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Discussion Starter #1
Good Day gentleman and ladies if any.

I have a bit of a problem on my w201 2.6. About 2 weeks ago I noticed some smoke (a bit heavy) upon acceleration on my rear view mirror. I couldn't tell whether it was blue or white smoke. Now I use the car daily and about a week ago I when I started the car in the morning it had a misfire. I thought it would go away but it didn't. I checked all plugs and found plug number 1 (or 6) which is the first one from the firewall to be wet and was pretty black.

I replaced the plug with a used one (previous plugs from last service) and it fired nicely with no misfire. I drove the car for the full day and on my way home the car started misfiring. I bought 6 new plugs and it has been fine eversince only the smoking is an issue.

Car also smokes when I'm going downhill and I select the transmission to lock gear on "3" and it puts out a huge smoke cloud until I change it back to "D"

Could the fault be my piston rings or valve guides? My valve stem seals are pretty new as I changed them when I had my valves cleaned due to non-seating.

Any suggestions welcome


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89 190E 2.6 x2
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If your cylinder head has never been refreshed then it's most likely the valve guides are worn as well. Valve stem seals do help with excessive oil burning, but they're often considered more of a "band-aid"
I would have a machine shop do the guides, seals and valve springs while they're at it. Not sure where you are located, but it's best to find a machine shop that knows MB engines well.
 

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W201 Moderator
89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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2,516 Posts
I would do some diagnostic testing first because removing the head to do anything is a lot of work. In order of ease:

(1) Compression check to see if #6 is worse than others. If you do not have a smoking gun
(2) Do a leakdown test. Pretty easy as well if you have an air compressor, in your case it will be a lot more useful than a compression test.
(3) Make sure you are not loosing transmission fluid. Is it your engine oil level going down or your transmission fluid. What are you burning?

If you are seeing smoke out the tailpipe that is pretty serious and is indicative of a single cylinder issue if it indeed is your engine oil. Evenly burnt engine oil is not visible even down below 400mi / quart.

It could be a stuck piston ring or a messed up valve guide/seal. You will know which one by doing tests 1 and 2 above.
If you are a DIY person, cost is minimal to none if you have a compressor and a leakdown tester (<$100). Very useful to have these shop tools.

BTW, you could have a bad valve seal as well at the #6 intake. Family had a brand new W115 that had a bad seal with similar symptoms at <10K miles. That one is easy to replace if it is the case. Your symptoms (blowing smoke at high compression (downhill in low gear) is what this W115 had. One bad valve seal.

But I have also heard of the transmission fluid getting into the intake through the vacuum valve. I do not know if that could be your problem.

First do #1 and #2 above assuming it is engine oil that is burning.

Nice looking car BTW....
 

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Discussion Starter #4
If your cylinder head has never been refreshed then it's most likely the valve guides are worn as well. Valve stem seals do help with excessive oil burning, but they're often considered more of a "band-aid"
I would have a machine shop do the guides, seals and valve springs while they're at it. Not sure where you are located, but it's best to find a machine shop that knows MB engines well.
Thanks a lot I will definately look into it. But I've noticed that it doesn't burn much oil. I use it daily and I have not topped up any oil in the last few weeks and it's still on the same level. However Transmission fluid seems to dissappear. I put about 4 quarts every 2 weeks.

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Discussion Starter #5
I would do some diagnostic testing first because removing the head to do anything is a lot of work. In order of ease:

(1) Compression check to see if #6 is worse than others. If you do not have a smoking gun
(2) Do a leakdown test. Pretty easy as well if you have an air compressor, in your case it will be a lot more useful than a compression test.
(3) Make sure you are not loosing transmission fluid. Is it your engine oil level going down or your transmission fluid. What are you burning?

If you are seeing smoke out the tailpipe that is pretty serious and is indicative of a single cylinder issue if it indeed is your engine oil. Evenly burnt engine oil is not visible even down below 400mi / quart.

It could be a stuck piston ring or a messed up valve guide/seal. You will know which one by doing tests 1 and 2 above.
If you are a DIY person, cost is minimal to none if you have a compressor and a leakdown tester (
BTW, you could have a bad valve seal as well at the #6 intake. Family had a brand new W115 that had a bad seal with similar symptoms at
But I have also heard of the transmission fluid getting into the intake through the vacuum valve. I do not know if that could be your problem.

First do #1 and #2 above assuming it is engine oil that is burning.

Nice looking car BTW....
Thanks a lot bud. I will start with the compression test so I can eliminate some of the problems you have listed. I do however lose quite a lot of transmission fluid about half a quart daily. I usually see a drops on my driveway of pink fluid and I always top it up every 3 to 4 days. Haven't really had time to get it checked as I use the car daily. Thought its a leaky gasket that needs replacing. Didn't know Transmission oil could get into the combustion chamber.

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Discussion Starter #6
Thanks a lot I will definately look into it. But I've noticed that it doesn't burn much oil. I use it daily and I have not topped up any oil in the last few weeks and it's still on the same level. However Transmission fluid seems to dissappear. I put about 4 quarts every 2 weeks.

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Also I haven't seen any significant oil consumption over the past few weeks. I check it every second day and it's more or less same amount. I'm sure if it was burning oil I would see a noticeable difference in the oil level.

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W201 Moderator
89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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2,516 Posts
If your oil is not disappearing, you can forget about all the engine diagnosis. I believe your auto transmission is sensing the intake vacuum so it can shift at the proper time/load.
It is this valve that can leak transmission fluid straight into your intake which goes right into your cylinder(s). It would make sense that more fluid will be sucked in when there is a lot of vacuum (engine compression) which is your situation. You will need to change that valve to solve this problem IMHO. I have read this in various posts as I mentioned before.
 
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