280C Advise

[rb6667]

I am looking at a 1975 280C  Would like to hear the pros and cons of these cars.  This car has new paint, sunroof.  Twin Cam engine.   

Advise appreciated.

RB6667

[Louis]

Great cars but the carbs can be troublesome in the wrong hands.....  :'(

[w113dude]

Are 280c injected or carbs?

[Louis]

Carbs.....

 A CE is the injected version and were only available in Europe.....

[rb6667]

Sorry, should have mentioned that this is a Solex carb twin cam engine.  Seems to run fine now, but I've heard that the carb can be a real problem.  Anything else about these cars that i should be looking at as a trouble area?

Rust I know, but not well versed on that twin cam engine and the trans.

Thanks for the replies.

RB6667

[KevinC]

I owned a 1973 280C for three years from 1982 to 1985 and no engine issues at all. Have heard that when well-maintained, this is a nice car-engine combination. My buddy had a 1974 and no issues either. The '73 had the tighter European-style bumpers but there was not much difference otherwise. 

[rb6667]

Thanks for the information. 

RB6667

[Louis]

Another problematic repair is to the heater . Make sure it's working well and if not , consider getting an estimate for its repair . Don't let any of these warnings scare you. These are great cars but you asked if there were any areas that needed cautionary mentioning before purchase and that's what I have pointed out. I have owned my 73 280CE for 10 years and have driven all over this country without any problems. Take a look at this other forum and ask questions there as well.

http://www.stroke8.org/

[rb6667]

Great advise Louis, and thanks for the link on the 114 forum.  I'll check it out.

RB6667

[ja17]

The 1975 USA and later were different animals. They  had lower compression, catalytic converters, and the carb was loaded down with emission devices as was the ignition. This de-tuned USA version also used a lot of fuel.  So compared to the 73 and 74 or the Euro model, it is a bit sluggish and loaded with emission devices and gulps fuel. If you look up the horsepower rating of that big heavy twin cam engine you will see that the 1975 USA version is down on power.

The biggest danger is having a unfamiliar tech in that engine compartment messing with all those vacuume lines and fiddling with that complex big Solex. Watch out for inconsistent idle or hesitations under acceleration.

Try to get service records to make sure the car has no nagging tuning issues. The fuel injected Euro versions were sweet and strong running cars.

I am sure there are some fine examples out there, and this may be one. Just thought you should hear some other concerns.

[Benz Dr.]

The carbs are not that hard to tune if you understand them. I had a '73 sedan as my first MB car ( the 190 SL was still being restored at the time ) and I got to know it well. Later, I had a '74 sedan that I drove into the ground. I have a '74 coupe with a fresh engine but I never put it back on the road.
The secondary throttle plates are about twice a large as the primary side. Above the secondaries you will find an air flap that controls the needle valves. There's a small spring which tensions the air flaps. I find that most of these springs are set too loose and the engine will bog down when you floor the gas pedal. Get the tension right and that twin cam will really pull hard. Great engine sound from one of those monsters.

Valves are all mechanical adjust and need to be set regularly.

[stickandrudderman]

There's a lot of idiosyncracies to know about with the Solex 4A1 carbs. Each carb is effectively two carbs in a single casting and each has to be individually set up. Some engines, including the M110, had two of these carbs so setting them up could easily take a couple of hours even for an experienced tech. Just finding the adjustment screws, even when you know where they are, is a drama.
I haven't seen one for about 10 years and am not unhappy about it!

[ja17]

Like I said the 1975 and later USA cars were different animals. Dan, most likely you did not have to deal much with USA emissions up there in Canada. The M110 engines were heavy and complicated.The emission laden carbureted USA  versions were interesting with the lower compression and catalytic converters. The fuel injected Euro models seemed to be the most popular. The Euro 280SL with the M110  and W07 chassis was a very popular in the rest of the world. Unfortunately they were not sold in the US.  Mercedes produced the M110 engine for a short time before going back to the single overhead cam engine. The new design were fuel injected used cross flow design of intake and exhaust, was simpler, lighter, and produced more horsepower than the previous twin cam engine.

