Pipe from the engine to the air filter ... smoke to the Carb!?

Question

There is a hose going from the engine compartment to the air filter. This air filter is passing this smoke to the carb, When I opened I found a load of oil remaining and slug in the carb. Shall I use carb cleaner into the air in --> to the carb? If yes then shall I block the pipe that is going to the air filter from the engine? It is continuous smoke coming to the carb.

Please help!

Yes it is a 1983 Mercedes Benz 200 Petrol Automatic Trans. Carb (not injecters).

Answer 1

I'm a mechanic, and several things can cause this. Lets examine the purpose of this pipe to begin with. This pipe is the engines means of venting the crankcase, and keeping the pressure under check. Too much pressure, and the engine throws oil out of it right past the seals, and valve cover gaskets. Smoke is there due to combustion gases blowing past the piston rings. Oil is present in the air cleaner due to too much pressure build up inside the crankcase. Too much wear in the rings and/or the piston walls will cause the engine to expel oil out the most likely place, and that being the big open pipe. Blocking off this pipe would only serve to force the oil out the seals and valve cover gaskets. Rings that have (varnish) built up deposits on them are not allowed to spring in and out with the bore as the piston goes up and down, can also cause this problem. This condition is called sticking rings, and can be helped by adding an oil treatment such as Risilone. This stuff will cut the build up off, and restore the compression, as well as reduce or eliminate the smoke and oil that is getting up inside the air cleaner. Change the oil & filter, and use 4 quarts of oil and one quart of Risilone. I'm not sure of the spelling on the product, but I do know it will do the job. Clean out the pipe, the air cleaner, and replace the PCV valve. Any hoses that are in this circuit that can leak must be replaced with good tight fitting hose. The hose that goes to the PCV valve must be free of obstruction. Where the PVC hose connects to the intake or base of the carburetor, must have good strong vacuum on it too. If you remove this hose with the engine running it should almost or stall the engine. If not, then you must clean out the circuit with a drill bit, or whatever it takes to open it up again. Usually this gets so clogged that it no longer has any vacuum on it. A coat hanger can be used to clean it along with some solvent such a carburetor/choke cleaner, but either way this circuit must be opened back up in order for the crankcase venting circuit to work properly. I know everyone is going to tell you the engine is worn out, but this may not be the case, as I have seen this many times in my lifetime. Fix any and all bad, cracked, spoongy, leaking vacuum hoses that are attached to the engine, and any fittings they attach to, to insure they are getting the vacuum to where it is designed to go. A varnish type build up on the piston rings, the sticking PCV valve, a lack of vacuum to the PCV valve can all contribute to the smoke, as well as the oil getting into the air filtration system. I have had to remove the carburetor in order to clean some of them out. This was a very common problem on Ford engines for some reason. I don't know what vehicle you have, but I would bet on it being a Ford. If you will follow my instructions, you will resolve the problem, if not, then you will have to rebuild the engine, and it is worn out. Some people used to turn the lid of the air cleaner up side down, in order to help with this problem. I'm not sure it would but it might?
Part 2:
The answer that is getting all of the votes is somewhat correct, but not totally. He did good at explaining how it works, but fell short of a solution other than what you already knew.
I have seen engines with less than 50,000 miles on them smoke out this pipe. Why would that be? Incorrect PVC valve. If the engine does not "vent" the crankcase, pressure builds up. As an engine builder, I know that piston rings seal off by building pressure between the compression ring, and the oil rings. If the crankcase is not vented properly, it builds up pressure on the other side of the rings, thus dropping the pressure required between the rings. The result is blow by! You didn't mention smoke out the exhaust pipe, and every engine I ever saw (that was worn out), smoked out the exhaust pipe. Reason? Too much evacuation of the crankcase due to the wrong PCV valve or the system stopped up. Oil that is allowed to go up the wrong side of the rings will burn and cause a varnish like substance to build up on them. This varnish stops the rings from expanding and contracting with the shape of the cylinder bore. The result of all of this is just what "your engine" is doing. I have tore into many engines that were so gummed up you wouldn't believe they would even run. They make a tool called a ring groove scrapper. Many engines that don't vent properly has rings that are so stuck, you have to beak the rings out of the pistons. Break the rings out, use the scrapper, intall new rings, and the engine runs as good as new, or you can try Risilone to free up those rings. The stuff is good, and works so good on engines such as yours. You can do what you wish, but I've been there and done that, and I think my quallifications ought to mean I should know what I'm talking about.
Glad I could help you, Good Luck!!!

Answer 2

Thick white smoke from the exhaust is either burning oil or steam from a bad head gasket. There is no silicon IN the engine, so where it really was needs to be clarified- possibly used in place of a gasket, but where- possibly on the valve cover where a gasket should be used instead. But, that would not explain the smoke. If you used silicon INSTEAD of a proper head gasket, the car will never be right until the head gasket is replaced and properly torqued and that is IF the head isn't warped or cracked. I would not be surprised if the head was warped, because it doesn't seem like any work done on this engine was done right and that whoever did any work on this engine had little idea how to do the job. The oil IN the spark plugs- I don't know what you mean. Spark plugs are not like bottles that can contain anything. They are installed in deep well-like configurations on the valve cover and into the cylinder head and the seal between the head and valve cover must be maintained by a gasket that retains the oil from coming up into the space the spark plug occupies, but you said it a different way that might not be what I said. Oil in that spot would not burn in the combustion chamber and make smoke out the exhaust. Your engine has many things wrong. Get a real mechanic to fix it. I suspect valve seal problems- the engine needs to be rebuilt. Good luck.

Answer 3

That hose is part of the crankcase evacuation system. Go ahead and clean it, replace the filter and buy a new PVC valve. Whats happening is that valve is clogged up and blow by from the rings in coming out into the air filter. If that doesn't work then do a compression check, my guess is you have a lot of miles and it may be time for a rebuild (if the PVC doesn't fix it).