I'd check the valve seals and guides as in most cars what you're describing is a function of bad seals and or valve guides. That would be my first step AFTER I checked the search function for similar issues.

 

Are both CATS removed(upstream & downstream) or only downstream ones?

 

BOTH Cats removed, upstream and downstream, O2 sensors are in place

I have been searching the Forum for days now... the only thing I haven't check is for crankcase blow-by - I am going to put it back together and check that.

I did find oil residue (not wet oil) in the valve cover vent tubes to the top of the throttle body and sticky oil smelling grime in the throttle body (cleaned it out)

If it does have worn rings why dosent it smoke all of the time?

I would hate to try and swap exhaust valve seals and still have the same problem

it looks like someone messed with the egr too, new gaskets etc


the ONLY thing I wouldn't be able to overcome is worn rings, but I don't think that is the issue

 

BOTH Cats removed, upstream and downstream, O2 sensors are in place

If both cats have been removed upstream and down stream, i'm not surprised it smokes.

 

the large hose to the snorkel before the throttle body was a little wet and grimy but...

 

Remove the new plug that has oil on it and install one of the old plugs that is dry. If that plug is wet again then in all probability you need valve seals.

Doing seals is not like the old days. It's a fairly big deal.

 

Ok I will try that in the morning (swapping plugs and/or inspecting them)

on the Passenger side valve cover I have noticed ALOT more restriction than the other side when I was going to put it back together - I have soaked the vent tube chamber all day and flushed it out several times I couldn't seem to get the cover off the valve cover it was like it is JB welded on...

I could blow compressed air into the right side vent tube and it seemed fine but I actually checked the suction and it seemed clogged - if that makes any sense - I could blow in it freely but not the other way around

WOULD THIS CAUSE the oil not to drain at the exhaust valve oil returns properly and cause it to fill up with too much oil for the seals to resist at idle or are the exhaust valves always submerged?

something is happening after it idles a long while, it is fine until that point ( I think ) unfortunately I haven't been able to put many miles on it waiting for a new tag but will have that tomorrow and engine parts will be back together I guess, so I can drive it and see what happens after running ten minutes or so... car is supposed to be fine but has been sitting lately

 

Bad valve stem seals will also normally leak after shut down and then blow a small bit of smoke at start up.

 

Questions and comments:

1. how (what procedure) did you determine there was no suction at the passenger side hose?

2. when you turn the key to pos. #2 , does your CEL illuminate?

3. isn't there a state inspection in Florida?

4. it's against Federal law to tamper with or remove Cat. Converters and no state can countermand that law?

5. the required oil for an ML is Mobil 1 0-W40 along with a fleece filter. Look at the link below as Mobil suggests using a spin-on filter which was never on an ML.

https://mobiloil.com/en/product-sel...00&Make=TWVyY2VkZXMtQmVueg==&Model=TUwzMjA=&Engine=QmFzZSA2LUN5bCAzLjIgKEdBUyk=

 

See bolded words below. I think you have recourse to the seller.

Catalytic Converter Laws

Rules for Replacing Converters
In 1986, the U.S. Environmental Protection Agency issued new guidelines for the construction, efficiency and installation of aftermarket catalytic converters. All CleanAir converters listed in this catalog have been designed, tested and manufactured to meet this policy.
In addition, CleanAir converter listed in this catalog is appropriate for use under the current requirements of the California Air Resources Board (C.A.R.B.).
E.P.A. guidelines state that replacement converters may be installed only in the following situations:
1. The vehicle is missing a converter
2. A state or local inspection program has determined that the existing converter needs replacement
3. Vehicles manufactured prior to 1996 must have more than 50,000 miles, and a legitimate need for replacement must be established and documented
4. In cases of OBD Il-equipped vehicles (1996 and later), the O.E. manufacturer's 8-year/80,000-mile warranty must have expired and a legitimate need for replacement must be established and documented.
Please note that Federal law prohibits removal or replacement of a properly functioning O.E. converter.
When replacement of the converter is appropriate (as outlined above), the E.P.A. further requires that:
1. It be installed in the same location as the original
2. It be the same type as the original (i.e., two-way, three-way, three-way plus air/three-way plus oxidation)
3. It be the proper model for the vehicle application as determined and specified by the manufacturer
4. It be properly connected to any existing air injection components on the vehicle
5. It be installed with any other required converter for a particular application
6. It be accompanied by a warranty information card to be completed by the installer.
Catalytic Converter Laws

It is possible that the catalytic converter was stolen and the seller was unaware of this. Stealing catalytic converters seems to be the latest craze among thieves. They contain valuable metals for recyclers.

http://www.nytimes.com/2008/03/29/us...rssnyt&emc=rss

Driving a car without a catalytic converter is illegal unless age of vehicle is exempt. Car will not pass emissions test. It is illegal to sell a car with tampered emissions system.

 

I bought the ML at the Manheim Auto Auction in Daytona Beach Florida (USA) - I should have recourse BUT as I said I got it for my Daughter and I am willing to do whatever to make it right and last a couple years... except maybe pull the engine. I know where a junk ML is with good cats IF I can get it to stop smoking I will get them , otherwise it has to go bye bye or back to the Dealer I got it from and I will try and step her up to the newer 350 or a 430 (too bad if so because it is very very Clean in and out - 129,000miles)

I got the PCV cover off of the valve cover and there was some crust in there but not bad and was some white scale(?) around vent pin hole but not "clogged" like I suspected too bad at all.

