W109, 3.5: engine is smoking - PeachParts Mercedes-Benz Forum

werminghausen · #1 08-01-2011, 06:55 PM

I was driving 250 miles today and engine smoked 1 quart of oil.

It was unbearable. At engine start and from a stop I produced a cloud of smoke and also accelerating from low speeds I produced quite some smoke. I had some smoke before but not this.Engine had good power all the time.
What is the reason and how can I solve this?

Tomguy · #2 08-02-2011, 04:53 AM

Is there any visible sign of oil in your intake? Like where the passenger side valve cover vents into the air cleaner? If you don't see any there, how about on the driver's side tube to the AAV - is there any sign of heavy oil flow? Sounds like one, or both of your "Spark Arresters" in the valve covers are plugged up, allowing positive crankcase pressure to blow oil through your rings. Either that, or you just developed a major issue all of a sudden, like a stuck ring, broken valve guide, or worse. 1 quart in 250 miles is a LOT unless you're talking old Ford or Detroit Diesel!

werminghausen · #3 08-02-2011, 07:07 AM

Quote:

Originally Posted by Tomguy

Is there any visible sign of oil in your intake? Like where the passenger side valve cover vents into the air cleaner? If you don't see any there, how about on the driver's side tube to the AAV - is there any sign of heavy oil flow? Sounds like one, or both of your "Spark Arresters" in the valve covers are plugged up, allowing positive crankcase pressure to blow oil through your rings. Either that, or you just developed a major issue all of a sudden, like a stuck ring, broken valve guide, or worse. 1 quart in 250 miles is a LOT unless you're talking old Ford or Detroit Diesel!

Unfortunately I have the car shipped to my new place to live: Oman. I can't check anything right now. But I don't believe that from here to now a valve cover completely plugs?
As I said the engine had good power but was really scary to accelerate because of the burning oil. I also tested compression last fall and it was in a okay range, nothing to worry about.

I won't see the car for about 2 months but as soon as the car arrives on the other side I have something to do.

From what you are saying there are options causing smoke at acceleration:

1) oil is pushed from the oil pan up through the rings by clogged ventilation and burns in the engine.
2) valve guide are leaking...maybe I lost a seal completely. Oil is leaking down the valve and burns. This might be a possible scenario I can imagine as I had some minor smoke before at start ups accelerating from a stop....but nowhere near the new smoke.

If second option is true I might try and just change the rubber seals with the head still in place and test drive?
People say changing stem seals is doable in a day?

Any other option?

Tomguy · #4 08-02-2011, 07:36 AM

I don't think seals would cause a quart of loss per 250 miles. I could see a quart in 1000, maybe 500... but I would say one or more guides are broken completely, allowing oil to pour from the head's resevoir(s) into the combustion chamber or exhaust directly depending on which valve(s) are affected.

werminghausen · #5 08-02-2011, 07:44 AM

Quote:

Originally Posted by Tomguy

I don't think seals would cause a quart of loss per 250 miles. I could see a quart in 1000, maybe 500... but I would say one or more guides are broken completely, allowing oil to pour from the head's resevoir(s) into the combustion chamber or exhaust directly depending on which valve(s) are affected.

Thanks Tomguy. If true that guides are broken- What breaks at the guides in this scenario and another question: Can I still run the engine and drive or is this getting dangerous?
This means finally i need to remove the heads and redo the valves in Oman?
How much time, how difficult and how much money are involved there. What parts do I need to order?

werminghausen · #6 08-03-2011, 01:52 PM

I bet the engine is sucking in a lot of oil when decelerating or at idle which gets burned then when accelerating- therefore the smoke. Need to do the stem seals or valve guides and stem seals.
Who has good advise and a manual how to change valve guides on a 116 engine? I know one requires removing the heads and the other is just changing the seals with the heads still in place.

Benz Dr. · #7 08-04-2011, 01:21 PM

Valve guides don't usually break but they can come loose. I've seen worn or loose guides use a lot of oil. It's possible to have a plugged vent on the valve cover but I really doubt this is the problem.
Don't bother with trying to replace the valve stem seals. It's only useful for a while and they will wear and start leaking quickly. Have a look at your spark plugs. The one/ones with heavy deposits is the cylinder you will be having problems with. Heavy oil consumption in a cylinder with normal compression will cause it to run hot and/or lean out which will burn up piston rings. This will score the cylinder walls.

Once you find which cylnder/s that are affected you may need to remove the head/s to have it repaired.

werminghausen · #8 08-09-2011, 03:41 PM

Quote:

Originally Posted by Benz Dr.

Valve guides don't usually break but they can come loose. I've seen worn or loose guides use a lot of oil. It's possible to have a plugged vent on the valve cover but I really doubt this is the problem.
Don't bother with trying to replace the valve stem seals. It's only useful for a while and they will wear and start leaking quickly. Have a look at your spark plugs. The one/ones with heavy deposits is the cylinder you will be having problems with. Heavy oil consumption in a cylinder with normal compression will cause it to run hot and/or lean out which will burn up piston rings. This will score the cylinder walls.

Once you find which cylnder/s that are affected you may need to remove the head/s to have it repaired.

Thanks....You are saying that one or more cylinders might be at risk.
What I understand from your comment: worn valve guides and worn valve seals initially cause the high oil consumption I was reporting....and then as a consequence...the burning of engine oil causes additional damages...burned up piston rings for instance?
Well I was driving 250 miles only under this condition and I hope none of the rings are affected but if you are correct...I need to remove the cylinder blocks in order to get to the pistons....?
So what needs to be repaired at the cylinder heads? New Valves, new guides? For all cylinders? Or just the ones with the heavy spark plug deposits?