gray smoke after EGR replacement
Thread Starter
Newbie
Joined: Sep 2007
Posts: 9
Likes: 0
From: New York, NY
2014 CLA250 Coupe 4MATIC C117
gray smoke after EGR replacement
ML320 2001 190k. I replaced the EGR valve, cleaned the tube thoroughly, replaced all and the truck ran fine for two months or so with no codes. A noticeable shaking at idle appeared and I rechecked the vacuum hose connections associated with the EGR replacement and found one lose connection at the air distribution hose connector above the main intake area. The idle improved and the shaking stopped, however, after a 5 mile drive, a very large thick, gray smoke plume came bursting out of the exhaust. It stopped a few minutes later, but continues to come out in a steady, smaller amount for a minutes after a cold start or after the truck has sat off for a few hours. There is no noticeable lose of engine oil, coolant or over heating, yet, as it has only been 24 hours. I suspect a clog somewhere in the vacuum system, maybe in the valve covers, but may be wishful thinking. The check engine light comes on and the only code is PO301. I ordered new spark plugs yesterday. Any ideas?
Last edited by nycloving; Mar 16, 2015 at 04:53 PM. Reason: msispellings
Super Member
Joined: May 2013
Posts: 504
Likes: 7
From: Harare, Zimbabwe
2003 ML55,2007 ML63
P0301 is cylinder 1 misfire. Check the spark plug wire. Replace it with a similar one from another cylinder & see if the code will shift. If you get the same code, change the coil & see if the code shifts.
Plugs you ordered already.......Have you got the spark plug wire remover? You wont be able to change the plugs without it......
Plugs you ordered already.......Have you got the spark plug wire remover? You wont be able to change the plugs without it......
Thread Starter
Newbie
Joined: Sep 2007
Posts: 9
Likes: 0
From: New York, NY
2014 CLA250 Coupe 4MATIC C117
Thank you Art for the advice on the wire and coil, that makes sense and I will try it this weekend. I do not have the spark plug wire remover and will look for that to order. I am a little concerned that I did not have any smoking issue until I removed the air filter and air intake pipe to the actuator when looking for the vacuum leak. The leak turned out to be from the air distribution hose connector at the top of the accelerator actuator, so I made sure that it was fitting snugly. put everything back, it idled smoothly, but then the burst of gray smoke from time to time, mostly at start up. Thanks again and I will definitely try this then update over this coming weekend.
Super Member
Joined: May 2013
Posts: 504
Likes: 7
From: Harare, Zimbabwe
2003 ML55,2007 ML63
While you are at it you can also check that the Air Intake pipe is properly sited & clipped in correct position. Remember that ,even air leak in the intake pipe will create problems. You will have unmetered air entering the system which will confuse the Fuel mixture ratio......... So make sure all components of the Air Intake Pipe are properly secured & positioned.
Thread Starter
Newbie
Joined: Sep 2007
Posts: 9
Likes: 0
From: New York, NY
2014 CLA250 Coupe 4MATIC C117
I replaced the plugs today; cylinders 1 and 4 plugs were caked with black carbon. The 17 mm offset wrench made the plugs replacement a breeze, thanks Art! The check engine light is staying off, but I am still getting a periodic plume of dark gray smoke out of the exhaust. Again, this smoke did not show up until I removed the air intake and other hoses to replace the EGR valve. After the replacement, ran fine for several months, developed what I thought was a vacuum leak and PO301 codes. Checked vacuum hoses by removing intake and hoses + connector, replaced and then developed the gray smoke problem, which I have confirmed is oil. Any ideas
Trending Topics
MBWorld Fanatic!
Joined: Oct 2011
Posts: 7,107
Likes: 765
From: Bronx, N.Y.
2002 ML 320 & 2006 ML500
Did you remove the #164 valves from their respective hoses?
Are either of the two clips broken on the air intake tube?
With the engine cold, disconnect the three hose ends from the valve covers, start the engine and see if smoke comes out of the valve cover nipples. Continue to run the eng. and observe nipples.
Are either of the two clips broken on the air intake tube?
With the engine cold, disconnect the three hose ends from the valve covers, start the engine and see if smoke comes out of the valve cover nipples. Continue to run the eng. and observe nipples.
MB World Stories
The Best of Mercedes & AMG
6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)
Verdad Gallardo
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
Thread Starter
Newbie
Joined: Sep 2007
Posts: 9
Likes: 0
From: New York, NY
2014 CLA250 Coupe 4MATIC C117
Maj. Dundee, thanks for the schematic and response. I just removed the #164 valves and replaced the distribution #158 and checked the intake pipe connection last night. There was no smoke this morning, drove about 20 miles with no problem and then got the smoke again. I believe the connector at the bottom of the intake pipe is not making a "clip" and I am not sure if it goes "into" an opening or just clips over a lip. It is very difficult to see under the pipe working by myself. Do you know how that clip works? I may have broken it, although it does not appear to be broken. Thanks for the help.
MBWorld Fanatic!
Joined: Oct 2011
Posts: 7,107
Likes: 765
From: Bronx, N.Y.
2002 ML 320 & 2006 ML500
It clips onto the lip of the throttle actuator.
Did you remove the three hoses and run the eng. as I suggested?
You have to respond to all suggestions or this will be a waste of time.
Did you remove the three hoses and run the eng. as I suggested?
You have to respond to all suggestions or this will be a waste of time.
