C240, 2005 huge white smoke occasionally
 

On occasion there will be a tremendous, and I mean huge cloud of dense white smoke that comes out of the exaust. It is not coolant. Clearly burning oil. However, after a few swconds it clears up then a few miles down the road the engine is back to running as smooth as new.

I believe it may be a back pressure type condition causing something to push oil into the intake. I have been told it could be the PCV valv, but then told by others that this model does not have such a valve. Then i read another forum that suggest a malfuctioning EGR valve.

Thoughts.

I know this has to ahve come up, just cant fiind the thread.

Thanks in advance.

any check engine lights?

blue smoke is oil being burned

white smoke means your running lean..which is very bad for internal engine

have u checked the spark plugs? condition?

your valve stems are probally shot...check all the rubber on the block for leaks

mileage?

The car has 68,500 miles on it. It is clearly burning oil. Like 1-3 quarts per tank of gas. I pulled two spark plugs on cilinder #1 and they showe dsigns of too much oil. as in they were coated with it. so i changed those two out. did not pull any others. it idles perfectly smooth until its starts to smoke. the dense smoke lasts 3-5 seconds then stops. It then runs rough for about 5 minutes then back to its normal smooth running little car. until the smoke comes agian in about say 30 to 60 minutes of driving.

It does usually smoke a bit on start up, bit not much and only for a couple seconds and light smoke. This is new.

Normally, a car that smokes at start up has valve stem seal wear, not a major problem .

Smoking after start up & after a long hill decline can indicate worn piston rings as the increased vacuum above the pistons pull the oil vapour from the sump through the worn rings.

I also wonder about your turbo seals whether your engine is pulling oil from this source.

The engine roughness could be caused by oil wet plugs.

My first vehicle had badly worn rings & used 4 1/2 gallons of oil in 600 miles. The oil pressure was 70 PSI caused by passing combustion gases in the sump. You are not at this stage yet !!

You need to do a leakdown test on that engine to check things properly.

It could be a problem in the vacuum, or captive crankcase ventilation system.

It should not be rings at 68K miles unless the vehicle has been severely overheated.

Hi Ronball,

I have a similar problem with my W202 C240. Its the V6. Had the entire motor reconditioned top to bottom but the pronlem persists. It does smoke a bit on start up. But i find the huge clouds of smoke presents itself mostly when going up an incline. The can can idle with no signs of shortly thereafter. I doubt it's the rings and bore as it should smoke constantly. I decatted the car(no emissions control in SA yet) as well and noticed that the colour of the smoke has changed and it definitley is smoke.

I also had a problem with cylinder one plugs coated with oil. Looked shiny as though varnished when i pulled them.

I am at my wits end. Please let me know if you solve the problem.

any fix for this problem found yet, don't think it's stems, guides or rings? Something to do with crankcase ventilation?

2005 C240
 

Hello I have been trying to diagnose my 2005 C240 as well, It has the excact same problems. I mean to a EXACT, I dont know if anyone has come up with a solution, but it is causing me to lose sleep at nights having it just sit in my driveway not knowing the problem. I would love any feedback regaurding what I should do thanks so much. I think Mercedes should do a recall on this car and refund our money back or somehow fix these issues

White smoke is oil leaking onto the hot exhaust!
Have you checked your valve cover gasket? And you said your plugs had oil? That's definetly a spark plug gasket leak.

I am having a similar problem. When traveling down the road, the car will blow a huge a plume of oil smoke, and misfire. After a few moments it clears and runs beautifully. Last night I pulled the spark plugs from cylinders 1 and 2. I found oil on the spark plug holes outside the cylinder head. Any ideas?

Smoking c240
 

So tonight after a long drive on the highway, my 2004 c240 started smoking like crazy, covering four lanes of traffic. So after messing with it, I found out it ran better and smoked less without the air box. I think the air box is full of dirt and making a vacuum on the crank case breather, pouring oil into the intake manifold. So I took it off and all was well to drive home.

2003 mercedes C240 4matic huge amount of smoke periodically
 

My 2003 C240 4matic wagon is doing the same exact thing. Huge amount is an understatement. It only does it once in a wile. Removed and cleaned the valve covers and ventilation covers. New gaskets and seal. Both small vacuum hoses have high vacuum and the large one has no vacuum. the car runs perfect otherwise. No check engine lite. no noticeable oil usage or coolant usage. Can anyone HELP with dangerous problem?

well I had same problem and found out what the problem is .. yes it is the pcb system that those cars have. keep in mind that (system not a valve).. sucks in any case!. I cleaned the valve covers and the small covers from sludge buildup
I did have to change the hoses that connected in the back of the engine ... here comes the answer .... while I had the valve covers off , the on the left side, that is! the one on the passenger side.
there is a hole at the back top corner of the head. that! goes down deep in to the block,,I found it as I use a vacuum cleaner to suck most of the sludge. yet I stuck a wire in to the hole as it tapers in . the wire stop with out getting to the bottom ..
( my though was ) no way that is a blind hole, or the oil would just cook in there . yet did not follow that any further. I cleaned the rest and got everything back on turned the car on
with dextron trans oil in the engine so it would flush some carbon out (old trick My dad used to clean his engines and ran them for 30 Min.) . did the trick !!!( yet I need to do it one more time ) that red oil turned in to goo thick black goo . I flushed it out... keep in mind! I did use a new oil filter every time . I pored new oil in the engine
new filter and ran it no smoke came out yet when I turn the engine one the second time it smoke worst ... than I unplugged the pcv passenger hose from the valve cover and looked wet of oil from the in side .
I did the right side and it was clean and dry.. plugged back ! and the left side or passenger side off.plugged the hose and set a blind plug on the cover as to not let dirt in the engine and keep it clean. ran the car smoked a bit and stooped I figure what ever was in the exhaust system got burned. drove around went on the freeway like twenty miles and nothing no more smoke . WORKED ..(( I think that hole on the back top corner is an oil return from the top of the cover pvc system, sludge plugs it and builds oil up to the hose and gets sucked in by the pcv system hose)).. my car runs good ... still no smoke . I will remove the oil level censor and clean it looks like it is where that hole connects to and do a another flush . and clean that censor . maybe that hole gets cleaned . remember American cars only use one pcv valve on the engines Mercedes uses two why??? yet I will do the flush and see if I can clear that blocked hole in the back of the engine flush first.. (bad design in my view ) forgive My spelling and I hope it helps .. good life to you all ... you can see the hole that is plug at this link https://www.google.com/imgres?imgurl...NY05OC3lhoGm0M

[QUOTE= Omg I’m having the issue seems like no one knows … could I please get in contact with you for you to help me with this issue? I personally just want to do this myself I just need a walk through.