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New 280SE owner

Started by Feather535, 31 August 2022, 03:27 PM

Feather535

Hello,

I just acquired a 1977 280SE.  The car has been in California since new and it's complete, straight and original, but it has been off the road for 10 year, so everything needs attention.

The most immediate issue is that the engine runs poorly.  It bogs down on acceleration and pops back through the throttle body.  I'll do the usual tune-up, etc, but is there anything particular to this model/engine I should look for?

I've had lots of European cars from this era and other Mercedes models, but never an S-class or this engine, so I'll have lots of questions.

Thanks for your help!

BCDC

Welcome. I have a 1978 280SE with low km's. Lovely cars. These M110 engines are sweet and high revving when in good tune. Mine had been sitting for a while when I got it but was running pretty well but still I did the injectors, all fluids except the diff, new fuel accumulator and fuel filter, new plug leads and spark plugs and serviced the distributer. I'm not sure of the USA delivered cars, they may have more pollution gear than ours so check that out. The mechanical fuel injection is excellent normally but draining the fuel tank would be good idea I feel. Keep us posted and good luck. Sounds like an ignition timing issue to me.
BC
 
1978 280SE Cream with blue interior. With SLS

Randys01

There is no quick  answer.  I am assuming this is a K Jetronic.
The problem will be fuel starvation.

But start with Fuel delivery.
New pump..new accumulator.. new filter..new damper if you can find one.] New plumbing to all of this. New fuel. Try and drain the tank. Too late now but try not to run the motor until you have done these jobs.
Measure fuel output under the hood just before it enters the Fuel divider body. Should be about 2 litre per minute.
Even if the problem is further downstream, it's a start.

From here however you will need a fuel pressure gauge..of a special type.
About now refer to the TEch section on this site and acquaint your self with CIS injection.
Get yourself a fuel pressure gauge.
Check in when you have done the above if you like.

Feather535

Thanks.  I corrected the ignition timing (glad I still have a timing light) and that did help, but the engine still stumbles on acceleration.  Fuel will be the next issue to address.  I'll drain the tank and put in fresh fuel.  I can check volume and pressure, but what kind of pressure gauge do I need?  I have one, but it's an ordinary one for low pressure systems.

Randys01

read the Tech section on this forum. it will show you the special gauge. There will be a closed book exam when you have done it.!

raueda1

Quote from: Feather535 on 31 August 2022, 03:27 PMHello,

I just acquired a 1977 280SE.  The car has been in California since new and it's complete, straight and original, but it has been off the road for 10 year, so everything needs attention.

The most immediate issue is that the engine runs poorly.  It bogs down on acceleration and pops back through the throttle body. I'll do the usual tune-up, etc, but is there anything particular to this model/engine I should look for?

I've had lots of European cars from this era and other Mercedes models, but never an S-class or this engine, so I'll have lots of questions.

Thanks for your help!
The above caught my attention.  I recently went through something similar - different engine but still K-jet so same issues apply.  Anyway, suggest that you read through the recent threads on my adventures:
    Part 1
    Part 2
You'll get a lot of advice here on most of this stuff and procedures are outlined in the K-jet manual.  But what this stuff illuminates is the interplay of the different elements and how fixing one thing can break something else.  IOW, dealing with a real, old car and not parts in an engineering lab.

A couple philosophical points are worth mentioning. As Randys01 suggests, fuel delivery is always the starting point.  That said,
  • "Nothing works unless everything works."
  • Go through systematically instead of jumping around.
If I were able to remember and practice this I'd get things done a lot faster. Keep us up to date.  Good luck and cheers,

[sidebar - despite all my difficulties, after going through all the stuff above again and again, the car is now running fabulously well. Even the idle is very smooth, something 6.9s often don't do well.  Time for a road trip!]
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

SteveDuNord

Don't forget valve clearances. Easy job and can certainly help with power delivery issues. Spark plugs?
'77 280se

Feather535

I'll replace the plugs and adjust the valves.  All routine stuff.