I ran it at idle for about 15 minutes before the first real signs of smoke appeared - then I ran it at 2000+rpms for 3-4minutes and at first smoke poured out and then it thinned out and disappeared until I let off completely and revved it again and more smoke rolled out and thinned out again...

I am wondering (hoping actually) if the exhaust has oil in it that is just burning off because it had been sitting AND because the passenger side valve cover was leaking a bit and ending up seeping onto the exhaust and possibly soaked into manifold

OR the damn thing has bad rings or valve stem seals - I guess I gotta do a compression check in the morning and check/swap plugs... only way to know I guess

AM I GOING TO BE ABLE TO FIX THIS ?

if it is driven regularly will it not smoke? (it has been started only a few times to move it around in past month)

I put 10w30 Mobil 1 but I am in Florida so it should be fine(?)

why would a 129000 mile engine smoke like this?

 

will no cats cause it? or just not conceal same issue of oil burning but much cleaner due to superheated converter cores?

I fear its the exhaust valve guide seals - if I had to place a bet



*but I have NO maintenance history on this one so I cannot rule out worn rings/cylinders from lack of maintenance until after a compression check at least

I really am hoping the thing will be ok, but I am a little worried too I cant have my daughter going though cases of oil (possibly) and/or run too low from consumption OR be totally embarrassed at every light (possibly, I need to drive it I guess)

 

Cars did not smoke blue prior to 1976 when cats were mandated unless they have a problem.

30 weight oil seems thin for Florida's high temps. You should be running 0w40 Mobil 1. In the summer I run a 5w40. Both are Mercedes approved brands.

 

If you want to eliminate the ring issue do a compression test. Spec out what the compression should be and test. And there should be a difference I believe of 10% ( verify) between the compression values of the cylinders. If the compression is within parameters then look to valve guides and seals. Based upon your description I'm believing it's seals. As 43sqd said its not a quick job. As for your cats the dealer should not have permitted the vehicle to be sold without cats and the Seller has a problem as well. I replaced my stock broken noisey cats with good aftermarket cats and all lights are out and the snapon ultra says no codes. That was a real job because of cramped conditions but the change was made with the exhaust in place a tig welder and a tech who could weld anything.
How much oil is it using between changes? Rings tend to gulp oil while seals in early stages do not to the extent of the rings. Also with no maintenance records you must assume that nothing has been done so you need to change fluids in rears, transmission, transfer case and the radiator and brakes. But get the engine sorted out first. And there are reputable recyclers who pull engines and offer them for sale with warranty so if it's that clean I'd consider that option. If you want to keep the truck you can at a cost that won't break the bank. Good luck.

 

Car is running on map without info from cats. ECU will be freaked out and will be burning fuel for fun. Does the tail pipe smell of fuel. Remove a spark plug is it wet, does it smell of fuel. Blue smoke does indicate oil burning but if its been run without cats for a while i would suspect valve damage due to heat.

 

I didn't get to do a compression test today, however I did stat it up a couple times and NO smoke but didn't run it more than 10 minutes

It did have a slight stumble with the ac on but no smoke

I get the tag tomorrow and will drive it too

I WONDER HOW MUCH NEW AFTERMARKET CONVERTERS COST - I can get them welded in... something with flow but cheap

I am hoping what I was seeing was Soot burning off inside exhaust pipes and muffler

- and I am afraid that maybe the oil had been topped off with something other than Mobil 1 but I changed it

*The coolant is a very clean and is pink colored
*the engine was immaculate besides a small valve cover leak on passenger side
*the old oil was brown, but clear and no Debris or issues
*There is absolutely NO crankcase blow-by or pressure from oil fill

 

It has the wrong coolant in it.

You can get cats welded in. Search the W163 forum for Magnaflow. Here is just one example.
http://www.benzworld.org/forums/w163-m-class/2255626-my-catalatic-converter-i-think-making.html

 

OK - THIS CAR DOES NOT SMOKE!

there was some old built up soot or oil from the leaking valve cover gasket that seeped into the exhaust causing it to smoke I guess

it does NOT need rings, honed, seals, different oil, PCV system overhaul, or anything...

it does need cats but not to make it run any better (thank god)


I am so relieved - we drove it for 2 days and NO smoke and oil level never dropped , it is a Good Benz with no issues at all even with no cats it didn't miss a beat and averaged well over 20mpg w/ AC on

Thank You everybody for your interest and response to my issue - I really appreciate it

 

Thats hard to believe. my rear cat heater is throwing a code and its not happy on one side.

 

ya it runs good without the cats - it does stumble a little when idling in gear for a long time but I mean just a little, nothing wrong with acceleration or mpg or smoke.... nothing... I am surprised too but It is what it is and I am not complaining, it runs like a Triple Crown Champ

 

Your the first i have heard of who runs an ML without cats. Maybe there is some backup mapping in the ecu for such a thing. Whood a thought it. Nice one.
Bet you got more power without the restriction.

 

I have similar issue on my ML320. Can you please tell what was done to it please