Smokey Engine

[n/a]

Hi,

My 250SL is smoking quite badly and I'm considering using an oil additive. Have any of you used them and do they work? Which is the best?

Cheers
Andrew
1968 250SL
London

[rwmastel]

First, I've read many times that MB does not recommend any fuel or oil additives.  I belive this has been true for many decades.

Beyond that, I guess the first questions are:
- Is your engine smokey, or your exhaust?  I assume you don't have smoke coming directly from the engine!
- Why is it smoking?
- When is it smoking?
- How much is it smoking?
- What color/oder does the smoke have?
- What do you expect the oil additive will accomplish?

For example, my 230SL emits oily smoke out the tail pipe.  I have come to learn that car probably has over 225,000 miles on it and the engine needs a rebuild.  The valve guides are worn and the valve seals may be original!  It uses lots of oil and it comes out the most under hard acceleration or at maintained high (4,000) RPM.  The compression is at the low end of acceptable and the bearings on the crankshaft are worn & scored from poor oil filtration.  Do you know similar information about your car?  This would help us help you do the right thing.

Thanks,

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[n/a]

Rodd,

Smoke out the end of the exhaust. If you take the oil filler cap off you notice some smoke within. Yes, old engine that needs a rebuild but would prefer to hold that off until I transport her to Australia later this year or next year so looking for a short term fix. She also has excessive fuel consumption so not sure if related. Probably not as there is a slight smell of fuel in the car so it could be any number of things.

The smoke is cigarette smoke in colour - grey not blue and on the light grey side.

It smokes on start up and on heavy acceleration.

I would expect the oil additive to restrict the flow of oil over the rings but perhaps this is naive or too opptimistic.

Thanks for your help,
Andrew

[Cees Klumper]

When my engine smoked (blue) I tried an additive once - it made no difference at all. I had to go for the rebuild. Grey smoke might indicate there's something other than oil burning (does your engine consume a lot of oil? Oil burning can be spotted also when you see a brownish, greasy film develop on the right rear bumper and body after not washing the car for a while).

Cees Klumper in Amsterdam
'69 white 280 SL automatic

[Malc]

Smoke and excessive fuel consumption suggests that the petrol is washing the bores which will eventually result in piston ring wear and higher oil consumption. Also make sure engine breather hoses are not blocked as this can result in crankcase pressurisation and force oil into places it should not be.

what colour are the spark plugs?
white/silver - running weak,
light brown - just right
black - rich
black and sooty - way too rich
crusty deposits on tip and electrode - that cylinder is burning oil

check your compression in each cylinder low suggests worn rings or valves

This might sound silly but check that the air filter is ok. A damaged or clogged one will produce these symptoms especially if you have an engine breather which goes to the inlet manifold downstream of the filter as this will draw even more oil and oil vapour from the crankcase into the engine

Depending on the type of driving you are doing you may want to try a "hotter" spark plug especially if you are doing short journeys or alot of stop/start stuff.this can help to reduce smoke.
Hope this helps
Malc
Scotland

[ja17]

Hello Andrew,
If your engine is smoking it will be using excessive engine oil, or transmission fluid (if an automatic),  or engine coolant, or excessive fuel. You cannot begin to diagnose the problem if you do not determine in which area to look first. What more can you tell us?

Joe Alexander
Blacklick, Ohio