But I haven't dealt with CIS since it was new.  My work lately has been with older (dual Webers) or newer (Motronic) systems.  I'm still trying to identify the parts of the fuel system.  Where is the fuel accumulator on W116 cars? Where is the infamous WUR? 

raueda1

I don't know where the WUR is on 280SE except that it's someplace on the top near the spidery looking thing with all the tubes (fuel distributor aka FD). The WUR looks like this and is superficially the same on all these cars:

https://www.google.com/search?q=warmup+regulator&client=firefox-b-1-d&sxsrf=ALiCzsYtAJnDAHVvwmYWvT6RuKXAIY-4IA:1662259840711&source=lnms&tbm=isch&sa=X&ved=2ahUKEwiPzNG6kPr5AhV4DEQIHcvJDKMQ_AUoAnoECAEQBA&biw=1368&bih=723&dpr=2#imgrc=HiVA4pkgAurEDM

Fuel accumulator is one of the items on the fuel delivery module someplace under the car near the gas tank.  It's wedged in along with the fuel filter and fuel pump.

You're going to want to read the CIS troubleshooting manual in the tech section as randys01 suggests.  Cheers,
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

SteveDuNord

WUR is indeed behind the fuel distributer, bolted on the side of the engine.
'77 280se

Feather535

Quote from: SteveDuNord on 04 September 2022, 10:55 AMWUR is indeed behind the fuel distributer, bolted on the side of the engine.

Is it underneath the intake manifold?

SteveDuNord

Quote from: Feather535 on 05 September 2022, 02:59 PM
Quote from: SteveDuNord on 04 September 2022, 10:55 AMWUR is indeed behind the fuel distributer, bolted on the side of the engine.

Is it underneath the intake manifold?

Here:



Two hard lines, one soft, a plug and two allen bolts.

'77 280se

Feather535

Thanks for the great pictures of the WUR.  Exactly what I needed.

Feather535

Thanks for all the excellent advice about the fuel system issues on this car.  I've addressed most of those problems, and I've changed all the fluids and bled the brakes.  At this point, the car starts, runs, drives and stops.  There is still a bit of off-idle stumble when the engine is cold, but it runs well when it warms up.  WUR?

Now it's on to other things: the oil pressure gauge always reads at the top of the scale, the fuel level gauge always reads low (empty), the front passenger-side window won't go up all the way, the windshield washer doesn't work...  Where to start???

raueda1

Quote from: Feather535 on 19 September 2022, 09:19 AMThanks for all the excellent advice about the fuel system issues on this car.  I've addressed most of those problems, and I've changed all the fluids and bled the brakes.  At this point, the car starts, runs, drives and stops.  There is still a bit of off-idle stumble when the engine is cold, but it runs well when it warms up.  1. WUR?

Now it's on to other things: the 2. oil pressure gauge always reads at the top of the scale, the fuel level gauge always reads low (empty), 3. all the rest - the front passenger-side window won't go up all the way, the windshield washer doesn't work...  Where to start???
More or less in order:

1. Probably.  Maybe fuel mixture and/or idle setting too.  But all that stuff interacts with itself so best to start down the path of fuel injection troubleshooting per the Bosch CIS diagnostic manual.  I went through all that stuff earlier.  But I'd do this second after figuring out....

2.  Oil pressure.  Is the gauge always stuck all the way up or it just shoots up as soon as the engine starts and stays there regardless of rpm?  And never comes down after engine is fully warmed up?  If the latter I'd concerned.  Blockage someplace?  Check-valve not working? \\_(")_//  Others will have to comment on potential causes.

3. Start with the above.  Like most of us, "You didn't buy a car, you bought a hobby."  I remind my 86 year old neighbor of this weekly when she asks why I'm messing with my car again.
Lowest priority is obviously the washer, but that's probably also easiest.  Can you hear pump running when activated?  If not, find the pump and check that it's getting power.  If not look at fuses.  In fact, just replace all the fuses while you're at it and clean contacts with pencil eraser.  I think there's a relay too.  It never hurts to just replace them all too.  Not expensive and you head off potential problems in the future.  If pump is dead after you're sure it's getting power just replace.  In the meantime use compressed air to make sure tubing is intact and not blocked.  Unfortunately I don't know where any of this stuff is on 280SE. Good luck and cheers,
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0