Have a 91 560SEL, just got it a couple of weeks ago. It was suggested to me that I run a bottle of the Chevron fuel system cleaner through a tank of gas. I did this and started noticing a small puff of white smoke upon start up. Never noticed it before and still on that tank of gas and the smoke seems to be lessening.

As I am a new first time MB owner just wnated to know if it could be the additive and if I should be concerned?

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D. Thomas
1991 560SEL
New Owner as of 05/25/2002, first MB!
http://www.bellsouthpwp.net/d/n/dnt0512/1991.htmL

In other non-MB cars I've owned white smoke generally meant that coolant was being burned with gas. Does it smell sweet? It was usually a leaky intake manifold causing the problem. I don't know about MB though. If it is going away consider yourself lucky but look for more experienced voices on this issue.

I put some Vavoline synpower fuel injector cleaner in my 300e and I messed up the ratio to fuel completely. I thought more is better. So I decided to go up a steep incline going at 110 mph to burn all the deposits out after filling up with some gas. Nothing got messed up but I would never do such a thing, again ever. You want fuel injector cleaner put chevron techron supreme fuel from the pump. Techron is much milder than the concentrates in the bottle and also better mixed. The two things that you could really be messing up are the o2 sensors and the cats. Once the gunk removed from the fuel injector arrives at the o2 it will most likely foul it up. Also the gunk could clog your cat. You could also be dislodging some deposits in your tank and fuel pumps that could easily destroy your fuel pumps. Good gas doesnt need to be supplemented with other things. Just my 2 cents.

dnthomas,

Does the condition exist when the car is warmed up? It is typical for the moisture in normal exhaust, when the car is not warmed up and the cat is cold, to become visible white puffs that evaporate again in relatively short order. The higher the humidity the more visible the vapor coming out with the exhaust as water vapor is a major constituent of exhaust in a well running machine. If the water vapor is cooled by the ambient air enough to increase the relative humidity to near 100%, you see a cloud or puff of white looking stuff hanging around the exhaust pipe.

As the cat heats up, and the exhaust pipe and muffler heat up, the hotter exhaust keeps the relative humidity around the exhaust pipe opening lower, as it heats the ambient air enough to lower its relative humidity enough to keep the exhaust water vapor from becoming visible. When the car is moving the relatively small volume of exhaust mixes with the relatively large volume of ambient air, making the contribution of water vapor from the exhaust very minor, and it does not remain visible. Unless the ambient air is near or at 100% relative humidity, in which case the exhaust plume is visible even when the engine is warm. In my experience, these are not signs of head gasket leaks or any other impending doom. They are normal. If you see that you are consuming coolant, that is another story. Loss of coolant is always a concern, as if it is just leaking, leaks rarely get better on their own, and usually lead to a complete failure of a hose, connection or water pump seal that will incapacitate the vehicle. If it is being sucked into the combustion chamber, it can cause other problems. But water vapor at the tailpipe when the engine is cold is not necessarily a sign of coolant running through the engine combustion path. Good Luck, Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

Good info Jim,

Whe my 560 is parked overnight in a damp below-ground parking garage, I notice small puff of white smoke. The car is always at correct temp and coolant level is constant -- also the 117.968 motor isn't known for head gasket failure. Keep your eye on it and let us know what transpires.

Well I think that you have hit on the problem. Coolant level remains steady, temp seems to remain at 80-85 even on the hot days we have been geting here in Mississippi. Goes up to about 100 if in bumper to bumper rush hour traffic but comes right back down when traffic thins out. I have payed close attention and I see the small puff of white smoke usually in the morning or after the car has sat for a good while.

I recently took it on a short trip, couple hundred miles, and checked constantly for any leaks at all and found none. I will continue to check and I have a scheduled maintenance coming up. By the way, I sheduled it with the Mercedes dealer who originally sold the car and did it through the Mercedes website and called them and they offered to do a 130 something point check along with the maintenance at no additional charge. They were actually very nice and impressed that I was going to drive it to Florida to have this done. They told me just before I bought the car that they had done maintenance on it since it was new in 1991 and told me they would review all the records and so I decided to drive there (about 120 miles) and take a look.

Thanks so much for all the replies, I think I was very lucky to find the discussion board and particpate in it.

__________________
D. Thomas
1991 560SEL
New Owner as of 05/25/2002, first MB!
http://www.bellsouthpwp.net/d/n/dnt0512/1991.htmL