Chinny4290

Hey guys. I am currently the new owner of a 1975 280S with only 76k miles on it. Interior is immaculate, exterior is faded but we're gunna take care of that and the body is almost perfect Very little rust, surface if any.

Here are some issues though.

I get blue smoke from the exhaust when the engine is running.

Once in a while I get a huge big cloud of blue smoke. and i deciphered that when i go above 3-3500 RPM, then let go, stay off the gas, but get on it, that's when the huge cloud comes.

I already know that means oil is burning, after 4 hours of highway driving it burned 1 quart. But can anyone help me further diagnose this issue? OS, said that the valve cover gasket needs replacing, maybe valve seals...but my uncle, a fluent mechanic thinks its more. Before you start thinking, also read these:

Idle is rough. Engine seems very weak at the top end (I know this is a slow car, i was preparing for that but on the NJ Turnpike where it's nice and flat, I floored it and it took me 30 seconds to get from 79 to 82).

There's also an audible buzzing/whining from the inside when the engine is at speed and lessens when you lift off.

It's not a total loss because we didn't break down at all in the duration of the trip. So I know its something that could be salvageable.

I also know that my uncle and I are going to do a full tune up with the car, meaning spark plugs, rotor and cap for the distributer etc. We are also going to do the valve seals and the valve cover gasket, valve adjustments etc But what else could the other things be? Help? We also know its not electrical because the car starts right up with no hesitation.

Also the power steering fluid is brown, and when the car is in reverse, the steering gets jerky when you try and turn it, like power steering is cutting in and out. In drive or at normal speeds the steering is fine.

Other than that the car is perfect. Transmission is perfect, HVAC works, and all the other little things do.

Pics later. i promise, I live in Jersey but it's at my uncles house iN Staten Island right now. Thanks guys!

Untertürkheim

It does not make much sense to try to diagnose problems before you even have a chance to service the car. The whirring noise may be due to old motor oil or old differential fluid. Once all those things are changed and you have some high quality lubricant in the car, then it will be time to find the issues.

AH1W-COBRA

although i wouldent spend big dollars on the engine oil.just go with a standard castrol 30wt or any oil of your choice and a new filter.based on your description of somke and oil consumption your literally pumping oil into the hot exhaust manifold and creating those plumes as you are describing.on deceleration you create high vacume conditions within the engine which pulls oil past valve stem seals and worn/sticking/broken rings.as soon as you gas it the flow of combustion gases carries the oil into the hot exhaust manifold and you get that plume effect.when you pull the plugs look into the cylinder with a flashlight and attempt to see any valves that are open,is there oil dripping or are they wet with oil?stem seals.also spark plug threads that are saturated with oil is also a sign of stem seals.im looking into a 1974 MB tomorrow with 88k miles on it and im glad i read your thread.i have allways wanted an old benz but there is alot that can go wrong on cars this old.im thinking i better be prepaired for a complete disassembly of the engine with a minimum of complete engine seals and gaskets,valvejob and potentially bearings,hone and rings.good luck,there is a slight chance that it will run better with use.run the new oil for a couple hundred miles and if things start looking better than change the oil and filter again but stay with a single viscosity oil.

Chinny4290

I actually fixed it.

It was the vacuum pump which runs off the camshaft on the M110s in the 280Ss for the US. The cam seal was bad so oil under high engine pressure would flood the vacuum pump and go into the intake vacuum line, basically going into the cylinders and burning.

Piston rings are fine, compression is fine, valve seals are fine. All is well.

AH1W-COBRA

so this car stopped smoking completely?was the car maintaned at all or was it simply parked and never started for years.im headed over to check out the 1974 now.im most worried about the coolant just sitting in the block for the last 9 years and never being started.i do live in the ca high desert so rust isnt an issue.

Chinny4290

Yup.

The car sat for a year, and was maintained prior to sitting.

I did a complete tune up about 2-3 months ago and it runs as fine as ever.