[Benz Dr.]

I think that Canada and the USA have similar regulations with California being the exception.

I have a 300SE ( M 103 ) which is a great engine. The one I'm driving right now has just shy of 300,000 KM on it and it still runs well. Last time I did a compression test they were all within 10 PSI pf each other at close to 170 PSI. Interesting design with the cam shaft actually under the rocker arms. Gives it a sort of hemi combustion chamber as the vavles are canted inward. Only problem I had with it was when the lower portion of the rad blew out and the engine over heated. We pulled the head off, got it straightened, did a valve job, put liners in the exhaust guides and put it back together. It almost quit using oil after that.

One interesting side note:
One day about 3 years ago, the car simply died on the side of the road. It kept running but had no power. I tried everything I could think of. Sometimes it would run fine when it was cold but it would loose power and go into limp home mode once it warmed up a bit. This was a new car to me filled with all sorts of electronic gizmos and tons of wiring so I wasn't sure where to look.

Eventually, I found that if I turned the ignition of really fast and then turned it back on, the engine would often run properly - for a while. No one was ble to help me figure out what was wrong. The car had passed it's E test not more than a month before so I figured all those systems were working properly.

I tried a fuel pump relay, distributor cap, new wires, coil, spark plugs, fuel flter, EHA, and although there was some improvement, it still didn't fix it.

I did notice that it ran OK when stone cold or when I had it warmed up really well. Everything in between was taking a chance driving it. This led me to my eventual conclusion of what was wrong.

 Anyone want to hazard a guess? ( if you know for sure, hold off with your answer so we can give those with an interest a chance to try their luck )

 

[Louis]

Clogged catalytic converter?   

[w113dude]

Fuel pump?

[Bonnyboy]

Gas cap?? Plugged fuel return line??
I sure am glad that I'm not a mechanic for hire.

[ja17]

I think I know DAN so I will code its name. It uses three words starting with these three letters (not in necessarily in the correct order)  "ROV"

Yes, I agree that the M103 is a great engine. Wife"s wagon way over 300,000 miles never had the head off.

[Benz Dr.]

Nope, not yet.  Hint: the E test threw me off because it passed at .3 % CO.

  OVR was probably something I tried - I tried eveything until I figured it out through a series of deductions. Go back and read through my clues because it's how I figured it out. Fuel pressure and all mechanical parts were in working order so there was actually nothing wrong with the engine.

[stickandrudderman]

Since Dan has hinted at already giving clues I would be very interested in the fact that the fault only occurs when the engine is transitioning from cold to hot.
i have an idea but let's play the game......

[Benz Dr.]

Let loose the hounds of war........ ( or something like that )

 
  I will give a personal phone call ( within NA ) to who ever is the first one to get this right.
  I'll need your number first though........


   Yes, the Dr. makes house calls.

[ja17]

Ok Dan, My VOR was code for the "Over Voltage Relay".  Next I would guess the Warm Up Regulator, but  seems to obvious to be it?

[ja17]

How about a clogged fuel intake screen in the fuel distributor?

[Garry]

Do these have a coded key or electronic engine management system that when faulty can make it go to limp mode?

[Benz Dr.]

I changed the EHA which is the same as a warm up regulator which helped a bit but it still kept going into limp home mode. The problem seemed to be more electronics than mechanical or fuel. It wasn't fuel pressure related in any way but the faulty part probably controlled fuel pressure in some way.

 When I was driving, I could stop and start ther engine very quickly which would re-trigger the ECU ( I think ) and sometimes the engine would take off and run great for quite a while. If I stopped for a traffic light or a stop sign it would go dead again. This led me to believe that it was OK while everything was at optimal operating temps, or dead cold, but as soon as any cooled a bit by stopping or slowing down, something was either shutting off or not working.

 Think temperature of everything.