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1997 E320
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9 Posts
Discussion Starter #1
My car has some strange problem, it starts normally without any prob or smoke, but when I leave it idle for some time i.e for 15 mins as engine temp is normal it starts smoking (with some burning smell) as I press accelerator for first time, then the smoke disappear but when I leave the car idle for a more few mins then on first accelerator press it again starts smoking for a while. I want to say that the car smoke when it is idle but when running then there is no smoke.
A mechanic told me its due to a bad valve seal, that starts leaking when engine is hot and allow leakage of engine oil to combustion chamber causing grey smoke. But I think that is not the problem, the reason is if that was the cause of smoke, then the car should produce smoke continuously while the engine was hot. Can any body help......
 

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Premium Member
2001 E320 - Brilliant Silver/Ash: 107,000+
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17,193 Posts
Dear! while driving it don't smoke, I checked it by having a friend chasing my car....
O.K. so maybe that's not it. There is something I've heard called valve stem seals but maybe those are the same thing. Better wait for some other members to comment. How often do you have to add a quart of oil?

Another thing is it's hard for your friend to see smoke when you are driving unless it is smoking like a freight train!
 

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Premium Member
2001 E320 - Brilliant Silver/Ash: 107,000+
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17,193 Posts
BTW, what does your poll have to do with your problem? I voted for Toyota because my 1991 Camry is the most reliable member of my fleet.
 

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Registered
1997 E300D
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508 Posts
It sounds like valve stem seals to me. The reason it only does it at idle is because the vacuum is highest around the intake valves at idle. The vacuum is sucking oil past the seals on the intake valves. When you advance the throttle the intake vacuum drops and less oil is sucked by.

I would try one of the bottles of additives that claim to soften seals, and if they mention valve seals, so much the better. Thicker oil will also reduce the amount of oil sucked by. Of course, the replacement of the seals is the real fix, and can typically be done without opening up the engine, so it's cost should be somewhat affordable.
 

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Registered
1999 E55, 2001 E320, 1990 560 SEC, 2004 ML350, 2001 ML55, 1995 S500, 1998 SL500, 2010 E550 Sport zoo
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7,035 Posts
What mileage, a interesting fact you left out if the equation ?

Does the car "puff smoke" when you hit kickdown mode ?

Sure sounds like seals, who knows more with so little to go on.
 

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2,043 Posts
once you said smoke at idle, and none while accelerating it's a good chance it's the seals. if you're free this weekend i'd definitely try a DIY stem seals are cheap.
 

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Dallas, Texas
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7,764 Posts
It sounds like valve stem seals to me. The reason it only does it at idle is because the vacuum is highest around the intake valves at idle. The vacuum is sucking oil past the seals on the intake valves. When you advance the throttle the intake vacuum drops and less oil is sucked by.

I would try one of the bottles of additives that claim to soften seals, and if they mention valve seals, so much the better. Thicker oil will also reduce the amount of oil sucked by. Of course, the replacement of the seals is the real fix, and can typically be done without opening up the engine, so it's cost should be somewhat affordable.
As a suppository applied trough the tail pipe? Any specific instructions?
 

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Registered
2001 SLK 320(217K Miles), 2002 E320 Special Edition(183K Miles)
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3,467 Posts
As a suppository applied trough the tail pipe? Any specific instructions?

Well, you know fiber-optics has really made a big difference in those, uhm .. embarrassing procedures. ;):D
 

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Registered
1997 E300D
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508 Posts
Good one. You will definitely have to remove the valve cover but the head can stay on. I have never done it on an overhead cam engine so I can't be sure if cams and timing chain are involved. This is engine work and not suitable for an average DIYer, in my opinion, as there is the possibility of dropping a valve into the cylinder, at which point the head will have to come off.
 

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Registered
'99 W210 E320 100 Kmiles
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61 Posts
My car smoked and it was the valve cover breather clogged.
I had cleaned it, following the post in the stickies, and the smoke dissapears.
Hope this help.
 

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Registered
1997 E320
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9 Posts
Discussion Starter #13
Dear Friends, Thank u so much for providing me such useful information. I am now pretty sure it may be valve seal problem and I am agreed with @nelbur opinion. I am living in Saudi Arabia, here the mechanics are very expensive, I will try the Additive formula first, heard alot about STP Engine stop leak. would it be safe?
I am trying to find STP Engine stop leak but couldn't found it here yet.
Any ways thanx alot for participating, Take Care and have nice time...
 

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Premium Member
2001 E320 - Brilliant Silver/Ash: 107,000+
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17,193 Posts
STP engine stop leak is not recommended for a MB engine and I would not use it in my other 2 cars either. You own a Mercedes and proper maintenance is what it deserves. Have the valve seals replaced and you should be driving happily for a long time from now.
 

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'99 W210 E320 100 Kmiles
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61 Posts
These aditives will kill your engine in the medium/long term, so if the problem is valve seal, replace them (sooner or later, you will need to replace them) and better sooner than using an aditive (wich change the viscosity of your oil).
 

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1997 E300D
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508 Posts
While it is true that Mercedes does not recommend ANY oil additives, I see this as a cover your as* statement. Better to recommend no additives than recommend some and be blamed for a problem someone might think was caused by a recommended additive. The "high mileage" engine oils sold by name brand oil manufacturers have a small amount of seal softener already in the oil. I have never seen any indication that seal softeners shorten the life of an engine.

Seal softeners themselves do not increase the viscosity of engine oil, however they could be added to viscosity increasing polymers, which could be a good thing for an old engine in a hot climate. I am not aware of the STP stop leak product, But I have their oil thickener in an old diesel I own to give it enough compression to start. In other words, I am using it to extend the life of the engine.
 
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