some sort of head problem, but it's worth a shot as it's nearly free. If the code moves ...
 

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CLS550 Master Lease, 1990 300zxTT, 2000 camry
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361 Posts
Well if its white smoke your burning coolant. I would do a leakdown check on all cylinders to see if one is noticably leaking. How did you check your head gaskets?
 

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2000 mercedes c240
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16 Posts
Discussion Starter #6
Well if its white smoke your burning coolant. I would do a leakdown check on all cylinders to see if one is noticably leaking. How did you check your head gaskets?
well i just looked for external leaks and i checked my oil for coolant. also the level of my coolant is good and ive never had to add coolant or got a low level indicator light. is there a better test i can do to check the head gasket?
 

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2000 mercedes c240
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16 Posts
Discussion Starter #7
well i just looked for external leaks and i checked my oil for coolant. also the level of my coolant is good and ive never had to add coolant or got a low level indicator light. is there a better test i can do to check the head gasket?


Also, i can smell oil in the smoke. and when i check my intake its clogged up with oil
 

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CLS550 Master Lease, 1990 300zxTT, 2000 camry
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361 Posts
Your intake is clogged with oil? I dont understand, how can you tell that? Yes you should run a compression test and a cylinder leakdown test on each cylinder. There really shouldnt be anyway for oil to get into your intake on this engine.
 

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Puff of smoke at highway speed

My 05 C240 has just started this at 46k miles on the clock. So someone said to change the head. Do they mean the gasket? Thanks.
 

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2004 C230 Kompressor Sport Coupe
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1,903 Posts
Maybe! We don't know the details of your situation. Has a leakdown test been performed? Is there coolant contamination?
 

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05 C240 - Plumes of smoke

My 05 has started this madness as well, with 48k on the clock:

Symptoms:
1. On the highway doing 40mph, start to go up a grade, sounds like something gets stuck as I push the gas pedal at, boom, so much smoke, I fear that the other drivers behind me are put in possible peril.

2. Drove the streets to avoid number 1. Went about 24 miles, was going about 25 mph and headed up an upgrade and boom, a plume of smoke. I believe it was blueish/white in both cases.

3. After the car had sat for a couple of hours, started it up and a plume of nothing but white smoke came out the exhaust.


Work done recently:

1. All plugs/wires replaced.
2. All coils replaced.
3. Oil changed

My wife's car and sludge had built up, the mech cleaned everything as best he could. He's now saying its possibly the valve seal, and $4k or more. Please
help me get to the truth. How can I diagnose for certain. Thanks.
 

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W126 500se W202 C240
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4 Posts
Smoking C240

Has anyone found a cure for this ailment. I redid the motor on my W202 C240 to sure this problem but it persists. Smokes whitish blue on start up which seems to point to oil leaking onto plug when she is parked. Plumes of smoke when going up inclines. It is definitely oil as the plugs get fouled causing a misfire. The valve stem seals were done but i was not advised that the guides were worn so they werent touched. it is not the rings as it is does not smoke all the time. Could it be the oil breathers are clogged? I did do the rear main seal as well on a previous occassion. Could there be breathers that can be blocked there? There is no PCV. It seems like the EGR valve is clogged as well. Very lumpy idle and when stopped at red lights. can this cause it? Please help if anyone has a cure!:crybaby2:
 

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2001 C240, 1984 300D
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951 Posts
Serious engine problems on a C240 are very rare. When you say you redid your motor what do you mean? What kind of work on it did you do?
 

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2013 C250
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7,273 Posts
I had a 2001 C240 that did this, at 90K miles at end of 4 year Mercedes lease. Towed it in on flatbed, Service department was speculating about bad head, not sure. So I turned it in 1 month early, piece of crap, they sent me small check for unused miles, end of story. (Used car manager at dealership said the car was going to be wholesaled due to high miles, he didn't care)

Don't miss that car at all, too many electrical, suspension and engine problems in 4 year period. Like night and day compared to next gen C-class in terms of reliability.
 

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W126 500se W202 C240
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4 Posts
Serious engine problems on a C240 are very rare. When you say you redid your motor what do you mean? What kind of work on it did you do?
Sorry for the delayed response. I bought new rings, bearings, decoke sets with stem seals. Mechanic took motor out of the car and installed all the parts. Had engineers install the valve stem seals. All new gaskets were also installed.

I somehow get the feeling also that oil is dripping onto the plugs while the car is parked. Is it a possibility that the valve guides could be worn? The car has 217000kms on the clock.

I doubt its the bottom end as it doesnt smoke all the time. :confused:
 

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2001 C240, 1984 300D
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951 Posts
I'm very surprised to hear of a C240 needing new rings, bearings and valve stem seals with so few kms on it. It sounds like it must have suffered some kind of abuse.

At this point I'd suspect the machine work. Time to start with a compression and leakdown test. It certainly could be some other things but I'd start there.
 

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2013 C250
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7,273 Posts
I had a 2001 C240 that did this, at 90K miles at end of 4 year Mercedes lease. Towed it in on flatbed, Service department was speculating about bad head, not sure. So I turned it in 1 month early, piece of crap, they sent me small check for unused miles, end of story. (Used car manager at dealership said the car was going to be wholesaled due to high miles, he didn't care)

Don't miss that car at all, too many electrical, suspension and engine problems in 4 year period. Like night and day compared to next gen C-class in terms of reliability.
The end. (At least for my C240 thankfully)
 
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